Abstracts of Current Technical Literature in
Electrical Engineering
Vol.38; No.4; October - December 2015
CONTENTS
1.
Cables, Conductors & Winding Wires
2.
Electrical Machines: Motors & Drives
3.
Insulation System, Materials & Insulators
4.
Lamps & Luminaires
5.
Materials
6.
7.
Metallurgy
8.
Power Electronics
9.
Power System
10.
Power Transmission & Distribution
11.
Protection & Protective Devices
12.
Switchgear
13.
Testing
14.
15.
Transformers
Others
Power / Energy
1
1. CABLES, CONDUCTORS & WINDING WIRES
42575
Linfeng Cao & Grzybowski S.
Accelerated aging study on 15 kV XLPE and EPR cables insulation caused by switching
impulses
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2809
- 2817
Cross-linked polyethylene (XLPE) and Ethylene Propylene Rubber (EPR) are the common
polymeric materials used for power cable insulation in the USA. While in service, the main
threats to the cable insulation include electrical stress, thermal stress, and mechanical
stress. The electrical stress, from either operation voltages or abnormal over-voltages
during transients, has negative impacts to the power cables insulation. The excessive
electrical stress will trigger the aging of insulation materials, which will lead to the
failures of cables, resulting in outages of power systems. The aging phenomena of
polymeric power cables have been extensively studied during the past decades. Although
the study of aging mechanisms was done on molded samples, little is known about the
aging phenomena of the XLPE and EPR cables by switching impulses. In this experiment,
the 15 kV XLPE and EPR cable samples were aged up to 10,000 switching impulses. The
study helped to assess the reliability of the XLPE and EPR cables serving in electrical power
systems.
42576
Guerout F.M. & Boor R.G
Development of indentation techniques in support of cable condition monitoring
programs
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2818
- 2825
This paper summarizes work performed over the past few years at Atomic Energy of
Canada Limited (AECL) to further develop indentation techniques in support of cable
condition monitoring programs. Sensitivity to cable degradation of the commonly used
specific compressive stiffness (or indenter modulus) is assessed based on laboratory
testing of unaged, thermally aged, and irradiated cable samples. Another technique,
which consists of measuring recovery time during the post-indentation phase, is also
assessed for a variety of tested jacket and insulation materials. The document includes a
review of the effect of indenter design and testing parameters on indentation results and
provides input towards potential revisions of the IEC/IEEE 62582-2 Standard.
2
42577
Huang Z.Y et.al
Dielectric thermal-mechanical analysis and constrained high voltage DC cable rating
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2826
- 2832
For most mass-impregnated (MI) paper insulated HVDC cables, the dielectric strength is
found to be weakened when the cable cools, resulting from the creation of dielectric
cavities. To better understand the cavity creation, two mechanisms are frequently
compared, based on the imperfect impregnation process and sheath plastic deformation
respectively. This paper presents an analytical calculation of cable internal pressure,
which is applicable to both cavity creation mechanisms. It demonstrates that the two
mechanisms can jointly place constraints on the MI cable rating, by limiting the overall
rating-related thermal expansion.
42578
Xiangrong Chen et.al
Electrical treeing behavior at high temperature in XLPE cable insulation samples
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2841
- 2851
This paper reports on investigations aiming to understand the behavior of electrical trees
formed in XLPE cable insulation at elevated temperatures. Samples cut from a real high
voltage cable equipped with an embedded electrode system and composed of a needle
separated by 2 mm from counter electrode were used. The temperature was varied
between 50 and 90 °C and the range of voltage changed between 9 and 18 kV. The
electrical treeing process was followed by means of microscopic observation from the
moment of initiation until the leading branches connected the counter electrode and
partial discharge (PD) activity was monitored simultaneously. The shape and fractal
dimension of the resulting trees were analyzed. It was found that temperature and voltage
level had pronounced effect on the process of electrical tree formation. At lower voltages
different type of trees could be formed, whereas at higher voltages branch trees
dominated. Increase of test temperature reduced the time for tree initiation, whereas the
tree growth time was less affected, except for the lowest voltage level at which the
slowest tree development was observed at the highest test temperature. It is postulated
that the impeding effect of elevated temperature on tree growth is due to a change of
tree channel sidewall conductivity, whereas the observed reduction of tree initiation time
with the increase of temperature and voltage level is attributed to lowering of the
threshold energy for damage at higher temperature as well as increasing of the injection
current at higher voltage level.
3
42579
Babaee A. & Shahrtash S.M
On-line partial discharge defected phase selection and localization in cross-bonded
single core
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2995
- 3006
In this paper, a practical rule-based guideline has been presented for on-line detection of
partial discharge (PD) defected phase (i.e., phase selection) followed by discriminating
PD defected cable section (i.e., localization) in cross-bonded single core cable networks.
Both goals are met by relying on the proposed rules that take the advantages of an energybased index, calculated/measured at different junctions of cable network. The whole
process provides practicability needs, as it requires neither synchronized measurements
at different junctions of a network nor any PD pulse detection. Moreover, the proposed
procedure derives the required indices from the measurements out of the link boxes,
which provides enough safety in practical applications. Simulating and investigating four
popular cross-bonding schemes (including sectionalized and continuous by coaxial cable
and single core cable) as well as various characteristics of PD sources, different source
locations, and noisy condition have proven acceptable performance of the proposed
method in both tasks of phase selection and localization.
42580
Patel U.R. & Triverio P.
MoM-SO: A Complete Method for Computing the Impedance of Cable Systems Including
Skin, Proximity, and Ground Return Effects
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2110-2118
The availability of accurate and broadband models for underground and submarine cable
systems is of paramount importance for the correct prediction of electromagnetic
transients in power grids. Recently, we proposed the MoM-SO method for extracting the
series impedance of power cables while accounting for the skin and proximity effects in
the conductors. In this paper, we extend the method to include ground return effects and
to handle cables placed inside a tunnel. Numerical tests show that the proposed method
is more accurate than widely used analytic formulas, and is much faster than existing
proximity-aware approaches, such as finite elements. For a three-phase cable system in a
tunnel, the proposed method requires only 0.3 s of CPU time per frequency point, against
the 8.3 min taken by finite elements, for a speed up beyond 1000 X.
4
42581
Levesque F. et.al
Experimental Study of Dynamic Bending Stiffness of ACSR Overhead Conductors
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2252 – 2259
Aeolian vibrations of transmission-line conductors may cause fretting fatigue failure at or
near the location of clamped devices. At these locations, the bending stiffness variation
of the conductor has a large influence on its deformed shape and, hence, on its fatigue
mechanics. Variable bending stiffness models could be integrated in nonlinear finiteelement programs to obtain better mechanical behavior predictions. However, there is
very little data available in the literature to validate such numerical models. The objective
of this paper is to present experimental data for the deformed shape of two types of ACSR
conductors undergoing vibrations. The tests were performed on a 5.83-m test bench for
various tensions, displacement amplitudes, and frequencies. The displacement amplitude
was measured at the vibration anti-node and at five locations near the square-faced
bushing. The results suggest a large stiffness variation near the bushing. This experimental
study provides valuable data to compare with a numerical model of a vibrating conductor
that includes variable bending stiffness.
42582
Pfeiffer M. & Franck C.M.
Impact of Conductor Surface Type and Rain Intensity on HVDC Corona Losses
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2284 - 2292
This paper presents the results of a series of indoor laboratory experiments carried out on
dc-energized overhead conductors subjected to simulated rainfall. In a first set of
experiments, the impact of rain intensity on the corona onset voltage and total corona
losses was investigated. With regard to the onset voltage, no significant impact was
observed, whereas a weak positive correlation with total corona losses could be
established. In a second set of experiments, the impact of different conductor types on
the same two quantities was examined. The most notable result is that the combined use
of Z-profiled-strands and sand-blasted surfaces lead to reductions in the total corona
current of around 29% and 42%, for positive and negative polarity, respectively. The
corresponding reduction of ground-level ion currents and ion coupling with parallel
conductors is expected to be of the same order of magnitude.
5
42583
Yong Lin & Zheng Xu
Cable Sheath Loss Reduction Strategy Research Based on the Coupled Line Model
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2303 - 2311
Power cables are playing an increasingly important role in the power grid. The sheath loss
is one of the main shortcomings of the power cable which will cause thermal problems
and limit the cable's ampacity. We carry out a systematic research on the sheath loss of
cables with different arrangements, including single bonding, solid bonding, and cross
bonding. For cross-bonded cables, we study how the cross-bonding joints number and
segment length deviation influence the sheath loss. To reduce the sheath loss, this paper
studies a promising measure using connecting impedance in the cross-bonding joints, and
the characteristic of the connecting impedance is fully revealed. The computer efficient
algorithm is established to fulfill the loss calculation task, which is based on the improved
coupled line model. The key of the coupled line model is to use series expansion to
calculate the admittance matrix without diagonalizing the complex propagation matrix of
the cable line. The dimension of the nodal equation is also greatly reduced.
42584
Yongzan Zhen et.al
A Laboratory Study on the Ion-Flow Field Model of the DC Wires in Stable Wind
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2346 - 2352
Although transverse wind exerts an important influence on the distribution of the ion
current density under HVDC transmission lines, very few experiments involving stable wind
have been used to verify the numerical model. To overcome the variability of natural
wind, a low-speed wind tunnel was used to produce stable wind in this research. An
experimental platform was set up in the wind tunnel, to measure the ion current density
of dc wires. Based on the experiment, transverse wind exerted a significant influence over
the distribution of the ion current. The numerical model was discussed and the results
showed reasonable agreement with the measured values for different wind speeds.
2. ELECTRICAL MACHINES: MOTORS & DRIVES
2.1 Electrical Machines
42585
Yi Wang et.al
Ultrafast Steady-State Multiphysics Model for PM and Synchronous Reluctance
Machines
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3639 - 3646
A new technique for coupling the electromagnetic, thermal, and airflow analysis is
proposed particularly for electric machines that exhibit reduced dependence of core
losses with temperature and load and have low rotor losses. Within the overall iterative
loop, another inner loop that cycles only the thermal calculations and employs a
simplified model to estimate losses is introduced. The thermal and airflow analysis models
the conduction, radiation, and convection heat transfer and is based on equivalent circuit
6
networks. A computationally efficient finite-element (FE) technique is employed for the
electromagnetic field analysis. The combination of algorithms results in ultrafast
processing as the number of outer loop iterations, which include electromagnetic FE
analysis, is minimized. The overall computational time is significantly reduced in
comparison with the conventional method, such that the new technique is highly suitable
for large-scale optimization studies. Example simulation studies and measurements from
an integral horsepower interior permanent-magnet motor are included to support
validation.
42586
Ibrahim M. et.al
Design of Variable Flux Permanent-Magnet Machine for Reduced Inverter Rating
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3666 - 3674
This paper presents a design procedure for tangentially magnetized variable flux
machines that aims to reduce the machine inverter rating. The proposed design can
achieve high torque density at low speeds, and high efficiency at an extended speed
range, as armature d-axis current pulses are applied at high speeds to reduce the magnet
flux. In order to regain the full torque capability when the motor slows down, a
magnetizing current pulse has to be applied. The amplitude of the magnetizing current is
usually larger than the machine rated current. Therefore, the machine may require an
oversized inverter in order to be able to remagnetize the magnets. The impact of
different machine design parameters on the magnetization current requirement is
investigated in order to reduce the inverter cost. The proposed machine design procedure
is validated by experimental measurements on a variable flux machine prototype.
42587
Fengge Zhang et.al
Rotor Retaining Sleeve Design for a 1.12-MW High-Speed PM Machine
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3675 - 3685
Permanent-magnet (PM) synchronous machines (PMSMs) can provide excellent
performance in terms of torque density, energy efficiency, and controllability. However,
PMs on the rotor are prone to centrifugal force, which may break their physical integrity,
particularly at high-speed operation. Typically, PMs are bound with carbon fiber or
retained by alloy sleeves on the rotor surface. This paper is concerned with the design of
a rotor retaining sleeve for a 1.12-MW 18-kr/min PM machine; its electromagnetic
performance is investigated by the 2-D finite-element method (FEM). Theoretical and
numerical analyses of the rotor stress are carried out. For the carbon fiber protective
measure, the stresses of three PM configurations and three pole filler materials are
compared in terms of operating temperature, rotor speed, retaining sleeve thickness, and
interference fit. Then, a new hybrid protective measure is proposed and analyzed by the
2-D FEM for operational speeds up to 22 kr/min (1.2 times the rated speed). The rotor
losses and machine temperatures with the carbon fiber retaining sleeve and the hybrid
retaining sleeve are compared, and the sleeve design is refined. Two rotors using both
designs are prototyped and experimentally tested to validate the effectiveness of the
developed techniques for PM machines. The developed retaining sleeve makes it possible
to operate megawatt PM machines at high speeds of 22 kr/min. This opens doors for many
high-power high-speed applications such as turbo-generator, aerospace, and submarine
motor drives.
7
42588
Leilei Wu et.al
Influence of Pole Ratio and Winding Pole Numbers on Performance and Optimal Design
Parameters of Surface Permanent-Magnet Vernier Machines
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3707 - 3715
In recent years, surface permanent-magnet vernier machines (SPMVM) have been
attracting more and more attention for several advantages, including a high torque
density and a simple mechanical structure. However, the influence of the pole ratio,
which is defined as the ratio of rotor pole pair numbers to winding pole pair numbers,
and the winding pole pair numbers on the performance of SPMVMs has not been
investigated in literature. This paper mainly focuses on the effects of the pole ratio and
the winding pole pair numbers on the torque capacity, power factor, torque ripple, and
cogging torque of an SPMVM. The variations of optimal design parameters for maximum
torque, such as the split ratio (the ratio of the stator inner diameter to the outer
diameter), the slot opening width, and the permanent-magnet thickness, with the pole
ratio and the winding pole pair numbers are also investigated by finite-element analysis.
The analysis results reveal that the pole ratio and the winding pole pair numbers
significantly influence the performance and optimal design parameters of the SPMVM.
Finally, an SPMVM prototype is built, and experiments are conducted to validate the
aforementioned results.
42589
Dang T.T. et.al
Sizing Optimization of Tubular Linear Induction Generator and Its Possible Application
in High Acceleration Free-Piston Stirling Microcogeneration
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3716 - 3733
We usually find applications of rotary induction generator, direct-drive tubular linear
permanent-magnet generator, etc. for the mechanoelectrical conversion process within
Stirling microcogenerator systems. This paper presents the design optimization
investigation for a direct-drive tubular linear induction generator for a dual free-piston
Stirling microcogenerator system. On the one hand, a high oscillating frequency and a
relatively long piston's travel bring about a very high acceleration of the generator's
moving part, up to 1018 m/s 2. On the other hand, the tubular linear induction generator
offers many interesting assets in this application: low weight mover, appearance of
levitation force, no mechanical spring, low mechanical losses, no cogging force, easy
manufacture, very low investment and maintenance cost, and so on. However, the
tubular linear induction generator is sparsely used, because of its a priori relatively low
energetic efficiency. This paper presents a sizing optimization approach for maximizing
the performance and demonstrates that, with an astute arrangement of electrical
devices, the tubular linear induction generator can constitute a well-adapted solution for
free-piston Stirling microcogenerator systems.
8
42590
Deodhar R.P et.al
Design Method and Experimental Verification of a Novel Technique for Torque Ripple
Reduction in Stator Claw-Pole PM Machines
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3743 - 3750
Although relatively small in size and power output, automotive accessory motors play a
vital role in improving such critical vehicle characteristics as drivability, comfort, and,
most importantly, fuel economy. This paper describes a design method and experimental
verification of a novel technique for torque ripple reduction in stator claw-pole
permanent-magnet (PM) machines, which are a promising technology prospect for
automotive accessory motors.
42591
Howard E. et.al
Asymmetric Flux Barrier and Skew Design Optimization of Reluctance Synchronous
Machines
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3751 - 3760
In this paper, an investigation into an alternative topology for reluctance synchronous
machine rotor flux barriers is presented. The investigated topology employs a high
number of flux barrier variables with an alternative asymmetric rotor structure. The focus
in this paper is on maximizing average torque and minimizing torque ripple, using finite
element-based design optimization, in order to study the possibility of achieving
acceptably low torque ripple. A subsequent investigation into the effect of rotor skew on
the proposed optimized design to reduce torque ripple even further is also conducted, as
well as the manufacturing and testing of the proposed flux barrier prototype.
42592
Ludois D.C. & Reed J.K.
Brushless Mitigation of Bearing Currents in Electric Machines Via Capacitively Coupled
Shunting
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3783 - 3790
The overwhelming trend within the industry today is to pair electric machines with
variable-frequency drives. It is well known that the use of these drives can introduce
high-frequency bearing currents during semiconductor switching events. This paper
focuses on bearing discharge currents that gradually degrade the bearings by pitting their
surfaces and can lead to premature failure. Common solutions include insulating the
bearings, installing common-mode filters, or using a brush to ground the rotor shaft.
These solutions are not universally scalable and may require periodic maintenance. This
paper presents a new approach using noncontact (brushless) capacitive coupling. Here, a
rotating capacitor is placed electrically in parallel with the bearing. At high frequencies,
the impedance of the rotating capacitor is far lower than the bearing impedance, thereby
shunting current around the bearings and reducing shaft voltage. The technique is
experimentally demonstrated on a 3-hp (2.2-kW) induction machine. The experiment
demonstrates a bearing current reduction factor of at least 8x.
9
42593
Gan Zhang et.al
Investigation of an Improved Hybrid-Excitation Flux-Switching Brushless Machine for
HEV/EV Applications
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3791 - 3799
In this paper, based on 2-D finite-element analysis (FEA), the hybrid-excitation principle
of a hybrid-excitation flux-switching (HEFS) machine is analyzed, and consequently, an
improved topology is proposed to enhance the flux-regulation capability. These two
machines are termed as the basic HEFS machine and the improved HEFS machine,
respectively. In the basic HEFS machine, each permanent magnet (PM) is located at the
middle of the corresponding slot and wound by a field winding coil. When field excitation
is applied, it is found that the currents in the two field slots adjoining each PM exhibit
reversal excitation functions, thus reversal flux-regulation functions. Hence, to improve
the flux-regulation performances, an improved HEFS topology is proposed based on the
basic one by reversing current direction in one of the field slots. Therefore, the improved
topology shares identical structure with the basic one but has different field current
directions in some field slots and thus different field winding accommodations.
Comparisons of the FEA predictions indicated that both armature no-load flux-regulation
capability and armature load torque capability in the improved HEFS machine are much
better than those in the basic one. Finally, the FEA results are validated by experimental
measurements on two prototyped HEFS machines.
42594
Diaz Reigosa D. et.al
PMSM Magnetization State Estimation Based on Stator-Reflected PM Resistance Using
High-Frequency Signal Injection
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3800 - 3810
Permanent-magnet (PM) magnetization state estimation in PM synchronous machines
(PMSMs) is of great importance for torque control and monitoring purposes. The
magnetization state of a PMSM can change due to several reasons, injection of stator
current (d-axis or q-axis) and variation of magnet temperature being the primary reasons.
PM magnetization state estimation is not easy once the machine is assembled. Methods
based on the back electromotive force can be used, but they require that the machine is
rotating. This paper analyzes the use of high-frequency signal injection for PM
magnetization state estimation in PMSMs. The magnetization state of the PMs in PMSMs
affects the stator-reflected PM high-frequency resistance. The stator-reflected PM highfrequency resistance can be estimated by injecting a high-frequency voltage/current
using the inverter. The high-frequency signal is superposed on the fundamental excitation
used to produce torque, meaning that the method can operate at any speed, including
zero speed, and without interfering with the normal operation of the machine.
42595
Alberti L. et.al
High-Frequency – Model of Synchronous Machines for Sensorless Control
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3923 - 3931
This paper describes a d-q-axis model of synchronous permanent-magnet machines at high
frequency. Both the inductive and resistive saliencies are taken into account, and the
model is suitable for investigating the self-sensing capability of the machines. It is proved
that the high-frequency machine response can be described by means of three complex
parameters, which form a symmetrical matrix. It is also shown that the high-frequency
10
resistances between the d- and q-axes exist, and they may assume a negative value.
Experimental results are included in this paper to prove the developed theory.
42596
Low-Sampling-Frequency Stator Flux Linkage Observer for Interior Permanent-Magnet
Synchronous Machines
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3932 - 3942
Deadbeat-direct torque and flux control (DB-DTFC) is a direct torque control (DTC)
method that provides the fastest possible torque response with smooth and continuous
operation even at the voltage limits. DB-DTFC achieves the smoothest possible torque
and flux trajectory tracking performance by using the machine inverse model to select
volt-second solutions that will produce the desired torque and flux by the end of each
pulsewidth modulation (PWM) interval. Since the DB-DTFC inverse model requires
accurate steady-state and dynamic flux estimates, discrete-time stator current and flux
linkage observers are needed to properly implement DB-DTFC. The existing highsampling-frequency stator current and flux linkage observers are formed based on
approximate discrete-time models for IPMSMs by assuming high-sampling-frequency (10kHz) operation. This paper presents a more exact discrete-time model for IPMSMs, such
that, even at low sampling frequencies, proper stator current and flux linkage observers
can be formed to achieve accurate current and flux linkage estimation. The proposed
low-sampling-frequency stator current and flux observers are developed using discretetime modeling with an inverter-sourced volt-second input model. The proposed observers
are shown to be very feasible for real-time implementation, and their experimental
evaluation documents the improvement achieved compared to high-sampling-frequency
observers, even under machine parameter variations.
42597
Wang R.et.al
Incorporating Dynamics in a Mesh-Based Magnetic Equivalent Circuit Model of
Synchronous Machines
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 821 - 832
A mesh-based magnetic equivalent circuit has been derived to model the dynamics of
wound rotor synchronous machines (WRSMs). A particular focus has been placed on the
derivation of flux tubes to model machines with an arbitrary number of damper bars
placed at an arbitrary depth in the rotor pole tip. Faraday's Law is applied to establish a
state model in which winding and damper bar flux linkages are selected as state variables.
The resulting coupled magnetic equivalent circuit/state model is solved to predict
machine dynamics. An important attribute of the model is that saturation is represented
without the need for a relaxation factor, which enables its use as a practical tool in
machine design. Data obtained from hardware experiment and a finite-element model
are used to validate the proposed methods.
42598
Sapena-Bano A.et.al
Harmonic Order Tracking Analysis: A Novel Method for Fault Diagnosis in Induction
Machines
11
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 833 - 841
The diagnosis of induction machines using Fourier transform relies on tracking the
frequency signature of each type of fault in the current's spectrum, but this signature
depends on the machine's slip and the supply frequency, so it must be recomputed for
each working condition by trained personnel or by diagnostic software. Besides, sampling
the current at high rates during long times is needed to achieve a good spectral resolution,
which requires large memory space to store and process the current spectra. In this paper,
a novel approach is proposed to solve both problems. It is based on the fact that each
type of fault generates a series of harmonics in the current's spectrum, whose frequencies
are multiples of a characteristic main fault frequency. The tracking analysis of the fault
components using the harmonic order (defined as the frequency in per unit of the main
fault frequency) as independent variable instead of the frequency generates a unique
fault signature, which is the same for any working condition. Besides, this signature can
be concentrated in just a very small set of values, the amplitudes of the components with
integer harmonic order. This new approach is introduced theoretically and validated
experimentally.
42599
Dolisy B. et.al
A New Analytical Torque Formula for Axial Field Permanent Magnets Coupling
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 892 - 899
In this paper, we present a simple and accurate analytical expression to compute the
torque of axial-field magnetic couplings. The torque expression is obtained by solving the
three-dimensional (3-D) Maxwell equations by the method of separation of variables.
Here, we adopt the assumption of linearization at the mean radius, the problem is then
solved in 3-D Cartesian coordinate (we neglect the curvature effects). To show the
accuracy of the torque formula, the results are compared with those obtained from 3-D
finite-element simulations and from experimental tests. As the proposed formula needs
very low computational time and depends directly on the geometrical parameters, it is
used for a design optimization using multi-objective genetic algorithms.
42600
Sook Teng Vun & McCulloch M.D.
Optimal Design Method for Large-Scale YASA Machines
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 900 - 907
The objective of this paper is to develop an analytical optimal design tool to determine
a megawatt-scale yokelss and segmented armature (YASA) machine design that fulfills
the application requirements and constraints. This analytical tool considers both
electromagnetic and structural designs. Different designs that provide similar
performance will have emerged from this analytical process. A design reference map that
graphically shows the relationships and tradeoffs between each objective function is
introduced. A multicriteria optimization process is applied to determine a design
optimum. In the optimization process, the design objectives considered in this study are
to minimize the outer diameter, to minimize the structural mass of the machine, to
minimize the copper and iron losses, and to minimize the active materials cost. Three
variables considered in calculating the objective functions are the air-gap flux density,
12
the ratio of outer-to-inner machine diameter, and the current loading. The optimization
method uses a pseudoweight vector to provide the flexibility to prioritize one or more
objective functions, dependant on the specific application requirements.
42601
Ben Sedrine E. et.al
Fault-Tolerant Control Using the GA Optimization Considering the Reluctance Torque
of a Five-Phase Flux Switching Machine
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 927 - 938
This paper deals with the fault tolerance of a five-phase flux switching machine. Shortcircuit currents calculation considering inductances variation is developed. Machine
behavior (torque quality, copper losses, and homopolar current) under a single shortcircuit phase fault, two consecutive and nonconsecutive phases short-circuited, is
simulated with a two-dimensional finite elements (2-D FE) model and validated
experimentally. Then, a new method is developed to improve its performances in faulty
mode, by reconfiguring reference currents. In fact, an accurate torque model is
established and then used in a genetic algorithm to optimize reference currents in faulty
mode. In this approach of reference currents computation, the used algorithm has
multiobjectives and multiconstraints, thereby allowing choosing the appropriate faulttolerant current solution according to our application. The torque model is considered to
be more accurate and closer to the 2-D FE results in both healthy and faulty modes. Then,
a comparison of machine performances in healthy, degraded, and reconfigured modes is
presented. Experimental results corroborate the analysis.
42602
Haiwei Cai et.al
Modeling and Control for Cage Rotor Dual Mechanical Port Electric Machine–Part I:
Model Development
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 957 - 965
A new type of electric machine with two free rotating rotors [dual mechanical port (DMP)]
is investigated in this paper. Since this DMP machine has a squirrel-cage outer rotor, it is
named as SCDMP machine. First, the electromagnetic characteristic of the SCDMP
machine is analyzed. Then, the transient model and steady-state model of the SCDMP
machine are derived. The proposed machine models are verified by finite element method
and simulation. The results show that the proposed models accurately represent the
unique electromagnetic characteristics of the SCDMP machine.
42603
Haiwei Cai & Longya Xu
Modeling and Control for Cage Rotor Dual Mechanical Port Electric Machine—Part II:
Independent Control of Two Rotors
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 966 - 973
Application of electric machines in the traction and transmission systems of
hybrid/electric vehicles has been studied for many years. The hybrid vehicle based on
13
dual mechanical port (DMP) electric machine has gained more and more attention,
because it eliminates the need for planetary gear and combines the motor and the
generator into a compact electric machine. The DMP machine with a squirrel-cage outer
rotor (SCDMP) is investigated in this paper. Due to its unique electromagnetic
characteristics, control algorithms for conventional machines cannot be applied to the
SCDMP machine. The methods to calculate the correct current commands and estimate
the outer rotor flux position are proposed. Based on these two methods, a control
algorithm for the SCDMP machine is proposed and estimated by simulation. The results
show that the proposed control algorithm is able to independently control the torque
productions and the flux levels of the two rotors of the SCDMP machine.
42604
Esfandiari G. et.al
Dynamic Modeling and Analysis of Cascaded DFIMs in an Arbitrary Reference Frame
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 999 - 1007
This paper presents a comprehensive investigation of various reference frames and their
relative speeds in cascaded doubly-fed induction machines (CDFIMs). Then, a compact
space-phasor model of CDFIMs in the natural and arbitrary reference frames is presented
that is useful for performance analysis of CDFIMs based on rotating phasors. The merits
of the proposed model compared with existing models are using a common (single)
reference frame for all machines and parts of CDFIMs, and the model formulation is
independent of the rotor angle position. The reference frames in the suggested model
can be fixed on the common rotor of the CDFIM machines for dynamic analysis or it can
be fixed on the stator/rotor flux of each cascaded machines useful for CDFIMs controller
design. A two-axes equivalent circuit for a CDFIM is also presented, which enables analysis
of CDFIMs in commercially available power circuit simulation software tools. The validity
of the model is verified via the investigation of an experimental setup and consists of two
mechanically coupled 4-kW DFIMs and a 4-kW dc machine as a load. The setup is
investigated under various test scenarios, including free acceleration, load (torque)
change, and frequency step change conditions.
42605
Dongdong Zhao et.al
Parameter Sensitivity Analysis and Local Temperature Distribution Effect for a PEMFC
System
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1008 - 1018
Parameters identification and determination are important in the fuel cell model
development, especially for multiphysic modeling which includes many sensitive
semiempirical parameters. In this paper, the parameter sensitivities are investigated
based on a well-developed 1.2-kW multiphysic proton exchange membrane fuel cell
model. Moreover, to get a complete fuel cell system model, the models of auxiliaries such
as the air compressor and cooling fan are developed. Through the analysis, the effect of
some physical parameters on the fuel cell performance are obtained. Specifically, stack
temperature is a crucial parameter which influences not only the output voltage, but also
the water content in the fuel cell membrane. The influence of nonuniform distribution of
14
temperature on the fuel cell model is discussed as well, including the end plate and local
heating effects.
42606
Dong-Joon Kim et.al
A New Simplified Doubly Fed Induction Generator Model for Transient Stability Studies
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1030 - 1042
This paper proposes a new simplified model of a doubly fed induction generator (DFIG)
that is integrated with a rotor-side converter for studies of large-scale transient stability.
This model accurately considers the rotor field dynamics of an induction generator to
yield simulation results that are more accurate in terms of voltage stability, as well as
angle stability. The purpose of this paper is to provide a simple but effective DFIG model
for the study of large-scale transient stability, and to examine the important aspects of
rotor voltage and rotor slip power. This new simplified DFIG model with an
electric/turbine control system was tested against a six-machine and 23-bus system, and
the responses obtained in case studies of transient stability were compared with those of
a PSS/E program. Finally, the proposed DFIG model was also validated by comparing the
simulation results for a single-machine and infinite-bus system with those of
PSCAD/EMTDC.
42607
Al-Badri M. et.al
A Novel In Situ Efficiency Estimation Algorithm for Three-Phase IM Using GA, IEEE
Method F1 Calculations, and Pretested Motor Data
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1092 - 1102
The precise estimation of efficiency of induction motors is crucial in industries for energy
savings, auditing, and management. This paper presents a novel method for in situ
induction motors efficiency estimation by applying the genetic algorithm and utilizing
IEEE Form F2-Method F1 calculations with pretested motor data. The method requires a
dc test, full-load operating point rms voltages, currents, input power, and speed
measurements. The proposed algorithm uses a sensorless technique to determine motor
speed. The algorithm is not only an in situ tool; it can also be used as an on-site efficiency
estimation tool that might replace the expensive dynamometer procedure. The method
was validated by testing 30 induction motors.
42608
Yongchang Zhang & Haitao Yang
Model-Predictive Flux Control of Induction Motor Drives With Switching Instant
Optimization
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1113 - 1122
Conventional model-predictive torque control (MPTC) requires tedious and timeconsuming tuning work for stator flux weighting factor, and presents relatively high
torque ripples. To solve these problems, this paper proposes a model-predictive flux
control (MPFC) for two-level inverter-fed induction motor (IM) drives. The references of
15
stator flux magnitude and torque in conventional MPTC are converted into an equivalent
reference of stator flux vector in the proposed MPFC. As only the tracking error of stator
flux vector is required in the cost function, the use of weighting factor is eliminated. The
optimal voltage vector is selected based on the principle of stator flux error minimization
and its switching instant is optimized rather than being in the beginning of each control
period. The proposed MPFC with and without switching instant optimization are both
implemented in a 32-bit floating digital signal processor, and they are compared in detail
in terms of torque ripple, current harmonics, and average switching frequency. Both
digital simulations and experimental tests were carried out on a two-level inverter-fed
IM drive, and the obtained results validate the effectiveness of the proposed method.
42609
Laldin, O et.al
Magnetizing End-Effects in Salient Pole Machines
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1135 - 1136
Analytical models of electric machinery often utilize a two-axis lumped-circuit approach,
wherein the inductance parameters are obtained by applications of Ampere's law in a
two-dimensional (2-D) cross section of the machine. A method of incorporating endeffects in the magnetizing inductance calculations of wound rotor synchronous machines
is presented, allowing machines with high diameter-to-length ratios to be modeled more
accurately. The method is verified using three-dimensional (3-D) finite element analysis.
42610
Zheng Tan et.al
DFIG Machine Design for Maximizing Power Output Based on Surrogate Optimization
Algorithm
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1154 - 1162
This paper presents a surrogate-model-based optimization of a doubly-fed induction
generator (DFIG) machine winding design for maximizing power yield. Based on sitespecific wind profile data and the machine's previous operational performance, the DFIG's
stator and rotor windings are optimized to match the maximum efficiency with operating
conditions for rewinding purposes. The particle swarm optimization-based surrogate
optimization techniques are used in conjunction with the finite element method to
optimize the machine design utilizing the limited available information for the sitespecific wind profile and generator operating conditions. A response surface method in
the surrogate model is developed to formulate the design objectives and constraints.
Besides, the machine tests and efficiency calculations follow IEEE standard 112-B.
Numerical and experimental results validate the effectiveness of the proposed
technologies.
42611
Pakdelian S.et.al
Design of an Electric Machine Integrated with Trans-Rotary Magnetic Gear
16
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1180 - 1191
Design aspects of the trans-rotary magnetic gear (TROMAG) integrated rotary machine
are discussed in this paper, with particular focus on optimizing system cost and weight.
Analytical models are used for design of the TROMAG. Optimal designs of the rotary
machine are found by using a population-based genetic algorithm and two-dimensional
finite-element analysis and thermal considerations. Weight, volume, and cost of the
resultant system are then compared with the Pareto-optimal set of a permanent magnet
linear tubular machine that is designed for the same force and speed specification. It is
shown in this paper that, for high-force low-speed reciprocating motion applications, an
electromechanical motion system consisting of a TROMAG and a rotary electric machine
can far surpass a conventional direct drive linear machine in terms of weight, volume,
and initial and operating cost.
42612
Laldin O. et.al
Analysis and Design of Hybrid Machines for DC Generation
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1192 - 1199
In this research, six hybrid machine topologies, utilizing both a field winding and
permanent magnets, are investigated for fixed-speed dc generation. The hybrids are
compared with the wound-rotor and permanent magnet synchronous machines. To this
end, analytical system models are utilized to predict machine-rectifier behavior. A
general approach used to develop the machine models is discussed; the rectifier and filter
models are also presented. The system models are used in a multi-objective design
process to establish the tradeoff between overall mass and loss. Detailed losses,
geometries, and rectifier waveforms obtained from the design studies are presented for
four of the machine types.
42613
Abdi, S. et.al
A Study of Unbalanced Magnetic Pull in Brushless Doubly Fed Machines
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1218 – 1227
This paper studies the unbalanced magnetic pull in the brushless doubly fed machine
(BDFM) caused by both static and dynamic rotor eccentricities. Several parallel winding
designs for the two stator windings are proposed, and the practicality of such designs is
discussed with respect to direct coupling between the stator windings and with rotor
undesirable harmonic fields. Once practical parallel winding designs are established, their
effects on reducing deflection as a result of static and dynamic eccentricities are shown
and compared with series wound stator. This study has been carried out on a prototype
D400 250-kW BDFM.
42614
Kiani M.M. et.al
Elimination of System-Induced Torque Pulsations in Doubly-Fed Induction Generators
Via Field Reconstruction Method
17
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1228 - 1236
Effects of system unbalance and system harmonics on the operation of doubly-fed
induction generator (DFIG) used in wind energy harvesting are of great concern. This is
primarily due to the fact that system unbalance and harmonics can generate unwanted
torque undulations that can potentially undermine the mechanical integrity of the tower,
and reduce the lifetime of the moving components that are attached to the generator
shaft. This paper focuses on the development of a solution for the above problem by
judicious selection of the rotor currents to actively eliminate/mitigate these undesirable
vibrations. The enabling technology for optimal calculation of the rotor currents is based
on the field reconstruction method (FRM). FRM is an analytical tool for the approximation
of the magnetic field distribution in the middle of the air gap. Once the FRM formulation
is setup, it is capable to predict the tangential/normal components of the magnetic
forces. In this paper, the FRM is applied to compute the rotor phase currents in lieu of
the availability of the real-time stator currents such that the resultant field will generate
a smooth torque.
42615
Crider J.M. & Sudhoff S.D.
An Inner Rotor Flux-Modulated Permanent Magnet Synchronous Machine for LowSpeed High-Torque Applications
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1247 - 1254
Applications for low-speed high-torque machines include marine propulsion and wind
power generation. Since electric machinery size is more directly related to required
torque than to required power, high required torque leads to large machines. Mechanical
gears increase the speed and lower the required torque of the machine to reduce size.
This, however, results in increased noise and maintenance, and decreased reliability.
Magnetic gears offer the advantages of mechanical gears without the disadvantages
created by physical contact. Integrating magnetic gears into the machine structure offers
additional mass savings. This study proposes a novel machine architecture, which
integrates magnetic gearing and a permanent magnet synchronous machine to create an
inner rotor flux-modulated permanent magnet synchronous machine. Unlike previous
arrangements, the proposed machine utilizes a more desirable inner rotor configuration
and avoids multiple magnet arrays. This study presents a finite-element-based design
model of the proposed machine to be utilized in an optimization-based design
environment. A multiobjective design study is presented for a laboratory scale
application. The resulting tradeoff between mass and loss is compared with that of a
permanent magnet synchronous machine for the same application.
42616
Kumar V.S.S. & Thukaram D.
Accurate Steady-State Representation of a Doubly Fed Induction Machine
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5370 - 5375
This letter presents an accurate steady-state phasor model for a doubly fed induction
machine. The drawback of existing steady-state phasor model is discussed. In particular,
the inconsistency of existing equivalent model with respect to reactive power flows when
operated at supersynchronous speeds is highlighted. Relevant mathematical basis for the
18
proposed model is presented and its validity is illustrated on a 2-MW doubly fed induction
machine.
42617
Rigatos G. et.al
Control and Disturbances Compensation for Doubly Fed Induction Generators Using
the Derivative-Free Nonlinear Kalman Filter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5532 - 5547
The paper studies differential flatness properties and an input-output linearization
procedure for doubly fed induction generators (DFIGs). By defining flat outputs which are
associated with the rotor's turn angle and the magnetic flux of the stator, an equivalent
DFIG description in the Brunovksy (canonical) form is obtained. For the linearized
canonical model of the generator, a feedback controller is designed. Moreover, a
comparison of the differential flatness theory-based control method against Lie algebrabased control is provided. At the second stage, a novel Kalman Filtering method
(Derivative-free nonlinear Kalman Filtering) is introduced. The proposed Kalman Filter is
redesigned as disturbance observer for estimating additive input disturbances to the DFIG
model. These estimated disturbance terms are finally used by a feedback controller that
enables the generator's state variables to track desirable setpoints. The efficiency of the
proposed state estimation-based control scheme is tested through simulation
experiments.
42618
Kai-Wei Hu & Chang-Ming Liaw
Development of a Wind Interior Permanent-Magnet Synchronous Generator-Based
Microgrid and Its Operation Control
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4973 - 4985
This paper presents the development of a wind interior permanent-magnet synchronous
generator (IPMSG)-based dc microgrid and its operation control. First, the derated
characteristics of PMSG systems with various ac/dc converters and operation controls are
comparatively analyzed. Then, the IPMSG followed by a three-phase Vienna switch-mode
rectifier is developed to establish the common dc bus of dc microgrid. Good developed
power and voltage regulation characteristics are achieved via the proposed commutation
tuning, robust current, and voltage controls. Second, a single-phase three-wire inverter
is constructed to serve as the test load. Good ac 220 V/110 V output voltage waveforms
under unknown and nonlinear loads are preserved by the developed robust waveform
tracking control scheme. Third, a battery energy storage system is established, and the
fast energy storage support response is obtained via the proposed droop control approach
with adaptive predictive current control method. In addition, a chopped dump load is
equipped to enhance the energy balance control flexibility.
19
42619
Salles D. et.al
A Practical Method for Nondetection Zone Estimation of Passive Anti-Islanding
Schemes Applied to Synchronous Distributed Generators
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2066 - 2076
Unintentional islanding detection is a primary requirement for the interconnection of
synchronous distributed generators (DGs). For this purpose, voltage and frequencybased relays are largely employed due to their low cost and simplicity However, these
devices are not totally reliable due to their associated nondetection zone (NDZ). The
NDZ is an effective tool to evaluate the performance of these relays against islanding
occurrence. In this context, this paper presents a simple and practical analytical
method to estimate the NDZ of frequency and voltage-based relays without relying on
numerous, time-consuming electromagnetic transient (EMT) simulations. The main
contribution is that one can easily estimate the NDZ of these protection systems based
on a few analytical expressions. The effectiveness and generality of the analytical
method are verified by comparing its results with those obtained by repeated, intensive
EMT simulations for different power distribution networks and different relay types.
2.2 Electrical Motors & Drives
42620
Climente-Alarcon V. et.al
Diagnosis of Induction Motors under Varying Speed Operation by Principal Slot
Harmonic Tracking
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3591 - 3599
A detailed study on the energy content of a principal slot harmonic (PSH) in an induction
motor operating at variable slip is carried out. The machine is tested under different faulty
conditions, namely, broken rotor bar, mixed eccentricity, and interturn short circuit. The
use of a combined time-frequency analysis and particle filtering feature extraction
procedure allows tracking the evolution of a PSH under different load profiles and
integrating its energy. The proposed fault indicator provides values that are equivalent
with the traditional one for stationary operation even in the case of pulsating load. The
results show that the energy in the PSH reflects the overall state of the machine under
these conditions. Furthermore, procedures to discern the different faults in real
applications are proposed.
42621
Bianchi N. et.al
Selection of PM Flux Linkage for Maximum Low-Speed Torque Rating in a PM-Assisted
Synchronous Reluctance Machine
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3600 - 3608
In recent years, there is an increasing interest in adopting synchronous reluctance
machines for several applications. This is due to two main factors. The first is the
increasing and highly variable cost of rare-earth permanent-magnet (PM), such as NdFeB
and SmCo. The second is the requirement for more efficient machines with respect to
20
induction machines in general applications. However, a drawback of the synchronous
reluctance machine is the low power factor. Such a drawback is compensated by assisting
the machine by means of a proper volume of PM material, generally ferrite, which is
introduced in the rotor flux barriers. The PM flux saturates the rotor iron bridges, increases
the power factor of the machine (which corresponds to a decrease of the volt-ampere
ratings of the inverter), and adds a PM flux torque component. This paper investigates
how to select the amount of ferrite magnet in a PM-assisted reluctance machine, adopting
a model that considers the machine operation at low speed with both a current and a flux
linkage limit. It is shown that, by means of the aforementioned analysis, the machine
performance at low speed can be improved by means of a proper choice of the PM flux
linkage.
42622
Sikder C.
Cogging Torque Reduction in Flux-Switching Permanent-Magnet Machines by Rotor
Pole Shaping
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3609 - 3619
Cogging torque in flux-switching permanent-magnet (FSPM) machines is relatively high
compared with that of other types of PM machines because of their unique doubly salient
structure. Reducing the cogging torque in the FSPM machine is of particular importance to
make it a viable alternative to conventional rotor-PM machines. A new pole shaping
method has been proposed to reduce the cogging torque. The validity of the proposed
method has been confirmed by analytical methods and finite-element-analysis-based
simulation. The influence of the proposed pole shaping method on the back-electromotive
force (EMF) and average electromagnetic torque has also been investigated.
42623
Inoue T. et.al
Mathematical Model for MTPA Control of Permanent-Magnet Synchronous Motor in
Stator Flux Linkage Synchronous Frame
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3620 – 3628
A mathematical model is proposed for the maximum torque per ampere (MTPA) control
law of a permanent-magnet synchronous motor (PMSM) in the stator flux linkage
synchronous frame (M-T frame). The mathematical model takes into consideration
magnetic saturation and cross-magnetization effects. In taking into consideration
magnetic saturation effects, most of the mathematical models in the d-q frame are
complex. The M-T frame has several advantages, such as the simplicity of the fluxweakening control law and its applicability to various motors. In this paper, the control
characteristics of a PMSM in the M-T frame are analyzed, and a mathematical model for
estimating the MTPA control trajectory in the M-T frame is proposed. In addition, a method
of simply determining the parameters for the mathematical model is proposed. The
validity of the proposed model is confirmed by comparing the analytical and experimental
results.
21
42624
Omura M. et.al
Thrust Characteristics Improvement of a Circular Shaft Motor for Direct-Drive
Applications
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3647 - 3655
This paper presents a semicircular tubular linear machine model, which is called a circular
shaft motor (CSM), with trapezoidal magnets. For a conventional CSM system, the stator
is difficult to construct as designed, and the thrust characteristics are not high enough.
The proposed CSM model includes trapezoidal magnets that are magnetized in the axial
direction. This structure can facilitate the construction of the stator and decrease the
thrust ripple. In addition, the magnetic flux characteristics are shown as new results of a
CSM. Magnetic field is related to thrust characteristics closely. By investigating magnetic
distribution characteristics, it is shown that the proposed model can improve magnetic
field characteristics. In this paper, the structure of the proposed CSM model is described.
The improvement in the thrust characteristics is verified by magnetic field analysis. The
thrust characteristics of the proposed CSM system are verified in a thrust characteristics
test. The magnetic flux characteristics of the proposed CSM system are compared with
those of a conventional CSM system to evaluate the thrust characteristics.
42625
Mingardi D.
Ring Losses Evaluation in Ringed-Pole PM Motors
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3686 - 3695
In this paper, the ringed-pole surface-mounted permanent-magnet machine is investigated
from the point of view of the ring losses. The rings around the poles create a highfrequency anisotropy that is useful to detect the rotor position by means of a highfrequency signal injection. However, the presence of the rings causes additional rotor
losses. The causes of ring losses are investigated in the paper. The first cause is the highfrequency signal injection itself. The harmonics in the airgap magnetomotive force, which
are not synchronous with the rotor and hence induce currents in the rings, are the second
source of losses. The third source is the airgap flux fluctuation due to stator slotting.
Machines of different sizes and winding types are investigated. A finite-element analysis
and an analytical model are used to estimate the ring losses, comparing the results. The
influence of the ring cross-sectional area on the ring losses is analyzed, showing that the
ring losses can be reduced in certain configurations.
42626
Sugimoto H. et.al
Principle of a Novel Single-Drive Bearingless Motor with Cylindrical Radial Gap
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3696 - 3706
In this paper, a novel single-drive bearingless motor with cylindrical radial air-gap is
proposed. The single-drive bearingless motor has only one set of three-phase windings. It
generates both torque and axial suspension force independently with only one three-phase
inverter and one displacement sensor. Therefore, this single-drive bearingless motor has
the advantages of low cost and small size. Only axial direction z-axis is actively positioned.
The other axes, radial movements x and y, and tilting movements θ∞ and θy, are passively
stable. In the proposed motor, the rotor is a cylindrical permanent magnet magnetized in
a radial parallel direction. The stator consists of six C-shaped cores and one set of threephase windings. The principles of the suspension force and torque generations by the dand
22
q-axis currents, respectively, are shown. The proposed machine was fabricated and tested
only to confirm the principles. In the experiments, start-up was successfully achieved. In
an acceleration test up to 3600 r/min, stable magnetic suspension and speed regulation
by the d- and q-axis current regulations were confirmed.
42627
Corral-Hernandez J.A.
Transient-Based Rotor Cage Assessment in Induction Motors Operating With Soft
Starters
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3734 - 3742
The reliable assessment of the rotor condition in induction motors is a matter of increasing
concern in the industry. Although rotor damages are more likely in line-started motors
operating under high inertias, some cases of broken rotor bars in motors supplied via soft
starters have been also reported in the industry. Motor current signature analysis (MCSA)
is the most widely spread approach to diagnose such failures. However, its serious
drawbacks in many real industrial applications have encouraged investigation on
alternative methods enhancing the reliability of the diagnosis. This paper extends a
recently introduced diagnosis methodology relying on the startup current analysis to the
case of soft-starter-operated motors. The approach has proven to provide very satisfactory
results, even in cases where the classical MCSA does not lead to correct diagnosis
conclusions. However, its extension to operation under soft starters was still a pending
issue. The experimental results shown in this paper ratify the validity of the proposed
diagnosis approach in soft-starter-operated induction motors.
42628
Wrobel R. et.al
Winding Design for Minimum Power Loss and Low-Cost Manufacture in Application to
Fixed-Speed PM Generator
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3773 - 3782
This paper presents the results from a coupled thermal and power loss analysis of an openslot permanent-magnet (PM) generator. The research focus has been placed on the winding
design providing minimum power loss at an ac operation, together with low-cost
manufacture. The analyzed PM generator is intended to operate at a fixed speed, allowing
for the winding design to be finely tuned for a single operating point. Such a design
approach has not been widely reported in literature, and the existing body of work is
largely focused on variable-speed applications, where the winding design is a compromise
between the low-speed and high-speed operating points for a given torque-speed
envelope. The ac winding power loss has been analyzed for several winding variants with
different conductor dimensions, accounting for the winding operating temperature. The
calculated results suggest that, in the analyzed PM generator, a lower winding slot fill
factor is preferable as compared with the more common approach, where the highest
manufacturable winding slot fill factor is usually considered. The power loss predictions
have been supplemented with the thermal analysis of the complete generator assembly
for the winding variants considered, illustrating the importance and influence of the
appropriate winding design on the power output capability of the fixed-speed PM
generator. The most promising winding design for the minimum power loss at a rated
operating point has been down selected for prototyping. The theoretical findings from the
23
analysis have been compared with the experimental data from hardware tests on a stator
winding section,
42629
Tallam, R.M. et.al
Detection of Capacitor Degradation in Filters for AC Drives
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3822 - 3828
Adjustable-speed drives with regenerative pulse width modulation rectifiers-both voltage
source rectifiers and current source rectifiers-have LC filters on their input to attenuate
the high-frequency components of current and achieve reduced levels of total harmonic
distortion. The capacitors used in these filters are predominantly of the metalized film
construction and are prone to catastrophic failure. In this paper, a method is proposed for
the detection of capacitor degradation and location of the faulted phase. The method uses
measurements of voltages and currents-which may already be available for control
purposes, for line synchronization and active damping-to detect impedance asymmetry
and is impervious to input voltage unbalance.
42630
Pellegrino G. et.al
Plug-in Direct-Flux Vector Control of PM Synchronous Machine Drives
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3848 - 3857
A general-purpose control algorithm is proposed for permanent-magnet (PM) synchronous
machine drives based on the principle of direct-flux vector control. The algorithm does
not require regulator tuning, and it is tailored to different machines automatically via
identification of the stator resistance and flux linkage tables. The model parameters are
identified via a preliminary self-commissioning procedure that can be integrated into the
standard drive firmware with no need for extra hardware or offline manipulation. The
combination of the control and self-commissioning algorithms forms a “plug-in” controller,
which pertains to a controller that is capable of exploiting the full drive capabilities with
no prior knowledge of the PM machine in use. Experimental results are reported for two
prototype concentrated-winding PM machines designed for traction applications, i.e., one
with a surface-mounted PM rotor and another with an interior PM rotor.
42631
Swamy M.M. et.al
Power Loss, System Efficiency, and Leakage Current Comparison between Si IGBT VFD
and SiC FET VFD with Various Filtering Options
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3858 - 3866
SiC devices are gaining acceptance in the motor drive industry. This paper compares the
power loss and efficiency between two options that can be used with SiC-based variable
frequency drives (VFDs). In the first option, the SiC VFD is equipped with an output sinewave filter with carrier frequency at 50 kHz. A dv/dt filter is used for the second option
with the carrier frequency reduced to 8 kHz. Both options are compared with a standard
Si insulated-gate bipolar transistor (IGBT) VFD operating at a carrier frequency of 8 kHz
with no output filter. The focus of this paper is to present different filtering options for
SiC VFDs. The dv/dt filter is designed to meet the same specification as that of the
standard Si IGBT VFD with no output filter, so as to present a fair comparison between a
standard Si IGBT VFD and the next-generation SiC VFD. Results using a 460-V 11-kW system
show that the SiC VFD with an output sine-wave filter has a lower efficiency compared
24
with SiC VFD with a dv/dt filter. Influence of the various filtering options on leakage
current in the motor drive system has also been studied, and the results are presented in
this paper.
42632
Yanyu Wei et.al
Current Limit Strategy for BLDC Motor Drive with Minimized DC-Link Capacitor
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3907 - 3913
Brushless dc motor drive system employing minimized dc-link capacitor is becoming
popular for the reason of compactness and long lifetime. However, once the capacitance
is reduced, reversal dc-link current will lead to excessive voltage rise in the dc link when
conventional current limit strategy is used. In order to avoid the damage caused by
oversize pumping-up voltage, a novel current limit strategy without reversal dc-link
current is necessary. In this paper, the traditional all-turn-off current limit logic is
replaced by half-turn-off logic. Then, an improved current sampling scheme is presented
to replace the cycle-by-cycle mode, which induces failure of current limiting after the
elimination of reversal current. Finally, the proposed strategy is verified by simulation and
experiment.
42633
Paar C. et.al
Influence of Machine Integration on the Thermal Behavior of a PM Drive for Hybrid
Electric Traction
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3914 - 3922
This paper describes a method for fast identification of the thermal behavior of vehicle
integrated electric drives to propose a better understanding of electric machine design
tailored to driving cycles. A simple, but satisfactorily accurate, calculation method for the
estimation of machine losses, which is an input for the analytic thermal network, in the
early design stage is introduced. The analytic models, which are verified using
measurement data, are used for parameter and case studies for consideration of the
thermal environment, with a focus on the gearbox. The first case study analyzes the
influence of the gearbox on the thermal behavior of critical machine components. Aiming
to use the gearbox lubricant for cooling the winding heads, an improvement of machine
performance using an alternative cooling approach, which cools down the end windings,
is shown in the second case study.
42634
Scelba G. et.al
Current-Sharing Strategies for Fault-Tolerant AC Multidrives
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3943 - 3953
Due to their inner structural redundancy, ac multidrive systems (MDSs) can achieve a faulttolerance capability with minor circuit modifications. However, some additional
components are generally required in order to create emergency current paths. According
to a recently presented approach, the amount of additional components can be reduced
by exploiting healthy drives to support faulty drives. This can be obtained by connecting
together the neutral points of motor stator windings and suitably sharing the neutral
current of faulty units among some, or all, healthy units. Following such an approach,
25
three current-sharing methodologies for fault-tolerant MDSs are presented in this paper,
which are able to cope with single or multiple failures. They are first theoretically
introduced and then validated by mean of simulations and experimental test results.
42635
Kawamura W. et.al
A Low-Speed, High-Torque Motor Drive Using a Modular Multilevel Cascade Converter
Based on Triple-Star Bridge Cells (MMCC-TSBC)
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3965 - 3974
This paper provides experimental verification of a modular multilevel cascade converter
based on triple-star bridge cells (MMCC-TSBC) for a low-speed, high-torque motor drive.
The TSBC is one of direct ac-to-ac power converters capable of achieving bidirectional
power flow and drawing/feeding three-phase sinusoidal input (supply-side) and output
(motor-side) currents with any power factor at both sides. This paper designs, constructs,
and tests a downscaled drive system combining a 400-V, 15-kW, phase-shifted-carrier PWM
TSBC equipped with four bridge cells per cluster and a 320-V, 38-Hz, 6-pole, 15-kW
induction motor loaded at the rated torque. Experimental waveforms obtained from the
downscaled drive system verify stable operation across a broad range from a standstill to
the rated speed, showing satisfactory start-up performance.
42636
Swamy M.M.
An Electronically Isolated 12-Pulse Autotransformer Rectification Scheme to Improve
Input Power Factor and Lower Harmonic Distortion in Variable-Frequency Drives
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3986 - 3994
Diode rectifier front-ends with large dc bus capacitors used in variable-frequency drives
draw discontinuous current from the power system, resulting in a poor input power factor
and high input current distortion. The 12-pulse and 18-pulse techniques used to reduce
input current harmonics are popular because of their simplicity but are bulky and
expensive. Autotransformer techniques require additional external magnetic components
that are bulky and add to the cost of the system. A new electronically isolated 12-pulse
autotransformer topology that does not need bulky external magnetic components is
proposed in this paper. The proposed topology employs active switches to achieve
electronic isolation between the two rectifiers, resulting in continuous input current with
reduced harmonics. The proposed non regenerative active scheme achieves less than 5%
total harmonic distortion at a much lower cost compared with other passive or active
topologies currently in the market. Experimental results from a 240-V 75-hp system are
given to prove the concept.
42637
Olsen L.R et.al
Enhanced Safety Features in Motor Control Centers and Drives for Diagnostics and
Troubleshooting
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4255 - 4262
It is common practice in the industry for electrical workers to be exposed to shock and arc
blast and arc flash hazards as they perform routine maintenance and diagnostic testing on
equipment enclosed in motor control centers (MCCs). This paper will illustrate the
influence that various IEEE conferences, including the Electrical Safety Workshop, has had
26
on changing the electrical safety culture related to equipment diagnostics. End users are
now requesting manufacturers of low- and medium-voltage MCCs to develop or add
features and functionality into their products that enhance the ability of electrical
maintenance and operating personnel to conduct routine diagnostic and troubleshooting
tasks without being directly exposed to energized electrical equipment. This paper will
explore some of these features and provide some examples of routine maintenance and
diagnostic tasks that can be performed while doing troubleshooting and diagnostic tasks
on operating equipment without opening enclosure doors and exposing workers to the
hazards associated with exposed energized equipment.
42638
Kojooyan-Jafari H. et.al
Using the Instantaneous Power of a Free Acceleration Test for Squirrel-Cage Motor
Parameters Estimation
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 974 - 982
A new parameters determination method for squirrel-cage induction motors is presented.
As a main contribution, the method uses the instantaneous electrical power and the
mechanical speed measured in a free acceleration test to estimate the double-cage model
parameters. The parameters are estimated from the machine impedance calculated at
several points. At speed points where the double-cage effect is significant, i.e., between
the zero speed point and the maximum torque point, the machine impedance is evaluated
by the instantaneous power method, and at speed points where the double-cage effect is
not significant, i.e., between the maximum torque point and synchronism, the machine
impedance is evaluated by a dynamic-model-based linear least-square method. The
proposed method has been applied to obtain the parameters of three motors tested in the
laboratory. To check the method accuracy, the steady-state torque and current-slip curves
predicted by the estimated parameters are successfully compared with those measured in
the laboratory.
42639
Hongfeng Li et.al
Thermal Analysis of the Permanent-Magnet Spherical Motor
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 991 - 998
There are many kinds of permanent-magnet (PM) motors, which are widely used in modern
industry, but the problem of temperature rise is likely to affect the operation performance
and even the life of the motor. The semiclosed structure of the PM spherical motor (PMSM)
tends to increase the temperature when it works, so the thermal analysis of the PMSM is
considered necessary. Based on double Fourier series decomposition, this paper
establishes a three-dimensional (3-D) analytical model of PM eddy current loss in the
PMSM, which considers the effect of time and space harmonics. Meanwhile, the heat
sources such as hysteresis loss and copper loss are discussed. With those heat sources, a
3-D equivalent thermal network model is established. The thermal resistances are
calculated. By applying the thermal network model, the influence of different speed and
load on temperature rise is analyzed, and a steady-state thermal analysis of the motor is
performed by using finite element analysis. The structure of stator is improved and good
heat dissipation effect is achieved. This paper provides the theoretical basis for the design
of ventilation and cooling system of the PMSM.
27
42640
Yongchang Zhang & Haitao Yang
Model-Predictive Flux Control of Induction Motor Drives With Switching Instant
Optimization
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1113 - 1122
Conventional model-predictive torque control (MPTC) requires tedious and timeconsuming tuning work for stator flux weighting factor, and presents relatively high torque
ripples. To solve these problems, this paper proposes a model-predictive flux control
(MPFC) for two-level inverter-fed induction motor (IM) drives. The references of stator
flux magnitude and torque in conventional MPTC are converted into an equivalent
reference of stator flux vector in the proposed MPFC. As only the tracking error of stator
flux vector is required in the cost function, the use of weighting factor is eliminated. The
optimal voltage vector is selected based on the principle of stator flux error minimization
and its switching instant is optimized rather than being in the beginning of each control
period. The proposed MPFC with and without switching instant optimization are both
implemented in a 32-bit floating digital signal processor, and they are compared in detail
in terms of torque ripple, current harmonics, and average switching frequency. Both
digital simulations and experimental tests were carried out on a two-level inverter-fed IM
drive, and the obtained results validate the effectiveness of the proposed method.
42641
Jongwan Kim et.al
Power Spectrum-Based Detection of Induction Motor Rotor Faults for Immunity to False
Alarms
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1123 - 1132
It has recently been shown that spectrum analysis of instantaneous power can provide
sensitive online detection of rotor faults in induction motors compared with current,
torque, speed, or vibration spectrum analysis. However, it was reported that monitoring
of the twice slip frequency, 2sfs, components induced by the fundamental component can
produce false rotor fault alarms due to asymmetry in the rotor or low frequency load
oscillations. In this paper, the rotor fault components induced in the power spectrum by
the stator fifth and seventh space harmonics are derived to evaluate their immunity to
false alarms. It is shown that the (6 - 8s)fs component can provide reliable detection of
rotor faults under cases where existing methods produce false alarms. An experimental
study performed on custom built rotor samples shows that the new components are
capable of detecting rotor faults immune to false alarms produced by rotor axial air ducts,
rotor anisotropy, and low frequency load oscillations for cases where existing methods
fail. The components derived in this paper can also be applied to vibration, speed, torque,
or acoustic monitoring for reliable detection of rotor faults.
42642
Koteich M. et.al
Discussion on “A Differential Algebraic Estimator for Sensorless Permanent-Magnet
Synchronous Machine Drive”
28
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1137
Diao et al. are to be commended for proposing a new approach for permanent magnet
synchronous machine (PMSM) position estimation, using the differential algebraic theory.
In the following comments, we would like to highlight some points concerning the machine
observability under the applied approach. In paper by Diao et al., it is claimed that the
rotor position observability of the nonsalient PMSM is ensured regardless the speed, based
on the relationship.
42643
Diao S. & Diallo D.
Closure to Discussion on “A Differential Algebraic Estimator for Sensorless PermanentMagnet Synchronous Machine Drive”
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1138
This paper is a response to the comments on the paper “A Differential Algebraic Estimator
for Sensorless Permanent-Magnet Synchronous Machine Drive”. The authors clarifies some
points regarding the derivation of their position estimators and the extensibility of the
differential algebraic approach to salient permanent magnet synchronous motor (PMSM).
42644
Cong Ma & Liyan Qu
Multiobjective Optimization of Switched Reluctance Motors Based on Design of
Experiments and Particle Swarm Optimization
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1144 - 1153
This paper proposes a comprehensive framework for multiobjective design optimization of
switched reluctance motors (SRMs) based on a combination of the design of experiments
and particle swarm optimization (PSO) approaches. First, the definitive screening design
was employed to perform sensitivity analyses to identify significant design variables
without bias of interaction effects between design variables. Next, optimal third-order
response surface (RS) models were constructed based on the Audze-Eglais Latin hypercube
design using the selected significant design variables. The constructed optimal RS models
consist of only significant regression terms, which were selected by using PSO. Then, a
PSO-based multiobjective optimization coupled with the constructed RS models, instead
of the finite-element analysis, was performed to generate the Pareto front with a
significantly reduced computational cost. A sample SRM design with multiple optimization
objectives, i.e., maximizing torque per active mass, maximizing efficiency, and
minimizing torque ripple, was conducted to verify the effectiveness of the proposed
optimal design framework.
42645
Jikai Si et.al
Design and Analysis of a 2-DOF Split-Stator Induction Motor
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1200 - 1208
A two degrees of freedom (2-DOF) actuator capable of producing linear translation, rotary
motion, or helical motion would be a desirable asset to the fields of machine tools,
29
robotics, and various apparatuses. In this paper, a novel 2-DOF split-stator induction motor
was proposed and electromagnetic structure parameters of the motor were designed and
optimized. The feature of the direct-drive 2-DOF induction motor lies in its solid mover
arrangement. In order to study the complex distribution of the eddy current field on the
ferromagnetic cylinder mover and the motor's operating characteristics, the mathematical
model of the proposed motor was established, and characteristics of the motor were
analyzed by adopting the permeation depth method (PDM) and finite element method
(FEM). The analytical and numerical results from motor simulation clearly show a
correlation between the PDM and FEM models. This may be considered as a fair
justification for the proposed machine and design tools.
42646
Arbab N. et.al
Thermal Modeling and Analysis of a Double-Stator Switched Reluctance Motor
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1209 - 1217
In this paper, thermal modeling and analysis of a 10 kW double-stator switched reluctance
machine (DSSRM) is presented. Thermal management is an essential step of the machine
design, since overheated windings and cores might destroy the insulation and lead to
failure of the machine. A three-dimensional (3-D) finite-element method (FEM) has been
used to numerically calculate the temperature distribution in different parts of the
machine. Furthermore, to include the use of water as coolant, computational fluid
dynamics (CFD) has been utilized. Thermal performance of the prototype is then analyzed
at various load conditions. A 10 kW prototype of the DSSRM has been built and the results
have been experimentally verified.
42647
Alexandridis A.T. et.al
Advanced Integrated Modeling and Analysis for Adjustable Speed Drives of Induction
Motors Operating With Minimum Losses
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1237 - 1246
The nonlinear induction motor model is appropriately integrated by incorporating the
dynamics of the power electronic converter in a manner that permits the design of stable
field-oriented control (FOC) operating with minimum losses. As already proven, the
challenging issue of operating the induction machine with minimum copper losses requires
a varying rotor flux opposed to the standard FOC technique, which keeps the rotor field
magnitude constant and tracks the electric torque to the desired level. To this end,
exploiting the Hamiltonian structure of the developed motor/converter model, an
innovated nonlinear controller is proposed that guarantees the technical limits of the
converter (linear modulation) and simultaneously operates under FOC at steady state to
achieve accurate speed regulation with varying rotor flux according to the minimal losses
requirements. Under these circumstances, the conventional FOC stability analysis does not
hold anymore, and therefore for the first time, a new rigorous analysis is provided that
proves stability and convergence to the desired equilibrium for the complete closed-loop
motor converter system. Finally, the theoretical contribution is examined in comparison
to the traditional FOC operation by simulations obtained for an industrial size induction
motor, while it is further evaluated by real-time results of a motor with similar
parameters.
30
42648
Zheyu Zhang et.al
Evaluation of Switching Performance of SiC Devices in PWM Inverter-Fed Induction
Motor Drives
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5701 - 5711
Double pulse test (DPT) is a widely accepted method to evaluate the switching
characteristics of semiconductor switches, including SiC devices. However, the observed
switching performance of SiC devices in a PWM inverter for induction motor drives is
almost always worse than the DPT characterization, with slower switching speed, more
switching losses, and more serious parasitic ringing. This paper systematically investigates
the factors that limit the SiC switching performance from both the motor side and inverter
side, including the load characteristics of induction motor and power cable, two more
phase legs for the three-phase PWM inverter in comparison with the DPT, and the parasitic
capacitive coupling effect between power devices and heat sink. Based on a three-phase
PWM inverter with 1200 V SiC MOSFETs, test results show that the induction motor,
especially with a relatively long power cable, will significantly impact the switching
performance, leading to a switching time increase by a factor of 2, switching loss increase
up to 30% in comparison with that yielded from DPT, and serious parasitic ringing with 1.5
µs duration, which is more than 50 times of the corresponding switching time. In addition,
the interactions among the three phase legs cannot be ignored unless the decoupling
capacitors are mounted close to each phase leg to support the dc bus voltage during
switching transients. Also, the coupling capacitance due to the heat sink equivalently
increases the junction capacitance of power devices; however, its influence on the
switching behavior in the motor drives is small considering the relatively large capacitance
of the motor load.
42649
Chenjun Cui et.al
A Novel Drive Method for High-Speed Brushless DC Motor Operating in a Wide Range
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4998 - 5008
In this paper, a novel drive method, which is different from the traditional motor drive
techniques, for high-speed brushless DC (BLDC) motor is proposed and verified by a series
of experiments. It is well known that the BLDC motor can be driven by either pulse-width
modulation (PWM) techniques with a constant dc-link voltage or pulse-amplitude
modulation (PAM) techniques with an adjustable dc-link voltage. However, to our best
knowledge, there is rare study providing a proper drive method for a high-speed BLDC
motor with a large power over a wide speed range. Therefore, the detailed theoretical
analysis comparison of the PWM control and the PAM control for high-speed BLDC motor is
first given. Then, a conclusion that the PAM control is superior to the PWM control at high
speed is obtained because of decreasing the commutation delay and high-frequency
harmonic wave. Meanwhile, a new high-speed BLDC motor drive method based on the
hybrid approach combining PWM and PAM is proposed. Finally, the feasibility and
effectiveness of the performance analysis comparison and the new drive method are
verified by several experiments.
31
42650
Tianfu Sun et.al
Maximum Torque Per Ampere (MTPA) Control for Interior Permanent Magnet
Synchronous Machine Drives Based on Virtual Signal Injection
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5036 - 5045
This paper introduces a novel virtual signal injection-based control method for maximum
torque per ampere (MTPA) operation of interior permanent magnet synchronous machine
(IPMSM) drives. The proposed method injects a small virtual current angle signal
mathematically for tracking the MTPA operating point and generating d-axis current
command by utilizing the inherent characteristic of the MTPA operation. This method is
parameter independent in tracking the MTPA points, and it does not inject any real signal
to current or voltage command. Consequently, the problems associated with real highfrequency signal injection, such as increases in copper and iron loss can be avoided.
Moreover, it is robust to current/voltage harmonics and motor torque disturbances. The
proposed method is verified by simulations and experiments under various operating
conditions on a prototype IPMSM drive system.
42651
Rongli Zhao et.al
The Dynamic Control of Reactive Power for the Brushless Doubly Fed Induction
Machine With Indirect Stator-Quantities Control Scheme
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5046 - 5057
Compared to the doubly fed induction machine (DFIM), the brushless doubly fed induction
machine (BDFIM) has higher reliability by virtue of the absence of a brush gear. Recent
research on structure optimization design and control strategy of BDFIM has made
remarkable progress. BDFIM indirect stator-quantities control (ISC) is a new control
strategy, which, in comparison to vector control strategy, requires fewer parameters and
does not need rotating coordinate transformation. This paper further develops the
dynamic control of reactive power for the BDFIM with ISC scheme. Detailed theoretical
analysis is done to show the controller structure of the reactive power. The experimental
results of the prototype show the feasibility of the proposed scheme. As a result, the
proposed ISC controllers have been able to control not only speed and torque, but also the
reactive power.
3. INSULATION SYSTEM, MATERIALS & INSULATORS
42652
Baur M.et.al
Scatter reduction of the 50-60 Hz breakdown voltage test for insulating liquids
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2401
- 2407
32
There are several reasons to test the breakdown voltage of insulating liquids: acceptance
tests on new deliveries, testing of treated liquids prior to or during filling into electrical
equipment, and monitoring and maintaining oil-filled apparatus in service. Among others,
the test for the determination of breakdown voltage at 50 or 60 Hz is one of the most
important. In fact, it is worldwide accepted that this test gives quickly very useful
information even if mainly related with moisture and particle content than the intrinsic
properties of the insulating liquids. This test is standardized by IEC and ASTM but has some
limitations in terms of the statistical scatter of mean value of the breakdown voltage. The
present paper presents an improvement on the scatter of the mean values of the
breakdown voltage by increasing the number of requested shots and discarding the most
disperse results. In addition, it is presented as a revised test cell having stirring device on
the top and round edges at the bottom may further reduce the standard deviation of the
same breakdown voltage. Others experimental parameters which may still influence the
scatter of the same standardized test are also examined and discussed.
42653
Abdelmalik A.A.
Analysis of thermally aged insulation paper in a natural ester-based dielectric fluid
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2408
- 2414
The compatibility of a newly developed ester fluid (PKOAE) with cellulose insulation paper
is evaluated by performing thermal ageing of Kraft paper in the new ester fluid. Thermally
accelerated ageing was performed in sealed mild steel pressure vessel containing ageing
catalysts, thermally upgraded insulation paper, and dielectric fluid (mineral oil and palm
kernel oil alkyl ester) at 150°C for 28, 56, and 84 days. Under the same illumination, the
color level of ester aged paper samples decreased by 33% after 84 days of ageing as
compared with the color level of aged mineral oil impregnated paper samples which
decreased by 73% within the same time. Whilst the samples of PKOAE impregnated paper
exhibited approximately 5% reduction in tensile strength after 28 days of ageing, the kraft
paper samples closer to copper strips were found to have a significant faster degradation
rate. The tensile strength of paper samples closer to copper plates dropped to about 35%
of the tensile strength of the unaged sample after ageing for 28 days, and the paper layers
farther away from the copper plates decreased by about 10%. The mechanisms that could
be responsible for the slower ageing rate of kraft paper in PKOAE fluid are discussed. The
characteristic breakdown strength of PKOAE impregnated paper is on the average, 42%
better than mineral oil impregnated paper. The high breakdown strength of PKOAE fluid
may be responsible for the higher breakdown field of ester-paper system since the applied
electrical stress is shared by the oil-paper combination.
42654
Yadav K.S. & Sarathi R.
Influence of thermally aged barrier on corona discharge activity in transformer oil
under AC voltages
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2415
- 2423
Corona Inception voltage (CIV) / breakdown voltage increases when the barrier is placed
anywhere from needle tip to the 20% of the needle-plane electrode gap above which a
marginal reduction in breakdown voltage is observed but its value is much higher than the
breakdown strength of the electrode gap without barrier. Thermally aged oil impregnated
33
pressboard insulation, as barrier, have high impact on CIV and breakdown voltage. The
injected current due to corona activity, its rise time, measured using HFCT, in the negative
and positive half cycle of the AC voltage measured to be 600 ps and 500 ps respectively.
The shape of the current pulse is the same with the aged pressboard insulation barrier in
the electrode gap. The corona inception voltage was measured by using UHF sensor and
the signal has frequency contents between 0.5 -2.2 GHz. The surface charge
measurements indicates that the amount of charge accumulated is high with thermally
aged oil impregnated pressboard (OIP) than the unused material. Polarity of surface charge
acquired by OIP due to corona charging depends on the surface condition of the material.
To understand the mechanical behavior of the aged specimen, tensile test and flexural
test were carried out and could conclude that ageing of material reduces the fundamental
mechanical properties of the material. SEM analysis indicates that scission of fibers occurs
due to thermal ageing at high temperatures. Partial Discharge studies on corona activity
indicate, on corona inception, discharges occur near peak of the applied AC voltage,
irrespective of position of barrier. The phase width of the PD generated due to corona
discharge activity is slightly high with thermally aged specimen compared with unused
specimen.
42655
Schmidt W.F. & Yoshino K
Ion mobilities in non-polar dielectric liquids: silicone oils
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2424
- 2427
Silicone oils have been applied as replacements for mineral oils in transformers and other
electrical equipment. Investigations of their electrical and thermo-physical properties
have been carried out. Few studies of the measurements of positive and negative ions in
these liquids exist. The present paper summarizes the data published. The modes of
charge transport in these liquids are discussed on the basis of the Stokes model, which
leads to the Walden's rule. Comparison with data of other dielectric liquids leads to the
conclusion that Walden's rule is not applicable for a variety of dielectric liquids.
42656
Naidis G.V & Naidis G.V
On streamer inception in hydrocarbon liquids in point-plane gaps
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2428
- 2432
Estimates for the discharge initiation voltage in hydrocarbon liquids in point-plane gaps
are obtained, basing on evaluation of the ionization integral describing electron
multiplication in avalanches in liquids. An approach for estimation of the voltage required
to inception of filamentary streamers is presented. It assumes that, like in gases, a
minimum radius of streamers propagating in liquids exist. It is shown, in agreement with
published experimental data for cyclohexane and pentane that at point radii smaller than
some threshold value (of several micrometers) the discharge initiation voltage is lower
than the voltage of inception of filamentary streamers. At point radii exceeding this
threshold, filamentary streamers occur just at the discharge inception.
34
42657
Sitorus H.B.H. et.al
Pre-breakdown phenomena in new vegetable oil - based jatropha curcas seeds as
substitute of mineral oil in high voltage equipment
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2442
- 2448
Due to their high biodegradability, non-toxicity and higher fire safety guarantee,
vegetable-based oils are considered today as a potential substitute for mineral and
synthetic liquids for electrical insulation and especially in high voltage power
transformers. However most of known vegetable oils are derived from food materials
(rape-seeds, sunflower, soybeans, palms, corns and others). And one has to be vigilant to
the fact that the replacement of mineral oil by natural ester fluids based on “renewably
sourced” vegetable oils, does not create new problems as this could cause global food
crisis due to diversion of food into insulating material oils or others (fuel). An interesting
product can be jatropha curcas oil (JCO) extracted from the fruit seeds of jatropha curcas
plants (“miracle tree”) which is non-food crops. These plants can be grown on marginal or
degraded soils and thus enables to avoid the need to utilize those more fertile soils
currently being used by smallholders to grow their staple crops; and they readily grow in
areas where annual rainfall levels are significantly lower than those required by other
species such as rape-seeds, sunflower, palm, soybeans, corns and others. This paper
presents an experimental study of streamers phenomena in jatropha curcas methyl ester
oil (JMEO) and mineral oil (MO) under positive and negative lightning impulse voltages
(1.2/50 µs); JMEO is obtained by alkali base catalyzed trans-esterification process of JCO
to reduce the viscosity and acidity. It is shown that basing on the streamer characteristics
(shape, stopping length, velocity, current and electrical charge), JMEO could constitute a
potential substitute for mineral for electrical insulation and especially in high voltage
power transformers.
42658
Gonzalez B. et.al
Effect of electric field at 150 °C on the formation of corrosive sulfur in mineral
transformer oil
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2449
- 2454
The effect of the application of 12 kV at 150 °C on the formation of corrosive mineral
copper sulfide in mineral transformer oil was investigated. It is considered that the
presence of sulfur corrosion causes failures in operating windings transformers above 35
kV. Research trials on mineral transformer oils were performed at 150 °C without an
electric field, and also at 150 °C in electric field based on the norms for the detection of
corrosive sulfur established by ASTM D-1275 and IEC 62535. The effect of the applied
electric field on the process of corrosive sulfur formation was determined. Varying
amounts of copper sulfide were found, both on bare Cu electrodes and Cu electrodes
covered with Kraft paper, pure Cu formation was also found in the oil. Copper sulfide was
quantified using the X-ray dispersion technique with a scanning electron microscope, with
EDX.SEM E., and chemical methods are used to determine the quantity of Cu in the oil
after the test.
35
42659
Atiya E.G. et.al
Dispersion behavior and breakdown strength of transformer oil filled with TiO2
nanoparticles
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2463
- 2472
Recently, the study of transformer oil-based nanofluids became of great interest, due to
their prospective properties as a dielectric and cooling medium. However, agglomeration
of nanoparticles limits the beneficial properties that can be obtained from nanofluids. So,
the work presented in this paper aims to get enhanced dispersion behavior of nanoparticles
within transformer oil-based nanofluids. Then, breakdown strength with the enhanced
dispersion behavior is evaluated. In order to get enhanced dispersion behavior, nanofluids
were prepared using nanoparticles with a surfactant. The surfactant plays a role in the
stabilization of nanoparticles and maintaining suspension stability. The considered type of
nanoparticles is TiO2 nanoparticles. Two series of nanofluid samples were prepared.
Through the first series, the effect of surfactant concentration on dispersion behavior and
agglomerate size was studied. The dispersion of nanoparticles was characterized using
three different techniques. These techniques are optical microscope analysis, transmission
electron microscope (TEM) analysis and zeta potential measurements. Based on these
techniques, the suitable concentration of surfactant was identified. The second series of
nanofluid samples was prepared with different weight percents of nanoparticles for
assessing the breakdown strength. Weibull distribution was used to calculate the
breakdown probability for the base oil as well as nanofluid samples. The results showed
an enhancement in the breakdown strength by about 27% in comparison to the base oil.
Based on the obtained results, mechanisms behind the dispersion behavior and breakdown
strength were proposed and discussed.
42660
Yuan Zhou et.al
Study of the charge dynamics in mineral oil under a non-homogeneous field
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2473
- 2482
The presence of mobile charge carriers can affect the frequency response of complex
permittivity of insulating liquid when the frequency is low. It has been found that the
experimental results of the complex permittivity of mineral oils are in a good agreement
with Coelho's frequency response theory when an extra contribution to the complex
permittivity arising from DC conduction is taken into account. It has been reported that
small quantity of high mobility charge carriers are responsible for this DC conduction. In
our previous work, we have found that if the charge carriers are fast enough so that they
can reach the opposite electrode in a cycle, the motion of these fast charge carriers can
only contribute to the imaginary part of the complex permittivity under a homogeneous
field. In this paper, the polarization induced by the motion of those fast charge carriers
under a non- homogeneous field has been studied. It has been found when the field is not
high, the total current caused by the drift and diffusion of those fast charge carriers is
proportional to the external voltage. A modified space charge polarization theory has been
proposed. The frequency dependence of the complex permittivity obtained
experimentally has been fitted using this modified Coelho model and compared with our
previous simulation. This modified model enables one to gain a better understanding of
the frequency response in mineral oil in low frequency regions.
36
42661
Wenxia Sima et.al
Effect of space charge on the accumulative characteristics of oil paper insulation under
repeated lightning impulses
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2483
- 2490
Repeated impulses have long been considered to affect the insulation properties of
electrical equipment. This interesting but rarely studied phenomenon may pose great risks
to the reliable operation of power equipment. Therefore, in this work, we focus on the
accumulative effect of repeated lightning impulses on the oil-impregnated paper (OIP)
used in power transformers. Specifically, we study the effect of space charge on the
accumulative characteristics of OIP. A repetitive impulse accumulating test platform was
set up, and the tests were conducted to obtain the accumulative characteristics of OIP
under repeated lightning impulses. The accumulative characteristics of OIP with various
interval time were experimentally identified to study the influence of interval time on the
accumulative effect. Then, space charge in OIP samples were investigated using the pulsed
electro-acoustic technique. Charge behavior in OIP was analyzed under different
conditions, i.e., changing the applied times, amplitude and interval time of the applied
lightning impulses. Charge injection and transport occurred during lightning impulse
accumulation. The increased application of lightning impulses, high applied voltage, and
short interval time contributed to the accumulation and transport of space charges. At
last, the possible mechanisms of the accumulative effect are discussed in this article based
on the experimental results.
42662
Loiselle L.et.al
Comparative studies of the stability of various fluids under electrical discharge and
thermal stresses
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2491
- 2499
It is a well-known fact that the service reliability of power transformers largely depends
upon the condition of the dielectric fluid. The steady deterioration (under the influence
of the multiple stresses) of the insulation has an important impact on the condition of the
transformers themselves. This contribution reports some investigations on some
commercially available ester, silicone and mineral oil fluids. Some of their
physicochemical properties are studied by submitting them to various stresses: electrical,
thermal and oxidation. Many comparisons are made according to the quality test results
of mineral oil, as it is very familiar to the transformer industry. A new technique using a
reactive free radical reagent, 2,2-diphenyl-1- picrylhydrazyl (DPPH), added to both new
oil for reference purposes and different aged oil to assess free radical concentration is
presented. The gassing tendency under either thermal or electrical stress, along with the
physicochemical properties of the fluids, is affected; it is assessed with the production of
oxidative aging by-products. The gassing performance characteristics of natural ester
fluids are far superior to those of conventional mineral oil. A significant reduction in
insulation aging rate was observed with synthetic ester fluids.
37
42663
Mansour D.-E.A. et.al
Development of a new graphical technique for dissolved gas analysis in power
transformers based on the five combustible gases
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2507
- 2512
Several methods have been proposed for dissolved gas analysis (DGA) of mineral oil in
power transformers. One of the simple and most widely used methods is Duval triangle.
However, Duval triangle does not consider the concentrations of two combustible gases,
namely ethane (C2H6) and hydrogen (H2). As a result, Duval triangle exhibits a lower
accuracy in diagnosing certain fault types, for which these gases are the key gases, such
as low overheating and corona discharge. Accordingly, this paper proposes a novel
graphical technique for DGA based on all the five combustible gases. The proposed
graphical technique is developed in the form of a pentagon shape. The pentagon heads
represents the percentage concentration of each individual gas to the total combustible
gases. The corresponding point for a certain faulty case is determined by the center of
mass of all pentagon heads. The knowledge extracted from previous DGA methods and
field experiences are used to estimate the preliminary fault regions within the pentagon.
The exact boundaries between fault regions are then specified using actual DGA data with
corresponding fault types collected from the Egyptian Electricity Network and published
cases. The overall performance of the proposed pentagon has been evaluated using a set
of fault cases and it is revealed that the proposed pentagon has higher diagnostic accuracy
compared to other methods including Duval triangles and IEC standard 60599.
42664
Sarathi R. et.al
Understanding the surface discharge characteristics of thermally aged copper sulphide
diffused oil impregnated pressboard material
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2513
- 2521
An attempt has been made to understand the impact of thermal aging with copper sulphide
diffused oil impregnated pressboard (OIP) material for surface discharge inception voltage
(SDIV) variation. The SDIV of Copper sulphide diffused OIP material reduces with increase
in thermal aging. The UHF signals generated due to surface discharges with copper
sulphide diffused OIP at the point of inception have frequency content in the range 0.71.5 GHz with its dominant frequency at 0.9GHz. HFCT measurement indicated that the
rise time of injected current pulse due to surface discharge activity in the negative and
positive half cycle of the AC voltage are about 0.8ns and 1ns respectively. It is also found
that increase in thermal aging of copper sulphide diffused OIP, the amplitude and width
of the current pulse increases. The magnitude of surface charge and its mean life is high
with thermal aging temperature of copper sulphide diffused OIP material. Polarity of
surface charge acquired by OIP due to AC corona charging depends on the surface condition
of the pressboard material and its charge decay rate is lower than under DC voltage.
Atomic Absorption Spectroscopy (AAS) and Energy Dispersive Spectrometry (EDS) study
confirms the presence of copper sulphide on the surface of OIP and is found to be increased
for copper sulfide diffused OIP material compare to unused OIP material. Scanning
Electron Microscope (SEM) analysis indicates formation of cracks with thermally aged OIP
material. Phase Resolved Partial Discharge (PRPD) study indicates that the surface
38
discharge activity occurs near the peaks of the applied AC voltage at inception and at the
rising portion of the applied AC voltage at higher voltages. It is found that the tensile and
flexural strength reduces drastically for thermally aged copper sulphide diffused OIP
material compare to unused specimen.
42665
Lecuna, R et.al
Thermal-fluid characterization of alternative liquids of power transformers: A
numerical approach
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2522
- 2529
The transformers lifespan depends importantly on its refrigeration. Mineral oils perform
this work in the majority of the power transformers. However, this type of coolant has
two main drawbacks: low biodegradability and low ignition point. Several alternative
liquids are being developed in order to overcome these drawbacks. This paper compares
their thermal-fluid behavior with a mineral oil by means of several parameters, such as
temperature, flow rate, fluids velocity, convective heat transfer coefficient (h) and the
cooling criterion (P). These are calculated using the numerical results of the simulation of
a 3D-model of a Low Voltage Winding that belongs to a power transformer with ONAN
cooling. The software COMSOL Multiphysics has allowed the simulation of the geometry
using a physical model in which buoyancies and viscous forces are the only considered
establishing the natural convection. As a result of the comparison, it is clear that the
mineral oil is the best coolant liquid. Among the alternative liquids, silicone oil would be
the second best coolant fluid, followed by the synthetic and natural esters, respectively.
On the other hand, it seems to be clear that the 3D simulations can be used to compare
properly the cooling capacities of the liquids.
42666
Du B.X. et.al
Thermal conductivity and dielectric characteristics of transformer oil filled with bn
and Fe3O4 nanoparticles
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2530
- 2536
The purpose of this paper is to investigate the influence of different types of nanoparticles
on thermal and dielectric properties along with the relation between them. Boron nitride
(BN) nanoparticles with high thermal conductivity and ferriferrous oxide (Fe3O4)
nanoparticles as a typical magnetic oxide were dispersed into transformer oil to form
different types of nanooil. Thermal and dielectric properties of the nanooil with different
mass fractions were measured. Thermal conductivity and thermal diffusivity under
different temperature were measured for each type of the nanooil in order to investigate
the effect of nanoparticles on thermal property. Dielectric property experiments were
performed in accordance with IEC standard. Relative permittivity, dissipation factor and
electrical resistivity tests for the nanooil were conducted along with ac and dc breakdown
strength in a range of temperature. It is found that both types of the nanooil showed
improved thermal property compared with non-modified oil. The nanooil exhibits different
performance in dielectric property due to the different properties of the nanoparticles.
The obtained results show significant improvement in heat transfer process with increasing
the mass fraction of BN nanoparticles while the oil modified by Fe3O4 nanoparticles shows
considerable enhancement in dielectric breakdown strength. Through further comparison
39
between the two types of nanooil, it is proposed that the improved thermal property
contributes to the enhancement of the breakdown strength.
42667
Leblanc P.et.al
Behavior of the charge accumulation at the pressboard/oil interface under DC external
electric field stress
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2537
- 2542
Mineral oils are commonly used for cooling and electrical insulation purposes in electrical
power transformers. The physicochemical process appearing at the Pressboard/Oil
interface, leads to the formation of an Electrical Double Layer (EDL). Therefore the
interface is polarized by the EDL, the charge of one sign is generated within the solid
medium and the opposite charge remains in the liquid medium. The process of flow
electrification is due to the convection of the diffuse layer inside the liquid. The test loop
was recently optimized with the addition of an energized wrapped copper electrode in the
sensor. This modification allows studying the effect of an external electric field on the
charge production and the distribution of the EDL: in the liquid via the streaming current
(global charge production) and in the pressboard via the capacitive current. This
capacitive current allows quantifying the accumulated charge within the pressboard plate
(local charge production). Therefore, the dynamics of the accumulated charge refer to
two EDL affected in the same way by the DC electric field. This paper proposes to show
the influence of an external DC electric field on the accumulated charge within the
pressboard as well as on the streaming current.
42668
Lu W. & Liu Q.
Effect of cellulose particles on impulse breakdown in ester transformer liquids in
uniform electric fields
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2554
- 2564
This paper presents experimental studies on the effect of cellulose particles on breakdown
voltages and breakdown mechanisms of a synthetic ester and a natural ester under
standard lightning impulse voltages. A mineral oil was also tested and used as the
benchmark. In total, liquids with four particle contamination levels, i.e. low, normal,
marginal and high; two moisture levels, i.e. dry and wet conditions, and three types of
electrodes, i.e. plane-plane, rod-rod, and VDE electrodes were investigated. Results
showed that the presence of cellulose particles reduces the 50% breakdown voltages of
the ester liquids and the mineral oil in uniform fields, which is further enhanced when the
particle is combined with the moisture. The particle effect on breakdown voltages also
becomes more prominent when the effective stressed area/volume of the electrode
configurations is increased. Nevertheless, at the same conditions, 50% lightning impulse
breakdown voltages of the ester liquids are always comparable to that of the mineral oil.
Linking with previously published results under AC voltages, it is summarised that the
particle effect on liquid breakdown is associated with the effective stressed area, the
duration of electric stress and the viscosity of the liquid itself. In addition, the streamer
imaging tests revealed that the detrimental effect of cellulose particles on breakdowns in
liquids is due to the promotion on streamer initiations rather than on streamer
40
propagations. This paper presents experimental studies on the effect of cellulose particles
on breakdown voltages and breakdown mechanisms of a synthetic ester and a natural ester
under standard lightning impulse voltages. A mineral oil was also tested and used as the
benchmark. In total, liquids with four particle contamination levels, i.e. low, normal,
marginal and high; two moisture levels, i.e. dry and wet conditions, and three types of
electrodes, i.e. plane-plane, rod-rod, and VDE electrodes were investigated- Results
showed that the presence of cellulose particles reduces the 50% breakdown voltages of
the ester liquids and the mineral oil in uniform fields, which is further enhanced when the
particle is combined with the moisture. The particle effect on breakdown voltages also
becomes more prominent when the effective stressed area/volume of the electrode
configurations is increased. Nevertheless, at the same conditions, 50% lightning impulse
breakdown voltages of the ester liquids are always comparable to that of the mineral oil.
Linking with previously published results under AC voltages, it is summarised that the
particle effect on liquid breakdown is associated with the effective stressed area, the
duration of electric stress and the viscosity of the liquid itself. In addition, the streamer
imaging tests revealed that the detrimental effect of cellulose particles on breakdowns in
liquids is due to the promotion on streamer initiations rather than on streamer
propagations.
42669
Akshatha A. et.al
Laboratory validation of method of solvent extraction for removal of sulphur
compounds from mineral oil
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2572
- 2580
The presence of corrosive sulphur compounds in mineral oil is a serious problem affecting
the life of transformers. There are several techniques available to remove corrosive
sulphur and among them the method of solvent extraction is useful for complete removal
of sulphur compounds. In this investigation, laboratory experiments were carried out to
validate method of solvent extraction for removal of sulphur compounds like Dibenzyl
disulphide and Mercaptan sulphur from mineral oil. The optimum oil to solvent ratio,
solvent to co-solvent ratio are investigated and discussed. Efficiency of method of solvent
extraction for removal of sulphur compounds is demonstrated on a laboratory scale and
further improvements to properties of mineral oil is proposed by the use of conventional
reclamation techniques.
42670
Cavallini, A. et.al
The effect of magnetite, graphene oxide and silicone oxide nanoparticles on dielectric
withstand characteristics of mineral oil
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2592
- 2600
In this work, we compare the dielectric withstand performance of nanofluids prepared
using Shell Diala D as a base fluid, and magnetite, graphene oxide and silicone dioxide as
nanoadditives. The ac withstand capability of the nanofluids was investigated as well as
partial discharge inception voltage, partial discharge and repetition rate under ac, dc
positive and dc negative voltages. The results indicate that, for all nanofluids,
nanoparticle concentrations around 0.2 g/l enhance dielectric withstand properties under
41
quasi uniform fields. Under divergent fields, partial discharge characteristics are improved
under ac conditions. Under dc conditions silica nanofluid performs better than mineral oil,
but the other two nanofluids do not perform well.
42671
Yuandi Lin et.al
Effect of oil replacement on furfural analysis and aging assessment of power
transformers
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2611
- 2619
Furfural analysis is considered as a reliable method to estimate aging of cellulose
insulation paper and is widely applied in assessing the condition of field transformers.
However, the actual concentration of furfural in insulating oil is influenced by oil
replacement, and the correction method is seldom studied. In this research, an
accelerated thermal aging test of oil-paper samples was conducted at 130 °C for 35 days.
Insulating oil was replaced at early, middle, and late aging stages to investigate furfural
loss during the oil replacement process and its effects on assessing the aging of insulation
paper. Results showed that furfural in oil obviously declined after oil replacement, which
caused a severe error in paper aging evaluation. To correct furfural loss, the furfural
correction factor, which is defined as the ratio of the furfural content in oil after oil
replacement to the furfural content before oil replacement, was introduced into the
furfural analysis method. The parameters and influencing factors of the furfural correction
function were researched. The furfural correction function was verified using
experimental data obtained under laboratory conditions and field data collected from 44
in-service transformers. The results showed that the furfural correction function
effectively corrects furfural loss during oil replacement and improves the accuracy of
estimating paper aging. Finally, the furfural correction function was extended to the
operating conditions of field transformers.
42672
Zhe Wang et.al
Breakdown characteristics of oil-paper insulation under lightning impulse waveforms
with oscillations
EEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2620
- 2627
The non-standard lightning impulse waveforms (N-SLIWs) including oscillating lightning
impulses, very fast transient voltages (VFTOs) and steep waveforms in the power system
gravely endanger the inner insulation of power transformer. To prevent insulation failure
and provide guidance for robust transformer design, in this paper, two typical insulation
models of oil-immersed transformer were established and their breakdown characteristics
under N-SLIWs were investigated. The research mainly focused on the influence of front
time and oscillation frequency of N-SLIWs on the breakdown characteristics. The
experimental results showed that the breakdown voltage increased with the decrease of
front time. For low frequency-oscillating lightning impulse waveforms (LF-OLIWs),
breakdown voltage increased with the increase of oscillation frequency and was up to 30%
higher than that under standard lightning impulse waveform (SLIW). For VFTOs, with the
increase of frequency, breakdown voltages presented a law of inverted "U" type. Insulation
42
model could withstand the highest value of VFTO when the oscillation frequency was
around 2.4 MHz. But when the frequency was as high as 9 MHz, breakdown voltage was
close to that under SLIW. A very high frequency oscillation was the main reason for the
reduction of breakdown voltage as its steepness dV/dt assisted the effective transmission
of the sphere's potential to the head of the streamer channel.
42673
Du B.X. et.al
Interface charge behavior of multi-layer oil???paper insulation under DC and polarity
reversal voltages
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2628
- 2638
Transformer oil, insulating paper, high voltage direct current (HVDC) bushings and on-load
tap changer (OLTC) are essential parts of converter transformers. When the power flow of
the HVDC system is reversed or a sudden outrage occurs, the charge field will deform the
dielectric internal electric field, thus easily leading to the occurrence of discharge or
insulation damage. In this case, it is necessary to carry out the characterization of the oilpaper interface to avoid these consequences. This paper analyses the interface charge
accumulation and dissipation characteristics of an oil-paper insulation system under DC
and polarity reversal voltages. In this paper, induced electrification was used to charge
the composite oil-paper insulation. The amplitude of DC and polarity reversal voltages
applied in this paper was 4 kV, and paper with thicknesses of 0.08 and 0.13 mm was used.
This research offers a theoretical exploration to optimize the transformer oil- paper
insulation structure and prevent damage to its insulation systems. From the research on
different layers and thicknesses of paper, it can be concluded that the decay is fast in the
initial period and then becomes slower with the lapse of time until finally the decay curve
tends to become flat. With an increase in the number of the paper layers, the interface
charge density decreases. So in real life multilayer paper is used to avoid failures owing
to its structural weakness. Regarding the DC polarity reversal effect, increasing the
thickness of the paper is equivalent to adding paper layers. The dissipation rate of the
positive interface charge is quicker than that of the negative one. In the polarity reversal
test, the dissipation rate becomes smaller as the reversal time gets longer.
42674
Jian Wu et.al
Complex flow patterns at the onset of annular electroconvection in a dielectric liquid
subjected to an arbitrary unipolar injection
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2637
- 2645
We numerically investigated the annular electroconvection that takes place in a dielectric
liquid lying between two concentric cylinder electrodes. A uniform injection of arbitrary
strengths either from the inner or outer cylinder introduces free charge carriers into the
system, and the resulting Coulomb force induces electroconvection. The problem is
characterized by a linear instability that corresponds to the onset of flow motion. The
linear stability criteria were determined from direct numerical results and by linear
stability analysis, and the results obtained with the two approaches show an excellent
agreement. We focused on the fully developed flow pattern in the finite amplitude regime.
43
We observed very different flow motions that were highly dependent on the injection
strength.
42675
Ju Tang et.al
Influence of microbubbles motion state on partial discharge in transformer oil
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2646
- 2652
To study the influence of microbubbles motion state on partial discharge (PD) in
transformer oil, an experimental platform of suspended microbubbles in transformer oil is
established. Deformations of suspended microbubbles in mobile and stationary states are
observed. The Ultra-high frequency (UHF) and pulsed current methods are applied to
detect the PD of mobile and stationary microbubbles. In addition, the time-frequency
characteristic of different PD is analyzed, and an x-U-N map is constructed. A deformation
parameter (c) of microbubble is defined, and the electric field distribution is analyzed
with the change of c. The results show that oil flow has a significant influence on the PD
of microbubbles. When the motion state of microbubble changes from stationary to
mobile, we find that the stretched shape of microbubble changes from horizontal ellipsoid
to vertical one, the PD inception voltage increases, and the electric field strength inside
microbubble decreases. Therefore, mobile microbubbles are harder to lead to PD than
stationary microbubbles, signifying that increasing the oil flow helps to enhance the
dielectric strength of oil.
42676
Ming-xiao Zhu et.al
Influence of thermal degradation on surface discharge characteristics for oilpolypropylene insulation
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2661
- 2668
Oil-polypropylene (PP) composite insulation has been widely used in power capacitors,
and also being extended to other equipment such as specific transformers, etc. As
discharge can readily creep along PP surface, the interface between oil and PP is a weak
point in the insulation structure. The oil-PP insulation degrades under the impact of
thermal and electrical stress during normal operation. In this study, the influence of
thermal degradation on surface discharge characteristics for oil-PP insulation is
investigated. Degraded samples are obtained by thermally accelerated aging of virgin oilPP samples. The microscopic morphology of PP samples are observed with SEM, and the
physical and electrical properties of degraded oil are measured. In addition, the
isothermal surface potential decay (ISPD) measurement is employed to investigate the
charge keeping capability of PP samples. After that, surface discharge detection
experiments under AC voltage are performed for the virgin and degraded samples. The
ISPD results indicate that charge decay rate of degraded PP sample is faster than virgin
sample, which imply that space charge memory effect of virgin PP samples is more
remarkable. For this reason, the PD inception phase of virgin sample is smaller than those
of degraded samples. It is found that thermal degradation of oil-PP insulation enhances
the surface discharge activity. It is considered that rough surface profile and higher bubble
44
conservation capability of degraded PP sample, and impurities in degraded oil are
responsible for the enhancement effect of thermal degradation on surface discharge.
42677
Chirkov V.A.et.al
Simulation of the integral electric current characteristics of unsteady-state current
passage through liquid dielectrics
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2763
- 2769
The paper presents the technique for computing current-time characteristics of the
transient regime, taking place after the pulsed application or change of high voltage, and
dynamical current-voltage ones obtained with the voltage saw tooth modulation. The basis
of the simulation is the complete set of electrohydrodynamic equations with both the
convective and the migration mechanisms of charge transport being taken into account
jointly. The numerical calculations were performed using commercial software package
COMSOL Multiphysics based on the finite element method. The simulation was carried out
for the needle-plane electrode system. The unsteady-state current passage processes,
including electrohydrodynamic flow formation, were calculated. The interrelation
between the latter and the total current passing through the electrical circuit were
investigated. The shape and features of the current-voltage characteristics obtained with
the voltage saw tooth modulation were shown to be dependent on the mechanism of
charge formation. The qualitative comparison between the simulated dynamical currentvoltage characteristics and the original experimental data has shown a good agreement.
42678
Traore P. et.al
Numerical study of a plane poiseuille channel flow of a dielectric liquid subjected to
unipolar injection
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2779
- 2785
In this paper, the interaction between a plane Poiseuille channel flow and an electroconvective movement induced by the electric field is numerically investigated. A flow is
generated by an inlet parabolic profile in a rectangular duct. Space charges are injected
in the flow through a metallic electrode placed on one of the channel walls and brought
to a given potential. Transient numerical simulations have been carried out to investigate
the structure of the flow. The entire set of the coupled Navier-Stokes and EHD equations
is solved using an efficient finite volume technique. The behavior of the flow subjected to
an applied voltage between the two electrodes is analyzed and time evolution of the
charge density distributions is presented. The interaction between the convective
movement induced by space charge injection and electric field and the mainstream flow,
emphasizes the appearance of periodic transverse traveling waves convected in the
channel. The dynamic of the flow through the variation of the ionic mobility parameter M
is investigated. For a given Reynolds number and ionoc mobility parameter M it exists a
threshold value Tc of the instability parameters T above which the transverse traveling
rolls appear or not. When T is increased, different flow regimes have been highlighted
starting from a complete steady state up to a fully unsteady electro-plumes flow
configuration.
45
42679
Akshatha A. et.al
Study of degradation of sulphur compounds and depletion of metal passivators during
thermal ageing of mineral oil
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2786
- 2797
Presence of sulphur compounds in mineral transformer oil poses serious problems of
corrosion of copper conductors. Thermal degradation of sulphur compounds like DBDS, 2mercaptobenzothiozole and depletion of metal passivators like Irgamet 39 and BTA in
mineral oil are complex processes. This paper presents results of investigations on
degradation of mineral oil with these additives under thermal ageing in air and nitrogen.
Efforts are made to explain independently the observed degradation of DBDS, 2mercaptobenzothiozole and depletion of Irgamet 39 and BTA over a range of
temperatures. The effect of sulphur compounds on the performance and depletion of BTA
and Irgamet 39 are also explained. Irgamet 39 and BTA deplete in oil under thermal ageing
to lower levels, but continue to protect copper from corrosion due to their adsorption by
paper which acts as reservoir of metal passivators. The advantages and limitations in the
use of Irgamet 39 and BTA are also discussed. To further substantiate the results of the
study, effect of these additives on acid formation, interfacial tension and copper ion
concentration are discussed.
42680
Dukhi, V. et.al
Unique antioxidant and sulfur corrosion retardant properties of transformer oil
blended with turmerone extract
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2798
- 2808
One of the most detrimental effects associated with transformer insulating materials
(paper and oil) and copper windings is the corrosive action of certain sulfur components
found in transformer oil. Consequently, transformer oil is typically blended with both
antioxidant and anti-corrosive agents in an attempt to prolong ageing effects and hinder
copper sulfide deposition respectively. This study focusses on the effect antioxidants have
on corrosive sulfur deposition on copper metal surfaces. To this end transformer oil was
blended with a natural extract from turmeric powder and tested for its ability to act as
an antioxidant and to retard copper sulfide deposition. The efficacy of this blended oil
was compared with that of oil blended with either of two commonly used antioxidants,
namely, 2,6-di-tert-butyl- 4-methylphenol or 2,6-di-tert-butylphenol. Tests for corrosive
sulfur showed that for the turmerone oil blend there was a substantial delay in the onset
of copper sulfide deposition on the surface of copper metal. Open circuit potential studies
showed that the turmerone fraction that was blended into the transformer oil was
adsorbed onto the copper surface. This unique property was not observed for the other
two antioxidants in this study and can account for the retardation of copper sulfide
deposition. In addition, the turmerone-virgin oil blend did not alter the thermal stability
of the Kraft insulation paper in direct contact with the oil. The performance of the
turmerone oil blend as a dual antioxidant and retardant of copper sulfide deposition
46
renders it eminently suitable for extending the lifetime of insulation in fluid-filled
transformers.
42681
Shengchang Ji et.al
SF6 decomposition of typical CT defect models
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2864
- 2870
Detection of decomposition products is a newly-emerging method for the condition
diagnosis of SF6-insulated equipment. Based on the two grading structures that are
commonly adopted in SF6-insulated current transformers (CT), three models consisting of
the needle-to-plane, the ball-to-plane, and the plane-to-plane were established. Gas
decomposition was investigated in a 90 L discharge chamber under operating conditions.
Products were analyzed with gas chromatography (GC) and X-ray photoelectron
spectroscopy (XPS). Typical gas decomposition products are CF4, SO2F2, CS2, SO2, and
S2OF10. For the needle-to-plane with a gap of 30 mm, near-linear growths with time are
observed in the concentrations of SO2F2, SO2, and S2OF10 when the applied voltage is set
as 33 kV. Addition of the adsorbent suppresses the concentrations of all three products,
especially SO2. Besides, CF4 and CS2 are also found to be the characteristic components
of partial discharge involving polyester films. And their concentrations are higher when
the electric field lines are parallel to the surface of the polyester. As for the polyester
films, the atomic ratio of C decreases, the atomic ratio of S increases, and the atomic
ratio of F increases significantly as the deterioration becomes more serious. Moreover, the
concentration ratio of S2OF10/SO2F2 in the needle-to-plane is mostly within the range of
0- 2, whether with the addition of adsorbent or not. And the ratio is much higher (2-10)
when polyester is involved in the discharge process. It could be used to diagnose the
insulation condition of CT effectively.
42682
Xuebao Li et.al
Statistical characteristics and stochastic model of DC corona-generated sound pressure
pulses from single corona source
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2898
- 2906
The sound pressure level (SPL) has been generally accepted in the measurement and
evaluation of degree of nuisance to the corona-generated audible noise from transmission
lines. Quite many scholars have studied the spectrum and statistical characteristics of the
SPL from transmission lines through the long-term frequency measurement. In fact, the
corona sources on the transmission lines usually act as sound sources emitting sound
pressure pulses with random amplitudes and random time intervals, yet the statistical
characteristics of the random sound pressure pulses and their correlation to the SPL have
barely been investigated. In this paper, a series of experiments with single positive corona
source in a coaxial cylindrical structure were carried out to investigate the statistical
characteristics of the pulse amplitudes and time intervals of sound pressure pulses. In the
experiment, time-domain measurement for the audible noise was employed. Based on the
statistical results, a stochastic model was developed to simulate the sound pressure
pulses. The validity of the stochastic model was testified by comparing the simulated and
measured A-weighted sound pressure levels. On the basis of the stochastic model, the
47
influence of random pulse amplitudes and time intervals of the sound pressure pulses on
the resultant SPL was demonstrated.
42683
Qingguo Chen et.al
Flow electrification characteristics of oil-pressboard insulation under ac superimposed
on DC electric field
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2915
- 2922
Converter transformer plays an important role in the HVDC transmission system. The valve
side insulation in converter transformer withstands AC superimposed DC electric field
during operation. In order to investigate the flow electrification characteristics of oilpaper insulation under the AC superimposed DC electric field, an oil-paper tube model
with concentric cylindrical electrode geometry was built in laboratory. Experiment study
on flow electrification under DC electric field was carried using the closed oil circulating
system, and the influence rule and mechanism of amplitude of AC superimposed DC
electric field, the DC component ratio and oil flow velocity on the flow electrification was
analyzed. The experiment results demonstrated that influences of oil flow velocity and
amplitude of applied voltage on streaming currents were related to temperature. At low
temperature the streaming currents increased linearly with flow velocity and amplitude
of applied voltage. Increase the DC component ratio enhanced the streaming currents. At
high temperature the streaming currents increased exponentially with flow velocity and
showed peak effect with amplitude of applied voltage. The peak point voltage decreased
with the DC component ratio. The theoretical analysis based on the experiment results
demonstrated that ions generation speed at the oil-paper interface depended on the
dissipation speed of positive and negative ions. Saturation of negative ions migration
current in the paper and leakage current at the outer electrode lead to peak effect of
streaming currents. Changing of temperature can influence the flow electrification
characteristics by affecting the ions migration speed and the electric field distribution in
the insulation.
42684
Kiiza R.C. et.al
The effect of partial discharge by-products on the dielectric frequency response of oilpaper insulation comprising of a small cavity
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2923
- 2930
This work investigates the effect of alternating current partial discharge (AC PD)
byproducts on the dielectric frequency response (DFR) of oil-paper insulation comprising
of a small cavity, in the frequency range of 1.0 mHz to 1.0 kHz. The investigations were
done by utilizing experimental results in combination with a Finite Element Method (FEM)
model. The results presented in this paper show that ageing by-products in the cavity (PD
stressed volume) alone will not result into the change in DFR of oil-paper insulation.
According to simulation results, the significant change in the DFR results is mainly caused
by PD by-products (positive and negative charges, and electrons) which tend to conduct
or diffuse into the bulk of oil-paper insulation. The change in a dissipation factor curve
due to PD by-products was observed to occur mainly in the middle and low frequency
48
regions. The results indicate that the dissipation factor curves in the middle and low
frequency regions depend on the level of PD by-products in oil and paper, respectively.
42685
Yi Cui et.al
Understanding Moisture Dynamics and Its Effect on the Dielectric Response of
Transformer Insulation
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2195 - 2204
Dielectric response measurement has recently been adopted by utilities for evaluating
moisture content in cellulose insulation (paper and pressboard) of transformers. Moisture
distribution is highly dependent on temperature. Since the temperature inside a
transformer may change during the dielectric response measurement, the moisture in the
transformer's cellulose and oil insulation can hardly attain an equilibrium state. Instead,
moisture dynamics exist inside the transformer: 1) cellulose absorbs (desorbs) moisture
from (to) oil with the changes in temperature and 2) moisture migrates inside cellulose
due to a moisture gradient. This paper investigates moisture dynamics and its effect on
the dielectric response of a transformer's cellulose insulation. It proposes a distributed
parameter model to reveal the correlation between moisture distribution (under
nonequilibrium conditions due to thermal transients) and dielectric response parameters
(dielectric losses and permittivity) of cellulose insulation. It then estimates these
parameters under moisture nonequilibrium conditions. The accelerated ageing and
moisture diffusion experiments are conducted on a prototype transformer to verify the
proposed model. The methodology developed in this paper can help the proper
interpretation of dielectric response measurement of field transformers under thermal
transients.
4. LAMPS AND LUMINAIRES
42686
Yoo-Chae Chung et.al
Low-Cost Drive Circuit for AC-Direct LED Lamps
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5776 - 5782
This paper proposes a drive circuit for ac-direct LED lamps. The proposed circuit consists
only of a line filter, an LED bridge, a load inductor, a bidirectional switch, and a switchcontrol circuit. The switch connects the LED bridge to the power line directly. Each leg of
the LED bridge consists of LEDs and a protection diode, all connected in series. The load
inductor limits the bridge current. The switch operates at a zero current switching
condition, so the circuit has high power efficiency. The circuit can operate at a free-volt
input condition (85 <; Vin,rms <; 265 V). For all input voltage conditions the circuit had PE
> 89%, luminous efficiency ~90 lm/W, power factor >0.9, and 120-Hz flicker index ~0.3.
The circuit satisfies the IEC 61000-3-2 Class C and the EN 55015 regulations. The proposed
LED driver is well suited for use in household LED lamps.
49
42687
Xiaohui Qu et.al
An Improved LCLC Current-Source-Output Multistring LED Driver with Capacitive
Current Balancing
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5783 - 5791
Passive or active current balancing circuits are usually used to mitigate current imbalance
in driving multiple light-emitting-diode (LED) strings. Passive current balancing schemes
adopting capacitors with high reliability, small size and low cost are very popular in many
applications. However, the high reactive power of the capacitive balancing scheme with
variable frequency control will bring high power stress on the VA rating of the main
switches which drive this passive current balancing circuit and decrease the overall
efficiency. Fixed frequency control does not permit zero-voltage switching (ZVS) under
load variations. Hence, this paper proposes a current-source-output LED driver based on
LCLC resonant circuit to provide a constant output current regardless of variations in LED
parameters. In the LCLC circuit, the number of additional capacitors is scalable with the
number of LED strings for current balancing. Moreover, the input impedance of the
improved LCLC circuit is designed to be resistive at the operating frequency to minimize
reactive power. The conventional duty cycle control can easily incorporate ZVS. The
analysis, implementation and verification are detailed in this paper.
42688
Wai Man Ng & Hui S.Y.R.
Ultralow-Loss Passive T5 Fluorescent Lamp Ballasts for Subzero Temperature
Operation
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5792 - 5799
Ultralow-loss passive ballasts for T5 fluorescent lamps have previously been proven to be
more energy efficient than their electronic counterparts at room temperature operation.
The absence of electrolytic capacitor, switched-mode circuit, and control integrated
circuit makes them particularly suitable for extreme temperature conditions. This paper
first describes the challenges required for low-temperature operation and frequent
ignition of T5 high-efficiency lamps. Then, the design of passive inductive-capacitive (LC)
ballast for T5 28-W lamps based on a physical discharge lamp model is illustrated. To
reduce the blackening effects of the filaments, a bypass resistor is incorporated to each
filament to avoid local hot spot formation. Frequent ignition tests have been conducted
for the proposed ballast and electronic ballast to confirm the effectiveness of the bypass
resistors in protecting the filaments.
42689
Rongli Zhao et.al
The Dynamic Control of Reactive Power for the Brushless Doubly Fed Induction Machine
With Indirect Stator-Quantities Control Scheme
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5046 - 5057
Compared to the doubly fed induction machine (DFIM), the brushless doubly fed induction
machine (BDFIM) has higher reliability by virtue of the absence of a brush gear. Recent
research on structure optimization design and control strategy of BDFIM has made
remarkable progress. BDFIM indirect stator-quantities control (ISC) is a new control
50
strategy, which, in comparison to vector control strategy, requires fewer parameters and
does not need rotating coordinate transformation. This paper further develops the
dynamic control of reactive power for the BDFIM with ISC scheme. Detailed theoretical
analysis is done to show the controller structure of the reactive power. The experimental
results of the prototype show the feasibility of the proposed scheme. As a result, the
proposed ISC controllers have been able to control not only speed and torque, but also the
reactive power.
42690
Tsorng-Juu Liang et.al
A Novel Line Frequency Multistage Conduction LED Driver With High Power Factor
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5103 - 5115
This paper proposes a novel line frequency multistage conduction LED driver with currentlimiting mechanism. By operating the LED driver in multistage conduction, the number of
LEDs can be automatically adjusted to be driven with low ac voltage, which increases the
LED utilization rate. The current-limiting mechanism offers overcurrent protection to the
LEDs. With the aim of shaping the input current into a sinusoidal waveform, the number
of LEDs and the current-limit values are determined by the proposed analysis methods;
these steps improve the power factor (PF) and the total harmonic distortion of input
current (THDi). Finally, two prototype circuits--two-stage conduction and three-stage
conduction LED drivers- are built to verify the performances, such as LED utilization rate,
THDi, PF, and system efficiency.
5. MATERIALS
42691
Macey C
Unconventional Binders in Refractory Concrete for Cement Plant Use
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4229 - 4232
The physical properties of three 60% alumina monolithic refractories with different types
of binders were evaluated to determine the optimum conditions of use and product
selection for several applications within a cement pyro-processing train.
42692
Meichsner C. et.al
Protective layer of AL2O3 nanocomposites and surface composition after electrical
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2944
- 2950
The performance of nanocomposites for improved resistance to electrical discharges has
resulted in increased interest in nano-loaded thermosetting resins. First assessments of
the performance of new systems can be obtained by a plate-electrode construction
according to IEC(b). Epoxy resins loaded with different amounts of spherical alumina
particles were tested following this procedure and parameters such as erosion depth and
51
standardized volume analyzed. Transmission electron microscopy (TEM) and a threedimensional (3D) reconstruction using electron tomography were used to determine the
particle size distribution. TEM analysis after preparation of the eroded samples indicates
the advantages and disadvantages of using alumina nanoparticles to improve the erosion
resistance and showed a novel effect of the surface-grafted polysiloxanes. A comparison
with conventional nano-silica-loaded resins reveals that the lower sintering tendency of
Al2O3 is important.
42693
Zhenjun Zhang
Surface flashover characteristics in polyimide/ZnO nanocomposite under DC voltage in
vacuum
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 5951
- 5957
It is well known that the solid materials flashover phenomenon is very complicated and
influenced by many factors, such as surface conditions, electrodes and traps, etc. In this
paper, dc flashover experiments of polyimide (PI) and PI/ZnO nano-composite are studied
in vacuum to reveal the surface flashover mechanism. The trap levels and space charge
distributions were obtained by thermally stimulated current (TSC) and pulsed electroacoustic (PEA) methods respectively. Further researches on surface states of flashover
tested sample, such as observation by scanning electron microscopy (SEM), and
measurement of secondary electron emission (SEE) coefficient, were carried out as well.
Experimental results showed that the dc surface flashover voltage of PI/ZnO nanocomposite is significantly enhanced compared to that of pure PI. The experiments results
can be explained as that the doped ZnO nano-particles introduced deeper traps, which can
reduce the level of charge carrier mobility, secondary electron emission and space charge
accumulation. Meanwhile, the gas desorption efficiency of nano-composite is much lower
than that of pure PI. It suggests that the doped ZnO nano-particles plays a critical role in
affecting the surface flashover performance under dc voltage in vacuum.
42694
Danli Xie et.al
Highly hydrophobic and partially conductive polydimethylsiloxane surface produced by
direct fluorination and subsequent annealing
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2968
- 2977
Highly hydrophobic materials are of interest in many scientific and technological areas. To
improve surface properties of polydimethylsiloxane (PDMS), PDMS sheets were surface
fluorinated in a laboratory vessel using a F2/N2 mixture with 12.5% F2 by volume at about
55 °C under 0.1 MPa for different times of 15, 30, and 60min. Surface wettability and
surface energy were evaluated by contact angle measurements and surface energy
calculations, and surface electrical properties were investigated by measurements of
surface conductivity and surface potential decay. These results show that direct
fluorination produced a highly hydrophobic and partially conductive PDMS surface with low
surface energy, which had little correlation with fluorination time in the investigated
range of 15 to 60 min. Moreover, annealing of the surface fluorinated PDMS sheets at 150
°C for 60 min caused a further increase in surface hydrophobicity, while reduced surface
conduction of the fluorinated PDMS sheets. Attenuated total reflection infrared analyses
and scanning electron microscope surface and cross-section observations reveal
52
substantial changes in physicochemical characteristics of the sheet surface layers due to
direct fluorination. The high hydrophobicity or low surface energy is attributed to the
changes in chemical composition and structure of the surface layers and in their surface
roughness. The partial conductivity of the fluorinated PDMS surfaces is a result of the
competition between the compositional change and the structural change.
42695
Allen B. et.al
Investigation into the effects of environmental stresses on RTV-1 silicone-based caulk
materials
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2978
- 2986
Single component room temperature vulcanized (RTV-1) caulks are used in a variety of
electrical and other applications. In high voltage Non Ceramic Insulators (NCIs) they are
used as part of a triple seal system near the metal end-fittings to protect insulators against
environmental stressors including moisture and acid ingress and salt contamination. In
service they must resist chemical aging for long periods of time. MacLean Power Systems,
Inc. provided three RTV-1 caulk materials for evaluation, of which all three materials
maintained their hydrophobicity or increased their hydrophobicity during acid immersion
and UV/condensation tests. However, all three materials showed significant mass and
hydrophobicity loss upon exposure to salt water at elevated temperatures. Our results
show that RTV-1 materials perform differently when compared to Silicon Rubber (SIR)
insulator shed materials as reported in the literature when exposed to acid immersion.
This is due to the absence of aluminum hydroxide in RTV-1, also referred to as aluminum
trihydrate (ATH). Additional acid immersion testing was conducted with ATH resulting in
depolymerization of the RTV-1 material.
42696
Ilhan S. et.al
Numerical and experimental investigation of the effects of pollution on glass
suspension-type insulators
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2987
- 2994
This study presents both numerical and experimental results regarding the effects of
pollution on the flashover performance of glass suspension-type insulators. The finite
element method (FEM) was used for simulating polluted insulators both at power frequency
and at lightning impulse voltages. Partially conductive epoxy resin with graphite powder
was used for modeling pollution on the insulators, which enabled the measurement of the
electrical potentials on the polluted insulators. Numerical studies demonstrated the
variations in the field distributions caused by the location and severity of the pollution as
well as by the type of voltage applied. The simulations, which were verified to a degree
through measurement, showed that pollution conductivities greater than 10-6 S/m and 103 S/m alter field distributions for power frequency and lightning impulse voltages,
respectively. Unlike the results obtained for partially polluted insulators, the voltage
distribution was almost linear for fully polluted insulators. Experimental studies revealed
that the location of the partial pollution plays an important role in flashover performance
for lightning impulse voltages but has a negligible effect for power frequency voltages.
53
42697
Tiwari B. & Choudhary R.N.P.
Effect of mn on structural and dielectric properties of Pb(Zr0.5Tti0.48)O3 electroceramic
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 3046
- 3052
Lead zirconate titanate (PZT) samples were prepared near morphotropical phase boundary
(MPB) (i.e., Pb(Zr0.52-xMnxTi0.48)O3 (x = 0, 0.02, 0.06, 0.10)). These samples were prepared
using solid-state reaction technique. Formation of compounds was confirmed by X-ray
diffraction (XRD), as a part of our preliminary structural analysis. We observed a significant
change in grain size and density on the sample surface due to substitution of Mn. This
microstructural analysis of the sample surface was done by scanning electron microscopy
(SEM). Tc shift, dielectric constant improvement and reduction in the disordering of the
material were observed while doing the detailed studies of the dielectric properties.
42698
Diaham S. et.al
Novel high glass transition polyamide-imide: Tg influence on electrical conductivity at
high temperature
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 3053
– 3058
The dielectric properties of a novel high-glass transition polyamide-imide (hTg-PAI,
Tg=333°C) are investigated for its high temperature use as an insulating material in the
range above 250°C in order to extend the limit of conventional PAI (c-PAI, Tg=277°C). Four
dielectric processes are identified between 50°C and 400°C. Among them, the electrical
conduction (σ-conduction) is clearly reduced particularly in the range from 250°C to
320°C, i.e. Tg(c-PAI)≤T≤ Tg(hTg-PAI). The main reason explaining such an enhancement is
the shift of ionic conduction contribution towards higher temperatures in hTg-PAI
compared to c-PAI. In hTg-PAI, the higher-Tg value allows better controlling the free
volume expansion responsible of large ions motions in the bulk. In the range of potential
applications (i.e. 250 to 320°C), the σ-conduction of hTg- PAI has an activation energy of
2.3 eV (~221.9 kJ mol-1).
6. METTALLURGY
42699
Pittner J & Simaan M.A
Advanced Control to Reduce the Likelihood of Cobbles in the Tandem Rolling of Hot
Metal Strip
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4305 - 4312
The performance of our state-dependent Riccati equation-based controller in the face of
various extended uncertainties and disturbances was shown in our previous work to be
highly successful. In our previous investigation, we have taken the material of the
workpiece to be of one phase (austenite) and of medium and low carbon equivalents.
However, it is recognized that a disturbance such as a greater decrease in temperature
54
while processing a material of extra-low carbon equivalent could result in a change in the
phase of the workpiece. Such a change in phase can result in a wreck (a cobble) in the
mill, with resulting downtime and the possibility of equipment damage. In this paper, we
expand our previous work to examine the effects of changes in the temperature of a
workpiece of extra-low carbon equivalent and show that any resulting changes in the phase
of the workpiece are effectively handled by our controller to reduce the likelihood of
cobbles in the mill.
42700
Fuzeng Zhang et.al
Study of test method for accelerated electrolytic corrosion of iron caps of DC disc
porcelain insulators
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2937
- 2943
In order to provide reference for the operation and maintenance of porcelain insulators
on DC transmission lines, the test method for electrolytic corrosion of iron caps was studied
in National Engineering Laboratory for Ultra High Voltage Engineering Technology
(Kunming) of China, with XZP2-300 porcelain insulators that had no protection zinc collar.
The results indicated that the spray water method could simulate the field corrosion
condition when the conductivity and volume flow rate were 12 mS/cm and 6-12 L/h
respectively, and the differences in the length, width and depth of corrosion area between
the test results and the field condition were less than 8%. Besides, the differences in the
test results with spray water method from two experimenters were less than 7%. Our study
demonstrated that the spray water method proposed in this paper had good equivalence
and repeatability, which could be used to research the electrolytic corrosion problem of
iron caps of porcelain insulator on HVDC transmission line.
42701
Jooncheol Kim et.al
Electrodeposited Nanolaminated CoNiFe Cores for Ultracompact DC–DC Power
Conversion
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5078 - 5087
Laminated metallic alloy cores (i.e., alternating layers of thin film metallic alloy and
insulating material) of appropriate lamination thickness enable suppression of eddy
current losses at high frequencies. Magnetic cores comprised of many such laminations
yield substantial overall magnetic volume, thereby enabling high-power operation.
Previously, we reported nanolaminated permalloy (Ni80Fe20) cores based on a sequential
electrodeposition technique, demonstrating negligible eddy current losses at peak flux
densities up to 0.5 T and operating at megahertz frequencies. This paper demonstrates
improved performance of nanolaminated cores comprising tens to hundreds of layers of
300-500-nm-thick CoNiFe films that exhibit superior magnetic properties (e.g., higher
saturation flux density and lower coercivity) than permalloy. Nanolaminated CoNiFe cores
can be operated up to a peak flux density of 0.9 T, demonstrating improved power handling
capacity and exhibiting 30% reduced volumetric core loss, attributed to lowered hysteresis
losses compared to the nanolaminated permalloy core of the same geometry. Operating
these cores in a buck dc-dc power converter at a switching frequency of 1 MHz, the
nanolaminated CoNiFe cores achieved a conversion efficiency exceeding 90% at output
55
power levels up to 7 W, compared to an achieved permalloy core conversion efficiency
below 86% at 6 W.
7. POWER / ENERGY
42702
Zheng Chen et.al
Loss-Minimization-Based Charging Strategy for Lithium-Ion Battery
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4121 - 4129
In this paper, an optimal charging strategy for lithium-ion batteries is proposed to
minimize charging loss. To reach this target, a one-RC electric model is employed to model
the loss for the battery, and an efficiency map is measured for the charger, considering
different charging currents and voltages. A dynamic programming algorithm is applied to
determine the optimal charging current profiles for minimizing the losses of the battery
and the charger separately and collectively. Experiment results prove that the proposed
method is more efficient compared with a constant-current charging method without
influencing the charging time.
42703
Taesic Kim et.al
A Rayleigh Quotient-Based Recursive Total-Least-Squares Online Maximum Capacity
Estimation for Lithium-Ion Batteries
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 842 - 851
The maximum capacity, the amount of maximal electric charge that a battery can store,
not only indicates the state of health, but also is required in numerous methods for stateof-charge estimation. This paper proposes an alternative approach to perform online
estimation of the maximum capacity by solving the recursive total-least-squares (RTLS)
problem. Different from prior art, the proposed approach poses and solves the RTLS as a
Rayleigh quotient optimization problem. The Rayleigh quotient-based approach can be
readily generalized to other parameter estimation problems including impedance
estimation. Compared with other capacity estimation methods, the proposed algorithm
enjoys the advantages of existing RTLS-based algorithms for instance, low computation,
simple implementation, and high accuracy, and thus is suitable for use in real-time
embedded battery management systems. The proposed method is compared with existing
methods via simulations and experiments.
42704
El-Naggar A. & Erlich I.
Fault Current Contribution Analysis of Doubly Fed Induction Generator-Based Wind
Turbines
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 874 - 882
The fault current contribution of the doubly fed induction generator-based wind turbines
(DFIG-WTs) is dictated by a combination of factors, including the electrical parameters of
the machine and the controller configuration of the converters. This paper presents an
analytical derivation of short-circuit current quantities considering the controller
56
influences. Mathematical models of the short-circuit current were first developed based
on the closed-loop transfer functions, and approximate expressions for time constants and
frequencies were derived. The mathematical models and the expressions for time
constants and frequencies were later validated using a manufacturer-based simulation
model and a nonlinear optimization for parameter extraction.
42705
Hongzhi Liu & Zhe Chen
Contribution of VSC-HVDC to Frequency Regulation of Power Systems With Offshore
Wind Generation
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 918 - 926
Modern large wind farms are required to provide frequency regulation service like
conventional synchronous generation units. The frequency support capability of modern
wind farms has been widely investigated and implemented. Remotely located large
offshore wind farms are probably connected to the onshore system grid through voltagesource converter-based-high voltage direct current (VSC-HVdc) transmission systems. Due
to the decoupling of VSC-HVdc and signal transmission delay, offshore wind farms may not
be able to respond to the onshore grid frequency excursion in time and, consequently, the
stability and security of the power system will be put at risk, especially for those with high
wind penetration. This paper proposes a coordinated control scheme to allow VSC-HVdc
link to contribute to the system frequency regulation by adjusting its dc-link voltage. By
means of this approach, the dc capacitors of VSC-HVdc are controlled to absorb or release
energy so as to provide frequency support. To further enhance the system frequency
response, the frequency support from VSC-HVdc is also finely coordinated with that from
offshore wind farm according to the latency of offshore wind farm responding to onshore
grid frequency excursion. The control scheme is evaluated for both under frequency and
over frequency events, and results are presented to demonstrate its effectiveness.
42706
Ting Lei et.al
Using Improved Power Electronics Modeling and Turbine Control to Improve Wind
Turbine Reliability
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1043 - 1051
Improving offshore wind turbine reliability is a key industry goal to improve the availability
of this renewable energy generation source. The semiconductor devices in the wind
turbine power converter are traditionally considered as the most sensitive and important
components to achieve this and managing their thermomechanical stressing is vital, since
this is one of their principal long-term aging mechanisms. Conventional deterministic
reliability prediction methods used in industrial applications are not suitable for wind
turbine applications, due to the stochastic nature of the wind speed. This paper develops
an electrothermal model of the power devices, which is integrated with a wind turbine
system model for the investigation of power converter thermal cycling under various
operating conditions. The model has been developed to eliminate the problems of pulse
width modulation switching, substantially reducing simulation time. The model is used to
improve the current controller tuning method to reduce thermal stresses suffered by the
converter during a grid fault. The model is finally used to design a control method to
57
alleviate a key problem of the doubly fed induction generator-severe thermal cycling
caused during operation near synchronous speed.
42707
Zian Qin et.al
A Rotating Speed Controller Design Method for Power Leveling by Means of Inertia
Energy in Wind Power Systems
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1052 - 1060
Power fluctuation caused by wind speed variations may be harmful for the stability of the
power system as well as the reliability of the wind power converter, since it may induce
thermal excursions in the solder joints of the power modules. Using the wind turbine rotor
inertia energy for power leveling has been studied before, but no quantified analysis or
generic design method have been found. In this paper, the transfer functions from the
wind speed to electrical power, electromagnetic torque, and rotating speed are built
based on which the rotating speed controller is designed in the frequency domain for
power leveling. Moreover, the impact of other parameters on power leveling, including
the time constant of maximum power point tracking (MPPT) and the rotor inertia, are also
studied. With the proposed optimal design, the power fluctuations are mitigated as much
as possible, while the stability of the rotating speed is still guaranteed. Moreover, the
oscillation of the electromagnetic torque is also reduced, and the performance of the
MPPT is only weakened slightly.
42708
Jia-Yang Ruan et.al
Transient Stability of Wind Turbine Adopting a Generic Model of DFIG and SingularityInduced Instability of Generators/Units With Power–Electronic Interface
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1069 - 1080
A generic model of grid-connected doubly-fed induction generator (DFIG)-type wind
turbines represented by differential-algebraic equations (DAE) is proposed for short-term
transient-stability analysis. From the view of analytical research, vital simplifications are
made to the complex physical model of DFIGs, whereas characteristic dynamics are still
preserved. When the connection between the wind turbine and grid is weak, transient
voltage collapse caused by singularity-induced instability (SII) is observed and analyzed
adopting the generic model. In addition, it is shown that collapse might also occur when
state variables of the dynamical system get out of control when the connection between
the wind turbine and grid is stiff, where fast drop of dc-bus voltage occurs. Critical indices
for evaluating transient-stability performances of the DFIG are proposed and parameter
sensitivity analysis is carried out. Physical meanings of SII in generators/units with powerelectronic interface in vector-oriented control frame are generalized. Novel interaction
between the grid and these nonconventional generators/units is highlighted.
42709
Chen Zhao et.al
Equivalent Series Resistance-Based Energy Loss Analysis of a Battery Semiactive Hybrid
Energy Storage System
58
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1081 - 1091
This paper provides a theoretical analysis on the energy loss of a battery-ultracapacitor
hybrid energy storage system based on the equivalent series resistances and a pulsed
current load profile. The optimal current distribution that minimizes the overall energy
loss is proved to be solely determined by the ratio of internal resistances between battery
and ultracapacitor packs. Due to a large difference in the internal resistances, a quasioptimal current distribution can be considered to let the battery pack provide the average
load current and ultracapacitor pack supply the entire dynamic load current. This result
clearly demonstrates that the ultracapacitor pack should supply the most of the dynamic
load current not only because of battery protection, but also for energy loss minimization.
Finally, the theoretical analysis is validated by both simulation and experimental results.
Additional discussions, such as sensitivity analysis, the influence of the sizing of
ultracapacitors, and a realistic test cycle are also added for reference purposes.
42710
Prieto-Araujo E. et.al
Decentralized Control of a Nine-Phase Permanent Magnet Generator for Offshore Wind
Turbines
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1103 - 1112
This paper presents a decentralized current control approach for a nine-phase wind
turbine generator. This type of generator has three different three-phase stators sharing
the same machine yoke and connected to the grid by means of three different voltage
source back-to-back power converters. Due to the machine configuration, magnetic
couplings are present between the three stators, complicating the design and
implementation of the machine current controllers. Rather than a centralized control
approach, this paper proposes a methodology to design a decentralized machine control
to regulate the active and reactive power flowing through each stator independently. A
complete dynamic analysis is performed in order to design the controller to reduce the
coupling effects within the machine, while ensuring a proper dynamic performance. The
control strategy is validated through simulation and experimental results.
42711
Aung H.et.al
State-of-Charge Estimation of Lithium-Ion Battery Using Square Root Spherical
Unscented Kalman Filter (Sqrt-UKFST) in Nanosatellite
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4774 - 4783
State-of-charge (SOC) estimation is an important aspect for modern battery management
system. Dynamic and closed loop model-based methods such as extended Kalman filter
(EKF) have been extensively used in SOC estimation. However, the EKF suffers from
drawbacks such as Jacobian matrix derivation and linearization accuracy. In this paper, a
new SOC estimation method based on square root unscented Kalman filter using spherical
transform (Sqrt-UKFST) with unit hyper sphere is proposed. The Sqrt-UKFST does not
require the linearization for nonlinear model and uses fewer sigma points with spherical
transform, which reduces the computational requirement of traditional unscented
transform. The square root characteristics improve the numerical properties of state
covariance. The proposed method has been experimentally validated. The results are
compared with existing SOC estimation methods such as Coulomb counting, portable fuel
59
gauge, and EKF. The proposed method has an absolute root mean square error (RMSE) of
1.42% and an absolute maximum error of 4.96%. These errors are lower than the other
three methods. When compared with EKF, it represents 37% and 44% improvement in RMSE
and maximum error respectively. Furthermore, the Sqrt-UKFST is less sensitive to
parameter variation than EKF and it requires 32% less computational requirement than the
regular UKF.
42712
Urtasun A. et.al
Frequency-Based Energy-Management
Distributed Battery
Strategy for Stand-Alone Systems With
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4794 - 4808
Distributed generation is an attractive solution for stand-alone ac supply systems. In such
systems, the installation of two or more energy-storage units is recommended for system
redundancy and may also be required when there is a consumption increase following
installation. However, energy management with multiple energy-storage units has been,
but vaguely analyzed in the literature and the few studies made are based on
communication cables with a central supervisor. This paper proposes an energymanagement strategy for a multiple-battery system which makes it possible to avoid the
use of communication cables, rendering the system more cost effective and reliable. The
strategy modifies the conventional droop method so that the power becomes unbalanced,
allowing for the regulation of one or more battery voltages or currents, as required.
Furthermore, whenever the frequency is high, the PV inverters reduce their power in order
to prevent the battery from overcharge or high charging currents. On the other hand,
whenever the frequency is low, then either the noncritical loads are regulated or the
system stops in order to prevent the battery from overdischarge or high discharging
currents. Simulation and experimental validation are performed for a system with twobattery inverters, two-PV inverters, and a number of loads.
42713
Jain S. et.al
A Single-Stage Photovoltaic System for a Dual-Inverter-Fed Open-End Winding
Induction Motor Drive for Pumping Applications
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4809 - 4818
This paper presents an integrated solution for a photovoltaic (PV)-fed water-pump drive
system, which uses an open-end winding induction motor (OEWIM). The dual-inverter-fed
OEWIM drive achieves the functionality of a three-level inverter and requires low value
dc-bus voltage. This helps in an optimal arrangement of PV modules, which could avoid
large strings and helps in improving the PV performance with wide bandwidth of operating
voltage. It also reduces the voltage rating of the dc-link capacitors and switching devices
used in the system. The proposed control strategy achieves an integration of both
maximum power point tracking and V/f control for the efficient utilization of the PV panels
and the motor. The proposed control scheme requires the sensing of PV voltage and
current only. Thus, the system requires less number of sensors. All the analytical,
simulation, and experimental results of this work under different environmental conditions
are presented in this paper.
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42714
Cheng-Wei Chen et.al
Modeling and Controller Design of a Semi-isolated Multi-input Converter for a Hybrid
PV/Wind Power Charger System
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4843 - 4853
The objective of this paper is to propose the development of a multiinput dc-dc converter
(MIC) family, which is composed of isolated and/or nonisolated dc-dc converters. By
analyzing five basic isolated dc-dc converters, four isolated pulsating voltage source cells
and three isolated pulsating current source cells are generated. Moreover, a semiisolated
multiinput converter (S-MIC) for hybrid PV/wind power charger system which can simplify
the power system, reduce the cost, deliver continuous power, and overcome high-voltagetransfer-ratio problems is proposed. In this paper, the operational principle of the
proposed S-MIC is explained, the small-signal ac model is derived, and the controller design
is developed. Computer simulations and experimental results are presented to verify the
accuracy of the proposed small-signal ac model and the performance of the proposed SMIC.
42715
Yun Yang et.al
Nonlinear Dynamic Power Tracking of Low-Power Wind Energy Conversion System
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5223 - 5236
This paper addresses the use of variable structure control (i.e., sliding mode (SM) control)
for improving the dynamic performance of a low-power wind energy conversion system
(WECS) that is connected to a dc grid. The SM control is applied to simultaneously match
1) the maximum power generation of the wind turbine system from the wind with 2) the
maximum power injection of the grid-connected power converter into the grid. The
amount of energy extractable from a dynamically changing wind using the WECS with SM
control is compared with that of classic PI control. Both the simulation and experimental
results show that more energy can be harvested with the SM control as compared to the
PI control for any dynamically changing or random wind conditions.
42716
Zhen Zhang et.al
Energy Encryption for Wireless Power Transfer
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5237 - 5246
This paper presents a novel energy encryption strategy for wireless power transfer (WPT)
systems, which can effectively improve the security performance of wirelessly transferred
energy. In a WPT system, energy is expected to transfer to specific receptors as well as to
switch off other unauthorized energy transmission channels, so the security of energy
transmission is an important issue. In the proposed secure WPT system, the energy is
encrypted by chaotically regulating the frequency of the power source. Then, the
authorized receptor can receive the energy by simultaneously adjusting the circuit to
decrypt the encrypted energy based on the security key obtained from the power supply,
while the unauthorized receptor cannot receive the energy without knowledge of the
security key. Hence, a secure energy transmission channel is established to effectively
prevent unauthorized receptors from stealing the energy. In this paper, both simulation
61
and experimental results are provided to verify the validity of the proposed encrypted
WPT system.
42717
Mirhosseini M. et.al
Individual Phase Current Control with the Capability to Avoid Overvoltage in GridConnected Photovoltaic Power Plants under Unbalanced Voltage Sags
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5346 - 5351
Independent current control of each phase of a three-phase voltage source inverter under
unbalanced voltage sags is proposed to effectively meet grid code requirements for gridconnected photovoltaic power plants (GCPPPs). Under current grid codes, GCPPPs should
support grid voltages by injecting reactive currents during voltage sags. Such injection
must not allow the grid voltages of the nonfaulty phases to exceed 110% of their nominal
value. However, grid overvoltages can occur in the nonfaulty phases, especially if the
currents injected into the grid by the GCPPP are balanced. Based on a new requirement
of the European network of transmission system operators published in 2012, a
transmission system operator is allowed to introduce a requirement for unbalanced current
injection. In this letter, this grid code is addressed by controlling individual phases and
injecting unbalanced currents into the grid during voltage sags. Experimental results from
a 2.8-kV.A inverter are presented, confirming the effectiveness of the proposed control
method.
42718
Dao Zhou et.al
Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine
System with Optimized Grid Filter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5581 - 5590
The modern grid requirement has caused that the wind power system behaves more like
conventional rotating generators, and it is able to support certain amount of the reactive
power. For a typical doubly fed induction generator (DFIG) wind turbine system, the
reactive power can be supported either through the rotor-side converter or the grid-side
converter. This paper first compares the current ripples and supportive reactive power
ranges between the conventional L and optimized LCL filter, if the reactive power is
injected from the grid-side converter. Then, the loss distribution is evaluated both for the
generator and the wind power converter in terms of the reactive power done by the rotorside converter or the grid-side converter with various grid filters. Afterward, the annual
energy loss is also estimated based on yearly wind profile. Finally, experimental results of
the loss distribution are performed in a down-scaled DFIG system. It is concluded that
overexcited reactive power injected from the grid-side converter has lower energy loss
per year compared to the overexcited reactive power covered by the rotor-side converter.
Furthermore, it is also found that the annual energy loss could even become lower with
the optimized filter and thereby more energy production for the wind turbine.
62
42719
Abeywardana D.B.W. et.al
Single-Phase Grid-Connected LiFePO Battery–Supercapacitor Hybrid Energy Storage
System with Interleaved Boost Inverter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5591 - 5604
AC line integrated energy storage systems are attractive as they increase the system
efficiency by reducing the number of required power processing stages. In this paper,
operation of a recently proposed battery-supercapacitor hybrid energy storage system
(HESS) comprising two DC/AC boost converters, battery, supercapacitors, grid connection,
state of charge (SOC) estimation, and associated control systems is experimentally verified
and further improved. The improvement is achieved by a phase-shifted interleaved
operation of the boost converters. The proposed phase-shifted interleaved operation
reduces the switching frequency current ripple component in both the battery and
supercapacitor currents. Experimental results show that during the interleaved operation,
the HESS operates as expected and allocates all fast current variations to the
supercapacitor, while the battery responds to slow varying current demands. At the same
time, the control system maintains the supercapacitor voltage at around a predefined
value and the battery's SOC, estimated using an extended Kalman filter, is maintained
within the specified SOC limits.
42720
Arias M. et.al
Practical Application of the Wave-Trap Concept in Battery–Cell Equalizers
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5616 - 5631
The use of battery-cell equalizers is mandatory in order to assure that all the cells
connected in series are charged to its maximum capacity, even when they present small
differences in this parameter due to several factors, such as aging, manufacturing, or
temperature. Active equalizers, with a higher efficiency in comparison to passive ones,
have the disadvantage of using a considerable number of components. Moreover, in the
case of active equalizers with very high performance, this number can be even higher. In
this paper, the use of the wave-trap concept, widely used in telecommunication systems,
is studied. This concept allows the battery-cell equalizer to use its switching frequency as
the control variable that decides which cell is being charged. Hence, it is not necessary to
use a complex system based on a high number of controlled switches in order to determine
which cell is being charged. In this way, the number of switches (and the corresponding
driving signals) can be strongly minimized without reducing the performance of the
system. In order to proof the validity of this concept (i.e., wave traps) in the design of
battery-cell equalizers, a topology based on a half-bridge structure is also proposed in this
paper. It uses only two controlled switches in order to decide which cell is charged.
Experimental results are provided for a four-cell equalizer as a proof of concept.
42721
Dini M. et.al
A Nanocurrent Power Management IC for Multiple Heterogeneous Energy Harvesting
Sources
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5665 - 5680
This paper presents a fully autonomous power converter IC for energy harvesting from
multiple and multitype sources, such as piezoelectric, photovoltaic, thermoelectric, and
63
RF transducers. The converter performs an independent self-adapting input power
tracking process for each source. The peak power conversion efficiency measured during
single-source operation is 89.6%. With all sources enabled, the intrinsic current
consumption is as low as 47.9 nA/source. A self-starting battery-less architecture has been
implemented in a 0.32-µm STMicroelectronics BCD technology with a 2142 µm × 2142 µm
die area. The IC only requires a single-shared inductor and an external storage capacitor
for the basic working configuration. With respect to other multisource energy harvesters,
this design specifically introduces a series of nanopower design techniques for extreme
minimization of the intrinsic consumption during operation. The small chip size combined
with the limited number of required external component, the high conversion efficiency,
and the state-of-the-art intrinsic nanocurrent consumption make the IC suitable for many
critical applications with very limited available power, such as wearable devices or
unobtrusive wireless sensor networks.
2722
Qiuye Sun et.al
Hybrid Three-Phase/Single-Phase Microgrid Architecture with Power Management
Capabilities
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5964 - 5977
With the fast proliferation of single-phase distributed generation (DG) units and loads
integrated into residential microgrids, independent power sharing per phase and full use
of the energy generated by DGs have become crucial. To address these issues, this paper
proposes a hybrid microgrid architecture and its power management strategy. In this
microgrid structure, a power sharing unit (PSU), composed of three single-phase back-toback (SPBTB) converters, is proposed to be installed at the point of common coupling. The
aim of the PSU is mainly to realize the power exchange and coordinated control of load
power sharing among phases, as well as to allow full utilization of the energy generated
by DGs. Meanwhile, the method combining the modified adaptive backstepping-sliding
mode control approach and droop control is also proposed to design the SPBTB system
controllers. With the application of the proposed PSU and its power management strategy,
the loads among different phases can be properly supplied and the energy can be fully
utilized, as well as obtaining better load sharing. Simulation and experimental results are
provided to demonstrate the validity of the proposed hybrid microgrid structure and
control.
42723
Ping Lu et.al
A Compact Frequency Reconfigurable Rectenna for 5.2- and 5.8-GHz Wireless Power
Transmission
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6006 - 6010
A compact reconfigurable rectifying antenna (rectenna) has been proposed for 5.2- and
5.8-GHz microwave power transmission. The proposed rectenna consists of a frequency
reconfigurable microstrip antenna and a frequency reconfigurable rectifying circuit. Here,
the use of the odd-symmetry mode has significantly cut down the antenna size by half. By
controlling the switches installed in the antenna and the rectifying circuit, the rectenna
is able to switch operation between 5.2 and 5.8 GHz. Simulated conversion efficiencies of
70.5% and 69.4% are achievable at the operating frequencies of 5.2 and 5.8 GHz,
respectively, when the rectenna is given with an input power of 16.5 dBm. Experiment has
been conducted to verify the design idea. Due to fabrication tolerances and parametric
deviation of the actual diode, the resonant frequencies of the rectenna are measured to
64
be 4.9 and 5.9 GHz. When supplied with input powers of 16 and 15 dBm, the measured
maximum conversion efficiencies of the proposed rectenna are found to be 65.2% and
64.8% at 4.9 and 5.9 GHz, respectively, which are higher than its contemporary
counterparts.
42724
Bac Xuan Nguyen et.al
An Efficiency Optimization Scheme for Bidirectional Inductive Power Transfer Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6310 - 6319
Unidirectional inductive power transfer systems allow loads to consume power, while
bidirectional inductive power transfer (BIPT) systems are more suitable for loads requiring
two-way power flow such as vehicle to grid applications with electric vehicles. Many
attempts have been made to improve the performance of BIPT systems. In a typical BIPT
system, the output power is controlled using the pickup converter phase shift angle, while
the primary converter regulates the input current. This paper proposes an optimized
phase-shift modulation strategy to minimize the coil losses of a series-series compensated
BIPT system. In addition, a comprehensive study on the impact of power converters on the
overall efficiency of the system is also presented. A closed-loop controller is proposed to
optimize the overall efficiency of the BIPT system. Theoretical results are presented in
comparison to both simulations and measurements of a 0.5 kW prototype to show the
benefits of the proposed concept. Results convincingly demonstrate the applicability of
the proposed system offering high efficiency over a wide range of output power.
42725
Xiaohui Qu et.al
Hybrid IPT Topologies With Constant Current or Constant Voltage Output for Battery
Charging Applications
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6329 - 6337
The inductive power transfer (IPT) technique in battery charging applications has many
advantages compared to conventional plug-in systems. Due to the dependencies on
transformer characteristics, loading profile, and operating frequency of an IPT system, it
is not a trivial design task to provide the battery the required constant charging current
(CC) or constant battery charging voltage (CV) efficiently under the condition of a wide
load range possibly defined by the charging profile. This paper analyzes four basic IPT
circuits with series-series (SS), series-parallel (SP), parallel-series (PS), and parallelparallel (PP) compensations systematically to identify conditions for realizing loadindependent output current or voltage, as well as resistive input impedance. Specifically,
one load-independent current output circuit and one load-independent voltage output
circuit having the same transformer, compensating capacitors, and operating frequency
can be readily combined into a hybrid topology with fewest additional switches to
facilitate the transition from CC to CV. Finally, hybrid topologies using either SS and PS
compensation or SP and PP compensation are proposed for battery charging. Fixedfrequency duty cycle control can be easily implemented for the converters.
65
42726
Wei Zhang et.al
Loosely Coupled Transformer Structure and Interoperability Study for EV Wireless
Charging Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6356 - 6367
As the wireless power transfer (WPT) technology has been proved to be a convenient and
reliable charging method to plug-in hybrid electric vehicles and electric vehicles, the
loosely coupled transformer structure and size are the primary and fundamental concern
to design an efficient WPT system. In this paper, a double D (DD) coil and a unipolar coil
are selected to conduct the study. We focus on the coil structure design to achieve the
maximum coupling coefficient as well as efficiency with two situations: 1) with no
misalignment, and 2) with a 75-mm door-to-door and 100-mm front-to-back misalignment
at which the maximum operating capability can still be achieved. A coil size optimization
process is proposed for both the DD coil and the unipolar coil configurations. The
relationship between the size of the secondary (receiving) coil, which determines the
weight of the pad on the vehicle, and achievable maximum efficiency is studied for both
coil topologies. The interoperability between the two coil topologies is studied. The
proposed transformer structures with aluminum shielding meet human exposure
regulations of the International Commission on Non-Ionizing Radiation Protection
guidelines as a foundation. Finally, experiments validated the analyses.
42727
Seungmin Jeong et.al
Economic Analysis of the Dynamic Charging Electric Vehicle
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6368 - 6377
A wireless charging or inductive charging electric vehicle (EV) is a type of EVs with a
battery that is charged from a charging infrastructure, using a wireless power transfer
technology. Wireless charging EVs are classified as stationary or dynamic charging EVs.
Stationary charging EVs charge wirelessly when they are parked, and dynamic charging EVs
can charge while they are in motion. The online electric vehicle developed at the Korea
Advanced Institute of Science and Technology is an example of a commercially available
dynamic charging transportation system. Numerous studies have reported that one of the
benefits of dynamic charging is that it allows smaller and lighter batteries to be used, due
to frequent charging using the charging infrastructure embedded under roads. In this
paper, we quantitatively analyze the benefits of dynamic charging with an economic model
of battery size and charging infrastructure allocation, using a mathematical optimization
model. Particularly, we analyze by how much battery size can be reduced and what the
cost saving of reducing the battery size is with the model. We also show that the dynamic
charging can be beneficial to battery life.
42728
Nan Liu & Habetler T.G.
Design of a Universal Inductive Charger for Multiple Electric Vehicle Models
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6378 - 6390
66
Inductive power transfer technology has become a popular solution for battery charging
of electric vehicles (EVs). However, problems such as varied magnetic coupling caused by
coil misalignment still limit its practical applications, by safety and stability issues.
Meanwhile, the growing market of EVs asks for a universal charger for various models. This
paper presents the design process of a universal inductive charger (UIC) for EVs. The
proposed UIC is capable of adaptively providing a constant or controllable charging voltage
to various EVs, with a wide range of varied magnetic coupling between the transmitting
and receiving coils. With a series-connected LC circuit, zero-voltage switching of the
primary dc-ac inverter is universally realized in every charging cycle. A simple yet
effective control method based on the frequency variation is used to automatically select
the optimal frequency in different coupling conditions and adjust the frequency during
the charging process. The design of the charging interface is also optimized with higher
efficiency and power-transfer capability. Simulations and prototypes validate that the
proposed UIC is accurate, robust, and applicable.
42729
Fei Yang Lin et.al
Evaluation of Magnetic Pad Sizes and Topologies for Electric Vehicle Charging
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6391 - 6407
Inductive power transfer is becoming increasingly popular in stationary electric vehicle
charging systems due to improved designs. However, such optimizations are normally
performed for matched topologies which are similarly sized, over constant air gaps and
without significant misalignment. In a real situation where the primary and secondary pads
may not be matched and may be misaligned, pad designs must take into consideration
coupling factors, leakage fluxes, pad quality factors, reflected impedance, and size. This
paper analyzes the effects which variations in pad sizes, topologies, and displacements in
three dimensions has on these parameters. It was found that solenoid pads should not be
used as a primary pad due to high leakage fluxes, low native quality factors, and the fact
that they are not fully interoperable over the whole desired range of use. Bipolar pad
primaries are able to couple to any secondary pad over the entire range of use required
and tend to have high native quality factors. Nonpolarized pads tend to have the lowest
leakage fluxes but also low coupling. Suggestions on techniques to optimize these pads
have also been included.
42730
Esteban B. et.al
A Comparative Study of Power Supply Architectures in Wireless EV Charging Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6408 - 6422
This paper examines two of the primary power supply architectures being predominantly
used for wireless electric vehicle (EV) charging, namely the series LC (SLC) resonant and
the hybrid series-parallel (LCL) resonant full-bridge inverter topologies. The study of both
of these topologies is presented in the context of designing a 3-kW primary-side controlled
stationary wireless EV charger with nominal operating parameters of 30-kHz center
frequency, a range of coupling in the neighborhood of 0.18-0.26, and a parallel secondary
pick-up with partial series coil compensation. A comparison of both architectures is made
in terms of their design methodology, physical size, cost, complexity, and efficiency. It is
found that the SLC architecture is 2.45% less costly than the LCL topology. On the other
hand, it is observed that the LCL architecture achieves almost 10% higher peak efficiency
67
at rated load and minimum coupling. The study also showed that the SLC topology suffers
from poor light load efficiency, while the LCL topology maintains very high efficiency over
its full range of coupling and loading. The study also revealed that the capacitor voltage
stress is significantly higher in the SLC topology. Finally, it is also shown that the control
complexity of the SLC architecture is higher than that of the LCL architecture because of
its sensitivity to changes in the reflected secondary impedance, which result in loss of
constant current source and ZVS operation unless a suitable combination of parameters
are modulated by the closed-loop controller.
42731
McDonough M. et.al
Integration of Inductively Coupled Power Transfer and Hybrid Energy Storage System:
A Multiport Power Electronics Interface for Battery-Powered Electric Vehicles
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6423 - 6433
Detailed in this paper is a multiport power electronics interface which serves as an energy
router for on-board electric and plug-in hybrid electric vehicles with inductively coupled
power transfer (ICPT) and hybrid energy storage systems (HESS). The existing body of
literature on HESSs lacks a unified controller and modular, flexible structure as well as
integration of ICPT. In battery/ultracapacitor systems, this leads to piece-meal control of
sources resulting in battery currents which are not fully decoupled from highfrequency/high-magnitude current and ultra-capacitor (UC) state of charge (SoC) not
being properly controlled. A central controller is proposed in this paper which completely
decouples the battery from both high-frequency and high-magnitude current, controls the
SoC of the UCs, and models the SoC of the UCs in the stability analysis of the system. This
system is particularly useful for online charging of HEVs in highway-type applications
where ICPT pulse charging will be present. Solving the challenges of pulse charging will
bring ICPT technology one step closer to widespread integration which has the potential
to greatly reduce societies' dependence on fossil fuel. Simulation and experimental results
verify the feasibility of the proposed techniques.
42732
Changbyung Park et.al
Uniform Power I-Type Inductive Power Transfer System With DQ-Power Supply Rails
for On-Line Electric Vehicles
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6446 - 6455
A narrow-width power-invariant inductive power transfer system (IPTS) along the driving
direction is newly proposed in this paper. The conventional I-type power supply rail for
on-line electric vehicles (OLEVs) has a very narrow power supply rail with 10-cm width and
exposes pedestrians to a very low electromagnetic field due to its alternatively arranged
magnetic poles along the driving direction of electric vehicles; however, it has a major
drawback: Sinusoidal variation of the induced pick-up voltage depending on pick-up
positions on the power supply rail along driving direction. To overcome this disadvantage,
a dq-power supply rail fed by two high-frequency ac currents of the d-phase and q-phase
is introduced in this paper. The d -phase and q-phase magnetic poles are alternatively
arranged in a line; hence, the induced voltage of a pickup becomes spatially uniform. The
68
power invariant characteristic of the proposed IPTS for OLEV has been verified by analysis,
simulations, and experiments. A practical winding method is suggested as well.
42733
Merino J. et.al
Islanding Detection in Microgrids Using Harmonic Signatures
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2102 - 2109
In recent years, there has been a growing interest in incorporating microgrids in electrical
power networks. This is due to various advantages they present, particularly the possibility
of working in either autonomous mode or grid connected, which makes them highly
versatile structures for incorporating intermittent generation and energy storage.
However, they pose safety issues in being able to support a local island in case of utility
disconnection. Thus, in the event of an unintentional island situation, they should be able
to detect the loss of mains and disconnect for self-protection and safety reasons. Most of
the anti-islanding schemes are implemented within control of single generation devices,
such as dc-ac inverters used with solar electric systems being incompatible with the
concept of microgrids due to the variety and multiplicity of sources within the microgrid.
In this paper, a passive islanding detection method based on the change of the 5th
harmonic voltage magnitude at the point of common coupling between grid-connected and
islanded modes of operation is presented. Hardware test results from the application of
this approach to a laboratory scale microgrid are shown. The experimental results
demonstrate the validity of the proposed method, in meeting the requirements of IEEE
1547 standards.
42734
Hongyu Wu et.al
Thermal Generation Flexibility with Ramping Costs and Hourly Demand Response in
Stochastic Security-Constrained Scheduling of Variable Energy Sources
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 2955 - 2964
This paper proposes a stochastic day-ahead scheduling of electric power systems with
flexible resources for managing the variability of renewable energy sources (RES). The
flexible resources include thermal units with up/down ramping capability, energy storage,
and hourly demand response (DR). The Monte Carlo simulation (MCS) is used in this paper
for simulating random outages of generation units and transmission lines as well as
representing hourly forecast errors of loads and RES. Numerical tests are conducted for a
6-bus system and a modified IEEE 118-bus system and the results demonstrate the benefits
of applying demand response as a viable option for managing the RES variability in the
least-cost stochastic power system operations.
42735
Tabone M.D. & Callaway D.S.
Modeling Variability and Uncertainty of Photovoltaic Generation: A Hidden State
Spatial Statistical Approach
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 2965 - 2973
In this paper, we construct, fit, and validate a hidden Markov model for predicting
variability and uncertainty in generation from distributed (PV) systems. The model is
unique in that it: 1) predicts metrics that are directly related to operational reserves, 2)
69
accounts for the effects of stochastic volatility and geographic autocorrelation, and 3)
conditions on latent variables referred to as “volatility states.” We fit and validate the
model using 1-min resolution generation data from approximately 100 PV systems in the
California Central Valley or the Los Angeles coastal area, and condition the volatility state
of each system at each time on 15-min resolution generation data from nearby PV systems
(which are available from over 6000 PV systems in our data set). We find that PV variability
distributions are roughly Gaussian after conditioning on hidden states. We also propose a
method for simulating hidden states that results in a very good upper bound for the
probability of extreme events. Therefore, the model can be used as a tool for planning
additional reserve capacity requirements to balance solar variability over large and small
spatial areas.
42736
Xiaping Zhang et.al
Security-Constrained Co-Optimization Planning of Electricity and Natural Gas
Transportation Infrastructures
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 2984 - 2993
This paper presents a co-optimization planning model that considers the long-term
interdependency of natural gas and electricity infrastructures. The model incorporates the
natural gas transportation planning objective in the co-optimization planning of power
generation and transmission systems. The co-optimization planning model is decomposed
into a least-cost master investment problem for natural gas and electricity systems which
interacts with two operation subproblems representing the feasibility (security) and the
optimality (economic) of the proposed co-optimization. In addition, the natural gas
subproblem would check the feasibility of fuel supply transportation system as part of the
proposed co-optimization planning. The co-optimization planning of electricity and natural
gas infrastructures would satisfy the desired power system reliability criterion. The
iterative process will continue between the co-optimization investment and the operation
subproblems until an economic, secure, reliable, and fuel-supply feasible planning for the
two interdependent infrastructures is obtained. Numerical simulations demonstrate the
effectiveness of the proposed co-optimization planning approach.
42737
Heejung Park et.al
Stochastic Transmission Planning Model with Dependent Load and Wind Forecasts
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3003 - 3011
This paper introduces a two-stage stochastic program for transmission planning. The model
has two dependent random variables, namely, total electric load and available wind
power. Given univariate marginal distributions for these two random variables and their
correlation coefficient, the joint distribution is modeled using a Gaussian copula. The
optimal power flow (OPF) problem is solved based on the linearized direct current (DC)
power flow. The Electric Reliability Council of Texas (ERCOT) network model and its load
and wind data are used for a test case. A 95% confidence interval is formed on the
optimality gap of candidate solutions obtained using a sample average approximation with
200 and 300 samples from the joint distribution of load and wind.
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42738
Hao Xing et.al
Distributed Bisection Method for Economic Power Dispatch in Smart Grid
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3024 - 3035
In this paper, we present a fully distributed bisection algorithm for the economic dispatch
problem (EDP) in a smart grid scenario, with the goal to minimize the aggregated cost of
a network of generators, which cooperatively furnish a given amount of power within their
individual capacity constraints. Our distributed algorithm adopts the method of bisection,
and is based on a consensus-like iterative method, with no need for a central decision
maker or a leader node. Under strong connectivity conditions and allowance for local
communications, we show that the iterative solution converges to the globally optimal
solution. Furthermore, two stopping criteria are presented for the practical
implementation of the proposed algorithm, for which sign consensus is defined. Finally,
numerical simulations based on the IEEE 14-bus and 118-bus systems are given to illustrate
the performance of the algorithm.
42739
Hui Liu et.al
Vehicle-to-Grid Control for Supplementary Frequency Regulation Considering Charging
Demands
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3110 - 3119
Electric vehicles (EVs) as distributed storage devices have the potential to provide
frequency regulation services due to the fast adjustment of charging/discharging power.
In our previous research, decentralized vehicle-to-grid (V2G) control methods for EVs were
proposed to participate in primary frequency control. In this paper, our attention is on
bringing a large number of EVs into the centralized supplementary frequency regulation
(SFR) of interconnected power systems. An aggregator is the coordinator between EVs and
the power system control center. The aggregator calculates the total frequency regulation
capacity (FRC) and expected V2G (EV2G) power of EVs based on the data communicated
between the aggregator and individual EVs or EV charging stations. With FRC and EV2G
power, a V2G control strategy is proposed for the aggregator to dispatch regulation
requirements to EVs and EV charging stations. In individual EV charging stations, the FRC
is calculated on the basis of the V2G power at present time, and EV2G power is presented
considering both frequency regulation and charging demands. Besides, V2G control
strategies are developed to distribute regulation requirements to each EV. Simulations on
an interconnected power grid based on a practical power grid in China have demonstrated
the effectiveness of the proposed strategies.
42740
Zhaoyu Wang & Jianhui Wang
Self-Healing Resilient Distribution Systems Based on Sectionalization into Microgrids
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3139 - 3149
This paper proposes a novel comprehensive operation and self-healing strategy for a
distribution system with both dispatchable and nondispatchable distributed generators
(DGs). In the normal operation mode, the control objective of the system is to minimize
the operation costs and maximize the revenues. A rolling-horizon optimization method is
used to schedule the outputs of dispatchable DGs based on forecasts. In the self-healing
mode, the on-outage portion of the distribution system will be optimally sectionalized into
networked self-supplied microgrids (MGs) so as to provide reliable power supply to the
71
maximum loads continuously. The outputs of the dispatchable DGs will be rescheduled
accordingly too. In order to take into account the uncertainties of DG outputs and load
consumptions, we formulate the problems as a stochastic program. A scenario reduction
method is applied to achieve a tradeoff between the accuracy of the solution and the
computational burden. A modified IEEE 123-node distribution system is used as a test
system. The results of case studies demonstrate the effectiveness of the proposed
methodology.
42741
Skajaa A. et.al
Intraday Trading of Wind Energy
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3181 - 3189
In this paper, we tackle the problem of a wind power producer participating in a shortterm electricity market that allows for the continuous, but potentially illiquid, intraday
trading of energy. Considering the realistic case of a wind farm operating in the western
Danish price area of Nord Pool, we build a simple but effective algorithm for the wind
power producer to fully benefit from the Elbas intraday market. We then investigate the
sensitivity of the obtained benefits to the maximum volume of energy the wind power
producer is willing to trade in the intraday market, the ultimate aim of the trade (either
to decrease energy imbalances or to increase profits) and to the installed capacity of the
wind farm. Our numerical results reveal that the wind power producer can substantially
increase his revenues by partaking in the intraday market but with diminishing returns to
scale-a result that we attribute to the low liquidity of Elbas.
42742
Azzouz M.A. et.al
Real-Time Optimal Voltage Regulation for Distribution Networks Incorporating High
Penetration of PEVs
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3234 - 3245
This paper proposes a vehicle-to-grid reactive power support (V2GQ) strategy for optimal
coordinated voltage regulation in distribution networks with high distributed generation
(DG) penetration. The proposed algorithm employs plug-in electric vehicles (PEVs), DG,
and on-load tap changer (OLTC) to satisfy PEV charging demand and grid voltage
requirements with relaxed tap operation, and minimum DG active power curtailment. The
voltage regulation problem is formulated as a nonlinear programming and consists of three
consecutive stages, in which successive stages apply the outputs of their preceding stages
as constraints. The first stage aims to maximize the energy delivered to PEVs to assure
PEV owner satisfactions. The second stage maximizes the DG extracted active power. Third
stage minimizes the voltage deviation from its nominal value utilizing the available PEV
and DG reactive powers. The main implicit objective of the third stage problem is relaxing
the OLTC tap operation. In addition, the conventional OLTC control is replaced by a
proposed centralized controller that utilizes the output of the third stage to set its tap
position. Real-time simulations are developed to demonstrate the effectiveness of the
proposed optimal coordinated algorithm on a typical distribution network using OPAL-RT
real-time simulator (RTS) in a hardware-in-the-loop (HIL) application.
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42743
Yun Zhang et.al
Online Dynamic Security Assessment of Microgrid Interconnections in Smart
Distribution Systems
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3246 - 3254
This paper studies the online dynamic security assessment (DSA) of future distribution
systems in which multiple electrically coupled microgrids are operated as an
interconnection. By leveraging the highly controllable power-electronics-based interfaces,
we propose a novel interface control strategy for desirable load sharing among
interconnected microgrids. Under such a control framework, theoretical results on systemwide stability criteria in the sense of Lyapunov are obtained. Potential application of these
results for microgrid-based smart distribution system DSA is presented. Minimum
information exchange is required among microgrid modules and the distribution system
operator, which is a highly desirable feature in future distribution management systems.
Numerical studies of a five-microgrid study system designed based on the IEEE 123-node
test feeder show the effectiveness of the proposed control strategy and DSA framework.
42744
Asimakopoulou G.E. et.al
Hierarchical Decision Making for Aggregated Energy Management of Distributed
Resources
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3255 - 3264
This paper presents a bi-level model for describing the interdependence of decisions
between a retailer/aggregator and the distributed resources owners that the former serves
and represents. Decision making is performed in a hierarchical fashion. The retailer
performs the energy management of various resources indirectly; price signals are used as
incentives for inducing the entities owning the distributed resources in a behavior that
optimizes the operation and economic profit of the microgrid that they compose. The twolevel interaction is formulated mathematically as a mathematical programming problem
with complementarity constraints, while nonlinearities are replaced by equivalent linear
expressions. The results of a characteristic case study indicate the efficiency and
scalability of the proposed model.
42745
Freire L.et.al
A Hybrid MILP and Benders Decomposition Approach to Find the Nucleolus Quota
Allocation for a Renewable Energy Portfolio
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3265 - 3275
Portfolios of renewable electricity sources are interesting risk-management mechanisms
for trading in electricity contract markets. When formed by players belonging to different
companies, their stability relies on the way the benefit generated by the optimal portfolio
is allocated. The challenge of finding a fair and efficient allocation can be mathematically
formulated in terms of finding the Core of a cooperative game, which in turn is stated as
an optimization problem with a set of constraints that exponentially grows with the
number of participants, quickly becoming computationally intractable. Moreover, the
right-hand-side of each constraint relies on a given coalition value, which in our case is
obtained by a two-stage stochastic optimization model. This paper presents an efficient
methodology based on mixed -linear programming and Benders decomposition to find the
73
Nucleolus share of large-scale renewable portfolios. Case studies are presented with data
from the Brazilian power system.
42746
Wogrin S. & Gayme D.F.
Optimizing Storage Siting, Sizing, and Technology Portfolios in TransmissionConstrained Networks
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3304 - 3313
In this paper, we propose a DC optimal power flow (OPF) framework for storage portfolio
optimization in transmission-constrained power networks. In particular, this model is
designed to investigate two problems: 1) optimizing storage operation and allocation over
a network given a fixed technology portfolio and 2) optimizing the storage portfolio (i.e.,
the size, technology, and network allocation of these resources). We demonstrate this
framework using case studies based on the IEEE 14-bus test system with four different
storage technologies. Our results show that although certain technologies are generally
classified as being suitable for either power or energy services, many technologies can add
value to the system by performing both fast-time scale regulation (power) and loadshifting (energy) services. These results suggest that limiting the type of service that a
certain technology is compensated for may result in inefficiencies at the system level and
under-valuation of storage.
42747
Hao Jiang et.al
MPC-Based Frequency Control with Demand-Side Participation: A Case Study in an
Isolated Wind-Aluminum Power System
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3327 - 3337
Aluminum production relies on the smelting process which consumes huge amounts of
electrical energy. One possible solution to reduce the fossil fuel consumption by aluminum
production is the integration of wind power. Based on this background, this paper studies
an isolated power system for aluminum smelting production with a high penetration of
wind power. A dynamic model of the aluminum smelter load (ASL) is introduced in this
paper using the field experiment data. Based on this model, the dynamic model of the
isolated system considering demand side participation is proposed. The MPC-based
frequency controller is proposed to keep the frequency deviation within a proper range (
±0.1 Hz) under wind power fluctuation as well as to recover the system frequency after a
large disturbance (such as one generator trip). Finally, simulation results demonstrate the
effectiveness of the proposed MPC based frequency controller.
42748
Correa-Posada C.M. & Sanchez-Martin P.
Integrated Power and Natural Gas Model for Energy Adequacy in Short-Term Operation
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3347 - 3355
The significant growth in gas-fired units worldwide has increased the grade of
interdependency between power and natural gas networks. Since these units are usually
required to ramp up during the peak and backup intermittent renewable generation and
contingencies, the power system tends to demand more flexibility and reliability from the
gas system. This paper contributes with a novel mixed-integer linear programming (MILP)
formulation that couples power and gas networks taking into account the gas traveling
velocity and compressibility. As a result, the model accounts for the gas adequacy needed
74
to assure the power system reliability in the short term. The robustness of the MILP
formulation allows guaranteeing global optimality within predefined tolerances. Case
studies integrate the IEEE 24-bus system and Belgian high-calorific gas network for
validating the formulation.
42749
Zhengshuo Li et.al
Transmission Contingency Analysis Based on Integrated Transmission and Distribution
Power Flow in Smart Grid
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3356 - 3367
In future smart grids, with distribution networks having loops more frequently, current
transmission contingency analysis (TCA) which usually neglects the distribution power flow
variations after a contingency may leave out severe outages. With more distribution
management systems deployed on the distribution side, a new transmission CA method
based on global power flow (GPF) analysis which integrates both the transmission and
distribution power flow is proposed in this paper (named as GTCA) to address the problem.
The definition and new features of GTCA are first introduced. Then, the necessity of GTCA
is physically illustrated. Difference in the results of GTCA and TCA is mathematically
analyzed. A GPF-embedded algorithm of performing GTCA is then provided. The data
exchange process and the performance with communication interruptions are discussed.
As multiple contingencies are considered in GTCA, several approaches are proposed and
discussed to reduce communication burdens and improve the computational efficiency.
Plenty of numerical tests are performed in several systems to verify the theoretical
analysis. With theoretical analysis and numerical verification, it is suggested that GTCA
should be performed instead of TCA to avoid potential false alarms, especially in the
condition that DNs are more frequently looped in the future smart grids.
42750
Kekatos V. et.al
Stochastic Reactive Power Management in Microgrids with Renewables
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3386 - 3395
Distribution microgrids are being challenged by reverse power flows and voltage
fluctuations due to renewable generation, demand response, and electric vehicles.
Advances in photovoltaic (PV) inverters offer new opportunities for reactive power
management provided PV owners have the right investment incentives. In this context,
reactive power compensation is considered here as an ancillary service. Accounting for
the increasing time-variability of distributed generation and demand, a stochastic reactive
power compensation scheme is developed. Given uncertain active power injections, an
online reactive control scheme is devised. This scheme is distribution-free and relies solely
on power injection data. Reactive injections are updated using the Lagrange multipliers
of a second-order cone program. Numerical tests on an industrial 47-bus microgrid and the
residential IEEE 123-bus feeder corroborate the reactive power management efficiency of
the novel stochastic scheme over its deterministic alternative, as well as its capability to
track variations in solar generation and household demand.
75
42751
Rabiee A. et.al
Information Gap Decision Theory Based OPF with HVDC Connected Wind Farms
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3396 - 3406
A method for solving the optimal power flow (OPF) problem including HVDC connected
offshore wind farms is presented in this paper. Different factors have been considered in
the proposed method, namely, voltage source converter (VSC-HVDC) and line-commutated
converter high-voltage DC (LCC-HVDC) link constraints, doubly fed induction generators'
(DFIGs) capability curve as well as the uncertainties of wind power generation. Information
gap decision theory (IGDT) is utilized for handling the uncertainties associated with the
volatility of wind power generation. It is computationally efficient and does not require
the probability density function of wind speed. The proposed decision-making framework
finds the optimal decision variables in a way that they remain robust against the
considered uncertainties. To illustrate the effectiveness of the proposed approach, it is
applied on the IEEE 118-bus system. The obtained results validate the applicability of the
proposed IGDT-based OPF model for optimal operation of AC/DC power systems with high
penetration of offshore wind farms.
42752
Kawabe K. & Tanaka K.
Impact of Dynamic Behavior of Photovoltaic Power Generation Systems on Short-Term
Voltage Stability
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3416 - 3424
In this study, we investigate the impact of the dynamic behavior of photovoltaic (PV)
power generation systems on short-term voltage stability of the transmission system. First,
the impact of the fault ride-through capability of a PV model is studied by setting several
recovery speeds of the active current output when the operation of the PV system is
interrupted because of a voltage sag. The results are analyzed by using transient P-V
curves and a stability boundary, which has been proposed in our previous research.
Further, we show that the installation of PVs severely impairs the short-term voltage
stability if the PVs shut off after a voltage sag, and its recovery speed is low. Next, two
countermeasures to control short-term voltage instability phenomena are tested. One is
the operation of the PV system at a leading power factor in the normal state, and the
other is the dynamic reactive power control by the inverters of the PV system after a
voltage sag. Numerical examples are carried out for a one-load infinite-bus power system
and a five-machine five-load power system. The results show that these countermeasures
can play a substantial role in preventing the voltage instability phenomena caused when
a PV system is suddenly interrupted because of a fault.
42753
Majumder R.
An Efficient Method of Multiple Storage Control in Microgrids
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3437 - 3444
This paper proposes a control method to coordinate multiple energy storage systems (ESS)
spread across an AC microgrid. Each storage unit controls its own local node voltage (i.e.,
where the storage is connected in the network) as well as a global node voltage (i.e., a
remote location in the network) that is controlled by all ESSs together. The storage power
output is controlled in a way that the node voltage is restored and maintained in case it
76
drops or rises outside the predefined limits. This can occur due to disturbances, such as
load changes, loss of distributed generators (DGs), or power limitations in the DGs. In order
to determine the power reference for each storage unit, a state of charge (SoC) based
adaptive deadband droop control is used. In this decentralized control, the storage power
output is inversely proportional to its SoC. By using this approach, the ESS with higher SoC
will inject more power whereas storage units with lower SoC will inject less power, leading
to more balanced SoC levels among the ESSs. The controller is tested in a microgrid in
both island- and grid-connected modes in different scenarios. The microgrid includes
several DGs that operate in different control modes depending on the microgrid operation.
The storage unit configurations differ in their response time and capacity. This has
significant implication in dynamic response of the storage units which is scrutinized in this
paper with time-domain simulation.
8. POWER ELECTRONICS
42754
Bedetti N. et.al
Self-Commissioning of Inverter Dead-Time Compensation by Multiple Linear Regression
Based on a Physical Model
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015;3954 – 3964
Dead-time and switch voltage drops represent the most important sources of distortion of
the (average) output voltage in pulsewidth modulation inverters. Their effect is a function
of the parameters of the drive system and of the operating conditions and is often
intolerable in many drives applications, thus requiring a proper compensation strategy.
Many techniques are implemented in industrial drives and reported in the literature, even
very recently. Differently from standard approaches, the proposed methodology is based
on a detailed physical model of the power converter (including output capacitance),
described by a small set of parameters. A novel self-commissioning identification
procedure is introduced, adopting multiple linear regression. The technique is tested on a
commercial drive in comparison with state-of-the-art techniques. In addition, back
electromotive force estimation improvements in a permanent-magnet synchronous motor
sensorless drive system are shown to provide additional validation of the method.
42755
Alonge F. et.al
Identification and Robust Control of a Quadratic DC/DC Boost Converter by
Hammerstein Model
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3975 – 3985
This paper deals with the theoretical framework definition and the experimental
application of the Hammerstein (HM) identification and related robust control technique
to a quadratic dc/dc single-switch boost (Q-boost) converter. A set of fourth-order transfer
functions (TFs) has been identified with the Hammerstein approach, on the basis of a
pseudorandom-binary-sequence (PRBS) excitation signal. The set of identified TFs has
been then used to design a suitable robust control technique, able to properly deal with
the converter parameter uncertainty and load variations. The proposed approach has been
77
tested in numerical simulation and validated experimentally on a suitably developed test
set-up. It has been further compared with a classic proportional-integral (PI) controller.
42756
Solanki, J. et.al
Voltage-Sequence-Control-Based High-Current Rectifier System
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3995 - 4005
This paper presents a thyristor-based tap changing transformer and a diode rectifier for
variable-voltage high-current dc applications. Back-to-back thyristors are connected in
series with the transformer taps on the primary side. Thyristors are phase controlled in a
continuous manner to achieve variable ac voltage at the secondary side of the transformer.
This leads to a variable voltage at the output of the three-phase diode rectifier connected
at the secondary side of the transformer. A passive filter is added at the primary side to
achieve power factor improvement over the range of output voltage. This scheme is
optimized to determine optimum turns ratio of the transformer and optimum reactive
power rating of the passive filter. Design guidelines are presented for various values of
power factor along with optimum turns ratios and passive filter rating. A 62.5-kW
experimental system with a passive filter of 17.5 kVA (reactive) is developed to verify the
system performance. In the end, a comparison of the proposed topology with other stateof-the-art topologies is also presented.
42757
Seung-Jun Chee et.al
Common-Mode Voltage Reduction of Three-Level Four-Leg PWM Converter
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4006 - 4016
This paper presents a carrier-based pulsewidth modulation (PWM) method that reduces
the common-mode voltage (CMV) of a three-level four-leg converter. Based on an analysis
of space vector PWM (SVPWM) and sinusoidal-PWM switching patterns, the fourth-leg pole
voltage of a three-phase converter, known as the “f pole voltage,” is manipulated to
reduce the CMV. To synthesize the f pole voltage for the suppression of the CMV, positive
and negative pole voltage references of the f leg are calculated. In addition, the offset
voltage to prevent distortion of the a, b, and c phase voltages regarding the neutral point
is deduced. The proposed PWM strategy can be easily implemented in the software of a
DSP-based converter control. The three-level four-leg converter with the proposed PWM
algorithm results in a remarkable reduction in the peak-to-peak value of the CMV. From
the simulation and the experimental results, the peak-to-peak value of the CMV when
using the proposed PWM method is 33% compared to that when using the SVPWM method,
while the number of CMV transitions during the switching period in the proposed PWM
method is only 25% of that when using the SVPWM method.
42758
Myoungho Kim ewgt.al
Modeling and Controller Design for a Series-Connected Output Universal Link Converter
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015;4017 - 4027
This paper conducts modeling and controller design for a SEries-connected Output
Universal Link (SEOUL) converter. The SEOUL converter was proposed to interface multiple
distributed power sources to the grid with a reduced amount of reactive components. It
employs a high-frequency (HF) transformer instead of a bulky line-frequency transformer
78
like solid-state transformers (SSTs). In addition, it does not use a large dc-link capacitor
at the input side and reduces the size of the input filter. This is inherently possible due to
its original operating characteristic. The input phase current is not actively controlled but
synthesized indirectly by HF power transfer between input and output sides of the SEOUL
converter. Therefore, it is important to properly control the HF power transfer part, on
which this paper focuses. An analytic model is developed, and a control strategy is
proposed based on the model with a decoupling control method. The developed model and
the proposed control method were verified by experiments.
42759
Tarisciotti, L.et.sl
Multiobjective Modulated Model Predictive Control for a Multilevel Solid-State
Transformer
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4051 - 4060
Finite control set model predictive control (FCS-MPC) offers many advantages over more
traditional control techniques, such as the ability to avoid cascaded control loops, easy
inclusion of constraint, and fast transient response of the control system. This control
scheme has been recently applied to several power conversion systems, such as two, three,
or more level converters, matrix converters, etc. Unfortunately, because of the lack of
the presence of a modulation strategy, this approach produces spread spectrum harmonics
which are difficult to filter effectively. This may result in a degraded power quality when
compared to more traditional control schemes. Furthermore, high switching frequencies
may be needed, considering the limited number of switching states in the converter. This
paper presents a novel multiobjective modulated predictive control strategy, which
preserves the desired characteristics of FCS-MPC but produces superior waveform quality.
The proposed method is validated by experimental tests on a seven-level cascaded Hbridge back-to-back converter and compared to a classic MPC scheme.
42760
Van der Broeck et.al
Unified Control of a Buck Converter for Wide-Load-Range Applications
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015;4061 - 4071
A new discrete-time state feedback controller is presented, which allows high-bandwidth
voltage control of a buck converter for any load condition, whether it operates in
discontinuous conduction mode (DCM), continuous conduction mode (CCM), or at the
boundary of these regions. This makes the buck converter applicable for a wide range of
applications. For the control design process, two large-signal models, which represent the
buck converter's discrete time dynamics in CCM and DCM, are developed. A simple
proportional-integral regulator is used for the voltage control of the converter. The
operation mode is detected and the voltage controller is connected in cascade to a current
controller in CCM or to a nonlinear state feedback decoupling structure in DCM. In this
paper, the modeling and design of the proposed control topology are introduced and its
performance is demonstrated in simulation and experiment.
42761
Farhangi B. et.al
Piecewise Linear Model for Snubberless Dual Active Bridge Commutation
79
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4072 – 4078
A dual active bridge (DAB) converter promises high power density. The highest power
transfer can be achieved by phase shift modulation inside the zero-voltage switching
boundaries. This paper analyzes the transients of DAB commutation. Although
commutation has been previously analyzed for DAB with the linear turn-off snubbers, in
today's industries, the output capacitors of the switches are utilized as the snubberless
approach. The presence of these time-variant capacitors leads to nonlinear equations. This
paper applies a piecewise linear model for analyzing the commutation of the ac-link
current into the switches. The study is inspired by practical experiments, and the results
are experimentally verified.
42762
Schrittwieser, L. et.al
Novel Principle for Flux Sensing in the Application of a DC + AC Current Sensor
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4100 – 4110
This paper presents a new concept for measuring DC and AC magnetic flux densities within
a ferromagnetic material. It is based on a measurement of the material's magnetostriction,
which is its relative change in length due to the magnetic flux density inside the material.
This dimensional change is converted to an electrical signal using a piezoelectric strain
sensor. An additional sinusoidal AC excitation of the core material provides higher
sensitivity of the length measurement and overcomes the inherent high-pass characteristic
of the piezoelectric sensor. Therefore, flux density signals from DC to the kilohertz range
can be measured. The concept's feasibility is demonstrated with the design and
implementation of an isolated DC + AC current sensor with a measurement range of ±20 A
and a bandwidth from DC to 20 MHz.
42763
Edpuganti, A. & Rathore, A.K.
A Survey of Low Switching Frequency Modulation Techniques for Medium-Voltage
Multilevel Converters
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4212 - 4228
Multilevel converters (MLCs) have emerged as standard power electronic converters for
medium-voltage high-power industrial applications. Owing to dominating device switching
losses in high-power applications, it is preferable to use low device switching frequency
(LDSF) modulation techniques. Then, it is possible to achieve higher device utilization,
higher converter efficiency, and reduced cooling requirements. However, there exists a
tradeoff between device switching frequency and harmonic distortion of converter output
currents. Therefore, the main challenge for LDSF modulation techniques is to minimize
the harmonic distortion of the output currents. The goal of this paper is to provide a review
of various LDSF modulation techniques proposed in the literature and also discuss in detail
about one of the emerging LDSF control techniques known as synchronous optimal
pulsewidth modulation. Finally, challenges to LDSF modulation techniques for emerging
multilevel topologies and future trends in applications of MLCs are discussed to motivate
further research, to enhance the proposed LDSF techniques, and to explore for new
alternatives.
80
42764
Abdelmalik, A.A. et.al
Influence of fast rise voltage and pressure on partial discharges in liquid embedded
power electronics
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2770
- 2779
Initiation of partial discharges at the highly stressed regions of an Insulated Gate Bipolar
Transistor (IGBT) can lead to degradation of the insulation and eventual total breakdown
of the system. In this work, an experimental setup has been designed for the study of
partial discharges (PDs) under different voltage waveforms. PD behavior of IGBT insulation
was investigated using conventional and optical techniques. Influence of pressure and
voltage wave shape is documented. The test environment was first characterized with
point-plane geometry under sinusoidal and slow rise square voltage of up to 20 kVpeak and
fast rise square voltage of up to +50 kV. The measured electrical and optical PDs showed
good correlation, revealing that optical PDs can be relied on for the characterization of
PD phenomena. High slew rate of the square voltage reduced the inception voltage and
increased magnitude. The PD pattern from the trench shows the existence of space
charges. The PDs which occurred within the triple point region are most likely attracted
along the board interface and become surface discharges. Pressure suppresses the
initiation and propagation of the discharge.
42765
Caiyong Ye et.al
Optimal Design and Experimental Research of a Capacitor-Charging Pulsed Alternator
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 948 - 956
The high power pulsed charging power supply is usually necessary for the pulsed power
devices with high power repetitive discharge. This paper first introduces a new topology
structure of a charge and discharge system for high voltage capacitor and its operating
principle, then comes up with technical requirements for the pulsed alternator. Afterward,
design features of the inductor pulsed alternator, including the structure, main
dimensions, and sizes of rotor teeth and slots are studied, and the main parameters of
homopolar inductor pulsed alternator (HIPA) prototype are provided. The choice of rotor
material and bearing failure phenomenon are also investigated to find a responsible
solution. Finally, the experimental waveforms of HIPA prototype without and rated load
when charging capacitor are given. The research shows that the pulsed power supply based
on the inductor pulsed alternator is competitive for its high energy storage density,
moderate power density, and high reliability, which is suited to the charging power supply
of pulsed capacitor.
42766
Ze Wang & Wei Qiao
An Online Frequency-Domain Junction Temperature Estimation Method for IGBT
Modules
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4633 - 4637
81
This letter proposes a new frequency-domain thermal model for online junction
temperature estimation of insulated-gate bipolar transistor (IGBT) modules. The proposed
model characterizes the thermal behavior of an IGBT module by a linear time-invariant
(LTI) system, whose frequency response is obtained by applying the fast Fourier transform
(FFT) to the time derivative of the transient thermal impedance from junction to a
reference position of the IGBT module. The junction temperature of the IGBT is then
estimated using the frequency responses of the LTI system and the heat sources of the
IGBT module. Simulation results show that the proposed method is computationally
efficient for an accurate online junction temperature estimation of IGBT modules in both
steady-state and transient loading conditions.
42767
Rahimo M. et.al
Characterization of a Silicon IGBT and Silicon Carbide MOSFET Cross-Switch Hybrid
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4638 - 4642
A parallel arrangement of a silicon (Si) IGBT and a silicon carbide (SiC) MOSFET is
experimentally demonstrated. The concept referred to as the cross-switch (XS) hybrid aims
to reach optimum power device performance by providing low static and dynamic losses
while improving the overall electrical and thermal properties due to the combination of
both the bipolar Si IGBT and unipolar SiC MOSFET characteristics. For the purpose of
demonstrating the XS hybrid, the parallel configuration is implemented experimentally in
a single package for devices rated at 1200 V. Test results are obtained to validate this
approach with respect to the static and dynamic performance when compared to a full Si
IGBT and a full SiC MOSFET reference devices having the same power ratings as for the XS
hybrid samples.
42768
Urciuoli D. et.al
Performance of a 1-kV, Silicon Carbide Avalanche Breakdown Diode
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4643 - 4645
A SiC avalanche breakdown diode (ABD) having a nominal 1-kV breakdown voltage was
fabricated to provide improved suppression of voltage transients induced during hardswitched turn-off of solid-state devices. Three SiC ABDs were pulsed 1000 times in an
inductive load circuit at peak currents of over 100 A. Superior performance in peak pulse
current, clamping voltage, and peak pulse power was seen, compared to the results of two
series-connected commercial TVS devices, collectively having a comparable breakdown
voltage. The transient thermal response of the SiC ABDs was calculated using a model for
energy dissipation in short pulses. SiC ABD design parameters and test data were used to
show that the reported performance of these devices was not related to package thermal
impedance.
42769
Ghias, A.M.Y.M. et.al
On Reducing Power Losses in Stack Multi-cell Converters with Optimal Voltage
Balancing Method
82
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4682 - 4695
This paper proposes a voltage balancing method for stacked multicell converters (SMCs)
based on phase-disposition pulse-width modulation (PD-PWM). In order to reduce the
switching transitions of the power devices, only optimal transitions between consecutive
voltage levels are used. Selection of the optimal transition sequence is performed by
evaluating a cost function. Significant reductions in the switching transitions and power
losses of the power devices are achieved as compared to the optimal-state voltage
balancing method where nonoptimal transitions are allowed. Simulation and experimental
results from a seven-level 3×2 SMC verifies that the proposed PD-PWM voltage balancing
method is robust under linear/nonlinear loads and transients.
42770
Kuo-Ching Tseng et.al
High Step-Up Interleaved Forward-Flyback Boost Converter With Three-Winding
Coupled Inductors
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4696 - 4703
A novel high step-up interleaved converter for high-power high-voltage applications is
proposed in this paper. Through three-winding coupled inductors, a high step-up
conversion with high efficiency is obtained. The proposed converter not only reduces the
current stress, but also constrains the input current ripple, which decreases the conduction
losses and lengthens the life time of input source. In addition, due to the lossless passive
clamp performance, leakage energy is recycled to the output terminal. Hence, large
voltage spikes across the main switches are alleviated and the efficiency is improved.
Even, the low-voltage stresses on semiconductor components are substantially lower than
the output voltage. Finally, the prototype circuit with input voltage 48 V, output voltage
380 V, and output power 2 kW is operated to verify its performance. The highest efficiency
is 96.5%, and the full-load efficiency is 92.6%.
42771
Picas R. et.al
Closed-Loop Discontinuous Modulation Technique for Capacitor Voltage Ripples and
Switching Losses Reduction in Modular Multilevel Converters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4714 - 4725
In this paper, a new discontinuous modulation technique is presented for the operation of
the modular multilevel converter (MMC). The modulation technique is based on adding a
zero sequence to the original modulation signals so that the MMC arms are clamped to the
upper or lower terminals of the dc-link bus. The clamping intervals are controlled
according to the absolute value of the output current to minimize the switching losses of
the MMC. A significant reduction in the capacitor voltage ripples is achieved, especially
when operating with low modulation indices. Furthermore, a circulating current control
strategy suitable for this modulation technique is also proposed. Simulation and
experimental results under various operating points are reported along with evaluation
and comparison results against a conventional carrier-based pulse width modulation
method.
83
42772
Xiongfei Wang et.al
Virtual RC Damping of LCL-Filtered Voltage Source Converters with Extended Selective
Harmonic Compensation
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4726 - 4737
Active damping and harmonic compensation are two common challenges faced by LCLfiltered voltage source converters. To manage them holistically, this paper begins by
proposing a virtual RC damper in parallel with the passive filter capacitor. The virtual
damper is actively inserted by feeding back the passive capacitor current through a highpass filter, which indirectly, furnishes two superior features. They are the mitigation of
phase lag experienced by a conventional damper and the avoidance of instability caused
by the negative resistance inserted unintentionally. Moreover, with the virtual RC damper,
the frequency region, within which the harmonic compensation is effective, can be
extended beyond the gain crossover frequency. This is of interest to some highperformance applications, but has presently not been achieved by existing schemes.
Performance of the proposed scheme has been tested in the laboratory with results
obtained for demonstrating stability and harmonic compensation.
42773
Sung Min Park & Sung-Yeul Park
Versatile Control of Unidirectional AC–DC Boost Converters for Power Quality Mitigation
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015;4738 - 4749
This paper introduces a versatile control scheme for unidirectional ac-dc boost converters
for the purpose of mitigating grid power quality. Since most power factor correction
circuits available in the commercial market utilize unidirectional ac-dc boost converter
topologies, this is an almost no-cost solution for compensating harmonic current and
reactive power in residential applications. Harmonic current and reactive power
compensation methods in the unidirectional ac-dc boost converter are investigated. The
additional focus of this paper is to quantify the input current distortions by the
unidirectional ac-dc boost converter used for supplying not only active power to the load
but also reactive power. Due to input current distortions, the amount of reactive power
injected from an individual converter to the grid should be restricted. Experimental results
are presented to validate the effectiveness of the proposed control method.
42774
Ben Guo et.al
Modulation Scheme Analysis for High-Efficiency Three-Phase Buck-Type Rectifier
Considering Different Device Combinations
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4750 - 4761
The three-phase buck-type rectifier features a step-down ac-dc conversion function,
smaller filter size, inrush current limiting capability, and potential for high efficiency,
where its switching loss is dependent on the modulation scheme and the specific
semiconductors used. In this paper, three different device combinations are compared
through experiments on their switching characteristics for the buck rectifier application.
It is shown that the switching performance of two series-connected devices becomes worse
than a single device due to the superposition of the nonideal semiconductor
84
characteristics. Moreover, the switching loss in the commutation between two switches is
usually higher than the one in the commutation between a switch and the freewheeling
diode. Taking into consideration both types of commutations, the switching loss of the
buck rectifier is then modeled and the analytical equations are derived for four space
vector modulation schemes. According to the analysis, each modulation scheme has its
own field for high-efficiency application. The most advantageous modulation scheme is
identified in this paper for each of the device combinations investigated.
42775
Yu Zhang et.al
Alleviation of Electromagnetic Interference Noise Using a Resonant Shunt for Balanced
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4762 - 4773
Balanced converter is an effective way to reduce the CM noise. However, the parasitic
capacitance between the switch and heat sink leads to resonant problems, resulting in
high noise in certain frequency range. This paper proposes a novel coupled inductor
structure based on the balanced technique for the Boost converter to further reduce the
CM noise at certain frequency range. A shunt resonant path is adopted to offer a maximum
suppression. The analytical estimation for shunt winding's performance is provided for
better design. Some simulation and experimental results of this new technique are
presented to validate its effectiveness. The experiments about the capacitance unbalance,
different load current, and reduction of the CM inductor size are also discussed for better
understanding of this technique.
42776
Weimin Wu et.al
Aalborg Inverter - A New Type of “Buck in Buck, Boost in Boost” Grid-Tied Inverter
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4784 - 4793
This paper presents a new family of high efficiency dc/ac grid-tied inverter with a wide
variation of input dc voltage. It is a “boost in boost, buck in buck” inverter, meaning that
only one power stage works at high frequency in order to achieve minimum switching loss.
The minimum voltage drop of the filtering inductor in the power loop is achieved to reduce
the conduction power loss in both “boost” and “buck” mode. The principle of operation is
demonstrated through the analysis on the equivalent circuits of a “half-bridge” singlephase inverter. The theoretical analysis shows that when input dc voltage is larger than
the magnitude of the ac voltage, it is a voltage-source inverter, and on the contrary it is
current-source inverter in the other mode. A 220 V/50 Hz/ 2000 W prototype has been
constructed. Simulations and experiments show that it has a good control and system
performance.
42777
Jun Zeng et.al
A Voltage-Feed High-Frequency Resonant Inverter With Controlled Current Output as
a High-Frequency AC Power Source
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4854 - 4863
85
A current-based power distribution is presented for the applications of high-frequency ac
power distribution system (PDS). Comparing with the traditional voltage-based
counterpart, the current-based system can be applied into some specific applications, such
as high-voltage gate-driving system, contactless power transmission, etc. A modified
resonant topology based on LCL-T tank is proposed to implement high-frequency current
source. The effective magnitude control and high conversion efficiency are both achieved.
First, the proposed topology is examined with circuit principle, operational cycle analysis,
and soft-switching description. Second, the phase-shifted control scheme is explored to
calculate the equivalent resonant capacitor of LCL-T resonant tank, as well as the relations
between current gain ratio and phase-shifted angle control are discussed in depth. Finally,
the simulation model and experiment prototype are implemented with rated peak current
of 2 A, rated output frequency of 30 kHz, and rated output power of 50 W. The
experimental results in accordance with simulation prove that the constant current
characteristics are maintained with high conversion efficiency. Hence, the proposed
circuit topology and control scheme are a feasible realization of current source that is
used to feed high-frequency PDS.
42778
Xinke Wu et.al
Interleaved Phase-Shift Full-Bridge Converter With Transformer Winding Series–
Parallel Autoregulated (SPAR) Current Doubler Rectifier
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4864 - 4873
The analysis and design guidelines for a two-phase interleaved phase-shift full-bridge
converter with transformer winding series-parallel auto-regulated current doubler
rectifier are presented in this paper. The secondary windings of two transformers work in
parallel when the equivalent duty cycle is smaller than 0.25 but in series when the duty
cycle is larger than 0.25 owing to the series-parallel autoregulated rectifier. With the
proposed rectifying structure, the voltage stress of the rectifier is reduced. Also, the
interleaving operation reduces the output current ripple. A 1-kW prototype with 200-400V input and 50-V/20-A output is built up to verify the theoretical analysis.
42779
Yu Tang et.al
Analysis of Active-Network Converter With Coupled Inductors
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4874 - 4882
High step-up voltage gain dc-dc converters are widely applied in fuel cell stacks,
photovoltaic arrays, battery sources, and high intensity discharge lamps power systems.
Active-network converters with coupled inductors (CL-ANC) are derived from switched
inductor active-network converters (SL-ANC). The proposed converter contains two
coupled inductors which can be integrated into one magnetic core and two power
switches. The converter can provide a relatively high voltage conversion ratio with a small
duty cycle; the voltage and current stress of power switches are low which is helpful to
reduce the losses. This paper shows the key waveforms of the CL-ANC and detailed
derivation of the steady-state operation principle. The voltage conversion ratio and the
effect of the leakage inductance on voltage gain are discussed. The voltage stress and
current stress on the power devices are illustrated and the comparison between the
proposed converter and SL-ANC are given. Finally, the prototype has been established in
86
the lab with 200 V and 400 V output under different turn ratios. Experimental results are
given to verify the correctness of the analysis.
42780
Minjae Kim & Sewan Choi
A Fully Soft-Switched Single Switch Isolated DC–DC Converter
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4883 - 4890
This paper proposes a soft-switched single switch isolated converter. The proposed
converter is able to offer low cost and high power density in step-up application due to
the following features: zero-current switching (ZCS) turn-on and zero-voltage switching
(ZVS) turn-off of switch and ZCS turn-off of diodes regardless of voltage and load variation;
low rated lossless snubber; reduced transformer volume compared to flyback-based
converters due to low magnetizing current. Experimental results on a 100 kHz, 250 W
prototype are provided to validate the proposed concept.
42781
Diab M.S. et.al
A Four-Switch Three-Phase SEPIC-Based Inverter
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4891 - 4905
The four-switch three-phase (FSTP) inverter has been proposed as an innovative inverter
design to reduce the cost, complexity, size, and switching losses of the dc-ac conversion
system. Traditional FSTP inverter usually operates at half the dc input voltage; hence, the
output line voltage cannot exceed this value. This paper proposes a novel design for the
FSTP inverter based on the topology of the single-ended primary-inductance converter
(SEPIC). The proposed topology provides pure sinusoidal output voltages with no need for
output filter. Compared to traditional FSTP inverter, the proposed FSTP SEPIC inverter
improves the voltage utilization factor of the input dc supply, where the proposed topology
provides higher output line voltage which can be extended up to the full value of the dc
input voltage. The integral sliding-mode control is used with the proposed topology to
optimize its dynamics and to ensure robustness of the system during different operating
conditions. Derivation of the equations describing the parameters design, components
ratings, and the operation of the proposed SEPIC inverter is presented in this paper.
Simulation model and experimental setup are used to validate the proposed concept.
Simulations and experimental results show the effectiveness of the proposed inverter.
42782
Bo Dong et.al
Parallel Architecture for Battery Charge Equalization
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4906 – 4913
One limitation of many battery charge equalizers is their slow equalization speed,
especially when there are a large number of batteries in the series-string in high-voltage
and high-power applications. This paper presents a new architecture for battery charge
equalization. In this architecture, independent equalizers are placed in different layers
and all the layers can equalize the corresponding batteries simultaneously, thus reducing
equalization time by 50%. We explore the operation, performance characteristics, and the
87
design of the architecture. Both simulation and experimental results are presented to
validate the analysis in this paper.
42783
Jae-Bum Lee et.al
A High-Efficiency PFM Half-Bridge Converter Utilizing a Half-Bridge LLC Converter
Under Light Load Conditions
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4931 - 4942
Recently, the various types of the half-bridge (HB) converters with the output inductor
have been developed, and they exhibit a good performance in medium power applications
such as the server power supplies and personal computer power supplies requiring high
output current. However, they have common problems such as the primary and secondary
switch turn-off losses and snubber loss in the secondary side caused by the output inductor,
which degrades light load efficiency. To relieve these limitations of the conventional HB
converters, a new HB converter, which employs one additional switch and capacitor in the
secondary side, is proposed for a high efficiency under light load conditions in this paper.
Since the proposed converter operates like the HB LLC converter with below operation by
turning on additional switch under light load conditions, the switch turn-off losses and
snubber loss can be minimized, and the zero-voltage switching (ZVS) capability can be
improved. Consequently, the proposed converter can achieve a high efficiency under light
load conditions. To confirm the operation, features, and validity of the proposed
converter, a 330-400 V input and 12 V/300 W output laboratory prototype is built and
tested.
42784
Santiago-Gonzalez J.A.
Design of Class E Resonant Rectifiers and Diode Evaluation for VHF Power Conversion
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4960 - 4972
Resonant rectifiers have important applications in very-high-frequency (VHF) power
conversion systems, including dc-dc converters, wireless power transfer systems, and
energy recovery circuits for radio-frequency systems. In many of these applications, it is
desirable for the rectifier to appear as a resistor at its ac input port. However, for a given
dc output voltage, the input impedance of a resonant rectifier varies in magnitude and
phase as output power changes. This paper presents a design methodology for class E
rectifiers that maintain near-resistive input impedance along with the experimental
demonstration of this approach. Resonant rectifiers operating at 30 MHz over 10:1 and 2:1
power ranges are used to validate the design methodology and identify its limits.
Furthermore, a number of Si Schottky diodes are experimentally evaluated for VHF
rectification and categorized based on performance.
42785
Prada D. et.al
On the Performance of Multi-objective Evolutionary Algorithms in Automatic
Parameter Extraction of Power Diodes
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4986 - 4997
88
In this paper, a general, robust, and automatic parameter extraction of nonlinear compact
models is presented. The parameter extraction is based on multiobjective optimization
using evolutionary algorithms, which allow fitting of several highly nonlinear and highly
conflicting characteristics simultaneously. Two multiobjective evolutionary algorithms
which have been proved to be robust for a wide range of multiobjective problems [1]-[3],
the nondominated sorting genetic algorithm II and the multiobjective covariance matrix
adaptation evolution strategy, are used in the parameter extraction of a novel power diode
compact model based on the lumped charge technique. The performance of the algorithms
is assessed using a systematic statistical approach. Good agreement between the
simulated and measured characteristics of the power diode shows the accuracy of the used
compact model and the efficiency and effectiveness of the proposed multiobjective
optimization scheme.
42786
Dagan K.J. & Rabinovici R.
Criteria-Based Modulation for Multilevel Inverters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5009 - 5018
Pulse width modulation schemes are aimed at adjusting the fundamental component while
reducing the harmonic content of an inverter output voltage or current. This paper
addresses the topic of optimal inverter operation in reference to a given objective
function. The objective function could embody either a single performance criterion, such
as voltage or current total harmonic distortion (THD), or a weighted sum of multiple
criteria. The proposed method ensures primacy of the chosen solution while imposing no
restriction over its modulation index. In particular, operating the inverter by the chosen
solution would result in performances superior to any other modulation scheme
commutating in an equal number of switching angles per fundamental cycle. The proposed
method allows for the consideration of practical inverter constraints and prevents the
possibility of impractical switching sequence. A detailed investigation of the method is
given, accompanied by two practical cases minimizing, respectively, phase-voltage THD
and line-current THD of a three-level inverter. Selected simulation and experimental
results are presented to validate the theoretical part.
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42787
Azizoglu B.T. & Karaca H
Investigating a MOSFET Driver (Buffer) Circuit Transition Ringings using an Analytical
Model
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5058 - 5066
In this paper, a new analytical model introduced extracting from datasheet of a MOSFET
and developed a MATLAB code for simulating a MOSFET driver circuit is proposed in the
literature to observe the ringings of its output for capacitively loaded case. The output
waveform is studied only for high-to-low transition. Gate drive resistance, wiring parasitics
of the printed circuit board layout, and the characteristic properties of the MOSFET affect
both the delay time of the MOSFET to become ON and performance of the driver circuit.
Also, voltage stress of the MOSFET and therefore safe operating range for the circuit all
depend on these effects. These effects are all considered in the design stage. The
simulation results obtained from CST Design Studio software are compared with the results
of experimental work. The analytical modeling results solved in the MATLAB are found
congruent with the simulation results and experimental results as well. The simulation
work showed that developed MATLAB code along with extracted models from datasheets
has less convergence problems and also requires less simulation time.
42788
Bauer F.D. et.al
Conceptual Study of Sub-600 V IGBTs
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5116 - 5124
Very low voltage, 60-600 V insulated-gate bipolar transistors (IGBTs) were compared to
power mosfet s with conventional and superjunction drift layers of identical voltage
classes using mixed-mode numerical device simulation. This study was done in the light of
forthcoming 400 V class IGBTs for use in electric vehicle/hybrid electric vehicle: the 600
V borderline, which previously separated the bulk of power mosfet from IGBT applications,
has become fragile recently. We find that the 400 V class must not represent a lower limit
for IGBTs based on silicon: in fact, LV IGBTs could offer lower losses down to the 60-100 V
level. Most importantly, low-voltage IGBTs may outperform power mosfets not only with
respect to on-state voltage drop but also regarding switching offering up to 30% lower
turn-off losses. This paper presents physics-based arguments focusing on the device
transconductance to augment these projections. LV IGBTs or hybrid devices (monolithic
integration of mosfet plus IGBT) could become lower cost, high performance alternatives
to SJ power mosfets thanks to short development cycles common in mature silicon
technologies.
42789
Colli-Menchi A.I. & Sanchez-Sinencio E.
A High-Efficiency Self-Oscillating Class-D Amplifier for Piezoelectric Speakers
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5125 - 5135
The design tradeoffs of the class-D amplifier (CDA) for driving piezoelectric (PZ) speakers
are presented, including efficiency, linearity, and electromagnetic interference. An
implementation is proposed to achieve high efficiency in the CDA architecture for PZ
90
speakers to extend battery life in mobile devices. A self-oscillating closed-loop
architecture is used to obviate the need for a carrier signal generator to achieve low power
consumption. The use of stacked-cascode CMOS transistors at the H-bridge output stage
provides low-input capacitance to allow high-switching frequency to improve linearity with
high efficiency. Moreover, the CDA monolithic implementation achieves 18 VPP output
voltage swing in a low-voltage CMOS technology without requiring expensive high-voltage
semiconductor devices. The prototype experimental results achieved a minimum THD + N
of 0.025%, and a maximum efficiency of 96%. Compared to available CDA for PZ speakers,
the proposed CDA achieved higher linearity, lower power consumption, and higher
efficiency.
42790
Orabi M. & Shawky A.
Proposed Switching Losses Model for Integrated Point-of-Load Synchronous Buck
Converters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5136 - 5150
Nowadays, point-of-load (POL) converters' investments are counted as a main part in
power management markets; especially the synchronous buck converters. Today's products
forces designers to highly integrate POL converters by increasing the switching frequency;
so the latest technology has used megahertz range to obtain this target. On the other
hand, increasing switching frequency means increasing the switching losses. Therefore, it
is very important to optimize the operating switching frequency tradeoff, which requires
an accurate model taking in consideration the converter operating conditions. This paper
presents an accurate mathematical loss model taking in consideration the physical
behavior of the MOSFET switch in addition to the converter operating conditions. This
model introduces accurate equations for every switching intervals and so accurate loss
calculations. An integrated POL synchronous buck converter of 5 MHz, 5-1.8 V/3 A
prototype is fabricated. The results of the proposed model are compared with simulation
and experimental results under variable operating conditions. Good matching between the
mathematical, experimental, and simulation results are obtained.
42791
Reusch D. & Strydom J.
Evaluation of Gallium Nitride Transistors in High Frequency Resonant and SoftSwitching DC–DC Converters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5151 - 5158
The emergence of gallium nitride (GaN)-based power devices offers the potential to
achieve higher efficiencies and higher switching frequencies than possible with mature
silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of gallium nitride
transistors to improve efficiency and output power density in high frequency resonant and
soft-switching applications. To experimentally verify the benefits of replacing Si MOSFETs
with enhancement mode GaN transistors (eGaNFETs) in a high frequency resonant
converter, 48-12 V unregulated isolated bus converter prototypes operating at a switching
frequency of 1.2 MHz and an output power of up to 400 W are compared using Si and GaN
power devices.
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42792
Yong-seong Roh et.al
A Multiphase Synchronous Buck Converter With a Fully Integrated Current Balancing
Scheme
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5159 - 5169
A multiphase synchronous buck converter has been developed, in which the number of
switching phases is determined by the sensed average load current. The maximum number
of switching phases is four. The dc resistance (DCR) of switching inductor is used to detect
the average current, which is also utilized to balance the load current among the multiple
switching phases. The instantaneous inductor current is sensed as well to generate the
pulsewidth modulation (PWM) signal to switch the inductors. The multiphase synchronous
buck converter implemented in a 0.13-µm BCDMOS process shows 91.1% maximum power
efficiency when the input voltage is 2.8 V, output voltage is 1.0 V, and output current is
2.0 A.
42793
Difu Zhan et.al
A Generalized Model of Non-isolated Multiphase DC–DC Converter Based on Novel
Switching Period Averaging Method
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5181 - 5191
The continuously innovated topologies of the nonisolated multiphase dc-dc converter
(NMDC) demand generalized and flexible models for the controller design. However, the
increased phase number, coupling of inductors, stray circuit parameters, and asymmetric
problems make the modeling work difficult. In this paper, a novel switching period
averaging method aiming to simplify the modeling process is proposed. The method takes
full advantage of the linear characteristic of the circuit differential equations to find out
the relationship between averaged state variables and switch duty cycles. Then, the
generalized model applicable to several different topologies of the NMDC is derived. The
analytical solutions of steady-state model, dynamic model in both time and frequency
domain are all approached. In order to verify the results, a MATLAB/Simulink model and
the corresponding experimental prototype of a four-phase boost converter with two groups
of two-phase coupled inductors are built. Both results coincide with the theoretical
derivation, which indicates the effectiveness of the proposed method. Finally, a design
process of the H∞ controller for the NMDC is presented to show the application of this
model.
42794
Svikovic V. et.al
Multiphase Current-Controlled Buck Converter With Energy Recycling Output
Impedance Correction Circuit (OICC)
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5207 - 5222
This study is related to the improvement of the output impedance of a multiphase buck
converter with peak current mode control (PCMC) by means of introducing an additional
power path, which virtually increases the output capacitance during transients. Various
solutions that can be employed to improve the dynamic behavior of the converter system
exist, but nearly all solutions are developed for a single-phase buck converter with voltage
92
mode control, while in the voltage regulation module applications, due to the high currents
and dynamic specifications, the system is usually implemented as a multiphase buck
converter with current mode control to ensure current sharing. The proposed circuit,
output impedance correction circuit (OICC), is used to inject or extract a current n - 1
times larger than the output capacitor current, thus virtually increasing n times the value
of the output capacitance during the transients. Furthermore, the OICC concept is
extended to a multiphase buck converter system and the proposed solution is compared
with the system that has n times bigger output capacitor in terms of dynamic behavior and
static and dynamic efficiency. The OICC is implemented as a synchronous buck converter
with PCMC, thus reducing its penalty on the system efficiency.
42795
Jiaxing Lei et.al
Active damping control strategy of matrix converter via modifying input reference
currents
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5260 - 5271
The matrix converter (MC) with an LC filter at source side suffers from system instability,
thereby requiring damping control. To improve system stability, this paper proposes a
novel active damping control strategy. First, the method of generating space vector
modulation signals is improved, in order to make the amplitude and phase angle of input
currents directly controllable without affecting the priority of output voltage control.
Then, the proposed strategy, which is realized by injecting damping signals into input
reference currents, is presented. In this way, the proposed strategy can suppress the
oscillations in source currents directly. Besides, it is effective with source voltages or
capacitor voltages sampled for modulation, regardless of the operation mode of MC.
Furthermore, it is applicable to most of existing modulation algorithms. Finally,
experimental results of four-quadrant operation on a 2.4-kW prototype illustrate that,
under the condition of the same parameters, the proposed active damping control strategy
performs better than passive damping control in filtering and the same in damping at
source side, without sacrificing the driving performance at output side.
42796
Adam G.P. et.al
Three-Phase AC-Side Voltage-Doubling High Power Density Voltage Source Converter
With Intrinsic Buck–Boost Cell and Common-Mode Voltage Suppression
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5284 - 5298
The three-phase two-level voltage source converter (VSC) is widely employed in power
conversions between ac and dc for its four-quadrant operation and control flexibility.
However, it suffers from the low output voltage range with a peak value of half dc-link
per phase, which necessitates the use of either high dc-link voltage or bulky step-up
transformer to enable the medium voltage operation. Additionally, the high commonmode (CM) voltage between ac loads neutral points and ground may reduce the service
life and reliability of electric machinery. In this paper, a three-phase ac-side voltagedoubling VSC topology with intrinsic buck-boost cell is analyzed. By this configuration,
the ac-side voltage is doubled with the phase peak value equal to dc link. That is, only
half of the dc-side capacitor bank is needed to generate the same output voltage. The
proposed converter uses its buck-boost cell as a virtual voltage source to synthesize
negative half of the output voltage by modulating its output ac phase voltage around the
93
negative bus (which is the real zero when grounded). This permits the average CM voltage
to be suppressed to zero, and loads connected to converter ac side not to withstand any
dc voltage stress (reducing the insulation requirement). Modeling and control design for
both rectifier and inverter modes of this converter in synchronous reference frame have
been investigated to ensure a four-quadrant three-phase back-to-back system.
Experimental results have verified the feasibility and the effectiveness of the proposed
configuration and the designed control strategies.
42797
Amir S. et.al
An Improved Modeling and Analysis Technique for Peak Current-Mode Control-Based
Boost Converters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5309 - 5317
A modeling approach is presented that calculates an accurate open-loop transfer
characteristic for a boost converter that employ peak current-mode control (PCMC). Many
techniques exist for modeling a PCMC-based boost converter; however, all these
techniques focus on purely resistive loads and are not always accurate for a purely
capacitive load. In this paper, a new modeling technique is presented, which is simple and
gives accurate results for both capacitive and resistive loads. Furthermore, the useful
expressions for dc gain and pole locations of a boost converter operating in continuousconduction mode with PCMC are derived and compare well to simulations and
measurements.
42798
Shaohua Lu et.al
A Highly Efficient P-SSHI Rectifier for Piezoelectric Energy Harvesting
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5364 - 5369
A highly efficient P-SSHI-based rectifier for piezoelectric energy harvesting is presented in
this paper. The proposed rectifier utilizes the voltages at the two ends of the piezoelectric
device (PD) to detect the polarity change of the current produced by the PD. The inversion
process of the voltage across the PD is automatically controlled by diodes along the
oscillating network. In contrast to prior works, the proposed rectifier exhibits several
advantages in terms of efficiency, circuit simplicity, compatibility with commercially
available PDs, and standalone operation. Experimental results show that the proposed
rectifier can provide a 5.8× boost in harvested energy compared to the conventional fullwave bridge rectifier.
42799
Ghias A.M.Y.M.et.al
Single-Carrier Phase-Disposition PWM Implementation for Multilevel Flying Capacitor
Converters
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5376 - 5380
This letter proposes a new implementation of phase-disposition pulse-width modulation
(PD-PWM) for multilevel flying capacitor (FC) converters using a single triangular carrier.
The proposed implementation is much simpler than conventional PD-PWM techniques
based on multiple trapezoidal-shaped carriers, generates the same results as far as natural
capacitor voltage balance is concerned and offers better quality line-to-line voltages when
94
compared to phase-shifted PWM. The proposed algorithm is based on reshaping the
reference signal to fit within the range of a single carrier and assigning each crossing of
the reference signal with the carrier to a particular pair of switches at any time. The
proposed algorithm is suitable for digital implementation taking maximum benefit from
the PWM units available in the processor. Simulation and experimental results are
presented from the five-level FC converter to verify the proposed PD-PWM
implementation.
42800
Hongfei Wu et.al
Secondary-Side Phase-Shift-Controlled Dual-Transformer-Based Asymmetrical DualBridge Converter with Wide Voltage Gai
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5381 - 5392
A novel dual-transformer-based asymmetrical dual-bridge (DT-ADB) converter with
secondary-side phase-shift control strategy is proposed. The primary side of the DT-ADB
converter is a fully active full bridge, and the secondary side is a semiactive bridge
comprising of one active leg and two passive legs. The current and power of the two
transformers in the converter are shared automatically by adopting primary-side-series
and secondary-side-parallel configuration, and the turns ratio of the transformer is
reduced by employing two transformers. The high-frequency-link inductor is reduced
because the voltage applied on the inductor is reduced compared to previous converters,
and hence the efficiency and power density can be improved. Zero-voltage turn-on of all
the active switches and zero-current turn-off of all the diodes are achieved in a wide
operation range. Furthermore, the turn-off losses of the secondary-side active switches
are reduced because only half of the output current flows through the switches. Moreover,
the proposed topology offers several other advantages including continuous output current
and smaller output filter requirement. The operation principle is analyzed and
experimental results are provided to verify the effectiveness and advantages of the
proposed converter.
42801
Bin Wu et.al
A Family of Two-Switch Boosting Switched-Capacitor Converters
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5413 - 5424
A family of “Two-Switch Boosting Switched-Capacitor Converters (TBSC)” is introduced,
which distinguishes itself from the prior arts by symmetrically interleaved operation,
reduced output ripple, low yet even voltage stress on components, and systematic
expandability. Along with the topologies, a modeling method is formulated, which
provokes the converter regulation method through duty cycle and frequency adjustment.
In addition, the paper also provides guidance for circuit components and parameter
selection. A 1-kW 3X TBSC was built to demonstrate the converter feasibility, regulation
capability via duty cycle and frequency, which achieved a peak efficiency of 97.5% at the
rated power.
42802
Nho-Van Nguyen et.al
A Reduced Switching Loss PWM Strategy to Eliminate Common-Mode Voltage in
Multilevel Inverters
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5425 - 5438
95
This paper introduces a novel pulse width modulation (PWM) technique to eliminate
common-mode voltage in odd-multilevel inverters using the three zero common-mode
vectors principles. Similarly, as in conventional PWM for multilevel inverters, this PWM can
be properly depicted in an active two-level voltage inverter. With the help of two
standardized PWM patterns, the characteristics of the PWM process can be fully explored
in that active inverter as a switching time diagram and switching state sequence. Due to
an unequal number of commutations of three phases in each sampling period, the
switching loss is optimized by a proposed current-based mapping algorithm. The switching
loss reduction can be up to 25% compared to the same PWM technique with nonoptimized
algorithms. The PWM method has been then generalized as an equipotential PWM control,
which is valid to both odd- and even-multilevel inverters. The theoretical analysis is
verified by simulation and experimental results.
42803
Gowaid I.A. et.al
Analysis and Design of a Modular Multilevel Converter with Trapezoidal Modulation for
Medium and High Voltage DC-DC Transformers
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5439 - 5457
Conventional dual-active bridge topologies provide galvanic isolation and soft-switching
over a reasonable operating range without dedicated resonant circuits. However, scaling
the two-level dual-active bridge to higher dc voltage levels is impeded by several
challenges among which the high dv/dt stress on the coupling transformer insulation.
Gating and thermal characteristics of series switch arrays add to the limitations. To avoid
the use of standard bulky modular multilevel bridges, this paper analyzes an alternative
modulation technique, where staircase approximated trapezoidal voltage waveforms are
produced; thus, alleviating developed dv/dt stresses. Modular design is realized by the
utilization of half-bridge chopper cells. This way the analyzed dc-dc transformer employs
modular multilevel converters operated in a new mode with minimal common-mode arm
currents, as well as reduced capacitor size, hence reduced cell footprint. Suitable
switching patterns are developed and various design and operation aspects are studied.
Soft-switching characteristics will be shown to be comparable to those of the two-level
dual-active bridge. Experimental results from a scaled test rig validate the presented
concept.
42804
Ling Gu & Ke Jin
A Three-Phase Isolated Bidirectional AC/DC Converter and its Modified SVPWM
Algorithm
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5458 - 5468
This paper proposes a three-phase isolated bidirectional ac/dc converter. The converter
achieves buck-boost ac/dc bidirectional conversion, sinusoidal ac current, and highfrequency electrical isolation with single-stage structure. The traditional SVPWM algorithm
should be modified to keep the voltage-second balance of the transformer. The circuit
derivation, operation principles, and SVPWM algorithm are presented specifically. The
solution for shoot-through problem is proposed, which does not need extra dead time. To
verify the theoretical analysis, the proposed converter was simulated by MATLAB/SIMULINK
and a 3 kW prototype was built in the lab. The simulation and experimental results show
the high power factor and the low harmonic distortion characteristics of the circuit.
96
42805
Runruo Chen et.al
DC Capacitor-Less Inverter for Single-Phase Power Conversion With Minimum Voltage
and Current Stress
IEEE Trans. on Power Electronics, Vol.30; No.10; October 2015; 5499 - 5507
Single-phase power conversion such as pulse width modulation rectifier, grid connected
PV inverter system, static synchronous compensator all can be implemented by an H-bridge
inverter and a large electrolytic dc capacitor to absorb the ripple power pulsating at twice
the line frequency (2ω ripple power). This paper proposed a dc capacitor-less inverter for
H-bridge with minimum voltage and current stress. By adding another phase leg to control
an ac capacitor, the 2ω ripple power can be absorbed by the capacitor and theoretically
2ω ripples to the dc capacitor can be eliminated completely. The H-bridge and the
addition phase leg can be analyzed together as an unbalanced three phase system. By
adopting space-vector pulse width modulation control and choosing the optimum ac
capacitance and the voltage reference, the voltage and current stress of the switches can
be minimized to the same as the conventional H-bridge. The size of capacitor is reduced
by ten times compared to the conventional H-bridge system. Simulation and experimental
results are shown to prove the effectiveness of the proposed dc capacitor-less inverter and
active power decoupling method.
42806
Peng Li et.al
Three-Phase AC–AC Hexagonal Chopper System with Heterodyne Modulation for Power
Flow Control Enhancement
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5508 - 5521
This paper proposes a three-phase ac chopper system for the interconnection of various
distributed generation (DG) farms or main utilities to enhance the active and reactive
power flow control. The absence of large energy storage component in direct ac-ac
converter makes the system footprint small and reliable. As the interface for different ac
sources, the presented converter can be configured as star or delta. However, delta
connection is preferred as it can trap the potential zero-sequence current and reduce the
current rating of the switching devices. In this way, the proposed converter resembles the
hexagonal chopper, and it offers an inherent degree of freedom for output voltage phase
shifting. Considering the scalability in high-voltage applications, a new version of the
hexagonal chopper with half-bridge cell modular multilevel structure is developed. The
modular multilevel ac hexagonal chopper (M2AHC) is operated in quasi-two-level mode to
suppress the electromagnetic interference (EMI) caused by high-voltage switching. Quasitwo-level operation divides the voltage level transition into multisteps, diminishing the
voltage rising and falling rates (dv/dt) in high-voltage condition. Then, heterodyne
modulation is adopted for the presented chopper system, supplying a new degree of
freedom to decouple the phase and amplitude regulation. Based on this idea, system
control strategy is developed in synchronous reference frame (SRF). Simulations and
experimentations have confirmed the validity of the proposed approaches.
97
42807
Bondarenko N. et.al
A Measurement-Based Model of the Electromagnetic Emissions from a Power Inverter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5522 - 5531
Rapidly switching semiconductors in modern high power inverter/motor-drive systems
generate fast changing voltages and currents which may result in unwanted emissions.
While models of power inverters have been built in the past to predict emissions, they are
typically “black box” models where the cause of and solution to emissions problems is
difficult to analyze. To improve inverter system design strategies, a detailed
measurement-based SPICE model of a power inverter system was built in which there is a
straightforward correlation between system geometry and parasitic circuit elements. This
model was validated through measurements. The model was able to predict transfer
characteristics between ports of the inverter within 4 dB from 100 kHz to 100 MHz. Once
built, this model was used to identify structures responsible for resonances and to
determine possible improvements of the power inverter design to reduce emissions.
Measurements of S21 and radiated emissions after adding these improvements
demonstrated that they were able to reduce emissions by 10-20 dB, thus confirming the
accuracy of the model and its ability to improve understanding of emission mechanisms
and to guide development of emissions reduction strategies.
42808
Nanakos A.C. et.al
Weighted Efficiency Optimization of Flyback Microinverter under Improved Boundary
Conduction Mode (i-BCM)
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5548 - 5564
The flyback topology is proven to be a very strong candidate solution for use in ac-PV
module applications. Operation in the boundary condition mode (BCM) provides high power
density, while maintaining the characteristics of a current source inverter. In this paper,
a design methodology is presented, that maximizes the weighted efficiency of the
converter through an optimization algorithm. The inverter operation is investigated and
the behavior under the improved BCM is documented by analytical equations followed by
the power loss calculations for each component. This enables to accurately define the
relation between the design parameters and the efficiency of the implemented converter
and so, an optimization algorithm is established, that takes into consideration the design
specifications and constraints. The proposed methodology is also verified with an
experimental prototype.
42809
Yutian Lei & Pilawa-Podgurski R.C.N.
A General Method for Analyzing Resonant and Soft-Charging Operation of SwitchedCapacitor Converters
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5650 - 5664
Traditionally, switched-capacitor (SC) converters have suffered from high transient
currents, which limit both the efficiency and power density of such converters. Softcharging operation can be employed to eliminate the current transients and greatly
98
improve the power density of SC converters. In this approach, a second-stage magnetic
converter is cascaded with the SC stage to act as a controlled current load. Another
approach is to use resonant SC converters with zero-current switching. This paper shows
that resonant and soft-charging operations of SC converters are closely related, and a
technique will be proposed, which achieves either operation by adding a single inductor
to existing SC topologies. In addition, since most preexisting resonant or soft-charging SC
converters were devised in an ad-hoc manner, this paper formulates an analytical method
that can determine whether an existing conventional SC converter topology is compatible
with the proposed approach. A number of common SC topologies are analyzed, including
Dickson, series-parallel, ladder, Fibonacci, and doubler configurations. Through
comparison to simulated results, as well as experimental work, the proposed method is
validated and a family of high-performance SC converters is obtained.
42810
Anh-Vu Ho et.al
Extended Boost Active-Switched-Capacitor/Switched-Inductor Quasi-Z-Source
Inverters
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5681 - 5690
This paper proposes a new topology named the active-switched-capacitor/switchedinductor quasi-Z -source inverter (ASC/SL-qZSI), which is based on a traditional qZSI
topology. Compared to other qZSI-based topologies under the same operating conditions,
the proposed ASC/SL-qZSI provides higher boost ability, requires fewer passive
components such as inductors and capacitors, and achieves lower voltage stress across the
switching devices of the main inverter. Another advantage of the topology is its
expandability. If a higher boosting rate is required, additional cells can easily be cascaded
at the impedance network by adding one inductor and three diodes. Both the simulation
studies and the experimental results obtained from a prototype built in the laboratory
validate proper operation and performance of the proposed ASC/SL-qZSI.
42811
Lemmen E. et.al
Advances in High-Precision Amplifiers— the Extra L Opposed Current Converter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5691 - 5700
In existing half/full-bridge high-precision amplifiers, output distortion is present due to
the required switch blanking time. The OCC topology does not require this blanking time
but has a much higher total inductor volume compared to the half bridge. In this paper, a
patented new topology is introduced that has the advantages of the OCC but with a much
lower total inductor volume. The basic operation and properties of the ELOCC topology
are explained including an extended optimization of the total inductor volume and an
average model for control design. A prototype ELOCC current amplifier has been
developed. The behavior of this prototype is in good agreement with the obtained
simulation results. Even though the prototype is not fully optimized, the linearity
compared to a full bridge is already impressive.
99
42812
Ningning Wang et.al
High Efficiency on Si-Integrated Microtransformers for Isolated Power Conversion
Applications
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5746 - 5754
This paper details the design, fabrication, and characterization of silicon-integrated
microtransformers for isolated bias supplies. Racetrack-shaped Microtransformers were
designed and fabricated using the advanced double-layer metal (DLM) microfabrication
process. The DLM devices have high inductance density of more than 80 nH/mm2 with an
efficiency of approximately 78.2% at 20 MHz at 0.5-W output. This is the highest efficiency
and power density reported for an integrated transformer in the literature. The inductance
drop is less than 20% with a bias current of 0.35 A with up to 6-kV dc breakdown voltage
achieved.
42813
Licciardo G.D et.al
Analytical Model of the Forward Operation of 4H-SiC Vertical DMOSFET in the Safe
Operating Temperature Range
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5800 - 5809
A new analytical model of 4H-SiC DMOSFETs that is useful to explore their thermal stability
is presented. The model is capable to describe, with closed-form equations, the dc forward
behavior of devices in a wide temperature range, including the effects of parasitic
resistances and oxide interface traps. The model allows to analyze the onset of
electrothermal stability of 4H-SiC DMOSFETs both in triode and in saturation region and to
monitor the impact of the series resistance and traps on reliable operation of devices. The
accuracy of the model has been verified by comparisons with numerical simulations that
evidence the effect of trap densities in the range [0-1014 ] cm-2 · eV-1 for operating
temperatures up to 500 K. Comparisons with experimental data of 1.2 and 1.7 kV
commercial devices are used to validate the model.
42814
Cortes J. et.al
V1 Concept: Designing a Voltage-Mode Control as Current Mode with Near TimeOptimal Response for Buck-Type Converters
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5829 - 5841
This paper introduces the v1concept that explains how by only measuring the output
voltage, designers have information about almost every signal of the power stage.
Following the v1concept, it is explained how to design a traditional type-III voltage-mode
control to behave like a current-mode control with near time-optimal response under load
transients. This study is validated in simulations and experimentally on a 300-kHz buck
converter.
42815
Scandola L. et.al
Small-Signal Modeling of Uniformly Sampled Phase-Shift Modulators
100
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5870 - 5880
Phase-shift modulation (PSM) is a commonly used technique for controlling the active
power flow in resonant dc-ac and dc-dc converters. Although traditionally developed as
an analog modulation scheme, PSM is being increasingly implemented digitally in
conjunction with advanced multivariable digital controllers and online efficiency
optimization algorithms. While analog PSM is known not to introduce additional dynamics
from a small-signal standpoint, the analysis disclosed in this study indicates that discretetime, or uniformly sampled, PSM introduces a transport delay of small-signal nature.
Furthermore, and in close analogy with the theory of uniformly sampled pulse width
modulators, such delay depends on the modulator carrier type as well as on the converter
operating point. This paper first clarifies the modeling procedure for describing the smallsignal dynamics of uniformly sampled phase-shift modulators. Second, it provides an
extension of the traditional phasor modeling to digital phase-controlled converters,
allowing to account for the additional modulator dynamics in the design of the closed-loop
compensation. Theoretical findings are validated via simulation and experimental results.
42816
Jinyu Wang et.al
A Method to Improve the Dynamic Performance of Moving Average Filter-Based PLL
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5978 - 5990
Phase-locked loop (PLL) technique is widely used for synchronization applications. A
variety of moving average filter (MAF)-based PLLs have been presented in recently
published literatures. MAF-based PLL can completely eliminate the effect of unbalanced
voltage, characteristic harmonics, and dc offset. Unfortunately, the open-loop bandwidth
is drastically reduced after incorporating MAF into the PLL structure. The problem is
analyzed in detail in this paper, and it is proved to be caused by the large MAF window
width which is determined by the lowest order harmonic. Then, an improved method
named differential MAF-PLL (DMAF-PLL) is proposed. This method can rapidly eliminate
the lowest order harmonic to narrow the MAF window width. DMAF-PLL is realized by
incorporating a special proportional component into the MAF-based PLL. The special
proportional component can online change its value according to the frequency of input
signal, and it will not introduce phase lag, so as not to deteriorate the stability of PLL.
DMAF-PLL increases the open-loop bandwidth and greatly improves the dynamic
performance of MAF-based PLL, and it is easy to be implemented with low computational
burden. DMAF-PLL can be used in both three-phase and single-phase voltage systems.
Simulation and experimental results are included to validate the effectiveness and
robustness of the proposed method.
42817
Kolluri S. & Narasamma N.L.
A New Isolated Auxiliary Current Pump Module for Load Transient Mitigation of Isolated
/ Nonisolated Step-Up/Step-Down DC–DC Converter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5991 - 6000
101
This paper presents a new isolated auxiliary current pump module (ACPM), to improve the
dynamic response of dc-dc converters under load transients. The developed isolated ACPM
can be used as a generic auxiliary module for both isolated and nonisolated step-up/stepdown dc-dc converters. The isolated ACPM is a low-power bidirectional converter,
designed with higher bandwidth and operates only during the load transients. The
performance of the developed auxiliary power converter has been evaluated in
conjunction with an interleaved boost converter as main converter, which suffers from
poor dynamic performance due to inherent right half plane zero effect. A suitable control
scheme is designed and implemented for interleaved boost converter operating in
conjunction with proposed isolated ACPM. Load current injection circuit employed in the
proposed control scheme eliminates the requirement of complex nonlinear control
algorithms. The proposed control scheme in particular suits for current-mode controlled
converters operating along with isolated ACPM. Experimental results for a 250-W 100-kHz
interleaved boost converter prototype with ACPM are presented. The peak
overshoot/undershoot and the transient recovery time are reduced significantly with the
incorporation of developed isolated ACPM.
42818
Zhigang Dang et.al
Reconfigurable Magnetic Resonance-Coupled Wireless Power Transfer System
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6057 - 6069
This paper presents a method for a reconfigurable magnetic resonance-coupled wireless
power transfer (R-MRC-WPT) system in order to achieve higher transmission efficiency
under various transmission distance and/or misalignment conditions. Higher efficiency,
longer transmission distance, and larger misalignment tolerance can be achieved with the
presented R-MRC-WPT system when compared to the conventional four-coil MRC-WPT (CMRC-WPT) system. The reconfigurability in the R-MRC-WPT system is achieved by
adaptively switching between different sizes of drive loops and load loops. All drive loops
are in the same plane and all load loops are also in the same plane; this method does not
require mechanical movements of the drive loop and load loop and does not result in the
system volume increase. Theoretical basis of the method for the R-MRC-WPT system is
derived based on a circuit model and an analytical model. Results from a proof-of-concept
experimental prototype, with transmitter and receiver coil diameter of 60 cm each, show
that the transmission efficiency of the R-MRC-WPT system is higher than the transmission
efficiency of the C-MRC-WPT system and the capacitor tuning system for all distances up
to 200 cm (~3.3 times the coil diameter) and for all lateral misalignment values within 60
cm (one coil diameter).
42819
Waffenschmidt E.
Dynamic Resonant Matching Method for a Wireless Power Transmission Receiver
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6070 - 6077
Wireless power transmission systems can be optimized by matching the resonance
frequency of a receiver. However, in certain applications, such as, e.g., a multi-receiver
system, it is desired to match the individual resonance frequencies of the receiver to a
102
fixed (e.g., common) operation frequency. In this publication, a method is proposed to
match the resonant frequency dynamically without changing the physical value of the
components. Instead, it is changed “virtually” by a method, which is named “frozen
resonance state” by the author. The basic idea is to maintain the state of a resonant circuit
(to “freeze” the state) for a fraction of the resonant period, e.g., by freewheeling the
current of the resonant inductor or maintaining the voltage of the resonant capacitor. This
additional time extends virtually the resonant period leading to an effective lower
resonant frequency. By adjusting the additional time, the effective resonant frequency
can be matched to the operation frequency individually for each receiver. This publication
explains the basic idea more in detail and gives an overview of the different possible circuit
topologies. Furthermore, the method is applied to an exemplary receiver of a capacitive
wireless power transmission system, where measurements are presented.
42820
Trigui A. et.al
Inductive Power Transfer System With Self-Calibrated Primary Resonant Frequency
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6078 - 6087
Inductive power transfer (IPT) is a commonly employed technique for wirelessly supplying
power to implantable medical devices. A major limit of this approach is the sensitivity of
the inductive link to coupling factor variations between transmitting and receiving coils.
We propose in this paper a new method for compensating these variations and improving
the inductive link efficiency. The proposed technique is based on a mechatronic module
that dynamically tunes the primary resonant capacitor value in order to maintain the
resonance state of the IPT system. The module is able to maintain resonance state for
apparent primary inductance range at least from 0.5 to 5 µH using a high capacitance
resolution of 0.032 pF. Experimentations conducted on a 13.56MHz IPT system showed a
65% higher power transfer compared to a traditional IPT system.
42821
Hoang Nguyen & Agbinya J.I.
Splitting Frequency Diversity in Wireless Power Transmission
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6088 - 6096
This paper investigates the methodology to create multiple frequency modes in a
multiresonator system of one transmitter and multiple receivers based on the circuit
theory. The multiple frequencies from natural responses of magnetic couplings could be
obtained by determining the eigenvalues of a matrix equation. This potentially allows us
to diversify transmissions to and from devices. Theoretical calculations and experiments
show similar results of the multiple frequencies at given coupling conditions. Models of
two, three, and four coils in straight line demonstrate the splitting mode in the spectral
domain, which are validated by envelopes of signals. In measurements, three frequencies
of 525, 625, and 695 kHz, and four frequencies of 495, 590, 670, and 755 kHz are achieved
at the receiver for three- and four-coil models, respectively, when coils are equally
distanced by 2 cm. When coupling coefficient of every adjacent coil in three-coil model is
0.2, aggregating the peak power at two and three splitting modes result in 28% and 71%,
respectively, more power than that at resonance frequency. Similarly, with two, three,
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and four modes in four-coil model, the increases are 43%, 23%, and 33% with two, three,
and four modes, respectively.
42822
Yue-Long Lyu & Fan-Yi
A Method of Using Nonidentical Resonant Coils for Frequency Splitting Elimination in
Wireless Power Transfer
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6097 - 6107
In this paper, an efficient method is proposed to eliminate frequency splitting in
nonradiative wireless power transfer via magnetic resonance coupling. In this method, two
nonidentical resonant coils (NIRCs) are used as wireless power transmitter and receiver,
respectively. According to the elliptic integral term in the analytical expression, the pole
of the mutual inductance function with respect to transfer distance can be eliminated by
using the two NIRCs, and hence overcoupling between transmitter and receiver with close
transfer distance is avoided. Therefore, frequency splitting caused by overcoupling can be
suppressed and stable output power can be achieved. The NIRCs are analytically
calculated, numerically simulated and finally, fabricated and tested to verify the theory.
All the calculated and experimental results show that frequency splitting is completely
eliminated and uniform voltage across the load is achieved. Furthermore, lateral
misalignment between the NIRCs barely introduces frequency splitting, and the
suppression level of frequency splitting can also be controlled freely.
42823
Cong Zheng et.al
Design Considerations to Reduce Gap Variation and Misalignment Effects for the
Inductive Power Transfer System
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6108 - 6119
An inductive power transfer (IPT) system usually consists of four parts: an ac-dc power
factor correction (PFC) converter, a high-frequency dc-ac inverter, a compensation
network comprising a loosely coupled transformer (LCT) and the resonant capacitors, and
a rectification output circuit. Due to the relatively large air gap, the magnetic coupling
coefficient of the IPT system is significantly lower than that with tightly coupled
transformer. As a result, the efficiency of the IPT system is always a main concern for
applications with possible gap variation or misalignment condition. To ensure high power
transfer efficiency, these IPT systems should have high tolerance for different gap
variation and horizontal misalignment conditions. In this paper, the effect of coupling
coefficient deviation to compensation network efficiency is analyzed, and design
considerations to reduce gap and misalignment effects for the IPT system are proposed.
By using finite-element analysis simulation method, the performance of different
transmitter and receiver coil dimensions is compared. In order to validate the performance
of the proposed design considerations, a 100-W hardware prototype with two sets of LCT
is built and the corresponding experiments are carried out. As compared to the
symmetrical LCT architecture, the proposed asymmetrical LCT prototype improves the
coupling coefficient reduction from 68% to 28% when the gap varies from 6 to 20 mm and
from 89% to 31% when the misalignment ranges from 0 to 50 mm. Therefore, the efficiency
deviation for the asymmetrical LCT is maintained within 3.5% over the entire tested gap
variation and misalignment ranges.
104
42824
Matsumoto H. et.al
Switched Compensator for Contactless Power Transfer Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6120 - 6129
Contactless power transfer systems require compensators to improve power factor
degradation caused by significant leakage inductance in the contactless power
transformer. The most commonly used compensators are LC series- and parallel-resonant
compensators. In this paper, we present a comparison between the characteristics of the
compensators with a focus on transfer efficiency. Based on these characteristics, a
compensator capable of switching between the LC parallel- and series-resonant topologies
is proposed, and its changeover algorithm is explained. The proposed compensator was
experimentally examined and was found to perform efficiently over a wider range of
output power than conventional LC resonant compensators.
42825
Junjun Deng et.al
Compact and Efficient Bipolar Coupler for Wireless Power Chargers: Design and
Analysis
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6130 - 6140
Compactness and efficiency are the two basic considerations of the wireless battery
chargers for electric vehicles (EVs) and plug-in hybrid EVs. The double-sided LCC
compensation topology for wireless power transfer (WPT) has been proved to be one of
the efficient solutions lately. However, with the increase of the numbers of compensation
components, the volume of the system may become larger, which makes it less attractive.
To improve the compactness, a bipolar coupler structure with a compensation-integrated
feature is proposed. The inductors of the LCC compensation networks are designed as
planar-type and attached to the power-transferring main coils. Extra space and magnetic
cores for the compensated inductors outside of the coupler are saved. The cost is that
extra couplings between the compensated coils (inductors) and the main coils are induced.
To validate the feasibility, the proposed coupler is modeled and investigated by 3-D finiteelement analysis tool first. The positioning of the compensated coils, the range of the
extra couplings, and the tolerance to misalignment are studied. This is followed by the
circuit modeling and characteristic analysis of the proposed WPT topology based on the
fundamental harmonic approximation. At last, a 600 mm × 600 mm with a nominal 150mm-gap wireless charger prototype, operated at a resonant frequency of 95 kHz and a
rated power of 5.6 kW has been built and tested. A peak efficiency of 95.36% from a dc
power source to the battery load is achieved at rated operation condition.
42826
Kamineni A. et.al
Analysis of Coplanar Intermediate Coil Structures in Inductive Power Transfer Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6141 - 6154
Intermediate couplers have been shown to increase the coupling from primary to
secondary pads in inductive power transfer (IPT) systems. This paper investigates
embedding a coplanar intermediate coupler coil with the primary coil inside the primary
pad to boost the coupling to the secondary pad and improve the efficiency of the system.
105
Several coil designs are simulated and a mathematical model is developed to evaluate the
efficiency of parallel-parallel and series-series tuned systems. As shown a coplanar,
independently tuned intermediate coupler coil improves the efficiency of a series-seriestuned system since it reduces source losses. However, there appears to be no benefit to
having an intermediate coupler with a parallel-parallel-tuned system. Furthermore, boosts
in coupling are a result of adding extra current carrying windings to the primary pad and
simulations show that operating the system as a traditional two coil IPT system may be
simpler and more effective based on tuning topology. An experimental system was
constructed to validate the simulations.
42827
Hurley W.G. et.al
A Unified Approach to the Calculation of Self- and Mutual-Inductance for Coaxial Coils
in Air
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6155 – 6162
This paper extends a previous formula for the mutual inductance between single-turn coils
to include all coils in air with rectangular cross sections, without any restrictions on the
dimensions (including overlapping coils). The formula is compared with a wide spectrum
of examples from the literature and agreement is excellent in every case. Experimental
results are presented to validate the formula for both solenoid and disk coils. The formula
is relevant to coreless transformers, inductive coupling, wireless power transfer, and
leakage inductance in resonant converters.
42828
Chabalko M.J. & Sample A.P.
Three-Dimensional Charging via Multimode Resonant Cavity Enabled Wireless Power
Transfer
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6163 - 6173
The majority of existing wireless power solutions are capable of 2-D surface charging of
one or two devices, but are not well suited to deliver power efficiently to large numbers
of devices placed throughout a large 3-D volume of space. In this paper, we propose an
unexplored type of wireless power transfer system based on electromagnetic cavity
resonance. Here, we use the natural electromagnetic modes of hollow metallic structures
to produce uniform magnetic fields which can simultaneously power multiple small
receiver coils contained almost anywhere inside. An analytical model is derived that
predicts the coupling coefficient and power transfer efficiency from the cavity resonator
to a small coil. These predictions are verified against simulated results with a coefficient
of determination of 0.9943. By using two resonant modes, we demonstrate that a 3-in
diameter receiver can be powered in nearly any location in a 140 cubic foot test chamber,
at greater than 50% efficiency. Additionally, we show that ten receivers can be powered
simultaneously and that this system is capable of recharging consumer electronics such as
a cell phone.
106
42829
Yiming Zhang et.al
Employing Load Coils for Multiple Loads of Resonant Wireless Power Transfer
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6174 – 6181
The load coils are employed for multiple loads of resonant wireless power transfer in this
paper. With the addition of the load coil, this three-coil structure has easy access to
transferring power to multiple loads with the advantages of a compact structure and
controllable power flow. Both single-load transfer and multiple-load transfer are modeled
and analyzed by means of the circuit theory. The transfer quality factor and the load
matching factor are utilized in the analysis of efficiency. In the single-load transfer, the
load matching condition is fully explored. Based on the single-load transfer, the multipleload transfer is researched. The double-load transfer, acting as an illustration, is studied
with the uncoupled and coupled load coils. Equivalent reflected resistances are introduced
to decouple the model of the double-load transfer with coupled load coils mathematically.
An experimental prototype is implemented to verify the aforementioned analysis. The
experimental results agree with the theoretical calculations.
42830
Stevens C.J.
Magneto-inductive Waves and Wireless Power Transfer
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6182 - 6190
Recent research in wireless power transfer has highlighted the potential benefits for
relaying power from source to receiver by a number of resonating relay coils coupled via
mutual inductance. A number of researchers have reported experimental systems based
on relay coils and have noted that power transfer efficiency to loads located at different
points on the structure can vary widely. Such structures, often known as magnetoinductive
waveguides are well known to carry signals known as magnetoinductive waves (MIW) when
excited with a frequency in their passband. This paper presents an investigation into their
impact on wireless power systems and methods by which negative effects may be
minimized. Using the physics of magneto-inductive waves it becomes possible to
understand the behavior of relay coil systems and to model them in a closed form. The
effects of reflections and standing waves on a one-dimensional system are considered and
their effect on the input impedance and the variation of matching conditions determined.
An optimum receiver load is proposed based on the results and tested experimentally. A
simple experimental demonstrator is used as a model for study, which achieves 58%
efficient power transfer to a single load at any point on its length.
42831
Qifan Li & Liang Y.C.
An Inductive Power Transfer System With a High-Q Resonant Tank for Mobile Device
Charging
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6203 - 6212
Inductive power transfer (IPT), which employs the principle of electromagnetic induction,
is widely applied to wireless charging applications. The efficiency of an IPT system is highly
dependent on the quality factor (Q) of the power resonant tank. In this paper, a novel
design on the structure of the resonant coil is used in the resonant tank to achieve a
107
significantly high Q above 1000 for the IPT system. Compensating capacitors are used in
both primary and secondary circuits to align the resonant frequencies in order for the
system resonant status to be maintained by a frequency tracking circuit. The experimental
results show that with a primary coil Q of 1200, the proposed IPT system allows power to
be transferred at a maximum air gap distance to coil diameter ratio of 1.46 for a highest
efficiency of 87% at the resonant frequency of 106 kHz.
42832
Zhen Zhang & Chau K.T.
Homogeneous Wireless Power Transfer for Move-and-Charge fn
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6213 - 6220
This paper presents a homogeneous wireless power transfer (WPT) technique to
continuously energize the moving target. Due to the mobility of the charging target, the
misalignment between the primary and secondary coils inevitably deteriorates the energy
transfer performance by adopting the conventional WPT technique, so the constant
energization mechanism is the most important issue for move-and-charge systems. The
proposed homogeneous WPT technique utilizes the alternate winding design to gaplessly
assemble primary coils, aiming to enhance the magnetic flux density. Besides, the verticaland-horizontal secondary coil is also implemented to further improve the capability of
acquiring energy for charging targets, especially in the area of the coils gap. In such ways,
the proposed homogeneous WPT technique can effectively fulfil a continuous charging
mechanism for moving targets. Also, this paper deduces the equivalent circuit model to
analyze the mutual effect among multiple primary coils, which offers the theory-based
view for the design of move-and-charge systems. Besides, both simulation and
experimental results are provided to verify the feasibility of the proposed homogeneous
WPT technique for move-and-charge systems.
42833
Weiyang Zhou & Ke Jin
Efficiency Evaluation of Laser Diode in Different Driving Modes for Wireless Power
Transmission
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6237 - 6244
The high-intensity laser power beaming (HILPB) system is one of the most promising system
in the field of long-range wireless power transfer. In HILPB system, the high-power laser
diode (LD) is employed for its excellent character of high efficiency, high reliability, and
small size. Normally, LD can operate in two different driving modes: the continuous mode
and the pulse mode. The injected current has a direct effect on the electro-optical
conversion efficiency of LD. This paper centers around LD model and its current source
driver. The conversion efficiencies of the two driving modes are evaluated by means of
simulations and experiments. The experimental results are shown to verify the theoretical
analysis.
42834
Hongchang Li et.al
Dynamic Modeling Based on Coupled Modes for Wireless Power Transfer Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6245 - 6253
108
A novel dynamic modeling method based on the concept of coupled modes is proposed for
wireless power transfer (WPT) systems which use magnetic resonant coupling. The
proposed method aims on the dynamics of the overall WPT system, including the nonlinear
inverter and rectifier. It uses the slowly varying amplitudes and phases of coupled modes
rather than resonant currents and voltages to describe the coupled resonances. Three
analytical models-averaged model, small signal model, and conductance network model
are developed sequentially by using the proposed method. The orders of the developed
models are equal to or lower than that of the discrete state space model. In contrast, the
existing dynamic modeling methods for WPT systems and resonant converters have to
transform the discrete state space model into a higher order model or use complex
currents and voltages in order to adopt the averaging method and obtain an analytical
model. Simulation and experimental results give a firm support to the proposed method
and models. The concept employed in this paper provides a deeper insight into the
dynamic behaviors of coupled resonances.
42835
Minh Quoc Nguyen et.al
Multiple-Inputs and Multiple-Outputs Wireless Power Combining and Delivering Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6254 - 6263
In this paper, we investigated the effect of power combining and delivering in multiinput
and multioutput wireless energy transmission systems, which consist of more than one
transmitter antennas as sources and more than one receiver antennas as loads and
repeaters. Theoretical expressions were developed to model the system operation that
can be in a large-scale wireless energy network architecture. System characteristics, such
as power transfer between antennas, power losses induced in each antenna, wireless
efficiency, coil misalignment, and power fluctuation due to the loss of frequency
synchronization were examined by theory and verified with experiments. Measurement
results matched well with the theory demonstrating the feasibility of combining and
delivering power with high efficiencies in large-scale wireless energy transmission systems.
42836
Nadakuduti J. et.al
Compliance Testing Methodology for Wireless Power Transfer Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6264 - 6273
Wireless power transfer (WPT) systems have become popular, with applications in charging
portable electronics via inductive coupling between a transmit and receive coil. Accurate
estimation of the induced exposure is required as the incident magnetic fields near the
coils often exceed the reference levels. Standardized procedures do not yet exist for the
demonstration of compliance of these products with electromagnetic guidelines for human
exposure. For this purpose, we propose a conservative methodology using simplified
homogeneous phantoms. An approximation for the minimum compliance distance for user
exposure is developed based on the theoretical evaluation of the induced fields and
simulations of detailed anatomical models. The simulation results are experimentally
validated for a practical WPT application at 6.78 MHz. Criteria for exclusion of WPT
systems from compliance evaluation are presented as a function of coil dimensions,
operating current and frequency.
109
42837
Yongseok Lim & Jongsun Park
A Novel Phase-Control-Based Energy Beamforming Techniques in Non-radiative
Wireless Power Transfer
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6274 - 6287
Recent efforts to increase the energy transfer efficiency in magnetic resonant couplingbased wireless power transfer (WPT) systems, have been focused on improving quality
factor, precision of impedance matching, and position alignment between the resonators.
Although those approaches are effective to increase transfer efficiencies, the transferred
energy can easily be wasted due to leakage flux of nondirectional fields. In this paper, we
present a novel magnetic field shaping technology for improving the energy efficiency in
a near-field WPT system. In this study, the beamforming techniques that have been used
for radio frequency systems are efficiently exploited in a WPT system to improve the
transfer efficiencies by minimizing unnecessary leakage flux. The optimal antenna
structure for energy forming is first determined through mathematical analysis. Using the
proposed crossed antennas, the phase-control method is effectively used to form magnetic
fields in particular directions. The proposed energy forming-based WPT system using
crossed antennas is implemented with the phase control of three-power stack
transmitters. The experimental results matches well with the theoretical analysis, and the
energy-forming approach for synthesizing the magnetic fields achieves average
improvements of the transfer efficiency and transfer distance of up to 20.1% and 30%,
respectively, over the conventional nonradiative energy transfer approach at 1 m distance.
42838
Colak K. et.al
A Novel Phase-Shift Control of Semi-bridgeless Active Rectifier f
or Wireless Power Transfer
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6288 - 6297
A novel phase-shift control of a semibridgeless active rectifier (S-BAR) is investigated in
order to utilize the S-BAR in wireless energy transfer applications. The standard receiverside rectifier topology is developed by replacing rectifier lower diodes with synchronous
switches controlled by a phase-shifted PWM signal. Theoretical and simulation results show
that with the proposed control technique, the output quantities can be regulated without
communication between the receiver and transmitter. To confirm the performance of the
proposed converter and control, experimental results are provided using 8-, 15-, and 23cm air gap coreless transformer which has dimension of 76 cm × 76 cm, with 120-V input
and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.
42839
Waters B.H.et.al
Power Delivery and Leakage Field Control Using an Adaptive Phased Array Wireless
Power
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6298 - 6309
Efficient wireless power transfer and precise control of power delivery and leakage field
strength can be achieved using a phased array wireless power transfer system. This has
particular importance for charging multiple devices simultaneously, or charging devices in
110
environments where humans or foreign objects will be in close proximity. The phased array
wireless power system consists of two or more phase-synchronized power amplifiers each
driving a respective transmit coil. The system can maximize power delivery to an intended
receiver in one location while simultaneously minimizing power delivery and leakage fields
in other locations. These functions are possible by varying the amplitude and phase of
each transmitter. This paper provides an analysis of a phased array wireless power transfer
system using near-field magnetically coupled resonators, and derives parameters that can
be used to automatically determine the optimal magnitude and phase of each transmitter
to deliver power to one or more receivers. Experimental results verify the theoretical
analysis and additional features of the full system are demonstrated.
42840
Diekhans T. & De Doncker R.W.
A Dual-Side Controlled Inductive Power Transfer System Optimized for Large Coupling
Factor Variations and Partial Load
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6320 - 6328
In this study, a 3-kW inductive power transfer system is investigated, specifically intended
for contactless vehicle charging. A series-series-compensated topology with dual-side
power control and a corresponding control strategy is proposed to significantly increase
the overall efficiency, especially for systems with large coupling factor variations and in
partial load mode. The topology, which is closely related to the dual-active bridge
converter, enables the dual-side power control without adding additional dc/dc converters
to the system, and thus keeping the additional hardware effort minimal. A detailed
analysis of the proposed topology is provided, and the benefits of the dual-side control are
demonstrated both theoretically and experimentally. A hardware prototype is built and a
peak dc-to-dc efficiency of 95.8% at 100 mm air gap and a minimal efficiency of 92.1% at
170 mm air gap is measured, including the power electronic components. The partial load
efficiency at 500 W output power is still as high as 90.6% at 135 mm air gap. Overall, the
proposed topology provides a practical method to overcome the main drawback of most
single-side controlled inductive power transfer systems, which is a significant efficiency
drop outside the nominal operating point.
42841
Berger A et.al
A Wireless Charging System Applying Phase-Shift and Amplitude Control to Maximize
Efficiency and Extractable Power
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6338 - 6348
Wireless power transfer (WPT) is an emerging technology with an increasing number of
potential applications to transfer power from a transmitter to a mobile receiver over a
relatively large air gap. However, its widespread application is hampered due to the
relatively low efficiency of current Wireless power transfer (WPT) systems. This study
presents a concept to maximize the efficiency as well as to increase the amount of
extractable power of a WPT system operating in nonresonant operation. The proposed
method is based on actively modifying the equivalent secondary-side load impedance by
controlling the phase-shift of the active rectifier and its output voltage level. The
presented hardware prototype represents a complete wireless charging system, including
a dc-dc converter which is used to charge a battery at the output of the system.
Experimental results are shown for the proposed concept in comparison to a conventional
111
synchronous rectification approach. The presented optimization method clearly
outperforms state-of-the-art solutions in terms of efficiency and extractable power.
42842
Yu-Gang Suet.al
Steady-State Load Identification Method of Inductive Power Transfer System Based on
Switching Capacitors
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6349 - 6355
An online steady-state load identification method is proposed to solve the problems
related to frequency drift, system robustness deterioration, difficulties in controller
design due to the uncertainties in load and mutual inductance variations of an inductive
power transfer (IPT) system. Take a Series-Series-type IPT system as an example, an
additional capacitor is added into the system to make the system work in two operating
modes, and a mathematical model is established according to the two modes for the
system identification. Simulation and experimental results have verified the proposed
online load identification method. It has demonstrated that the method is accurate and
reliable for identifying uncertain loads and magnetic coupling variations if other system
parameters are known. The method can be used to improve the system performance with
precise control.
42843
Vatani M. et.al
Control of the Modular Multilevel Converter Based on a Discrete-Time Bilinear Model
Using the Sum of Squares Decomposition Method
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2179 - 2188
The modular multilevel converter (MMC) has become one of the most promising candidates
for medium-/high-power applications, specifically for high-voltage direct current
transmission systems. This paper proposes a control strategy for the MMC based on the
sum-of-squares decomposition method. A bilinear mathematical discrete model of the
MMC is derived in the rotating reference frame by including the dynamics of ac-side
currents, circulating currents, dc-side current, and stored energy of the converter. The
coordinates of the developed model are transformed to the origin, and the steady-state
operating point of the MMC is calculated based on the desired reference values of the
states. A quadratic Lyapunov function is defined and by converting the Lyapunov
difference inequality to an SOS problem, a stabilizing controller is designed. The designed
controller not only guarantees the Lyapunov stability of the states, but also controls the
external and internal dynamics of the MMC with only one controller, instead of using
several proportional-integral controllers. To improve the region of stability of the MMC,
an optimization problem is formulated and solved, so the controller can stabilize the MMC
from an initial operating point far from the steady-state operating point. The performance
of the proposed strategy for a 20-level MMC is evaluated based on the time-domain
simulation studies and is compared with the existing control methods.
42844
On Capacitor Switching Transient Immunity of Inverter-Based Renewable Generations
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2339 - 2345
112
This paper highlights an immediate need for renewable generation developers,
manufacturers, utilities and industry standardization institutes to jointly address a
challenge of capacitor switching transient immunity in inverter-based wind or solar farms.
The need was identified from wide-area operation records which showed partial or full
generation loss in coincidence with routine utility-owned capacitor switching. The lack of
a clear industry guideline has caused confusion to all involved parties. This paper
recommends all entities to address this challenge collaboratively through enhanced
equipment specification, design, and test before a well-defined industry guideline
becomes available.
42845
Guha Thakurta P. et.al
Risk-Based Management of Overloads Caused by Power Injection Uncertainties Using
Power Flow Controlling Devices
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3082 - 3092
Increased penetration of renewable energy leads to increased challenges for the
transmission system operators (TSOs) to operate their system in a secure way. Through the
limited means available to the TSOs to manage power flows in the system, reliability is
jeopardized. Reliability must be managed differently, replacing the current ways of
reliability management which fails as uncertainty increases. In this paper, a novel riskbased approach of system operation is proposed that can be helpful for the TSOs to assess
the confidence of system operation day-ahead that is, the probability of the forecasted
system to end up in an insecure state is calculated. This paper only focuses on violation of
power flow constraints in the system. It also demonstrates the increase of this operation
confidence using already installed power flow controlling devices. It is shown that these
devices aid in enhancing confidence of system operation by shifting power flows to a more
optimal one in the light of generation uncertainty. The main emphasis is laid on preventive
action. The proposed approach is demonstrated on test systems.
42846
Jingchao Deng et.al
Coordinated Design of Multiple Robust FACTS Damping Controllers: A BMI-Based
Sequential Approach with Multi-Model Systems
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3150 - 3159
This paper presents the coordinated design of multiple FACTS supplementary damping
controllers to improve system small-signal stability. A BMI-based multi-objective multimodel system approach is formulated to solve the robust damping control problem. Twostep method is proposed to determine controller variables. Regional pole placement and
control effort optimization are set as the control objectives. An SVC and a TCSC damping
controller are designed sequentially with minimized decoupling effort. Selection of the
feedback signals for the FACTS damping controllers is realized by evaluating the modal
residues of each feedback signal to the system input. To cover multiple inter-area
oscillation modes, wide-area decentralized control methodology is proposed and remote
feedback signals are selected. Real-time simulation is carried out on real-time digital
simulator (RTDS) to test the performance of the proposed controller. The results show that
the FACTS damping controllers are feasible and able to increase system damping to a
satisfactory level under different system operating points.
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9. POWER SYSTEM
42847
Lan Zhu et.al
Direct Load Control in Microgrids to Enhance the Performance of Integrated Resources
Planning
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3553 - 3560
Load management is usually not considered in details during the planning stage due to its
complexity and uncertainty in nature. However, this practice is changed in microgrids
since the load composition in microgrids is more specific and manageable. In addition, the
development of advanced metering infrastructure provides a more convenient mechanism
for data collection and system control. This paper presents an integrated resources
planning model based on optimal direct load control (DLC) (such as control of the airconditioning load) in microgrids for load shifting and peak shaving to reduce/defer
investments and minimize total social costs. This paper begins with the introduction of
DLC and the models of the relevant distributed generation resources, including
photovoltaic, wind turbines, diesel engines, and batteries. An algorithm is presented to
combine the microgrid planning and DLC strategy. The results of the case study show that
the proposed model provides an effective approach for the least cost planning in
microgrids by using load management as competitive virtual power sources.
42848
Farhadi M et.al
Performance Enhancement of Actively Controlled Hybrid DC Microgrid Incorporating
Pulsed Load
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3570 - 3578
In this paper, a new energy control scheme is proposed for actively controlled hybrid dc
microgrid to reduce the adverse impact of pulsed power loads. The proposed energy
control is an adaptive current-voltage control (ACVC) scheme based on the moving average
measurement technique and an adaptive proportional compensator. Unlike conventional
energy control methods, the proposed ACVC approach has the advantage of controlling
both the voltage and current of the system while keeping the output current of the power
converter at a relatively constant value. For this study, a laboratory-scale hybrid dc
microgrid is developed to evaluate the performance of the ACVC strategy and to compare
its performance with other conventional energy control methods. Using experimental test
results, it is shown that the proposed strategy highly improves the dynamic performance
of the hybrid dc microgrid. Although the ACVC technique causes slightly more bus voltage
variation, it effectively eliminates the high current and power pulsation of the power
converters. The experimental test results for different pulse duty ratios demonstrated a
significant improvement achieved by the developed ACVC scheme in enhancing the system
efficiency, reducing the ac grid voltage drop and the frequency fluctuations.
42849
Coelho A.L.M.
Loss-of-Excitation Protection and under excitation
Synchronous Generators in a Real-Time Digital Simulator
Controls
Correlation
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 3579 - 3590
114
for
This paper presents the results of a study that analyzes the relationship between the
excitation system of a synchronous machine and the settings of the loss-of-excitation (LOE)
relay applied to protect this machine. A complete generation system taking into account
all the physical components was modeled in a real-time digital simulator, including a new
excitation system model (ST7B). By considering a method to protect the generator against
partial and total LOE, the settings of the LOE protection were made taking into account
the technical data of the synchronous machine. A hardware-in-the-loop simulation using a
numeric relay was implemented in a laboratory. Thus, several tests were performed in
order to evaluate the coordination between the protective relay and the limits of the
modeled excitation system during under excited operation.
42850
Kukkola J. et.al
Observer-Based State-Space Current Controller for a Grid Converter Equipped With an
LCL Filter: Analytical Method for Direct Discrete-Time Design
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4079 - 4090
State-space current control enables high dynamic performance of a three-phase gridconnected converter equipped with an LCL filter. In this paper, observer-based state-space
control is designed using direct pole placement in the discrete-time domain and in gridvoltage coordinates. Analytical expressions for the controller and observer gains are
derived as functions of the physical system parameters and design specifications. The
connection between the physical parameters and the control algorithm enables automatic
tuning. Parameter sensitivity of the control method is analyzed. The experimental results
show that the resonance of the LCL filter is well damped, and the dynamic performance
specified by direct pole placement is obtained for the reference tracking and grid-voltage
disturbance rejection.
42851
Tint Soe Win et.al
Novel Simple Reactive Power Control Strategy with DC Capacitor Voltage Control for
Active Load Balancer in Three-Phase Four-Wire Distribution Systems
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4091 - 4099
This paper proposes a novel simple reactive power control strategy for the active load
balancer (ALB) in three-phase four-wire distribution systems. The proposed reactive power
control strategy may be applicable for adjustment of the source-side power factor under
the balanced load condition. Only dc capacitor voltage control is used in the proposed
control strategy. Therefore, the calculation blocks of the active and reactive components
of the load currents are not necessary. The authors, thus, offer the simplest control
strategy to control reactive power under the balanced load condition on three-phase fourwire distribution feeders. The basic principle of dc-capacitor-voltage-control-based
reactive power control strategy is discussed in detail and then confirmed by digital
computer simulation. A prototype experimental system was constructed and tested.
Experimental results demonstrate that balanced source currents with reactive power
control are achieved on three-phase four-wire distribution feeders. These experimental
results also demonstrate that controlling the reactive power reduces the required power
rating of the ALB compared with that of the conventional unity power factor control
strategy.
115
42852
Blanco Charro C. et.al
Strategies for the Connection of Distributed Power Generation Units to Distorted
Networks
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4111 - 4120
Connection of distributed power generators (DPGs) to a utility grid requires the
synchronization between the DPG and the grid voltages with the goal of controlling the
power flow and limiting the currents at instant that the switch or breaker closes.
Synchronization methods typically match the positive sequence voltage component of the
two systems being connected, the connection being realized when the error is smaller than
a preset threshold. While synchronization using the positive sequence voltage provides
adequate results in the case of undistorted grid voltages, it can be inadequate if the grid
is polluted, e.g., in case of weak grids. Instantaneous voltage mismatches between the
DPG and the grid, e.g., due to the harmonic content or unbalances in the grid and/or DPG
voltages..., at the instant that the breaker closes, can cause over currents and result in
unwanted protection tripping or equipment damage, even if the corresponding positive
sequence voltages perfectly match. This paper analyzes the synchronization and
connection of DPGs to highly distorted grids with the goal of limiting the overcurrent due
to voltage mismatch. Once the connection is realized, a transition to the conventional
positive sequence voltage based synchronization occurs, as this is adequate to control the
power flow in steady state.
42853
Khan J. et.al
Embedded-Zerotree-Wavelet-Based Data Denoising and Compression for Smart Grid
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4190 - 4200
In this paper, an embedded zerotree wavelet transform (EZWT)-based technique is
employed for the data denoising and compression in the smart grid (SG). The EZWT is a
simple but effective data compression algorithm. This technique does not need any
training, prestored tables or codebooks, and prior knowledge of the data source. In this
paper, the analysis and subsequent compression and denoising properties of the EZWT are
examined for power system signals in SG. The proposed approach is evaluated using phasor
measurement units and power system data. Experimental results demonstrate that the
presented method both compresses the signal and depresses the noise contained in the
signal. Comparative compression and noise removal results are presented with the wavelet
transform.
42854
Kulkarni N. et.al
An Integrated Method for Optimal Placement and Tuning of a Power System Stabilizer
Based on Full Controllability Index and Generator Participation
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4201 - 4211
In this paper, an integrated architecture for optimal placement and tuning of power system
stabilizers (PSSs) in multimachine systems is proposed in order to improve system stability,
damp oscillations, and increase damping of the power system oscillatory modes. The
proposed approach provides full-rank optimal conditions for the PSS placement, which
provide complete controllability of the system. In addition, this method allows optimal
tuning of PSS parameters based on real and imaginary coefficients for damping. Test cases
116
are performed to evaluate the proposed concept, and it has been found that the proposed
architecture fully captures system dynamics and provides an efficient way for PSS
placement and tuning. The architecture is also verified using a real-time digital simulator
on a real experimental test bed and found that the method provides improvement in
system stability and reduces low-frequency oscillations in local and inter-area modes of
oscillations.
42855
Klement K.
DC Arc Flash Studies for Solar Photovoltaic Systems: Challenges and Recommendations
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4239 - 4244
A dc arc flash hazard exists in solar photovoltaic (PV) power systems, but there is no widely
accepted methodology for characterizing the severity of the hazard. Calculation methods
have been proposed, and most rely on the nameplate I-V characteristic of the PV modules
at standard test conditions to determine the worst case incident energy. This paper
proposes to consider other factors in performing a dc arc flash hazard analysis, including
possible weather conditions and variations of PV module characteristics from the
datasheet ratings. It is recommended to consider two conditions when determining the
worst case incident energy from a PV system: 1) the failure of all protective devices to
trip within 2 s due to insufficient current and 2) the array output power exceeding the
nameplate rating due to technological and environmental factors.
42856
Floyd H.L.
A Practical Guide for Applying the Hierarchy of Controls to Electrical Hazards
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4263 - 4266
The application of the hierarchy of risk control measures is fundamental to safety
management systems but is not incorporated directly in OSHA regulations for occupational
electrical safety or in NFPA 70E, Standard for Electrical Safety in the Workplace. The
application of a hierarchy of risk controls is a methodology used in safety management to
minimize or eliminate exposure to hazards and to eliminate or reduce risk of injury to as
low as reasonably practicable. It is a widely accepted methodology with applications
ranging from highly hazardous processes with potential for catastrophic consequences to
life, property, and the environment to preventing injuries when using portable hand tools.
This paper provides guidance on the practical application of the risk control measures in
both the design of workplace facilities and in task planning for construction, operation,
maintenance, and demolition work activities..
42857
Gammon T. et.al
“Arc Flash” Hazards, Incident Energy, PPE Ratings, and Thermal Burn Injury—A Deeper
Look
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4275 - 4283
Tremendous resources are being invested in arc flash studies and personal protective
equipment (PPE) to protect workers from “arc flash” hazards. In the flurry to comply with
OSHA regulations and NFPA 70 and 70E standards, the real understanding of the arc hazard
and incident energy may be lagging behind. The term “arc flash” does not adequately
117
convey the range of potential arc hazards-light, pressure, and heat transmission, as well
as others. The term “arc flash” also fails to emphasize that arc flash injuries primarily
arise from thermal burns and that the risk of a potentially severe or fatal arc burn is often
present when performing electrical work. Worker risk assessment and the appropriate PPE
are represented as definitive quantities in “cal/cm 2;” however, the quantitative potential
heat exposure and heat protection afforded by PPE are usually less precise than what
concrete numerical values imply. Basic concepts of incident energy, PPE ratings, and burn
injury are also explored in this paper to help identify factors influencing the burn hazards
posed by arcing faults in electrical power systems.
42858
Enrique E.H. & Walsh J.D.
Analysis of Touch Potentials in Solar Farms
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4291 - 4296
The grounding system in a solar farm has unique characteristics due to its extended
footprint and varying type of grounding components. The changing physical properties of
the soil within the perimeter of a solar farm result in the nonuniform resistivity of the top
soil layers. Measurements of the as-built grounding grid could indicate higher grounding
resistance than that predicted by design. Once this difference is detected, it is the duty
of the designer to modify the existing grounding grid such that the touch potential is below
the limits specified by the applicable codes. This paper presents the analysis of the touch
potentials in solar farms and also provides some recommendations to reduce these
potentials when the grounding resistance is higher than that predicted by the design. An
actual grounding grid design and field measurements are used in an example to illustrate
the concepts introduced in this paper.
42859
Kay J.A. & Mazur K.D.
Advancements in Vibration Monitoring for the Mining Industry
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4321 - 4328
Rotating machinery assets are a fundamental necessity in the mining industry.
Furthermore, the proper maintenance and ability to monitoring these key assets is
important to maximizing the operations. This paper will discuss the merits and
advancements in vibration monitor systems and the direct impact on supervisory control
and data acquisition and predictive maintenance models.
42860
Mendler R. et.al
Hazardous-Rated Electrical Equipment and the Arc-Flash Hazard
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4335 - 4341
This paper evaluates the relationship between hazardous-rated electrical equipment,
which is suitable for installation in Class I, Division 1 (Zone 1), or Division 2 (Zone 2)
locations, and an arc-rated switchgear, which is designed to withstand the effects of an
internal arcing fault. Using UL 1203 (Explosion-Proof and Dust-Ignition-Proof Electrical
Equipment for Use in Hazardous (Classified) Locations), IEEE C37.20.7 (IEEE Guide for
Testing Metal-Enclosed Switchgear Rated Up to 38 kV for Internal Arcing Faults), and the
paper titled “Pressure Developed by Arcs,” this paper will explore the applicability of
hazardous-rated equipment in the protection of personnel from an arc-flash hazard.
118
42861
Milicua A. et.al
Online Reference Limitation Method of Shunt-Connected Converters to the Grid to
Avoid Exceeding Voltage and Current Limits Under Unbalanced Operation—Part I:
Theory
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 852 - 863
This paper focuses the analysis around a grid-connected converter that operates under
unbalanced voltage and current conditions. Two different scenarios have been selected to
validate the proposed algorithms. In the first scenario, the converter operates as a reactive
power compensator, exchanging reactive power with the grid, and minimizing the dc bus
voltage oscillations. The second scenario is more challenging, since it operates as a load
balancer. In this application, the unbalanced current consumption of the load is
compensated by the converter, exchanging positive and negative sequence currents with
the grid. Another objective in this second scenario is to compensate the reactive power of
the unbalanced load. It is important to highlight that in both scenarios, any maximum limit
of the converter can be exceeded due to the specific unbalanced voltage and current
conditions. Three variables are considered critical for the converter: 1) output ac current
limit; 2) output ac voltage limit; and 3) dc bus voltage oscillation limit. Thus, this paper
proposes a control method, which limits online the reactive power reference in the first
scenario and the exchanged current references in the second scenario in order not to
exceed any of the mentioned critical variables. The corresponding experimental results
are shown in Part II of this paper so as to validate the limitation algorithm obtained by
means of the mathematical analysis carried out in Part I.
42862
Saarinen L. et.al
Field Measurements and System Identification of Three Frequency Controlling
Hydropower Plants
IEEE Trans. on Energy Conversion, Vol.30; No. 3; September 2015; 1061 - 1068
The dynamic behavior of hydropower plants participating in primary frequency control is
investigated in this paper through frequency response, step response, and setpoint change
tests on three Swedish hydropower plants. Gray-box system identification is used to
estimate the parameters of simple linear models suitable for power system analysis and
the major shortcomings of the linear models are discussed. It is found that frequency
response tests with sinusoidal input signals give more reliable information about the
dynamics of the plants than step response tests. It is also shown that backlash in the runner
and guide vane regulating mechanisms are of great importance for the dynamic behavior
of the plants, and that the incremental gain from guide vane opening to power varies
considerably with the operation point.
42863
Jie Yang et.al
The Hybrid-Cascaded DC–DC Converters Suitable for HVDC Applications
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5358 – 5363
119
A dc-dc converter is essential for interconnecting HVdc networks of different voltage
levels. This letter introduces a new family of dc-dc converters consisting of semiconductor
switches and stack of submodules, which is named as hybrid-cascaded dc-dc converter
(HCDC). This concept shows very attractive capital costs and low power losses. In this
letter, the detailed operating principle of the HCDC is analyzed. Simulation results are
obtained from PSCAD/EMTDC to verify the feasibility of the converters. The performances
of the converters are evaluated in detail.
42864
Xuejun Pei et.al
Analysis and Calculation of DC-Link Current and Voltage Ripples for Three-Phase
Inverter with Unbalanced Load
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5401 - 5412
In this paper, an analysis and calculation of the dc-link current and voltage ripples are
presented for a three-phase inverter with unbalanced load. A comparison of the dc-link
average and root-mean-square (rms) currents between considering and ignoring high
frequency harmonics of the output current is drawn. It is shown that high frequency
harmonic currents have little effect on the dc-link current, and therefore, they can be
ignored. Based on the symmetrical components method, the dc-link average and harmonic
rms currents are derived, and the dc-link voltage ripple is compared between the balanced
and unbalanced loads. It can be found that the dc-link current and voltage ripples consist
of not only high frequency harmonics but also the double fundamental frequency
harmonic, and the voltage ripple is independent of the positive-sequence component and
determined by the negative-sequence component, under the unbalanced load.
Experimental results are shown to verify the accuracy of the theoretical analysis.
42865
Kai Yao et.al
A Novel Control Scheme of DCM Boost PFC Converter
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5605 - 5615
The discontinuous current mode boost power factor (PF) correction converter features a
zero-current turn-on for the switch, no reverse recovery in diode, and constant frequency
operations. However, when the duty cycle is constant in a line cycle, the input current
contains rich third harmonic which has a phase difference of π with respect to the
fundamental component. The harmonic results in not only a lower PF but also larger peak
and RMS current values of the main power components, which lead to a higher conduction
and switching turn-off loss. In this paper, a variable duty cycle control scheme is proposed
to make the input current contain only third harmonic which is in phase with fundamental
component, while remaining the same PF at a certain input voltage as that of constant
duty cycle control. A method of fitting the duty cycle is further proposed for simplifying
the circuit implementation. The efficiency is improved as the critical inductance increases
and the peak and RMS current values consequently decrease. The proposed method also
achieves an output voltage ripple or the output storage capacitance reduction. The
experimental results from a prototype of 120 W are given to verify the effectiveness of
the proposed method.
120
42866
June-Seok Lee et.al
Comparison of Tolerance Controls for Open-Switch Fault in a Grid-Connected T-Type
Rectifier
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5810 - 5820
Multilevel rectifier topologies are commonly used in wide-power range applications. The
T-type rectifier topology, which is a three-level topology, has an advantage in terms of
efficiency compared to a neutral-point clamped (NPC)-type topology. In applications using
the T-type rectifier topology, improving reliability has gained increased attention
recently. A tolerance control for T-type rectifiers is necessary to improve the reliability of
applications. When an open fault of switches connected to the neutral-point occurs, the
NPC-type rectifier cannot restore distorted input currents, on the other hand, the T-type
rectifier can eliminate the input current distortion completely. In this paper, we report
two studies: 1) a three-level switching-oriented tolerance control, which is advantageous
in terms of efficiency, for the Sx2 and Sx3 open-switch faults of the T-type rectifier and
2) comparison of the proposed tolerance control with two existing tolerance controls. In
particular, the current total harmonic distortion, dc-link voltage ripple, and switch losses
of these tolerance controls are analyzed by using simulation and experimental results.
42867
Khosroshahi A. et.al
Reliability Evaluation of Conventional and Interleaved DC–DC Boost Converters
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5821 - 5828
Obviously for the correct operation of conventional boost converters, all components
should work correctly. Interleaved boost converters having several stages, can be used to
increase the reliability. So in this paper, a reliability comparison is done between the
conventional boost converter and the interleaved structure. Two different operation
modes are defined for the interleaved boost converter: half-power and full-power
operation modes. The reliability calculation is based on the Markov model of the
converters. The power loss effect of converter components on their failure rates, and
therefore, on the reliability of converter has been assessed. For the first time different
failure rates have been considered for different operation modes. Also a laboratory
prototype of a two-stage interleaved boost dc-dc converter has been built up and the
failure rate of components in different operation modes are calculated practically. Results
show that in addition to other benefits, interleaved structure has higher reliability and as
the power increases, there will be a decrease in the reliability.
42868
Marcos-Pastor A. et.al
Loss-Free Resistor-Based Power Factor Correction Using a Semi-Bridgeless Boost
Rectifier in Sliding-Mode Control
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5842 – 5853
121
In this paper, a loss-free resistor based on a semi-bridgeless rectifier is proposed for power
factor correction applications. This particular bridgeless rectifier type is composed of two
different boost cells which operate complementarily during each half-line cycle. In case
of two unbalanced inductors, many control techniques can produce different inductor
current ripples during each half-line cycle that can result in the addition of a dc component
to the line current. This paper demonstrates that the application of sliding-mode control
by means of hysteretic controllers results in a first-order stable system that can mitigate
these harmful consequences due to its capability to ensure the symmetry of the line input
current waveform for both positive and negative half-line cycles. Thus, the system does
not absorb any dc component from the grid and it is also capable of reducing dramatically
the amplitude of the third harmonic. The theoretical predictions have been validated by
means of PSIM simulations and experimentally on a prototype of 1 kW which has been
controlled using only one sliding control surface.
42869
Lingling Cao et.al
Systematic Derivation of a Family of Output-Impedance Shaping Methods for Power
Converters—A Case Study Using Fuel Cell-Battery-Powered Single-Phase Inverter
System
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5854 - 5869
For power converters used in renewable energy systems, output-impedance design has
become an important design consideration for minimizing the impacts of low-frequency
harmonic current on the lifetime of ripple-sensitive energy sources such as fuel cells and
photovoltaic cells. In the literature, various methods are proposed to tackle this design
issue but they are frequently treated in isolation from each other and specific to the
systems being discussed. In this paper, a systematic derivation of four basic modes of
output-impedance shaping method is presented. These basic modes can be directly
inferred from the Mason's gain formula and other methods are in essence derivatives or
combinations of these basic modes. By using a fuel-cell-battery-powered single-phase
inverter as an implementation example, their characteristics are discussed thoroughly and
their performances in shaping converter's output impedance are evaluated experimentally.
42870
Man-Chung Wong et.al
Self-Reconfiguration Property of a Mixed Signal Controller for Improving Power Quality
Compensation during Light Loading
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5938 - 5951
This paper proposes a FPAA-FPGA/DSP-based mixed signal controller that achieves superior
performance when compared with conventional digital controllers in power quality
compensation. This includes adaptive signal conditioning and programmability on-the-fly,
higher flexibility, parallel computation capability, and easy implementation. In practical
applications, the power quality compensator may suffer from poor compensation
performance, particularly during light loading. The adaptive signal gain and programmable
on-the-fly functions of the mixed signal controller are intended to improve the system
compensation performance, which cannot be achieved by using conventional digital
controllers alone. In this study, an approximate total harmonic distortion (ATHD) is
proposed to determine the total harmonic distortion value more quickly, reducing the
evaluation time of the power quality compensation system performance. With hysteresis
pulse width modulations, when the hysteresis error margin is designed, the ATHD can be
122
determined instantaneously. Finally, representative simulation and experimental results
of a three-phase four-wire center-split hybrid active power filter are presented. These
verify the validity and effectiveness of the proposed mixed signal controller in improving
current quality compensation performance during light load conditions, compared with a
conventional digital controller.
42871
Bo Wen et.al
Small-Signal Stability Analysis of Three-Phase AC Systems in the Presence of Constant
Power Loads Based on Measured d-q Frame Impedances
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5952 - 5963
Small-signal stability is of great concern for electrical power systems with a large number
of regulated power converters. In the case of dc systems, stability can be predicted by
examining the locus described by the ratio of the source and load impedances in the
complex plane per the Nyquist stability criterion. For balanced three-phase ac systems the
same impedance-based method applies, for which this paper uses impedances in the
synchronous rotating reference (d-q) frame. Small-signal stability can be determined by
applying the generalized Nyquist stability criterion (GNC). This approach relies on the
actual measurement of these impedances, which up to now has severely hindered its
applicability. Addressing this shortcoming, this paper investigates the small-signal stability
of a three-phase ac system using measured d-q frame impedances. The results obtained
show how the stability at the ac interface can be easily and readily predicted using the
measured impedances and the GNC, thus illustrating the practicality of the approach, and
validating the use of ac impedances as a valuable dynamic analysis tool for ac system
integration, in perfect dualism with the dc case.
42872
Guo Xu et.al
Decentralized
Converters
Inverse-Droop
Control
for
Input-Series–Output-Parallel
DC–DC
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4621 - 4625
Input-series-output-parallel dc-dc converters are suited for high-input voltage and low
output voltage applications. This letter presents a decentralized inverse-droop control for
this configuration. Each module is self-contained and no central controller is needed; thus,
improving the system modularity, reliability, and flexibility. With the proposed inversedroop control, the output voltage reference rises as the load becomes heavy. Even though
the input voltages are not used in the inverse-droop loop, the power sharing including
input voltage sharing and output current sharing can still be well achieved. Besides, the
output voltage regulation characteristic is not affected by the variation of input voltage.
The operation principle is introduced, and stability of the strategy is also revealed based
on small signal modeling. Finally, the experiment is conducted to verify the effectiveness
of the control strategy.
123
42873
Yang Jiao & Lee F.C.
LCL Filter Design and Inductor Current Ripple Analysis for a Three-Level NPC Grid
Interface Converter
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4659 - 4668
The harmonic filter for a three-level neutral-point-clamped (NPC) grid interface converter
is designed in this paper with good filtering performance and small component size. LCL
topology is selected because of the attenuation and size tradeoff. The design of the
inverter-side inductor L1 is emphasized due to its cost. A detailed inductor current ripple
analysis is given based on the space vector modulation. The analysis derives the inductor
volt-second and the maximum current ripple equation in line cycle. It also reveals the
switching cycle current ripple distribution over a line cycle, with the consideration of
power factor. The total system loss is calculated with different ripple current. Inductor L1
is determined by the loss and size tradeoff. Also the capacitor- and grid-side inductor L2
is designed based on attenuation requirement. Different damping circuits for LCL filter are
compared and investigated in detail. The filter design is verified by both simulation and
200-kVA three-level NPC converter hardware.
42874
Yao Sun et.al
Indirect Matrix Converter-Based Topology and Modulation Schemes for Enhancing Input
Reactive Power Capability
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4669 - 4681
A new topology based on indirect matrix converter (IMC) is proposed to enhance the input
reactive power capability. This topology consists of a conventional IMC and an auxiliary
switching network (ASN), which is connected to the dc-link of the IMC in parallel. With the
aid of ASN, an implicit current source converter-based static synchronous compensator can
be embedded into an IMC, which lays a foundation for the input reactive power control.
Based on the proposed topology, two modulation schemes are presented, and the
formations of the output voltage and input reactive current are decoupled in both of them.
To minimize power loss and improve input current quality, a double closed-loop control
algorithm is introduced, in which the current through the dc inductor in ASN is controlled
to be minimum. Different from the conventional IMC, the input reactive power of the
topology is independent of its load condition without considering the practical constraints.
The effectiveness of the proposed topology and modulation scheme is confirmed by
experimental results.
42875
Yipeng Song et.al
Modularized Control Strategy and Performance Analysis of DFIG System Under
Unbalanced and Harmonic Grid Voltage
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4831 - 4842
The paper presents a modularized control strategy of doubly fed induction generator
(DFIG) system, including the grid-side converter (GSC) and rotor-side converter (RSC),
under unbalanced and harmonic grid voltage. The sequence decomposition process and
124
complicated control reference calculation can be avoided in the proposed control strategy.
From the perspective of power grid friendly operation, the control targets of DFIG system
in this paper are chosen as: 1) smooth active and reactive power injected into the power
grid; 2) balanced and sinusoidal current injected into the power grid. The RSC and GSC
can work as two independent modules and the communication between RSC and GSC can
be removed. Furthermore, the third harmonic current component, dc-link voltage
fluctuation, and electromagnetic torque pulsation under the different control targets are
theoretically analyzed. Finally, the availability of the proposed modularized control
strategy of DFIG system under unbalanced and distorted grid voltage is verified by
experiment results.
42876
Cervera A. et.al
Resonant Switched-Capacitor Voltage Regulator With Ideal Transient Response
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4943 - 4951
A new, small and efficient voltage regulator, realized using a resonant switched-capacitor
converter technology, is introduced. Voltage regulation is implemented by means of simple
digital pulse density modulation. It displays an ideal transient response with a zero-order
nature to all disturbance types. The newly developed topology acts as a gyrator with a
wide range of voltage conversion ratios (below as well as above unity) with constant
efficiency characteristics for the entire operation range. The operation of the voltage
regulator is verified on a 20 W experimental prototype, demonstrating ideal transient
recovery without over/undershoots in response to load and line transients. Simple design
guidelines for the voltage regulation system are provided and verified by experiments.
42877
Sangshin Kwak & Sung-ki Mun
Model Predictive Control Methods to Reduce Common-Mode Voltage for Three-Phase
Voltage Source Inverters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5019 - 5035
In this paper, we propose model predictive control methods to reduce the common-mode
voltage of three-phase voltage source inverters (VSIs). In the reduced common-mode
voltage-model predictive control (RCMV-MPC) methods proposed in this paper, only
nonzero voltage vectors are utilized to reduce the common-mode voltage as well as to
control the load currents. In addition, two nonzero voltage vectors are selected from the
cost function at every sampling period, instead of using only one optimal vector during
one sampling period. The two selected nonzero vectors are distributed in one sampling
period in such a way as to minimize the error between the measured load current and the
reference. Without utilizing the zero vectors, the common-mode voltage controlled by the
proposed RCMV-MPC algorithms can be restricted within ±Vdc/6. Furthermore, application
of the two nonzero vectors with optimal time sharing between them can yield satisfactory
load current ripple performance without using the zero vectors. Thus, the proposed RCMVMPC methods can reduce the common-mode voltage as well as control the load currents
with fast transient response and satisfactory load current ripple performance compared
with the conventional model predictive control method. Simulation and experimental
results are included to verify the effectiveness of the proposed RCMV-MPC methods.
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42878
Sangshin Kwak & Sung-ki Mun
Model Predictive Control Methods to Reduce Common-Mode Voltage for Three-Phase
Voltage Source Inverters
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5019 - 5035
In this paper, we propose model predictive control methods to reduce the common-mode
voltage of three-phase voltage source inverters (VSIs). In the reduced common-mode
voltage-model predictive control (RCMV-MPC) methods proposed in this paper, only
nonzero voltage vectors are utilized to reduce the common-mode voltage as well as to
control the load currents. In addition, two nonzero voltage vectors are selected from the
cost function at every sampling period, instead of using only one optimal vector during
one sampling period. The two selected nonzero vectors are distributed in one sampling
period in such a way as to minimize the error between the measured load current and the
reference. Without utilizing the zero vectors, the common-mode voltage controlled by the
proposed RCMV-MPC algorithms can be restricted within ±Vdc/6. Furthermore, application
of the two nonzero vectors with optimal time sharing between them can yield satisfactory
load current ripple performance without using the zero vectors. Thus, the proposed RCMVMPC methods can reduce the common-mode voltage as well as control the load currents
with fast transient response and satisfactory load current ripple performance compared
with the conventional model predictive control method. Simulation and experimental
results are included to verify the effectiveness of the proposed RCMV-MPC methods.
42879
Fei Li et.al
An LCL-LC Filter for Grid-Connected Converter: Topology, Parameter, and Analysis
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5067 - 5077
In order to further cut down the cost of filter for grid-connected pulsewidth modulation
(PWM) converter under the more and more stringent grid code, a new kind of high-order
filter, named LCL-LC filter, is presented in this paper. The resonant frequency
characteristics of the filter are analyzed, and a parameter design method on the base of
the characteristics is also proposed in the paper. The proposed parameter design method
can easily make full use of the existing research results about the traditional LCL filter
parameter design. And then a parameter robustness analysis method based on fourdimensional graphics is proposed to analyze parameter robustness of the presented filter.
Compared with the traditional one, the proposed analysis method can analyze the filter
performance under variations of several parameters at a time without any iteration. The
comparative analysis and discussion considering the LCL filter, the trap filter, and the LCLLC filter, are presented and verified through the experiments on a 5 kW grid-connected
converter prototype. Experiment results demonstrate the accuracy of theoretical analysis
and prove that the presented filter has a better performance than two others.
42880
Benigni A. & Monti, A.
A Parallel Approach to Real-Time Simulation of Power Electronics Systems
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5192 - 5206
126
We define here a new parallel simulation method designed for real-time execution. This
method is highly parallelizable and scalable, and the simulation execution time is fully
predictable, which is very important for real-time execution. The stability conditions for
the method are defined. Furthermore, we show how to define appropriate flow variable
injections so that this method can be extended to multiphysic applications and how to
implement multirate time step in the defined method. Finally, we present simulation tests
that validate the presented method.
42881
Xiaoqiang Li et.al
Wide Damping Region for LCL-Type Grid-Connected Inverter With an Improved
Capacitor-Current-Feedback Method
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5247 - 5259
This paper has presented a stability analysis of a LCL-type grid-connected inverter in the
discrete-time domain. It has been found that even though the system is stable when the
resonance frequency f,. is higher than one-sixth of the sampling frequency (f8/6), an
effective damping scheme is still required due to the potential influence of the grid
impedance. With a conventional proportional capacitor-current-feedback active damping
(AD), the valid damping region is only up to f8/6. This however is not sufficient in the
design process for obtaining a high quality output current and the system can easily
become unstable due to the resonance frequency shifting. Considering the resonance
frequency design rules of the LCL filter, this paper proposes an improved capacitorcurrent-feedback AD method. With a detailed analysis and proper parameter design, the
upper limit of the damping region is extended to f8/4, which can cover all the possible
resonance frequencies. Then, the damping performance of the proposed AD method is
studied. It shows that the optimal damping is obtained when the actual resonance
frequency is (fr + f8/4)/2. Moreover, an approximate calculation for the optimal damping
coefficient R is given. Finally, the experimental results have validated the effectiveness
of the proposed AD method.
42882
Baoquan Liu et.al
A Three-Phase PLL Algorithm Based on Signal Reforming Under Distorted Grid
Conditions
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5272 - 5283
This paper proposes a novel three-phase phase-locked loop (PLL) algorithm, which focuses
on the reforming of the primary signals before grid synchronization rather than improving
the phase estimation methodologies. The unbalanced signals are reformed to balanced
ones without damage to the phase angle, through which the negative sequence of the grid
voltages is removed. This eliminates the estimation errors of conventional synchronous
reference frame PLL and enhances its response speed with a higher bandwidth. The
reforming process is supposed to be carried out at every zero-crossing point of the threephase voltages and choose one phase as reference to balance the other two. Coefficients
for the signal reforming are calculated at one zero-crossing point and updated until the
next comes. In implementation, a certain phase is chosen as the reference all along and
the reforming process will be suspended when it just crosses the zero line. This PLL
algorithm has a fast and precise character to reform the three-phase grid voltages and is
flexible for application. Under heavily distorted grid conditions, it can still perform
effectively even with multiple zero-crossings. Comprehensive experimental results from a
127
digital signal processor-based laboratory prototype are provided to validate the
performance of this PLL algorithm.
42883
Lin Ma et.al
A New PWM Strategy for Grid-Connected Half-Bridge Active NPC Converters With Losses
Distribution Balancing Mechanism
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5331 - 5340
Photovoltaic systems technological development is driven by the request for higher
efficiency and safety. These concerns influence also the choice of the power converter
stage. Several topologies have been proposed and many of them are available
commercially. Among them, the neutral point clamped (NPC) and derived topologies offers
high efficiency, low leakage current, and low EMI. However, one main disadvantage of the
NPC inverter is given by an unequal distribution of the losses in the semiconductor devices,
which leads to an unequal distribution of temperature that can affect lifetime. By using
the active NPC (ANPC) topology, where the clamping diodes are replaced by bidirectional
switches, the power losses distribution problem is alleviated. The modulation strategy is
a key issue for losses distribution in this topology. In this paper, two known strategies are
discussed and a new PWM strategy, namely the adjustable losses distribution is proposed
for better losses distribution in the ANPC topology. Simulations and experimental results
help in evaluating the modulation strategies.
42884
Goharrizi A.Y. et.al
A Parallel Multimodal Optimization Algorithm for Simulation-Based Design of Power
Systems
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2128 - 2137
This paper proposes a parallel multimodal optimization algorithm that is combined with
electromagnetic transient simulation in a platform that unifies the setup, test, and
execution of optimal designs for power systems. The algorithm speeds up the design of
power systems as its computations can be executed independently on a highly parallelized
environment. Additional speedup is achieved by using a surrogate model to estimate the
objective function in regions of suspected local optima. The estimated functions can be
used in the subsequent stages of postoptimization studies, such as sensitivity analyses.
Comparative studies, in terms of computation time, are conducted against sequential
execution of the proposed algorithm. The optimal design of a VSC-HVDC transmission is
described to demonstrate the capabilities of the proposed algorithm.
42885
Shi-Xiao Guo et.al
Impact of the EHV Power System on Geomagnetically Induced Currents in the UHV
Power System
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2163 - 2170
Earlier calculations of geomagnetically induced currents (GICs) in Chinese power grids have
mainly concentrated on the highest voltage-level system whose geomagnetic risk is
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considered to be the largest, thus ignoring secondary voltage-level systems. With the 1000kV system being newly added to China's power system, it is significant to figure out the
interaction between GIC in the 500 kV [extremely high voltage (EHV)] system and GIC in
the 1000 kV [ultra-high voltage (UHV)] system. Based on the North China-Central ChinaEast China Power Grids, this paper establishes a single-voltage grid by only considering the
1000-kV system and a dual-voltage grid by considering the 1000- and 500-kV systems and
investigates GIC in these two grids by developing their GIC “Full-node models.” The impact
of the 500-kV system on GIC in the 1000-kV system is analyzed. GIC risks in the UHV and
EHV systems are assessed by comparing calculated GIC data with monitored values of GIC.
The results show that the impact of the 500-kV system on GIC in the 1000-kV system is
obvious, both the EHV and the UHV grid have a high GIC risk. So calculating GIC in the UHV
system and in the EHV system should utilize GIC modeling methods for multivoltage power
grids.
42886
Zirka S.E. et.al
Implementation of Inverse Hysteresis Model Into EMTP—Part I: Static Model
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2224 - 2232
The main features of the history-dependent inverse model of magnetic hysteresis are
outlined. Its implementation into the Electromagnetic Transient Program-Alternative
Transients Program (EMTP-ATP) is described, and the fitting of the model to catalog data
is demonstrated. The abilities of the model are illustrated by its use in a single-phase
transformer model.
42887
Zirka S.E. et.al
Implementation of Inverse Hysteresis Model into EMTP—Part II: Dynamic Model
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2233 - 2241
The main features of a dynamic hysteresis model (DHM) and its implementation into the
electromagnetic transient program (EMTP-ATP) are described. A method of fitting the DHM
to catalog data is proposed. The implementation of the DHM within a transformer model
is illustrated by transient calculations. Possible methods of fitting the DHM-based
transformer model to a no-load test are outlined.
42888
Faleiro E. et.al
Interaction between Interconnected and Isolated Grounding Systems: A Case Study of
Transferred Potentials
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2260 - 2267
The effect caused by ground fault current in a complex system of interacting electrodes is
theoretically studied. The calculation applies to a specific case in which a set of
interconnected electrodes, which are part of a grounding facility network, are activated
by ground fault current. Transferred potentials to adjacent passive electrodes are
calculated and the most relevant parameters of the electrode system are evaluated.
Finally, the convenience of connecting the grounding electrodes is discussed.
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42889
Jian Zhang et.al
Suppressing Intermittent Subsynchronous Oscillation via Subsynchronous Modulation
of Reactive Current
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2321 - 2330
Recently, a new oscillation phenomenon-intermittent subsynchronous oscillation (ISSO)has been observed in a large interconnected power grid. Rather than leading to oscillatory
instability, ISSO causes cumulative fatigue damage and reduces the shaft life of the
generator. The existing phase-compensation-based damping technologies are found to be
limited in mitigating these types of oscillations. To mitigate ISSO, a subsynchronous
modulation of reactive current (SMRC) approach is established and implemented in the
voltage-source converters (VSCs) at the generator terminals. The contribution of SMRC to
system damping has been analyzed in order to select control parameters for the VSC. The
SMRC controller has been prototyped and extensively tested on a real-time closed-loop
simulation platform equipped with a newly developed speed sensor module for precisely
interfacing the real-time digital simulator with the rotating speed-acquisition board.
Extensive experiments on the input and output characteristics of the VSC have been
carried out to test and validate the damping current generating module. The effective
damping areas are obtained from test observations to fine tune the parameters of the VSC
controller for adapting to various system operating conditions, resulting in the common
optimal damping region. Real-time simulations, onsite commissioning, and statistics have
demonstrated the ability of the SMRC to mitigate ISSO and subsynchronous oscillation in
power plants.
42890
Badoni M. et.al
Variable Forgetting Factor Recursive Least Square Control Algorithm for DSTATCOM
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2353 - 2361
This paper proposes an implementation of distribution static compensator (DSTATCOM) for
the three-phase distribution system. The functions of DSTATCOM are harmonics
elimination, compensation of reactive power, and load balancing in power factor
correction and voltage regulation modes. A variable forgetting factor recursive least
square (VFFRLS)-based control algorithm is proposed for effective operation of DSTATCOM
to estimate weighted values of active and reactive power components of load current. The
proposed control algorithm is fast in convergence and has quick response. A prototype of
DSTATCOM is developed in the laboratory using a digital signal processor (dSPACE 1104)
and voltage-source converter and tested for various operating conditions under nonlinear
load. The performance of DSTATCOM is found satisfactory in mitigating various powerquality problems with the VFFRLS-based control algorithm.
42891
Tsuji T. et.al
A Partitioning Technique for a Waveform Relaxation Method Using Eigenvectors in the
Transient Stability Analysis of Power Systems
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2867 - 2879
130
It is of paramount importance that power system operators be able to assess transient
stability in order to realize a reliable and stable power supply. Transient stability analysis
can be formulated as a large-scale system of differential and algebraic equations (DAE).
However, as power systems are becoming larger and more complex, it is becoming difficult
to solve DAE in a practical amount of time for system operations. Parallel computing based
on the waveform relaxation method is an effective solution to achieve faster calculations
for transient stability analysis. To enhance the performance of the waveform relaxation
method, a proper partitioning of the original problem is essential. Although various
partitioning approaches have been used, those approaches might not be effective when
analyzing a weakly damped low-frequency oscillation. In particular, in the Japanese 60-Hz
power system, this oscillation becomes an important problem. To resolve this issue, in this
paper we have developed a new partitioning method that is better suited to analyzing a
weakly damped low-frequency oscillation based on eigenvalue analysis. Specifically,
effective partitioning can be automatically determined by the proposed index, which can
evaluate the validity of the partitioning. The proposed method was tested using the
Japanese standards of the IEEJ WEST10 system model and the WEST30 system model.
42892
Barchowsky A. et.al
Design and Realization of an Innovative Workbench for Electric Power Systems
Laboratories
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2894 - 2901
With the increasingly high demand for well-trained power systems engineers, the
University of Pittsburgh has partnered with Eaton in the creation of the new Electric Power
Systems Laboratory at the Swanson School of Engineering. This laboratory demands the
capability to perform a wide variety of experimental procedures while providing students
and researchers with a seamless working environment. To accomplish that goal, a novel
lab workbench was developed. This lab workbench integrates the load banks necessary for
laboratory procedures with advanced metering, controls and safety features, and contains
them within a work station ideally suited for the laboratory space. This paper details the
development of those lab workbenches, from concept, to design, to prototype
construction, to testing. Additionally, this work describes planned classroom experiments
utilizing the developed bench. Ultimately the realized workbench demonstrates its
capability to be reconfigured to suit the demands of both education as well as new
research projects for undergraduate and graduate studies.
42893
Pal B.C. et.al
A Dynamic Mode Decomposition Framework for Global Power System Oscillation
Analysis
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2902 - 2912
A global multiscale method based on a dynamic mode decomposition (DMD) algorithm to
characterize the global behavior of transient processes recorded using wide-area sensors
is proposed. The method interprets global dynamic behavior in terms of both, spatial
patterns or shapes and temporal patterns associated with dynamic modes containing
essentially single-frequency components, from which the mode shapes, frequencies and
growth and decay rates of the modes can be extracted simultaneously. These modes are
then used to detect the coherent and dominant structures within the data. The technique
is well suited for fast wide-area monitoring and assessment of global instability in the
131
context of modern data fusion-based estimation techniques. Results of the application of
the proposed method to large, high-dimensional data sets are encouraging.
42894
Jiawei Ning et.al
Two-Level Ambient Oscillation Modal Estimation from Synchrophasor Measurements
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2913 - 2922
This paper proposes a decentralized two-level structure for real-time modal estimation of
large power systems using ambient synchrophasor data. It introduces two distributed
algorithms that fit the structure well, namely, 1) decentralized frequency domain
decomposition and 2) decentralized recursive stochastic subspace identification. As
opposed to present-day oscillation monitoring methodologies, the bulk of the algorithmic
computations is done locally at the substation level in the two-level framework. Substation
modal estimates are sent to the control center where they are grouped, analyzed, and
combined to extract system modal properties of local and inter-area modes. The
framework and the proposed algorithms provide a scalable methodology for handling
oscillation monitoring from a large number of substations efficiently. The two-level
structure and the two decentralized algorithms are tested using simulated data from
standard test systems and from archived real power system synchrophasor data.
42895
Chongtao Li
Computing Interarea Oscillation Modes of Large-Scale Power Systems Using Two-Sided
Jacobi-Davidson Method
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2946 - 2954
The small-signal stability analysis of power systems concerns the critical modes as well as
the modes associated with a physical meaning, e.g., the interarea oscillation modes for
weakly connected systems and the modes sensitive to a particular parameter. As the order
of the power-system state matrix increases, it becomes more difficult to determine these
modes. In this paper, a method is proposed to compute the interarea oscillation modes of
large-scale power systems. The deviation in the active power of the transmission section
is selected to identify the interarea oscillation modes. Then, the two-sided JacobiDavidson method combined with this selection is employed to compute these modes.
Participation factors are used to separate the electromechanical oscillation modes.
Numerical tests show that the proposed method is valid and efficient.
42896
Paramasivam M. et.al
Contingency Analysis and Identification of Dynamic Voltage Control Area
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2974 - 2983
Contingency analysis has been an integral part of power system planning and operations.
Dynamic contingency analysis is often performed with offline simulation studies, due to
its intense computational effort. Due to a large number of possible system variations,
covering all combinations in planning studies is very challenging. Contingencies must be
chosen carefully to cover a wider group of possibilities, while ensuring system security.
This paper proposes a method to classify dynamic contingencies into different clusters,
according to their behavioral patterns, in particular, with respect to voltage recovery
patterns. The most severe contingency from each cluster becomes the representative of
132
other contingencies in the corresponding cluster. Using the information of contingency
clusters, a new concept called dynamic voltage control area (DVCA) is derived. The
concept of DVCA will address the importance of the location of dynamic reactive reserves.
Simulations have been completed on the modified IEEE 162-bus system to test and validate
the proposed method.
42897
Yazdanian M. et.al
Estimation of Electromechanical Oscillation Parameters Using an Extended Kalman
Filter
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2994 - 3002
Estimation of electromechanical modes of a power system has attracted attention in the
past few decades because it can provide vital information about the stability of the system.
In this paper, a new state-space model is proposed for online detection of parameters of
a ringdown signal using an extended Kalman filter (EKF). The proposed model can estimate
both constant and time-varying parameters. Furthermore, stability analysis of the
proposed model is performed to demonstrate the convergence of the parameters.
Simulation results confirm the desirable performance of the proposed method for ringdown
parameter estimation.
42898
Fatemi S.M. et.al
Introducing a Novel DC Power Flow Method with Reactive Power Considerations
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3012 - 3023
The DC power flow model is in widespread utilization in electricity-market applications
and contingency analysis. The presented versions of this model can be classified into two
categories: state-dependent, or Hot-Start, models and state-independent, or Cold-Start,
models. A reasonable accuracy is reported in the literature regarding Hot-Start models as
they take into account branch losses and bus voltages by using available base point. On
the contrary, due to the absence of base point in Cold-Start models, branch losses must
be either neglected or guessed (which is an uncertain precautionary measure), or
evaluated by a cumbersome iteration process. In addition, the bus voltage profiles are
inevitably considered to be flat. Hence, the accuracy of available Cold-Start models in
different circumstances remains of great concern. This paper addresses this concern and
unveils a new Cold-Start model that does not rely on a risky assumption. In other words,
there will be no lossless or flat voltage profile assumption in the presented approach
whereas the equations remain linear. Besides, the exact effect of the net reactive loads
on phase angles is considered and, consequently, the reactive power balance equations
are reflected in the model for the first time.
42899
Shouxiang Wang et.al
Uncertainty Tracing of Distributed Generations via Complex Affine Arithmetic Based
Unbalanced Three-Phase Power Flow
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3053 - 3062
133
Variations of load demands and generations bring multiple uncertainties to power system
operation. Under this situation, power flows become increasingly uncertain, especially
when significant distributed generations (DGs), such as wind and solar, are integrated into
power systems. In this paper, a Complex Affine arithmetic based unbalanced Three-phase
Forward-Backward Sweep power flow model (CATFBS) is proposed to study the impacts of
uncertainties in unbalanced three-phase distribution systems. An index of Relative
Influence of Uncertain Variables on Outcomes (RIUVO) is proposed for quantifying the
impacts of individual uncertain factors on power flows and bus voltages. The CATFBS
method is tested on the modified IEEE 13-bus system and a modified 292-bus system.
Numerical results show that the proposed method outperforms the Monte Carlo method
for exploring the impacts of uncertainties on the operation of distribution systems. The
proposed CATFBS method can be used by power system operators and planners to
effectively monitor and control unbalanced distribution systems under various
uncertainties.
42900
Poyrazoglu G. et.al
Optimal Topology Control with Physical Power Flow Constraints and N-1 Contingency
Criterion
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3063 - 3071
In this paper, a novel solution method is proposed for the optimal topology control problem
in AC framework with N-1 reliability. The resultant new topology of the proposed method
is guaranteed to yield a better objective function value than the global solution of the
problem with the original topology. In order to prove our statement, semi-definite
programming relaxation is formulated to find a lower bound to the objective function value
of the problem. The proposed method is favorable for parallelization to increase the
computational efficiency, and the parallel computing flowchart is presented.
Computational time of the algorithm for IEEE test cases is reported. An in-house power
market simulator is developed to simulate a market environment complete with optimal
topology control mechanism. Simulations held by participating human subjects are
analyzed under the subtitles of the total operating cost, real power losses, and locational
marginal price (LMP) variance. A simple example is illustrated to show that the resultant
network topology may increase the real power losses while still providing a lower operating
system cost than that of the original topology.
42901
Egea-Alvarez A. et.al
Advanced Vector Control for Voltage Source Converters Connected to Weak Grids
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3072 - 3081
This paper addresses an advanced vector current control for a voltage source converter
(VSC) connected to a weak grid. The proposed control methodology permits highperformance regulation of the active power and the voltage for the feasible VSC range of
operation. First, the steady state characteristics for a power converter connected to a
very weak system with a short circuit ratio (SCR) of 1 are discussed in order to identify the
system limits. Then, the conventional vector control (inner loop) and the conventional
power/voltage control (outer loop) stability and frequency responses are analyzed. From
the analysis of the classic structure, an enhanced outer loop based on a decoupled and
gain-scheduling controller is presented and its stability is analyzed. The proposed control
is validated by means of dynamic simulations and it is compared with classic vector current
control. Simulation results illustrate that the proposed control system could provide a
134
promising approach to tackle the challenging problem of VSC in connection with weak AC
grids.
42902
Minyuan Guan et.al
Synchronous Generator Emulation Control Strategy for Voltage Source Converter (VSC)
Stations
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3093 - 3101
The voltage source converter (VSC) station is playing a more important role in modern
power systems, but the dynamic behavior of the VSC station is quite different from that
of the synchronous generator. This paper presents the synchronous generator emulation
control (SGEC) strategy for the VSC-HVDC station. The SGEC strategy is divided into the
inner control loop and the outer control loop. The inner controller is developed for fast
current and voltage regulations. An inertia element is introduced into the frequency-power
droop to determine the command reference of the frequency, and the inertia response
and the primary frequency regulation are emulated. In addition, the secondary frequency
regulation can be achieved by modulating the scheduled power in the SGEC strategy. The
time-domain simulation results demonstrate the VSC station with the proposed control
strategy can provide desired frequency support to a low-inertia grid. Therefore, the SGEC
strategy provides a simple and practical solution for the VSC station to emulate the
behavior of a synchronous generator.
42903
Zhixin Miao et.al
Dynamic Phasor-Based Modeling of Unbalanced Radial Distribution Systems
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3102 - 3109
This paper develops an analytical model of an unbalanced radial distribution system
consisting of a single-phase photovoltaic (PV), a three-phase induction machine load, a
three-phase power factor correction capacitor (PFC), and a load. The analytical model is
based on dynamic phasors (DP) for abc phases. The single-phase PV model includes inverter
current control [proportional resonance (PR) controller], an L, or an LCL filter. The
induction machine model is based on positive-, negative-, and zero-sequence components'
dynamic phasors. The sequence-based induction machine model was converted to the DPabc reference frame and interconnected with other grid components. The developed
analytical model is capable of small-signal analysis and can be used to identify variety of
stability and/or harmonic issues in distribution networks, e.g., instability due to weak grid.
Impact of unbalance on system dynamic performance can also be investigated using this
model. The analytical model is benchmarked with a high-fidelity model built in
Matlab/SimPowerSystems where power electronic switching details are included. The
small-signal analysis results are validated via Matlab/SimPowerSystems time-domain
simulations.
42904
Mingrui Zhang & Jie Chen
Islanding and Scheduling of Power Distribution Systems with Distributed Generation
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3120 - 3129
This paper presents a short-term power regulation mechanism for post-segmentation
power distribution systems in the presence of severe fault or large disturbance. Firstly,
load priority is introduced into system separation and centroids of load clusters are
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allocated at nodes with distributed sources, respecting power balance and network
connectedness. Secondly, fast power flow calculation is performed on the primarily
formed islands to resolve load interruption for operational feasibility of partitions from
power quality perspective. Then the effect of distributed generation fluctuations on
durable operation of subsystems with various optimization objectives is examined. The
load response is instructed by the proposed cost-based pricing scheme contemplating
consumers' willingness. In addition, the influence of network congestion and load
controllability on results of economic scheduling is investigated. Numerical results from
the PG&E-69 distribution system are used to show the effectiveness of the developed
model in radial structure load clusters. Illustration on the IEEE 118-bus case further proves
its robustness and practicability for other distribution systems applications. This property
is also useful for transmission switching and micro-grid applications.
42905
Molzahn D.K. & Hiskens I.A.
Sparsity-Exploiting Moment-Based Relaxations of the Optimal Power Flow Problem
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3168 - 3180
Convex relaxations of non-convex optimal power flow (OPF) problems have recently
attracted significant interest. While existing relaxations globally solve many OPF
problems, there are practical problems for which existing relaxations fail to yield
physically meaningful solutions. This paper applies moment relaxations to solve many of
these OPF problems. The moment relaxations are developed from the Lasserre hierarchy
for solving generalized moment problems. Increasing the relaxation order in this hierarchy
results in “tighter” relaxations at the computational cost of larger semidefinite programs.
Low-order moment relaxations are capable of globally solving many small OPF problems
for which existing relaxations fail. By exploiting sparsity and only applying the higher-order
relaxation to specific buses, global solutions to larger problems are computationally
tractable through the use of an iterative algorithm informed by a heuristic for choosing
where to apply the higher-order constraints. With standard semidefinite programming
solvers, the algorithm globally solves many test systems with up to 300 buses for which
the existing semidefinite relaxation fails to yield globally optimal solutions.
42906
Lourenco E.M. et.al
Topology Error and Bad Data Processing in Generalized State Estimation
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3190 – 3200
This paper presents a method for processing real-time data error in generalized state
estimation (GSE). Attention is focused on the two main types of error: network topology
errors and bad data on analog measurements. The proposed approach is able to handle
both errors without making any previous assumption regarding the nature of those errors.
The degrading effects of topology errors over bad data processing when both topology and
measurement errors occur at the same time are evaluated and new strategy is proposed
to overcome it. GSE is treated as a constrained optimization problem where measurements
and circuit-breaker status are modeled as equality constraints. Geometric tests based on
the geometric interpretation of the Lagrange multiplier vector are then utilized to
determine the source of the error. The proposed strategy is tested on two model power
networks represented at the bus-section level which is derived from the IEEE 30-bus and
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42907
Hosseini S.A. et.al
A Fourier Based Wavelet Approach Using Heisenberg’s Uncertainty Principle and
Shannon’s Entropy Criterion to Monitor Power System Small Signal Oscillations
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3314 - 3326
This paper presents a novel approach to estimate modal parameters of power systems for
monitoring and analyzing the embedded modes of small signal oscillations. The proposed
approach applies continuous wavelet transform (CWT) to identify damping and frequency
of critical modes based on its time-frequency localization capability. The CWT has
modified Morlet function as its mother wavelet. A procedure is also presented to fine-tune
settings of the modified Morlet function of the CWT based on Heisenberg's uncertainty
principle and Shannon's entropy criterion. Additionally, high computational burden of the
time-frequency methods is an important obstacle in online monitoring of power systems
by these methods. To remedy this problem, the convolution integral of the CWT is
calculated by efficient fast Fourier transform (FFT) routine in the proposed approach
leading to a low computational burden. The proposed approach is compared with several
other signal processing methods for modal identification of power systems. These
comparisons illustrate effectiveness of the proposed approach, regarding run time,
persistency against noise and estimation accuracy for online monitoring of small signal
oscillations.
42908
Yinan Cui et.al
A Particle Filter for Dynamic State Estimation in Multi-Machine Systems with Detailed
Models
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3377 - 3385
Particle filters provide a general framework for dynamic state estimation (DSE) in
nonlinear systems. The scope for particle filter-based DSE can be significantly enhanced
by exploiting data from phasor measurement units (PMUs) when available at higher
sampling frequencies. In this paper, we present a particle filtering approach to
dynamically estimate the states of a synchronous generator in a multi-machine setting
considering the excitation and prime mover control systems. The filter relies on typical
output measurements assumed available from PMUs stationed at generator buses. The
performance of the proposed filter is illustrated with dynamic simulations on IEEE 14-bus
system including: 1) generators models with subtransient dynamics, 2) excitation units
(IEEE DC1A, DC2A, AC5A), and 3) turbine-governor models (steam and hydro). The
estimation accuracy of the proposed filter is assessed for three classes of disturbances
assuming noisy PMUs' measurements and comparative results are presented with the
unscented Kalman filter (UKF). The accuracy-computational burden trade-off is also
analyzed and the results strengthen the feasibility of using particle filters for dynamic
state estimation.
42909
Ahmadi H. & Marti J.R.
Load Decomposition at Smart Meters Level using Eigen loads Approach
IEEE Trans. on Power Systems, Vol.30; No. 6; Sept. – Oct. 2015; 3425 - 3436
The deployment of the advanced metering infrastructure (AMI) in distribution systems
provides an excellent opportunity for load monitoring applications. Load decomposition
can be done at the smart meters level, providing a better understanding of the load
behavior at near-real-time. In this paper, loads' current and voltage waveforms are
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processed offline to form a comprehensive library. This library consists of a set of
measurements projected onto the eigenloads space. Eigenloads are basically the
eigenvectors describing the load signatures space. Similar to human faces, every load has
a distinct signature. Each load measurement is transformed into a photo and an efficient
face recognition algorithm is applied to the set of photos. A list of all the online devices
is always stored and can be accessed at any time. The proposed method can be
implemented at the smart meters level. The distributed computation that can be achieved
by performing simple calculations at each smart meter, without the need for sending
intensive data to a central processor, is beneficial. From a system operator perspective,
load composition in near-real-time provides the loads' voltage dependence that are
needed, for example, in volt-VAR optimization (VVO) in distribution systems. Further
applications of load composition data are also discussed.
10. POWER TRANSMISSION & DISTRIBUTION
42910
Yunzhu An et.al
Experimental research on lightning shielding performance of large scaled UHV
transmission line
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2871
- 2878
In actual operation, the shielding failure rate of UHV transmission line is much higher than
that in simulation, so it is crucial to study the lightning shielding performance by
experimental research. The testing UHV transmission line model is scaled down in the ratio
of 12.5 which is relatively large comparing to other testing models. Two kinds of negative
switching impulse waveform were applied to HV rod to simulate the lightning descending
leader. The probability of transmission line being stroked was calculated statistically by
recording more than two thousand discharges and the factors that affecting the discharge
probability were studied through contrast tests. The results show that the grounding
condition, DC bias, the protection angle, the switching impulse voltages have an influence
on the discharge probability, breakdown voltage and breakdown time. The spatial
boundary of shielding failure area was determined in the middle of the span. The upper
and lower spatial boundary and the distance between them increased with the increasing
of the lateral distance between HV rod tip and transmission line model simultaneously.
42911
Yiming Zhang et.al
Selective Wireless Power Transfer to Multiple Loads Using Receivers of Different
Resonant Frequencies
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6001- 6005
In multiple receivers of resonant wireless power transfer, selective power flow among the
loads is an important issue. This paper proposes a new method to control power division.
The two-coil structure with different resonant frequencies of the sending and receiving
loops is modeled and analyzed. The efficiency is proved to peak at the resonant frequency
of the receiving loop, regardless of the resonant frequency of the sending loop. Using this
feature, selective power transfer can be achieved by setting the receiving loops at
different resonant frequencies. The efficiency of a particular load is greatly influenced by
the driving frequency. The multiple-load system with different resonant frequencies is
138
modeled and the efficiency expression of each load is deduced. The mutual inductances
of the receiving coils have a small impact on the efficiency distribution. The closer the
resonant frequencies of the receiving loops, the less isolated the related loads. The
calculations and the experiments confirm the analysis.
42912
Ping Lu et.al
A Compact Frequency Reconfigurable Rectenna for 5.2- and 5.8-GHz Wireless Power
Transmission
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6006 - 6010
A compact reconfigurable rectifying antenna (rectenna) has been proposed for 5.2- and
5.8-GHz microwave power transmission. The proposed rectenna consists of a frequency
reconfigurable microstrip antenna and a frequency reconfigurable rectifying circuit. Here,
the use of the odd-symmetry mode has significantly cut down the antenna size by half. By
controlling the switches installed in the antenna and the rectifying circuit, the rectenna
is able to switch operation between 5.2 and 5.8 GHz. Simulated conversion efficiencies of
70.5% and 69.4% are achievable at the operating frequencies of 5.2 and 5.8 GHz,
respectively, when the rectenna is given with an input power of 16.5 dBm. Experiment has
been conducted to verify the design idea. Due to fabrication tolerances and parametric
deviation of the actual diode, the resonant frequencies of the rectenna are measured to
be 4.9 and 5.9 GHz. When supplied with input powers of 16 and 15 dBm, the measured
maximum conversion efficiencies of the proposed rectenna are found to be 65.2% and
64.8% at 4.9 and 5.9 GHz, respectively, which are higher than its contemporary
counterparts.
42913
Yanxu Zhang et.al
Analytical Modeling of Traffic Flow in the Substation Communication Network
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2119 - 2127
A custom-designed and well-monitored substation communication network (SCN) can
maintain fast and reliable information transmission and lead to improved operation and
management of a substation automation system (SAS). In order to achieve this goal, a
traffic-flow model, including a port connection model, a traffic-flow source model, and a
traffic-flow service model of an SCN is developed in this paper. Based on the traffic-flow
model, a traffic-flow calculation algorithm is designed to obtain the distribution of traffic
load and maximum message delay. In order to verify the accuracy of the proposed method,
the SCN of a simplified substation is established in the laboratory. And the distribution of
traffic load and maximum message delay calculated using the proposed method are
compared to that measured by a network analyzer. Furthermore, possible applications,
such as network device selection, network performance analysis, and sensitivity analysis
of the proposed method are demonstrated based on a typical 220-kV substation.
42914
Black C.R. & Chisholm W.A.
Key Considerations for the Selection of Dynamic Thermal Line Rating Systems
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2154 - 2162
139
Recent reviews have shown that many methods can be used for estimating the dynamic
thermal capacity of overhead transmission lines. A number of approaches are described
and key features of each system are organized. Data from field trials provide a unique
basis for assessing the variation in ten different parameters. Characteristics of distributed
measurement systems are underscored and contrasted against point measurements
systems.
42915
Chaojun Gu et.al
Dynamic State Estimation under Communication Failure Using Kriging Based Bus Load
Forecasting
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2831 - 2840
Dynamic state estimation (DSE) in power system combines forecasting technique with
measurement data to accurately estimate system state. The current DSE techniques
cannot handle the situation where communication failure occurs and measurement data
are lost. In this paper, a new approach is proposed to address this problem. The proposed
approach combines the extended Kalman filter (EKF) with load forecasting technique that
predicts missing measurement data. A time-forward kriging model is used to forecast the
missing load data from the available measurement data. The forecast load is then
converted to forecast system state through power flow analysis. The EKF is used to
combine the measurement data with the forecast state to obtain a more accurate filtered
state. The proposed approach is tested on IEEE 14-bus system and IEEE 118-bus system
using realistic load pattern from NYISO and PJM with various scenarios of measurement
error and communication failure. The test results from the proposed approach are
compared with traditional weighted least square (WLS) state estimation and DSE with
multi-step ahead autoregressive integrated moving average (ARIMA) load forecasting. From
the case studies, we find that the proposed approach provides more accurate and faster
state estimation under most scenarios.
42916
Tao Ding et.al
A Bi-Level Branch and Bound Method for Economic Dispatch with Disjoint Prohibited
Zones Considering Network Losses
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2841 - 2855
This paper proposes a bi-level branch-and-bound ((B&B) method to solve the economic
dispatch problem with prohibited zones and network losses. The approach employs binary
variables for each prohibited zone and utilizes the B-coefficient for network losses, which
can be transformed into a mixed-integer quadratically constrained quadratic programming
(MIQCQP), where linear relaxation technique is applied on each bilinear term. Due to the
complexity in solving the MIQCQP problem, this paper proposes a bi-level B&B method to
achieve global optimum. A spatial B&B method is utilized in the higher level to solve the
quadratically constrained quadratic programming (QCQP) problem, whereas a simple B&B
method is employed in the lower level to solve a mixed-integer quadratic programming
(MIQP) problem. The bi-level B&B algorithm that combines spatial and simple B&B methods
is actually a deterministic optimization method and can produce global optimal solutions.
Numerical results on 6-unit, 15-unit, and 40-unit test systems show that the bi-level B&B
method can solve the MIQCQP problem with superior solution quality and convergence
characteristics.
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42917
De Oliveira-De Jesus P.M. Rojas Quintana A.A.
Distribution System State Estimation Model Using a Reduced Quasi-Symmetric
Impedance Matrix
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2856 - 2866
This paper presents a novel formulation of the Distribution System State Estimation (DSSE)
optimization model. For a given electric three-phase circuit feeder, network models are
built using a quasi-symmetric impedance matrix TRX representing the entire structure and
topology of the radial network. As a key contribution, the state variables of demands and
generators connected to large-scale distribution grids are obtained by using a convenient
matrix reduction technique. As a result, the size of the optimization problem is
considerably reduced with respect to the jacobian formulation by considering radial and
weakly meshed exploitation and elimination of interconnecting nodes. Results and
comparative analysis are presented using the IEEE 4-, 13-, 37-, 123-, and 8500-node test
systems.
42918
Bina M.T. & Ahmadi D.
Stochastic Modeling for the Next Day Domestic Demand Response Applications
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2880 - 2893
Demand response (DR) refers to the consumers' activities for changing the load profile with
the purpose of lowering cost, improving power quality or reliability of power system.
Enhancement in participation of the DR is widely recognized as a profit-making pattern in
distribution systems for both residential units (to increase their benefits) and distribution
companies (DISCO) (to reduce their peak demand and costs). The target of this research is
concentrated on proposing a new strategy for optimal scheduling of flexible loads for the
next day. Then, the day ahead pricing (DAP) is modeled using the inclining block rates
(IBR), assumed for retail electricity markets, to investigate the efficiency of the proposed
strategy. At the same time, the appliances stochastic time of use (ASTOU) are taken into
account in residential units for non-controllable part of the load during a day
stochastically. Among five various copulas, the Gaussian copula (GC) function shows the
best performance in modeling and estimation of non-controllable load consumption.
Finally, simulations, performed with the GAMS, illustrate the effectiveness of the
suggested approach which is formulated as a stochastic nonlinear programming (NLP)
modeled by the GC. Notice that copulas use samples of real data gathered from residential
units.
42919
Haiwang Zhong et.al
An Efficient Decomposition Method for the Integrated Dispatch of Generation and Load
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 2923 - 2933
In response to the computational challenges produced by the integrated dispatch of
generation and load (IDGL), this paper proposes a novel and efficient decomposition
method. The IDGL is formulated using the mixed-integer quadratic constrained
programming (MIQCP) method. To efficiently solve this complex optimization problem, the
nodal equivalent load shifting bidding curve (NELSBC) is proposed to represent the
aggregated response characteristics of customers at a node. The IDGL is subsequently
decomposed into a two-level optimization problem. At the upper level, grid operators
optimize load shifting schedules based on the NELSBC of each node. Transmission losses
are explicitly incorporated into the model to coordinate them with generating costs and
141
load shifting costs. At the bottom level, customer load adjustments are optimized at
individual nodes given the nodal load shifting requirement imposed by the grid operators.
The key advantage of the proposed method is that the load shifting among different nodes
can be coordinated via NELSBCs without iterations. The proposed decomposition method
significantly improves the efficiency of the IDGL. Parallel computing techniques are
utilized to accelerate the computations. Using numerical studies of IEEE 30-bus, 118-bus,
and practically sized 300-bus systems, this study demonstrates that accurate and efficient
IDGL scheduling results, which consider the nonlinear impact of transmission losses, can
be achieved.
42920
Ran Li et.al
Development of Low Voltage Network Templates—Part I: Substation Clustering and
Classification
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3036 - 3044
In order to improve low voltage (LV) network visibility without extensive monitoring and
integrate low carbon technologies (LCTs) in a cost-effective manner, this paper proposes
a novel three-stage network load profiling method. It uses real-time information
monitored from selective representative areas to develop network templates. The three
stages are: clustering, classification and scaling. It can be used to identify the loading
conditions of unmonitored LV systems with similar fixed data to those monitored LV
substations. In the clustering stage, hierarchical clustering and K-means are used to cluster
substations into groups based on the shape of the monitored load profiles. The
classification tool designed with multinomial logistic regression maps an unmonitored LV
substation into the most probable templates by using routinely available fixed data.
Finally, clusterwise weighted constrained regression is employed to estimate peak for
individual LV substations and the developed templates. The three-stage profiling is
demonstrated on a practical system in the U.K. under the umbrella of a smart grid trail
project. Ten LV templates are developed by using the metered data from 800 monitored
LV substations. A comprehensive comparison between the estimated peaks using the threestage process and the metered peaks suggests that the methodology can achieve superior
accuracy. This is part I of the paper, introducing clustering and classification. The scaling
(peak estimation) process will be introduced in part II of the paper.
42921
Ran Li et.al
Development of Low Voltage Network Templates—Part II: Peak Load Estimation by
Clusterwise Regression
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3045 - 3052
This paper proposes a novel contribution factor (CF) approach to predict diversified daily
peak load of low voltage (LV) substations. The CF for each LV template developed in part
I of the paper is determined by a novel method-clusterwise weighted constrained
regression (CWCR). It takes into account the contribution from different customer classes
to substation peaks, respecting the natural difference in time and magnitude between LV
substation peaks and the variance within the templates. In CWCR, intercept and
coefficients are constrained to ensure that the resultant coefficients do not lead to reverse
load flow and can respect zero-load substations. Cross validation is developed to validate
the stability of the proposed method and prevent over fitting. The proposed method shows
significant improvement in the accuracy of peak estimation over the current status quo
across 800 substations of different mixes of domestic, industrial and commercial (I&C)
142
customers. The work in the two parts of the paper is particularly useful for understanding
the capabilities of LV networks to accommodate the increasing penetration of low carbon
technologies without large-scale monitoring.
42922
Ramos De Araujo L. et.al
Voltage Security Assessment on Unbalanced Multiphase Distribution Systems
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3201 - 3208
This paper presents a multiphase continuation power flow (MCPF) methodology to perform
voltage security analyses on unbalanced multiphase distribution systems. The proposed
tool includes comprehensive models of most network components, and allows for explicit
representation of neutral cables and grounding connections. The methodology has been
validated through comparisons with a commercial software and with results available in
the literature. Additional analyses are presented using the IEEE 4-bus, the Neutral-to-Earth
(NEV) and the IEEE 8500 Test Systems. These systems have been developed to present
several challenges to distribution systems analytical tools. In particular, the influence of
the 3-phase transformer connections on the PV curves have been demonstrated and has
been useful to stress the importance of a complete system representation.
42923
Granell R. et.al
Impacts of Raw Data Temporal Resolution Using Selected Clustering Methods on
Residential Electricity Load Profiles
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3217 - 3224
There is growing interest in discerning behaviors of electricity users in both the residential
and commercial sectors. With the advent of high-resolution time-series power demand
data through advanced metering, mining this data could be costly from the computational
viewpoint. One of the popular techniques is clustering, but depending on the algorithm
the resolution of the data can have an important influence on the resulting clusters. This
paper shows how temporal resolution of power demand profiles affects the quality of the
clustering process, the consistency of cluster membership (profiles exhibiting similar
behavior), and the efficiency of the clustering process. This work uses both raw data from
household consumption data and synthetic profiles. The motivation for this work is to
improve the clustering of electricity load profiles to help distinguish user types for tariff
design and switching, fault and fraud detection, demand-side management, and energy
efficiency measures. The key criterion for mining very large data sets is how little
information needs to be used to get a reliable result, while maintaining privacy and
security.
42924
Xiaowen Lai et.al
Decentralized Multi-Area Economic Dispatch via Dynamic Multiplier-Based Lagrangian
Relaxation
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3225 - 3233
143
This paper introduces a dynamic multiplier-based Lagrangian relaxation approach for the
solution to multi-area economic dispatch (MAED) in a fully decentralized manner. Dynamic
multipliers refer to the multipliers associated with power balance equations at tie-line
buses in each area. Dynamic multipliers can be approximated as linear functions of tieline power exports via sensitivity analysis and can serve as the equivalent supply/demand
functions to neighboring areas. In contrast to the conventional static point-wise multiplier,
which is unable to reflect the marginal cost change that results from variations in the
power exchange level, the proposed dynamic multiplier provides each area the look-ahead
capability to foresee the range of the marginal cost for power export over a range of tieline exchange variations. In turn, this allows for a significantly faster convergence to the
global optimal solution. The algorithm is also shown to be early termination friendly, which
is very desirable in practice for ultra-large systems such as the State Grid of China.
Numerical examples in a 6-bus system, a 3-area 354-bus IEEE system, and large test
systems illustrate the benefits of the proposed algorithm.
42925
Jabr R.A. & Dzafic I.
A Fortescue Approach for Real-Time Short Circuit Computation in Multiphase
Distribution Networks
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3276 - 3285
This paper discusses the need for short circuit analysis in real-time applications of modern
distribution networks and presents a short circuit tool that builds on recent advances in
Fortescue-based current injection power flow. The proposed short circuit computation
(SCC) method is fundamentally based on the symmetrical components transformation of
three-phase, two-phase, and one-phase systems. Unlike the classical symmetrical
components SCC method that postulates a structurally symmetrical three-phase pre-fault
network with balanced loading, the proposed method accounts for multiphase networks
that are comprised of three-phase, two-phase, and one-phase network parts; given a prefault power flow solution, it requires a maximum of three current injection iterations to
compute the short circuit current flow in the entire network. Numerical results show that
the Fortescue SCC approach with multiphase lines exhibits significant computational
performance improvement on large-scale networks as compared to classical SCC in phase
coordinates.
42926
Majidi M. et.al
A Novel Method for Single and Simultaneous Fault Location in Distribution Networks
IEEE Trans. on Power Systems, Vol.30; No. 6; November 2015; 3368 - 3376
This paper introduces a novel method for single and simultaneous fault location in
distribution networks by means of a sparse representation (SR) vector, Fuzzy-clustering,
and machine-learning. The method requires few smart meters along the primary feeders
to measure the pre- and during-fault voltages. The voltage sag values for the measured
buses produce a vector whose dimension is less than the number of buses in the system.
By concatenating the corresponding rows of the bus impedance matrix, an
underdetermined set of equation is formed and is used to recover the fault current vector.
Since the current vector ideally contains few nonzero values corresponding to fault
currents at the faulted points, it is a sparse vector which can be determined by l1-norm
minimization. Because the number of nonzero values in the estimated current vector often
exceeds the number of fault points, we analyze the nonzero values by Fuzzy-c mean to
estimate four possible faults. Furthermore, the nonzero values are processed by a new
144
machine learning method based on the k-nearest neighborhood technique to estimate a
single fault location. The performance of our algorithms is validated by their
implementation on a real distribution network with noisy and noise-free measurement.
11. PROTECTION & PROTECTIVE DEVICES
42927
Sengupta A. et.al
Automated Verification of Power System Protection Schemes—Part I: Modeling and
Specifications
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2077 - 2086
Power system protection schemes are verified today using Monte-Carlo simulation and
manual interpretation of results. The limitation of this verification technique is
uncertainty of complete coverage of all possible operating conditions due to the time
complexity of simulation. In this two-part paper, an automated simulation-based
verification technique is proposed to verify the correctness of protection settings
efficiently using hybrid automata-temporal-logic framework. In Part I, hybrid automata
models of protection schemes and temporal-logic assertions for desired relay operations
are presented. An example is provided to demonstrate the automated verification
technique in detail. Its companion Part II presents a technique for test-case generation to
ensure early detection of design errors.
42928
Sengupta A. et.al
Automated Verification of Power System Protection Schemes—Part II: Test Case
Generation Using Swarm Intelligence
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2087 - 2095
In Part II, we develop an efficient method for generating test cases that ensure early
detection of design error. The proposed method uses the particle swarm optimization
technique for the same. Also, we propose a sensitivity-based approach to rectify design
errors. The proposed verification technique is applied on standard IEEE test systems and
it is seen that it is possible to achieve better accuracy at significantly reduced
computational complexity.
42929
Trindade F.C.L. et.al
Potential Solutions for Minimizing Voltage Sags Caused by DG Anti-Islanding Protection
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2242 - 2251
This paper proposes solutions to the problem of voltage sags caused by distributed
generators anti-islanding protection. This is a recently identified power-quality (PQ)
concern resulting from the increasing penetration of distributed generators into
distribution networks. This problem has been previously investigated by the authors and it
was revealed that it can seriously affect PQ indices as well as distributed generators
reconnection procedures. However, no solutions have been formerly proposed or
investigated. In this context, this paper investigates several potential solutions to be
145
adopted by the utility and/or by the DG owners and presents a thorough evaluation of
their main advantages and disadvantages. Besides this investigation, simple step-by-step
procedures for assessing the effectiveness of each solution are described. The presented
studies and procedures will guide the utility engineers in decision-making process
associated with the choice of reasonable mitigation techniques to this problem.
12. SWITCHGEAR & CONTROLGEAR
42930
Schueller M. et.al
Micro discharges in HVDC gas insulated systems
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2879
- 2888
In the present contribution, we analyze and quantify micro-discharge currents originating
from rough electrode surfaces in HVDC gas insulated switchgear (GIS) applications. These
currents can be significantly larger than those in the gas phase caused by natural ionization
or those from bulk conduction in the solid insulators. They may thus dominate the charging
of the insulator surface and are thus a key dimensioning criterion. Five different electrode
systems with different, but clearly defined, roughness were designed. To quantify the
amplitude of the micro discharge current as a function of the electrical field strength on
the electrode surface, the consequence of these discharges in the form of accumulated
charges on the surface of a PTFE sample was measured. The measurements were compared
to simulation results from a model that uses the Townsend approximation for unipolar
saturation ionic current, which is a widely used approximation in many areas of
applications. As a main finding of our investigations, to avoid micro discharges, electrical
field strengths of 7.1 kV/mm should not be exceeded in HVDC GIS design using typical
industrial electrode roughness around 2 µm and 0.5 MPa SF6.
42931
Okabe S. et.al
Behavior of metallic particles in GIS under DC voltage
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2889
- 2897
The paper investigated the behavior and partial discharge (PD) characteristics of a metallic
particle under residual dc voltage, using the setting conditions and length of the particle,
the applied dc voltage, and other factors as parameters and a gas insulated switchgear
(GIS) bus bar model equivalent to that of an actual 300 kV GIS. A metallic particle repeated
reciprocating movement at a relatively high frequency of about 5 times per second
between the high-voltage conductor and the sheath when the electric field at the bottom
surface of the tank exceeded its lift-off electric field. It emerged that, in the process of
this reciprocating movement, PD occurred at the moment when the particle collided with
the high-voltage conductor. In addition, when a particle collided with the electrode, the
electrical charges moved and the residual dc voltage was damped. Conversely, where the
sheath side was insulation-coated, the particle did not move at the normal operating
146
voltage level, and even though it moved if vibration was applied, its movement stopped
relatively soon. If a metallic particle exists in GIS and moves, there is concern that the
insulating performance may decline significantly. When a metallic particle moves under
dc voltage, a relatively stable PD is generated and consequently, for example, the PD
measurement is considered an effective way to detect a particle. It is also considered
effective to take physical measures, such as using an insulating sheath at the bottom
surface of the tank to restrain the behavior of particles.
42932
Ming Ren et.al
Partial discharges triggered by metal-particle on insulator surface under standard
oscillating impulses in SF6 gas
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 3007
- 3018
The characteristics of partial discharge (PD) triggered by a metal particle on an insulator's
surface were studied experimentally under standard oscillating lightning impulse (OLI) and
standard oscillating switching impulse (OSI) conditions. Light emission detection was
carried out to assist in PD measurement. Experiments showed that the largest number of
successive PDs occurred during the rise time of each oscillation period of applied impulses
and that a small number of reversed-polarity PDs occurred during the fall time. The
composition of the PD sequence was determined by the position of the particle on the
insulator's surface. Specifically, when a needle particle detached from the plate
electrodes, the PD sequences consisted of both negative point PDs and positive point PDs.
Two types of negative discharge, three types of positive discharge, and reversed-polarity
discharge were differentiated by their current and light pulse waveforms. In these
experiments, detectable partial discharge inception voltages (PDIVs) of the three particle
positions were investigated at gas pressures from 0.05 to 0.35 MPa. The light emission
inception voltages (LEIVs) were lower than PDIVs under OLI, OSI, and AC voltages. These
inception voltages of different particle positions could be sorted as follows: LEIV <; PDIV+
(d = 30 mm) <; PDIV- (d = 0 mm) <; PDIV+/- (d = 15 mm). We demonstrated that the OLI
voltages could excite PDs from defects at lower equivalent voltage levels than for OSI and
a 50 Hz AC voltage, and the PDs under OLI were more active in terms of occurrence
frequency than those under OSI and AC voltages. A simple model was proposed to explain
PD inception and propagation under oscillating impulses. The rapid change of background
electric field and the formation and accumulation of charges on the insulator's surface
were considered the main causes of the greater efficiencies of OLI and OSI at exciting PDs
compared with the AC voltage.
42933
Ju Tang
Feature parameters extraction of GIS partial discharge signal with multifractal
detrended fluctuation analysis
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 3037
- 3045
Ultra-high frequency (UHF) method is widely used in gas-insulated switchgear (GIS) partial
discharge (PD) online monitoring because this technique has excellent anti-interference
ability and high sensitivity. GIS PD pattern recognition is based on effective features
acquired from UHF PD signals. Therefore, this paper proposes a new feature extraction
147
method that is based on multifractal detrended fluctuation analysis (MFDFA). UHF PD
signals of four typical GIS discharge models that were collected in a laboratory were
analyzed. In addition, the multifractal feature of these signals was investigated. The
single-scale shortcoming of traditional detrended fluctuation analysis and its sensitivity to
interference information trends were overcame. Thus, the proposed method was able to
effectively characterized the multi-scaling behavior and nonlinear characteristics of UHF
PD signals. With the use of the shape and distribution difference of the multifractal
spectrum, seven feature parameters with clear physical meanings were extracted as
feature quantity for pattern recognition and input to the support vector machine for
classification. Results showed that the feature extraction method based on MFDFA could
effectively identify four kinds of insulation defects even with strong background noise.
The overall average recognition rate exceeded 90%, which is significantly better than that
of wavelet packet-based feature extraction.
42934
Shemshadi A.et.al
Dielectric recovery process in vacuum interrupters regarding to contact materials
during post arc interval
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 3059
- 3064
This investigation presents new practical achievements concerning the velocity of
dielectric recovery process inside a vacuum interrupter chamber. According to AndrewsVarey equations, a new model is developed using Matlab-Simulink software. This model is
used for doing a new research on inter electrode plasma diffusion, which is the most
important factor during insulation recovery interval. The developed model is performed
so that it can predict the ionic sheath expansion velocity and post-arc current waveform
caused by transient recovery voltage (TRV). One of the faced challenges is to obtain plasma
parameters to be utilized based on the previous experimental results. Considering the
initial conditions and the related software model Applied to nine different contact
materials, and similar 100A quenching current, the achieved results are investigated in
details. The main goal is to specify the influence of material (ion mass) and other
parameters on the speed of inter-electrode plasma dispersion and voltage recovery process
which will guide the designer towards selecting suitable contact material with regard to
TRV waveform. Furthermore the effect of TRV value which is applied to the chamber is
also investigated in details. In future works this model may be developed so that it can be
applied to new metallic alloys made of doped various chemical elements.
42935
Hassanpoor A. et.al
Technical Assessment of Load Commutation Switch in Hybrid HVDC Breaker
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5393 - 5400
The development of a large-scale high-voltage direct current (HVDC) power grid requires
a reliable, fast, and low-loss circuit breaker. The load commutation switch (LCS) is an
essential part of ABB's 1200-MW hybrid HVDC breaker concept, which builds up a low-loss
conducting path for the load current. The technical requirements for the LCS are expressed
in this paper by studying the operation principle of the hybrid HVDC breaker. The voltage
stress over the LCS is determined based on a dc grid with 320 and 2 kA rated voltage and
current. A system model of the hybrid HVDC breaker is developed in PSCAD/EMTDC to
study the design criteria for snubber circuit and arrester blocks. It is observed that
148
conventional snubber circuits are not suitable for a bidirectional LCS as the current of
snubber capacitors prevent the fast interruption action. A modified snubber circuit is
proposed in this paper along with two more alternatives for the LCS to overcome this
problem. Moreover, the power loss model for a semiconductor device is discussed in this
paper based on the 4.5-kV StakPak IGBT. The model is used to calculate the conduction
power losses for different LCS topologies. Ultimately, a matrix of 3 X 3 IGBT modules is
selected to provide a reliable LCS design which can handle several internal fault cases with
no interruption of operation. A full-scale prototype has been constructed and tested in
ABB HVDC Center, Ludvika, Sweden. The experimental test results are also included in the
paper in order to verify the calculation and simulation study.
42936
Luhui Liu et.al
A Hybrid DC Vacuum Circuit Breaker for Medium Voltage: Principle and First
Measurements
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2096 – 2101
A novel concept of hybrid dc vacuum circuit breakers (VCBs), based on the combination of
zero-voltage switching (ZVS) and zero current switching principle, was developed to meet
the needs of the dc zonal distribution system on shipboard rated for a current of several
kiloamperes and a voltage of several kilovolts. In normal operation, the VCB handles the
continuous flow of dc current, minimizing the onstate losses. When protection against the
fault is requested, the current is first divided between the VCB and the static branch
before being quickly interrupted under a forced commutation principle. Laboratory tests
have been dedicated to characterize the reliability of the high-current commutation from
the VCB to the static branch and the turnoff characteristic of the silicon-controlled
rectifier under high-current conditions. Finally, the critical design of the high-speed VCB
is discussed.
42937
Szewczyk M. et.al
High-Frequency Model of Magnetic Rings for Simulation of VFTO Damping in GasInsulated Switchgear with Full-Scale Validation
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2331 - 2338
Nanocrystalline magnetic rings have been experimentally proven for effective damping of
very fast transient overvoltages (VFTOs) in gas-insulated switchgear (GIS). The application
of any damping solution in a specific GIS setup (rated voltage, GIS arrangement) requires
simulation-based design, which, in turn, requires reliable models with proven accuracy in
demanding high-frequency and high-current VFTO conditions. This paper presents a new
model of a magnetic ring, employing full frequency-dependent characteristics of the ring's
complex impedance, as well as the dedicated approach on modeling the saturation effect
of the material magnetization characteristics. The saturation effect is modeled by a
bypassing branch, activated at a certain saturation current value calculated according to
the specific magnetic material properties and for the VFTO main frequency component.
The model was implemented in Electromagnetic Transients Program simulation software
and validated experimentally in a full-scale 550-kV GIS test setup. The validation proved
the applicability of the model for the assessment of VFTO damping effectiveness with the
use of nanocrystalline magnetic rings and, thus, for the design of a particular magneticbased damping solution in a specific GIS setting.
149
42938
Jun Zhong et.al
Incorporating a Condition Monitoring Based Aging Failure Model of a Circuit Breaker in
Substation Reliability Assessment
IEEE Trans. on Power Systems, Vol.30; No.6; November 2016; 3407 - 3415
This paper presents a circuit breaker (CB) aging failure model based on condition
monitoring. This model is inserted into a basic CB Markov model and applied in substation
reliability assessment. The proposed model can accurately incorporate the wearing status
and aging process of CBs. The results from applying the proposed method to a utility
substation configuration demonstrate that ignoring aging failures of CBs can lead to
significant underestimation of substation unreliability.
13. TESTING
42939
Wolny S.
Aging degree evaluation for paper-oil insulation using the recovery voltage method
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2455
- 2462
The paper presents new diagnostic method applied to assess aging degree for paper-oil
insulation used in professional electrical power device, primarily including medium and
high power transformers. The described method is based on modified diagnostics using the
recovery voltage effect occurring in dielectrics (RVM - Recovery Voltage Methods).
Modification of the RVM method applied so far, which is now used only to assess moistening
degree for paper-oil insulation in power transformers, consists in a new parametric analysis
of recovery voltage time characteristics. Simulation and experimental tests carried out in
laboratory conditions for adequately prepared insulation samples have proven that the
time-constant of recovery voltage decay (τR_MIN) is the most susceptible parameter as
regards quantitative change in the function of aging of the examined insulation. This
conclusion is also confirmed by statistical studies, in which a multi-parameter variance
analysis method has been applied. An original equivalent circuit diagram of the insulation
has been used to simulate aging degree of paper-oil insulation samples in numerical tests.
The diagram is based on the Cole-Cole type dielectric response model.
42940
Ozaki R. et.al
Electroviscous effect of ionic liquids measured by using shear horizontal wave
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2500
- 2506
The viscosity properties of an electrolyte solution, which consists of 1-methyl-3propylimidazolium iodide (MPI-I) as an electrolyte and ethylisopropylsulfone (EiPS) as a
solvent, using the shear horizontal (SH) wave device are investigated. The viscosities with
several concentrations of the electrolyte in solutions are measured. The viscosity increases
with increasing concentration of the electrolyte. The viscosity also increases with
150
increasing applied voltage and depends on not applied voltage but applied electric field.
Furthermore, the analytical solutions of the physical properties of the SH wave
propagation are derived.
42941
Denat A. et.al
Breakdown of liquids in long gaps: influence of distance, impulse shape, liquid nature,
and interpretation of measurements
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2581
- 2591
Breakdown measurements are carried out in liquids under point-sphere and pointplane
electrode geometries, over a large range of gap distances up to 35 cm. Non-polar
hydrocarbon liquids with different chemical structures are studied: saturated, aromatic,
polyaromatic, mineral oils, and ester. Two high voltage impulse shapes are used: the
standard lightning impulse (LI), and a specific “step” impulse (ST). Step impulses are
favorable to interpret breakdown measurements since the applied voltage remains
constant while prebreakdown streamers propagate. Conversely, with lightning impulse and
long gaps the propagation of streamers with a low propagation velocity (a few km/s) is
quenched due to the rapidly decaying voltage. In this case, breakdown can result only from
the propagation of faster streamers, which appear in very different conditions according
to the liquid nature. The results obtained allow us to interpret the large variations of
breakdown voltage observed in large gaps, when either the high voltage impulse shape or
the liquid nature is changed. These results also help to define proper conditions for testing
and comparing liquids. Testing with lightning impulse in short gaps, such as in standard
tests, does not provides data relevant for very high voltage applications.
42942
Yuan Zhou et.al
Quantitative study of electric conduction in mineral oil by time domain and frequency
domain measurement
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2601
- 2610
Polarization and depolarization current measurement is a non-destructive testing method
to study the dielectric properties of insulating materials. Two types of mineral oils with
different aging times have been studied using both time domain and frequency domain
methods separately. In this paper, a novel approach to understanding the correlation
between the electric conduction in time domain and frequency domain has been proposed.
When the charge carriers drift to the electrodes, they may be blocked and accumulated
near the electrode. The amount of charge in the vicinity of electrode has been estimated.
In the depolarization period, these charge layers will return to the bulk resulting in a
depolarization current. In this paper, an analytical solution to the time dependence of the
depolarization current has been developed and used to fit the experimental results. The
field and temperature dependence of the polarization and depolarization current have
been used to study the characteristics of charge carriers in mineral oil. The calculated
conductivity has been used to simulate the frequency response in mineral oil and the
simulating results have been compared with the experimental data.
151
42943
Hadjadj, Y. et.al
Assessing insulating oil degradation
spectrophotometry measurements
by
means
of
turbidity
and
UV/VIS
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2653
- 2660
Oil is a vital part of the transformer body and (similarly to blood in a human being body)
keeps responsibility for the condition of the entire organism. Oil is particularly responsible
for functional serviceability of the entire insulation system. The insulating oil must be kept
in pristine condition, since its condition can be a decisive factor, which determines the
life span of the transformer. Fields and laboratory experiences have shown that
transformer oil contains a vast amount of information. Oil analyses can be extremely useful
in monitoring the condition of power transformers. To meet pressing needs of power
industries, fast, inexpensive and reliable laboratory testing procedures are necessary. To
ensure long-term reliability of oil filled power transformers, it is important to identify
early sign of degradation of the insulating oil. In this paper, oil degradation was monitored
with various ASTM test methods. Investigations were performed on service-aged oil
samples as well as on oil samples aged in laboratory conditions. Many key parameters
actually used to monitor the condition of transformer oil relative to oxidation/degradation
were investigated. From the obtained results, correlations were found between some of
them. The results indicate that Dissolved Decay Products (DDP) and turbidity, which
change with a higher rate than interfacial tension (IFT) and Acid Number (AN) values, can
be possibly used as an effective index for insulating oil degradation assessment. Limits are
suggested which provide a “picture” of the fluid condition.
42944
Chenguo Yao et.al
Noninvasive method for online detection of internal winding faults of 750 kV EHV shunt
reactors
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2833
- 2840
Seven hundred fifty kilovolt extra-high voltage (EHV) shunt reactors are important power
equipment that stabilize the normal operation of an entire 750 kV power grid. Internal
winding faults of a reactor could be a difficult issue when the reactor is in service, and
result in sudden equipment failure and significant economic losses. To prevent sudden
catastrophic failure of equipment, online detection should be implemented to evaluate
the state of the reactor properties when requested. In this paper, a noninvasive method
based on online impulse frequency analysis was proposed and developed to detect internal
winding faults of a 750 kV EHV shunt reactor. Initially, the safe implementation of the
online detecting device was verified before field installation. Unlike in previous work, the
online detecting device was modified and improved according to the specific situation of
shunt reactors. Original fingerprints of 750 kV EHV shunt reactors were obtained and
analyzed after site installation and normal operation of the detecting device. A fault
simulation test was implemented to validate the method. This paper provides guidance on
actual implementation of online impulse frequency response analysis on power equipment.
152
42945
Pattanadech N. & Yutthagowith P.
Fast curve fitting algorithm for parameter evaluation in lightning impulse test
technique
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2931
- 2936
This paper proposes a fast curve fitting technique for the evaluation of the base curve of
lightning impulse voltage and current. The proposed method is based on the waveform
parameter estimation employing a numerical integration and linear least square method.
This method is derived from an ordinary differential equation. The proposed algorithm is
able to fit the base curve of lightning impulse voltage and current. The formula of the
base curve is in the complex form of two exponential functions. The proposed form is
superior to the conventional real exponential form, since it can be rewritten in a real
conventional form used for fitting the impulse voltage or in a damped/undamped
sinusoidal form with phase shift for fitting the impulse current. The decomposition base
curve procedure was tested with some impulse voltage and current waveforms collected
from the test data generator attached with IEC 61083- 2 (2013). The waveform parameters
evaluated by the proposed method are compared with those recommended by the
standards. The proposed method shows the better performance in computation time than
the conventional method recommended by the standards. Due to no requirement of
iteration in the proposed curve fitting method, the computation time is much shorter than
the conventional iterative method. Moreover, the utilization of the established method
does not allow the recorded impulse waveform distortion. Besides, the developed
algorithm technique can be done easily with markedly accuracy and noise immunity. For
the aforementioned reasons, there is no doubt that the proposed technique is a superior
one for impulse parameter evaluation.
42946
Yang Xu et.al
Investigation of disc-type sensors using the UHF method to detect partial discharge in
GIS
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 3019
- 3027
The disc-type UHF sensor is considered among the simplest couplers for partial discharge
(PD) detection in gas-insulated switchgear (GIS). This paper mainly focuses on the
improvement of the sensitivity of the disc-type sensor. Disc-type sensors with different
dimensions were tested on a 220 kV model GIS to find the critical parameters that
determine the sensitivity of the sensor. The waveform of the PD signal and the twoport
insertion loss were measured to see the amplitude of the output signal and the
transmission rate on different frequencies. The FD-TD method was used to investigate the
dimension factors in detail along with the effect of the dimension of the tank in which the
sensors are installed. The transformation process between the TEM mode and the higherorder modes of the electromagnetic (EM) wave was also simulated to investigate the
receiving efficiency of the disc-type sensors for different propagation modes. The results
showed that the diameter of the disc and the ratio of the height of the disc to the thickness
of the insulation were the most critical parameters that determined the sensitivity of the
disc-type sensor.
153
42947
Hamzehbahmani H et.al
Interlaminar Insulation Faults Detection and Quality Assessment of Magnetic Cores
Using Flux Injection Probe
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2205 - 2214
Interlaminar faults between laminations of the magnetic cores increase core losses and
could cause major damage to electrical machines. A system has been developed to detect
an interlaminar fault between the laminations of the magnetic cores by means of the flux
injection probe (FIP). Experimental work was carried out to calibrate the measuring system
and qualify its accuracy over a wide measurement range. Application of a prototype FIP
to quality assessment of transformer laminations was investigated in two stages: 1)
inspection of stack of laminations with known interlaminar faults applied by artificial
shorts and 2) inspection of stack of laminations with unknown quality. The experimental
results show that the developed system is capable of detecting an interlaminar fault
between as few as two laminations.
42948
Argyropoulos P.E. & Lev-Ari, H.
Wavelet Customization for Improved Fault-Location Quality in Power Networks
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2215 - 2223
A procedure for computing customized wavelets suitable for identifying the location of a
fault along the length of a transmission line is proposed. Measuring the time difference of
arrival (TDOA) between two consecutive transient reflections or the TDOA between the
two initial peaks of two synchronized voltage/current bus measurements provides an
accurate fault-location estimate. Reliable TDOA estimates can be obtained only when the
transformed fault signals consist of short/peaked pulses that arrive on a bus with a small
group delay. Our customization method improves the “peakedness” and shortens the group
delay of the transient signal by maximizing a suitable peakedness objective function. It is
shown that this approach is superior in terms of accuracy compared to the “classic”
(Daubechies) wavelet-based technique found in the literature. The proposed method is
independent of the fault type and can be used to reduce the required data sampling rate
while maintaining reliable TDOA estimates.
42949
Chong Wang et.al
Dynamic Coordinated Condition-Based Maintenance for Multiple Components with
External Conditions
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2362 - 2370
This paper proposes a method to establish an optimal dynamic coordinated conditionbased maintenance strategy that considers harsh external conditions, for example, harsh
weather conditions. Component deterioration is modeled as a Markov process based on
physical characteristics, with the effects of harsh external conditions represented as
probabilistic models. The proposed model involves interactions between different
maintenance strategies on various components, as well as influences on the operation of
the entire system. The optimal maintenance strategies are obtained by optimizing the
proposed model with the cost to go, including system reliability cost and maintenance
cost. This proposed model is solved using a backward induction algorithm associated with
a search space reduction approach developed to reduce the simulation time. Two IEEE
154
systems and one actual system validate the proposed model. The results show that this
optimal maintenance strategy model that considers harsh external conditions provides
insight for scheduling appropriate maintenance activities.
14. TRANSFORMERS
42950
Kassi K.S. et.al
Impact of local overheating on conventional and hybrid insulations for power
IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 22; No. 5; October 2015; 2543
- 2553
For more than a century, conventional mineral oil/cellulose insulation is being used as
main insulation for power transformers. The life span of these major assets is determined
amongst others by the insulation system's mechanical resistance to withstand short circuit
current forces. Since cellulose paper aging is accelerated by temperature, moisture and
oxygen, poly-aramid-based synthetic insulation paper, with better thermal stability
emerged for application in transformers. However the relatively limited number of studies
on hybrid insulation and the cost of aramid paper still limit their use in distribution
transformers. This contribution attempts to demonstrate that despite the high cost of
aramid paper, hybrid insulation could be used in large power transformers which represent
a significant financial investment. To do this, the quality of mineral oil aged with hybrid
solid insulation and the thermal aging of the cellulose paper of this insulation are
investigated. Comparison was made with traditional mineral oil impregnated cellulose
paper to provide a benchmark for comparison. The samples underwent thermal
accelerated aging procedure according to ASTM-D1934 standard and, furthermore, were
submitted to local overheating. The condition of oil samples collected from each aging
vessel was assessed using several diagnostic techniques, namely the relative amount of
the Dissolved Decay Products (DDP), Turbidity, and Interfacial Tension (IFT). The Degree
of Polymerisation (DPv) and Dissolved gas Analysis (DGA) were used to monitor the thermal
aging of the cellulose paper samples. The results indicate that oil aged with hybrid solid
insulation yield fewer decay products at some aging stages, especially after the application
of a local overheating. The results also indicate that the cellulose paper within solid hybrid
insulation is slightly less degraded compared to that of conventional insulation.
42951
Barrios E.L. et.al
High-Frequency Power Transformers with Foil Windings: Maximum Interleaving and
Optimal Design
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5712 - 5723
Foil conductors and primary and secondary interleaving are normally used to minimize
winding losses in high-frequency (HF) transformers used for high-current power
applications. However, winding interleaving complicates the transformer assembly, since
taps are required to connect the winding sections, and also complicates the transformer
design, since it introduces a new tradeoff between minimizing losses and reducing the
construction difficulty. This paper presents a novel interleaving technique, named
maximum interleaving, that makes it possible to minimize the winding losses as well as
the construction difficulty. An analytical design methodology is also proposed in order to
155
obtain free-cooled transformers with a high efficiency, low volume, and, therefore, a high
power density. For the purpose of evaluating the advantages of the proposed maximum
interleaving technique, the methodology is applied to design a transformer positioned in
the 5 kW-50 kHz intermediate HF resonant stage of a commercial PV inverter. The
proposed design achieves a transformer power density of 28 W/cm3 with an efficiency of
99.8%. Finally, a prototype of the maximum-interleaved transformer is assembled and
validated satisfactorily through experimental tests.
42952
Macrelli E. et.al
Modeling, Design, and Fabrication of High-Inductance Bond Wire Microtransformers
with Toroidal Ferrite Core
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5724 - 5737
This paper presents the design of miniaturized bond wire transformers assembled with
standard IC bonding wires and NiZn and MnZn ferrite toroidal cores. Several prototypes
are fabricated on a printed circuit board substrate with various layouts in a 4.95 mm ×
4.95 mm area. The devices are modeled by analytical means and characterized with
impedance measurements over a wide frequency range. Experimental results on 1:38
device show that the secondary self-inductance increases from 0.3 µH with aircore to 315
µH with ferrite core; the coupling coefficient improves from 0.1 with air-core to 0.9 with
ferrite core; the effective turns ratio enhances from 0.5 with air-core to 34 with ferrite
core. This approach is cost effective and enables a flexible design of efficient
micromagnetics on top of ICs with dc inductance to resistance ratio of 70 μH/Ω and an
inductance per unit area of 12.8 µH/mm2 up to 0.3 MHz. The design targets the
development of bootstrap circuits for ultralow voltage energy harvesting. In this context,
a low-voltage step-up oscillator suitable for thermoelectric generator sources is realized
with a commercial IC and the proposed microtransformers. Experimental measurements
on a discrete prototype report that the circuit bootstraps from voltages down to 260 mV
and outputs a dc voltage of 2 V.
42953
Bahmani M.A. & Thiringer T.
Accurate Evaluation of Leakage Inductance in High-Frequency Transformers Using an
Improved Frequency-Dependent Expression
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5738 - 5745
Moving toward higher power density in magnetic components, which is often realized by
increasing the operating frequency, leads to the need for development of more accurate
design tools, for example, more accurate expressions for core losses, winding losses, and
leakage inductance calculations. This paper presents a new analytical expression intended
to accurately evaluate the leakage inductance of transformers in the high-frequency range
in which the behavior of the magnetic field within the windings is altered. Unlike
conventional expressions, which usually overestimate the leakage inductance at higher
frequencies, this expression accounts for high-frequency behavior of the magnetic field
and provides high accuracy when operating at high frequencies. These high accuracy and
applicability makes the derived expression of interest for designers to avoid time
consuming finite-element simulations without compromising with accuracy. The
156
expression is validated by 2-D finite-element method simulation, as well as by
measurements.
42954
Thummala P. et.al
Efficiency Optimization by Considering the High-Voltage Flyback Transformer
Parasitics Using an Automatic Winding Layout Technique
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5755 - 5768
This paper presents an efficiency optimization approach for a high-voltage bidirectional
flyback dc-dc converter. The main goal is to optimize the converter for driving a capacitive
actuator, which must be charged and discharged from 0 V to 2.5 kV dc and vice versa,
supplied from a 24 V dc supply. The energy efficiency is optimized using a proposed new
automatic winding layout (AWL) technique and a comprehensive loss model. The AWL
technique generates a large number of transformer winding layouts. The transformer
parasitics, such as dc resistance, leakage inductance, and self-capacitance are calculated
for each winding layout. An optimization technique is formulated to minimize the sum of
energy losses during charge and discharge operations. The efficiency and energy loss
distribution results from the optimization routine provide a deep insight into the highvoltage transformer design and its impact on the total converter efficiency. The proposed
efficiency optimization approach is experimentally verified on a 25 W (average charging
power) with a 100 W (peak power) flyback dc-dc prototype.
42955
Ziwei Ouyang et.al
Calculation of Leakage Inductance for High-Frequency Transformers
IEEE Trans. on Power Electronics; Vol. 30; No.10; October 2015; 5769 - 5775
Frequency-dependent leakage inductance is often observed. The high-frequency eddy
current effects cause a reduction in leakage inductance. The proximity effect between
adjacent layers is responsible for the reduction of leakage inductance. This paper gives a
detailed analysis of high-frequency leakage inductance and proposes an accurate
prediction methodology. High-frequency leakage inductances in several interleaved
winding configurations are also discussed. Interleaved winding configurations actually give
a smaller degree of reduction of leakage induction at high frequency. Finite-element
analysis simulation and measurement validate the models.
42956
Meneses D. et.al
Grid-Connected Forward Micro-inverter With Primary-Parallel Secondary-Series
Transformer
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 4819 - 4830
This paper presents a primary-parallel secondary-series multicore forward microinverter
for photovoltaic ac-module application. The presented microinverter operates with a
constant off-time boundary mode control, providing MPPT capability and unity power
factor. The proposed multitransformer solution allows using low-profile unitary turns ratio
157
transformers. Therefore, the transformers are better coupled and the overall performance
of the microinverter is improved. Due to the multiphase solution, the number of devices
increases but the current stress and losses per device are reduced contributing to an easier
thermal management. Furthermore, the decoupling capacitor is split among the phases,
contributing to a low-profile solution without electrolytic capacitors suitable to be
mounted in the frame of a PV module. The proposed solution is compared to the classical
parallel-interleaved approach, showing better efficiency in a wide power range and
improving the weighted efficiency.
42957
Choi B.H. et.al
Lumped Impedance Transformers for Compact and Robust Coupled Magnetic
Resonance Systems
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6046 - 6056
An innovative coupled magnetic resonance system (CMRS), introducing two lumped
impedance transformers, is proposed. There are three major magnetic couplings between
coils in CMRS: source-transmitter (Tx), Tx-receiver (Rx), and Rx-load couplings. Except for
Tx-Rx coupling, other couplings do not directly contribute to wireless power transfer.
Hence, in this paper, this miscellaneous coupling is replaced with a lumped transformer
with ferrite core. Because there is only a Tx-Rx coupling, the CMRS becomes compact in
size and robust to ambient changes. Moreover, the design of CMRS is drastically simplified
without complicated multiresonance tunings due to little magnetic flux linkage from the
source coil or load coil. Coreless coils are used for Tx and Rx coils to examine the
characteristics of CMRS with lumped transformers. A detailed static analysis on the explicit
circuit model of the proposed CMRS and design procedures are fully established.
Experiments for 1- and 10-W prototype CMRSs with a class-E inverter at the switching
frequency of 500 kHz, where the quality factors are less than 100, verified the usefulness
of the proposed model, achieving 80% of the maximum Tx coil-to-load efficiency. It is
concluded in this paper that the conventional CMRS, in general, is just a special form of
an inductive power transfer system where the quality factor is extremely high.
42958
Sheng Yuan et.al
Magnetic Field Energy Harvesting Under Overhead Power Lines
IEEE Trans. on Power Electronics; Vol. 30; No.11; November 2015; 6191 - 6202
Condition monitoring for overhead power lines is critical for power transmission networks
to improve their reliability, detect potential problems in the early stage, and ensure the
utilization of the transmitting full capacity. Energy harvesting can be an effective solution
for autonomous self-powered wireless sensors. In this paper, a novel bow-tie-shaped coil
is proposed, which is placed directly under overhead power lines to scavenge the magnetic
field energy. Compared to the conventional method by mounting the energy harvester on
the power lines, this approach provides more flexibility and space to power bigger sensors
such as the weather station. As the harvesting coil cannot entirely enclose the power lines,
the demagnetization factor that is closely related to the core geometry should be
considered and optimized. Thus a new bow-tie-shape core is designed to produce a much
lower demagnetization factor (hence more power) than that of the conventional solenoid.
The selection of core material is studied and found that Mn-Zn ferrite is the most suitable
core material because it greatly reduces the eddy current losses and also has high
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permeability. Experiment results show that the bow-tie coil could have a power density of
1.86 µW/cm3 when placed in a magnetic flux density of 7 µTrms. This value is 15 times
greater than the reported results under the same condition. If a longer bow-tie coil with
more turns is placed in a magnetic flux density of 11µTrms, the produced power density is
103.5 µW/cm3, which is comparable to a solar panel working during a cloudy day. Thus,
the proposed solution is a very efficient and attractive method for harvesting the magnetic
field energy for a range of monitoring applications.
42959
Khalkhali B. & Sadeh J.
Transformer Differential Protection by Online Core Modeling and Orthogonal
Polynomials
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2146 – 2153
By expressing the newly defined “magnetic pseudo-characteristic” in terms of orthogonal
polynomials, a new method is proposed to discriminate between inrush and fault currents.
In this method, the operating segment of the magnetic pseudocharacteristic is extracted
over a half-cycle data window of differential current, and is then evaluated by some
criteria to detect fault/inrush currents. Independence from transformer models and high
accuracy are some merits of this method. The method is tested on the simulated data of
wye-delta and wye-wye-connected transformers (three limb) and the results show the
average fault detection delay of 16 ms (in 50-Hz base) with an accuracy above 97%. Also,
for a more practical assessment, the results are compared with those of the well-known
second harmonic restraint method, and this verifies greater accuracy of the proposed
method. Moreover, performance of the method in noisy environments is studied. Details
about efficient implementation by using fast Fourier transform algorithms are also
included.
42960
Navarro M.A. & Monteiro A.J.
Submersible Dry-Type Transformer
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2189 - 2194
This paper describes the concept and development of dry-type transformers for
underground distribution networks, capable of operating in the open air, partially
submerged or completely submerged without enclosure and in contact with water. The
rating is in the range of 500 kVA to about 2000 kVA and 15- or 25-kV voltage. Immersion
depth is limited to 3 m, due to the limits of the plug-in connectors on the high-voltage
(HV) side of the transformer. A tap panel is provided on HV coils for ±5.0%. Dimensions
and losses are comparable to those of liquid-immersed transformers. Electrical insulation
is fully solid. The HV coils are shielded and the shield is grounded.
42961
Pramanik S
Resonance Behavior and Sensitivity to Detect Mechanical Change in Transformer
Winding: Shunt Current versus Neutral Current
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2276 - 2283
Frequency-response measurement offers by far the most sensitive known technique to
detect any mechanical deformation in transformer windings. By default, during this
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measurement, the neutral or line current is considered as the winding response. The
overall sensitivity to detect a mechanical change depends not only on the response
quantity and the terminal connections chosen, but, also on the arrangement of poles and
zeros of the system function. Some pole-zero arrangements are inherently better suited
to reveal mechanical changes. Because of this, it is imperative to examine whether neutral
current is indeed the best response quantity to consider or if there exists any other
quantity, say, for example, total shunt current of the winding (also referred to as the tank
current), to accomplish this task better. With this motivation, this paper compares the
resonance behavior of neutral and tank current. Based on analytical derivations and actual
experiments, it emerges that for detecting simulated mechanical changes, the tank
current seems to be a more competent alternative compared to neutral current. It offers
enhanced detection sensitivity, especially for interleaved windings. The possible reasons
to explain why it is so are presented. The author believes that this finding needs
reinforcement by field trials to ascertain its viability.
42962
Hajipour E. et.al
Current-Transformer Saturation Compensation for Transformer Differential Relays
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2293 - 2302
Current-transformer (CT) saturation threatens accurate discrimination between internal
fault current and magnetizing inrush current of a transformer and endangers the proper
operation of a differential relay. Thus, compensation of CT saturation could substantially
improve the performance and security of transformer differential relays. So far, almost all
of the technical literature in this field has focused exclusively on fault current
compensation. However, this paper proposes an efficient compensation algorithm to
reconstruct the fault and inrush currents which are distorted by CT saturation. Some of
the attractive features of the proposed method are its accuracy, fast response time,
desired sample-by-sample output, no dependency on power system topology, immunity
against noise and harmonics, and its simplicity. These features are extracted through the
application of numerous test cases reflecting a wide range of variations in fault and inrush
currents. The proposed algorithm proves to be fast, accurate, and reliable.
42963
Jazebi S. & De Leon F.
Duality-Based Transformer Model Including Eddy Current Effects in the Windings
IEEE Trans. on Power Delivery, Vol.30; No.5; October 2016; 2312 - 2320
This paper presents a general method for building equivalent electric circuits of power
transformers, including eddy current effects in windings and core. A high-frequency
equivalent dual model for single- and three-phase transformers with two multilayer
windings is derived from the application of the principle of duality. The model is built from
elements available in circuit simulation programs, such as Electromagnetic Transients
Program (EMTP)-Alternative Transients Program, EMTP-RV, PSCAD, and PSpice. The
parameters of the frequency-dependent leakage inductance and winding resistance are
computed with analytical formulae obtained from the solution of Maxwell's equations that
are based on the geometrical dimensions and material information. Ideal transformers are
utilized to isolate the electric components (winding resistors and capacitors) from the
magnetic components (inductors). The physically correct connection points for electric
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and magnetic components are clearly identified. The proposed methodology is successfully
validated versus finite- element simulations and laboratory measurements.
15. OTHERS
42964
Sugimoto T et.al
An Electrostatic Field-Driven Ionizer for a Moving Charged Target
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4139 - 4144
An electrostatic field-driven (EFD) ionizer specifically designed for a moving charged
target is proposed. The ionizer, which is proximally positioned to the charged target, is
composed of a grounded mesh electrode and an array of positive and negative needle
electrodes. The positive and negative needles face each other to make a high space charge
density of positive and negative ions just above the grounded mesh. The electric field
formed between the grounded mesh and the charged target transports ions by
electrostatic force. The ion transportation brings a faster charge elimination rate than the
air drag force widely used in commercial ionizers. An evaluation method of the charge
elimination for a moving target is also proposed. The method employs parameters of
capacitance of the target, equivalent resistance of the ionized air, effective length of the
ionizing zone and moving speed of the target. The performance of the EFD ionizer and a
commercial fan-type ionizer were compared using the evaluation method. The EFD ionizer
was found to have significantly higher performance than the commercial fan-type ionizer.
42965
Brahami Y. et.al
Experimental Modeling of a New Triboelectrostatic Separation Process for Micronized
Plastics
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4145 - 4150
Triboelectrostatic separation of millimeter-size granular plastic mixtures is widely used in
recycling industry. However, electrostatic separation of micronized plastics is still
inefficient since the adhesion and aerodynamic forces surpass the electric force. The aim
of this paper is to optimize a new separation process for mixed fine granular plastics based
on a fluidized bed tribocharging system. A pair of opposite high-voltage parallel plate
electrodes are immersed in that bed and undergo a vertical alternating movement. The
fine polyvinyl chloride particles of average size 0.1-mm particles to be separated are
tribocharged using a fluidization air provided by a variable-speed blower. The charged
particles are pinned to the electrodes of opposite polarities. The separation depends on
several factors: the electric field, the speed of the electrode movement, the mass of the
granular product, and the fluidization rate. The latter was the most significant factor, and
the interval between the electrodes should not be less than 2 cm to avoid corona
discharge.
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42966
Touhami S. et.al
Numerical Simulation of the Trajectories of Insulating Particles in a Tribo-AeroElectrostatic Separator
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4151 - 4158
Electrostatic technologies have emerged as the solution of choice for the recycling of
insulation contained in waste materials. The main objective of this paper is to contribute
to the better understanding of the operating conditions of a new class of tribo-aeroelectrostatic separators. The study of the motion of charged particles under the influence
of an electric field by numerical tools facilitates the construction, implementation, and
control of new electrostatic separation equipment. In effect, the trajectory of the particle
can be determined precisely by the equation of forces that act on it in the electric field
of the separator. COMSOL software was employed for the analysis of the electric field. A
program written in MATLAB served then to simulating the trajectories of electrically
charged insulating particles in the separator and enables the study of the factors that
might influence the process of selective sorting of the various granular materials, i.e.,
geometry of the fluidized bed, velocity of the fluidization air, high-voltage applied to the
electrodes, electric charge of the particles, granule size, and specific mass. Thus, an
effective separation occurs in the case of particles characterized by charge/mass ratios
on the order of -9 and +9 µC/kg.
42967
Miloudi M. et.al
Improved Overall Performances of a Tribo-Aero-Electrostatic Separator for Granular
Plastics from Waste Electric and Electronic Equipment
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4159 - 4165
The two-conveyor-electrode tribo-aero-electrostatic separator patented in 2010 was
designed to sort granular mixtures of insulating materials in a fluidized bed subjected to
an electric field perpendicular to the direction of the fluidizing air. The prototype has
proven its efficiency for the separation of insulating granules ≤ 2 mm, attaining excellent
recovery rates. Its performances were less satisfactory for larger particles (2-5 mm). The
objective of this work is to evaluate three modifications of the construction of this device,
in order to increase the hourly throughput and improve the purity of the products, by
controlling the charge acquired by the granules and the electric field intensity. Numerical
simulations enabled the optimization of the electric field distribution in the active zone
of the separator, and an experimental study was carried out, in order to identify the best
conditions for granule charging by triboelectric effect. The tests were carried out for four
configurations of the electrode system, by using a mixture of acrylonitrile butadiene
styrene (ABS) and high-impact polystyrene (HIPS) originated from grinding out-of-use
computer cases. The typical granule size was 2-5 mm. The experimental approach
validated a change in the position of the fluidized bed, with respect to the conveyor
electrodes, to increase the residence time of the granular materials and hence the amount
of electric charge acquired by each particle. In order to intensify the electrical field, two
solutions were tested and validated: 1) add a grounding electrode in the proximity of the
high-voltage electrodes; 2) dispose vertically the high-voltage electrodes. For the tested
materials, the vertical arrangement of the electrodes gave the best hourly throughput
rates and purity of the separated products.
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42968
Mekhalef Benhafssa A. et.al
Study of a Tribo-Aero-Electrostatic Separator for Mixtures of Micronized Insulating
Materials
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4166 - 4172
This paper is aimed at the optimization of a new tribo-aero-electrostatic separator for
micronized isolating materials mixtures, with application at the recycling of waste
electrical and electronic equipment. The two high-voltage rotating-cylinder electrodes of
the electrostatic separator are partly immersed in a fluidized bed containing the material
to be separated. The control variables of the process are the high-voltage applied to the
electrodes, the speed of the fluidization air, and the feeding rate of the separator.
Experimental design methodology is employed for modeling the separation process. This
enables the determination of the values of these variables that ensure the optimal
operating condition of the installation.
42969
Hak-Joon Kim et.al
Sub-micrometer PM Removal of an ESP Combined With a Metallic Foam Filter for Large
Volumetric Diesel Engines
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4173 - 4179
An electrostatic diesel particulate matter (PM) filtration device was tested using 4000cm3 diesel engines operating at standard [European Stationary Cycle 13 and European
Transient Cycle] conditions, at temperatures between 100 °C and 500 °C and gas velocities
of up to 30 m/s. The device consisted of an edge-to-cylinder-type electrostatic
precipitator (ESP) and a metallic foam filter. To minimize the volume of the foam filter
and reduce pressure drop through the filtration device, the thickness of the layer of foam
filter was reduced from 34.5 to 11.5 mm. PM emissions with the filtration device, using a
foam sheet thickness of 11.5 mm, were less than 0.01 g/kWh, which met the diesel PM
standard given in Euro 6 regulations. Emissions using only a foam filter with 11.5-mm layers
were over 0.03 g/kWh. The pressure drop of the device with 11.5-mm foam sheets was
25% of that using 34.5-mm layers. A foam filter coated with Pt catalysts was tested at
temperatures ranging from 300 °C to 400 °C, and approximately, 12-g PMs were burned
out through natural regeneration.
42970
Saarakkala S.E
Identification of Two-Mass Mechanical Systems Using Torque Excitation: Design and
Experimental Evaluation
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4180 - 4189
This paper deals with methods for parameter estimation of two-mass mechanical systems
in electric drives. Estimates of mechanical parameters are needed in the start-up of a
drive for automatic tuning of model-based speed and position controllers. A discrete-time
output error (OE) model is applied to parameter estimation. The resulting pulse-transfer
function is transformed into a continuous-time transfer function, and parameters of the
two-mass system model are analytically solved from the coefficients of this transfer
function. An open-loop identification setup and two closed-speed-loop identification
setups (direct and indirect) are designed and experimentally compared. The experiments
are carried out at nonzero speed to reduce the effect of nonlinear friction phenomena on
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the parameter estimates. According to results, all three identification setups are
applicable for the parameter estimation of two-mass mechanical systems.
42971
Usamentiaga R. et.al
Flatness Measurement Using Two Laser Stripes to Remove the Effects of Vibrations
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4297 - 4304
Flatness measurement and control is a requirement in the production of high-quality rolled
steel products. One of the most popular measurement methods is based on laser lightsectioning sensors. This method is based on the projection of a laser stripe onto the steel
strip while it moves forward along a roll path. The extraction of the laser stripes provides
information about the lengths of the strip fibers, which are used to compute flatness. This
flatness measurement method is easy to maintain, provides accurate results, and can be
built using low-cost components. However, it has a major disadvantage: it is severely
affected by vibrations. Thus, when the movement of the strips is affected by vibrations,
the resulting flatness measurement is inaccurate. This paper proposes a solution: using a
second laser stripe and taking advantage of this redundant information to estimate and
remove vibrations. This paper presents the procedure required to combine the laser stripes
and produce a vibration-free result. In order to test the proposed approach, a mechanical
prototype is built and used to produce vibrations. Results show excellent performance and
indicate that the proposed approach presents a far more efficient solution than traditional
methods using a single laser stripe.
42972
Mazur D.C.et.al
Advancements in Vibration Monitoring for the Mining Industry
IEEE Trans. on Industry Applications; Vol.51; No.5; Sept. – Oct. 2015; 4321 - 4328
Rotating machinery assets are a fundamental necessity in the mining industry.
Furthermore, the proper maintenance and ability to monitoring these key assets is
important to maximizing the operations. This paper will discuss the merits and
advancements in vibration monitor systems and the direct impact on supervisory control
and data acquisition and predictive maintenance models.
42973
Huber L.& Jovanovic M.M.
Analysis and Comparison of Audible Noise Caused by Magnetic Components in SwitchMode Power Supplies Operating in Burst Mode and Frequency-Foldback Mode
IEEE Trans. on Power Electronics, Vol.30; No.9; September 2015; 5299 - 5308
In this paper, it is theoretically shown and experimentally verified that operation of
switch-mode power supplies in burst mode (BM) results in lower audible noise than
operation in frequency-foldback mode (FFM). However, the selection of the switching
frequency in a burst package can have a significant impact on the audible noise. In both
BM and FFM, the audible noise can be reduced by decreasing the peak value of current
pulses and proportionally increasing the burst frequency in BM and the switching frequency
in FFM. In BM, the audible noise can be further reduced if instead of increasing the burst
frequency, the number of burst pulses is increased without changing the burst frequency.
164
The presented BM and FFM audible noise analyses are experimentally verified on a dc-dc
boost test circuit.
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