IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 50, NO. 5, SEPTEMBER/OCTOBER 2014
3549
Validation of the Plug-and-Play AC/AC Power
Electronics Building Block (AC-PEBB) for
Medium-Voltage Grid Control Applications
Amrit R. Iyer, Student Member, IEEE, Rajendra Prasad Kandula, Student Member, IEEE,
Rohit Moghe, Member, IEEE, Jorge E. Hernandez, Student Member, IEEE,
Frank C. Lambert, Senior Member, IEEE, and Deepak Divan, Fellow, IEEE
Abstract—As ac-to-ac power conversion becomes increasingly
important in applications such as grid power control and motor
control, demand for a plug-and-play converter has increased. Traditional voltage-source-inverter-based ac-to-ac power converters
such as the back-to-back converter require dc-link capacitors
that limit their reliability or significantly increase their size and
cost. This paper examines a plug-and-play concept for achieving
ac-to-ac power conversion via the direct-ac/ac power electronic
building block (AC-PEBB). The AC-PEBB is a compact selfcontained cell requiring no intermediate energy storage. It can
be used in a variety of ac/ac power electronic applications such
as matrix converters and controllable network transformers. This
paper details the design of an 800-V 100-A AC-PEBB prototype to
be used in a 13-kV 1-MVA application. Successful test results using
several AC-PEBBs in a variety of configurations are demonstrated
at up to 11 kV and 600 kVA.
Index Terms—AC–AC power conversion, flexible ac transmission systems, high-voltage techniques, matrix converters, phase
control, power control, power semiconductor switches, snubbers.
I. I NTRODUCTION
A
C-TO-AC power conversion is becoming important in
many utility and industrial applications. The utility grid
is a prime example, where a dramatic increase in the level
of renewable resources connected to the grid is occurring in
order to increase energy security and reduce carbon emissions.
However, the spatial and temporal variability of new wind and
solar generation is poorly correlated with existing loads, leading
to the need for significant transmission investments in order
to reduce possible congestion [1], [2]. In lieu of transmission
improvements, which are typically difficult and time consuming
to negotiate and implement, dynamic grid power control can be
used to enhance system utilization [2]–[5]. Important metrics
Manuscript received October 29, 2013; accepted January 23, 2014. Date of
publication February 7, 2014; date of current version September 16, 2014.
Paper 2013-PEDCC-715, presented at the 2013 IEEE Energy Conversion
Congress and Exposition, Denver, CO, USA, September 16–20, and approved
for publication in the IEEE T RANSACTIONS ON I NDUSTRY A PPLICATIONS
by the Power Electronic Devices and Components Committee of the IEEE Industry Applications Society. This work was supported by the United States Department of Energy through the Advanced Research Projects Agency—Energy
program.
The authors are with the School of Electrical and Computer Engineering,
Georgia Institute of Technology, Atlanta, GA 30332 USA (e-mail: ariyer@
gatech.edu; krprasad@gatech.edu; rmoghe@varentec.com; jorge.hernandez@
gatech.edu; frank.lambert@neetrac.gatech.edu; deepak.divan@ece.gatech.
edu).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TIA.2014.2304583
for power controllers to be used for transmission applications
include high reliability, scalability to 345 kV and 200 MW,
and attractive cost. Traditional solutions for grid power control,
such as high-voltage dc (HVDC) lines and flexible ac transmission system (FACTS) devices, suffer from high cost [2],
[6], high complexity [6], relatively high losses [2], [5], and
relatively low reliability; typical HVDC and FACTS devices
realize reliability levels of 95%–98% [7]–[9], whereas the US
transmission network operates at levels in excess of 99.9%
[10]. To drive adoption of power controllers among utilities, a
technology is needed that is lower in cost, higher in efficiency,
easy to integrate, and does not lower single-point system reliability. One attractive solution that exists in the literature is the
controllable network transformer (CNT), which adds a directac/ac fractionally rated power electronics converter to a load
tap changer (LTC) transformer to achieve grid power control
[11]. The fractional rating of the CNT allows for efficiencies
greater than 99%, and its integrated fail-normal bypass switch
allows for enhanced reliability. The design and initial testing
of an ac/ac power electronic building block (AC-PEBB) for a
CNT application was previously outlined by Iyer et al. in [12].
This paper expands upon the AC-PEBB in [12], where a
compact, modular, and scalable direct-ac/ac building block is
examined. Important design considerations of the AC-PEBB
are explained, and experimental results are shown for a CNT
application at 11 kV and 600 kVA using six AC-PEBB cells in
a variety of configurations.
II. S CALING THE CNT W ITH AC-PEBB C ELLS
A. CNT Review
For a CNT with a tap ratio of 1 to n and a virtual quadrature
source (VQS)-based duty cycle of
D = K0 + K2 sin(2ωt + Φ)
(1)
active and reactive power can be controlled in a two-bus system,
such as in Fig. 1, according to (2) and (3), as shown in [11], i.e.,
V 2B
V 2A
sin δ −
cos(δ + Φ)
ωL
ωL
1 + n − 2K0 n
nK2
with A =
,
B=
(2)
1− n2
1
− n2
BV 2
V2
2
AV 2
cos δ+
sin δ. (3)
Qout =
A2 − B 2 −
ωL
3
ωL
ωL
Pout =
0093-9994 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.
See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
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Fig. 1. Conceptual one-line diagram of CNT connecting two buses.
Fig. 2.
cell.
Fig. 3.
Series stacking of AC-PEBBs in a CNT configuration.
Fig. 4.
Parallel stacking of AC-PEBBs in a CNT configuration.
(a) Schematic of the AC-PEBB cell. (b) Solid model of the AC-PEBB
B. AC-PEBB Overview
The PEBB concept, explained in [13], outlines a vision
for a singular building block that can reduce the size and
cost of power electronics, while facilitating easier installation,
maintenance, and manufacturing. PEBB technology has been
proven useful in transmission-level VSC applications, where
the modular multilevel converters (MMC or M2 C) have been
cascaded for use in HVDC power transmission [14]. For directac/ac converters, an ac PEBB design has been proposed in [15];
however, the topic of scaling to higher voltages for direct-ac
PEBBs has yet to be addressed.
The AC-PEBB described in this paper and shown in Fig. 2 is
a self-contained unit that provides a plug-and-play functionality
for ac-to-ac power conversion applications. It provides a compact modular building block for direct-ac/ac applications and
allows series and parallel connection of cells to enable scaling
to higher voltage and power levels.
An AC-PEBB cell contains four insulated-gate bipolar transistors (IGBTs, or MOSFETs), forming two ac switches with
a midpoint connection, as shown in Fig. 2(a). Each ACPEBB contains all necessary gate drive, snubber, and thermal
management components, allowing the cell to be used as a
standalone matrix or thin ac converter [16]. Through directac/ac conversion via the use of VQS as outlined in [17], large
dc storage elements are not needed, allowing the cell to be only
a few inches in size in each dimension, as shown in Fig. 2(b).
Compactness, combined with the cell’s modularity, allows it to
be easy to manufacture, install, and replace, thus reducing both
upfront and operation and maintenance costs.
cells. For example, Figs. 3 and 4 show various forms of a CNT
prototype built by series and parallel connection of AC-PEBBs
to the taps of a standard 1-MVA transformer. More advanced
topologies are discussed in companion paper [18].
The major obstacles encountered when scaling the AC-PEBB
to utility-scale power levels are ensuring equal voltage sharing between devices and providing protection from incorrect
commutation sequences. These challenges can be overcome by
the active snubber concept proposed in [19]. The half-wave
rectified sources connected through diodes across each device
in Fig. 2(a) are conceptual representations of the active snubber
technology being used in the AC-PEBB.
III. R EVIEW OF THE AC-PEBB
C. Scaling the AC-PEBB
Usage of the AC-PEBB at higher voltage and power levels
is accomplished via series and parallel connection of multiple
The AC-PEBB consists of five parts: the main switching
devices, the gate drivers, the snubber circuits, the bus bars, and
the thermal management system.
IYER et al.: VALIDATION OF THE PLUG-AND-PLAY AC-PEBB FOR GRID CONTROL APPLICATIONS
3551
Fig. 6. Hybrid snubber circuit for AC-PEBB.
Fig. 5.
AC-PEBB snubber board.
Fig. 7. Active snubber circuit and buck–boost control for AC-PEBB.
A. Main Device Selection
The main AC-PEBB switching devices are GeneSiC Semiconductor’s GA100XCP12-227. These are 1200-V 100-A silicon IGBTs with a built-in silicon carbide antiparallel diode. The
SiC diodes contained in this device have minimal reverse recovery and high temperature tolerances, allowing device operation
at tens of kilohertz and temperatures as high as 150 ◦ C. The
device’s 1200-V rating allows it to safely operate at voltages
with a peak of up to 800 V, corresponding to a root mean square
(RMS) voltage of 565 V; a 400-V buffer is in place to account
for voltage spikes during switching due to stray inductances.
An AC-PEBB built with these devices is capable of acting as
a 56.5-kVA standalone converter. Additionally, as AC-PEBBs
can operate as thin ac converters, to provide full power flow
control, they only need to be rated at about 10%–20% of
the level of the asset to be augmented, depending on the
controllability range needed. Therefore, a single AC-PEBB
composed of these GeneSiC devices can be used to route power
flows of as high as 565 kVA. Accounting for the small size
of GeneSiC’s devices, which are 1.3 × 1.6 inches, series and
parallel stacking of GeneSiC-based AC-PEBBs has the ability
to reach transmission level powers in a compact size.
B. Snubber Board Design
The AC-PEBB snubber board, as shown in Fig. 5, consists
of four snubber circuits organized on a single PCB, which is
directly screwed onto the IGBTs of the AC-PEBB. A hybrid
passive and active snubber approach is used, as shown in Fig. 6.
The passive snubber portion of the design protects the converter
during a system-level fault until external circuit breakers, relays, or fuses have a chance to react. The active snubber portion
of the hybrid snubber, as outlined in [19], creates a half-wave
rectified envelope around each IGBT, providing protection
from internal faults, such as incorrect commutations near zero
crossings, and ensuring that equal voltage is seen across every
device. A modified version of the buck–boost design in [19]
is employed in the AC-PEBB to control each active snubber
and is schematically shown in Fig. 7. More information on the
electrical design of the snubber circuit for an 800-V 100-A
application can be seen in [20].
Any stray inductance in the snubber-to-IGBT path leads to
voltage spikes during snubber operation, and because the snubber operates during incorrect commutations or fault conditions,
large currents and di/dt’s will be experienced during these situations. Therefore, parasitic inductances significantly reduce the
effectiveness of the snubber circuit in limiting voltage spikes.
The snubber board design in Fig. 5 places the snubber capacitor
(CS ), diode (DS ), and varistor (MOVS ) as close as possible to
the IGBTs they are protecting, thus minimizing the inductance
in the snubber path and maximizing their effectiveness. The
control circuitry for the snubber voltage envelope creation is
moved onto the gate drive board to reduce the overall size of
the AC-PEBB.
C. Gate Drive Board Design
The gate drivers for the AC-PEBB are chosen to be Powerex
VLA-502 modules mounted onto modified Powerex BG2A gate
drive boards. The BG2A boards are augmented with protection
and fault management circuitry, control circuitry for the ACPEBB’s snubber circuits, and fiber optic connections to carry
all signals to and from the converter’s main microcontroller
unit. If long signal wires are employed in lieu of fiber optic
connections, large amounts of switching noise induced by the
converter’s extremely high di/dt levels would compromise the
integrity of the digital control signals, even if a twisted-pair
configuration is used. Finally, gate drive board is designed to
directly plug into the main snubber board using low-inductance
bus-bar connections in order to minimize inductance in the
gate–emitter path of each IGBT. Fig. 8 shows the final gate
drive board as well as the layout of its various subcircuits. Each
board controls two IGBTs.
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TABLE I
AC-PEBB S PECIFICATION S UMMARY
Fig. 8. Gate drive board for AC-PEBB.
Fig. 10.
PTMS of 5 kW to 40 ◦ C for up to 12 AC-PEBB cells.
With the integration of the PTMS into the AC-PEBB, the cell
is able to independently operate from electrical, thermal, and
mechanical points of view. Additionally, the PTMS removes
the need for fans, pumps, and other moving parts, increasing
the expected lifetime of the converter to 30 years. This lifetime
puts the AC-PEBB alongside most other utility assets in terms
of robustness, increasing its commercial appeal and ease of
integration.
IV. AC-PEBB-BASED 1-MW CNT D ESIGN
A. 1-MW Test Bed Design
Fig. 9. Complete AC-PEBB cell.
D. Completed Cell Specifications
The completed AC-PEBB, mounted on a heat sink, is shown
in Fig. 9. Again, inductance was kept to a minimum through the
use of wide bus bars and a compact design. Spacers and 30-mil
Nomex insulation are present to keep the various layers of the
AC-PEBB electrically isolated. The entire cell is a cube that is
approximately 6 × 6 × 10 inches in size. The specifications of
the designed AC-PEBB are summarized in Table I.
E. Thermal Management
For higher power applications, cooling is provided by a novel
passive thermal management system (PTMS), shown in Fig. 10,
that is capable of supporting up to 12 cells. The PTMS involves
a main AC-PEBB heat sink feeding into an oil tank and fin
array. The losses generated by the system are used to create
a thermosiphon to circulate the oil between the main AC-PEBB
heat sink and external fin array [21].
The AC-PEBB-based CNT laboratory prototype consists of
two 13-kV primary, 1300-V/650-V secondary, 167-kVA transformers, whose primary and secondary windings are series connected, and a set of line inductors, as shown in Figs. 11 and 12.
The two transformer sets are representative of two buses in an
arbitrary power system. A set of AC-PEBBs is connected across
one of the transformers between its +/−650-V taps, achieving
a CNT configuration with a tap ratio of n = 9.5%. Current
can be circulated between the system’s transformers without
power transfer occurring with the grid. Using a POWERSTAT,
voltage levels on the system’s input and output voltage buses
are scalable from 0 to 13650 V (RMS). For safety reasons and
to limit the voltage seen by the converter’s PTMS, the center
tap of the transformer of bus 1 was used as ground.
Without the AC-PEBB-based converter, both bus 1 and bus 2
have the same voltage magnitude and phase, and there is
no power transfer across the line. With the AC-PEBB-based
converter, the effective voltage of bus 1 is controlled to be
different from bus 2, in magnitude or phase or both, to induce
energy flow on the line. Hence, the functionality of the CNT
and AC-PEBBs can be demonstrated by controlling the power
between the two buses.
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3553
Fig. 11. Two-bus system of 13 kV with an input-side LTC transformer, of tap ratio n = 9.5%, connected in a CNT configuration.
Fig. 12. Two-bus system of 13 kV, 1 MW and AC-PEBB/CNT test bed.
B. AC-PEBB Control Board Design
Fig. 13 shows the control flow diagram for the AC-PEBB
cell-based CNT. Switching signals originating from a digital
signal processor (DSP) are sent to an electrically erasable
programmable read-only memory (EEPROM), which keeps
track of the state of the system and its switching devices. The
EEPROM is preprogrammed with switching sequences that
ensure proper ac commutation of the converter and prevent any
short circuiting of the source or open circuiting of the line
inductor current; two-level, three-level, voltage, and currentbased commutation sequences have all been implemented (for
more information on multilevel commutation, refer to companion paper [18]). The EEPROM switching signals are sent
to the converter’s gate driver circuits. Converter status, fault
status, and switch voltage and line current measurements, used
in voltage and current commutation algorithms by the DSP, are
then collected from the converter, conditioned, and sent back to
the DSP. Communication of signals between the DSP control
and the AC-PEBB occurs via fiber optic links.
V. E XPERIMENTAL R ESULTS
A. Parallel Operation of Modules
With six AC-PEBB cells configured as two parallel, threelevel, direct-ac/ac, the CNT was shown to be able to control
600 kVA of power at a bus voltage of 8 kV and line current of
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Fig. 15. Six AC-PEBB cells connected as dual three-level converters, as
shown in Fig. 14, and mounted to a custom PTMS.
Fig. 13. Control flow for direct-ac/ac converter and CNT comprised of up to
12 AC-PEBB cells.
Fig. 16. Real power demonstration of an 8-kV, 75-A, 600-kVA two-bus
system with a three-level CNT.
Fig. 14. Parallel three-level direct-ac/ac converter system made up of six
AC-PEBB cells.
75 A. Fig. 14 shows the schematic representation of the ACPEBB layout, with companion paper [18] providing more details on the three-level converter topology. Fig. 15 shows the
test setup with six AC-PEBB cells mounted on the PTMS and
connected to the two-bus system.
Figs. 16–19 demonstrate the CNT’s ability to have complete
control over the phase angle of the line current, showing correct
operation of the AC-PEBB cells. In those plots, the 8-kV (RMS)
Fig. 17. Negative-real power demonstration of an 8-kV, 75-A, 600-kVA twobus system with a three-level CNT.
line voltage is the uppermost waveform, followed by the 75-A
(RMS) line current. In Fig. 16, these two waveforms are in
phase; in Fig. 17, they are 180◦ out of phase; in Fig. 18, the
current is lagging the voltage by 90◦ ; and in Fig. 19, the current
is leading by 90◦ . This variation of phase was done in real
time; thus, full power control is seen with operation shown
in positive-real, negative-real, lagging-reactive, and leadingreactive power flow modes at 600 kVA. Power magnitude
control was also demonstrated, although not shown.
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3555
Fig. 18. Lagging-reactive power demonstration of an 8-kV, 75-A, 600-kVA
two-bus system with a three-level CNT.
Fig. 20. Frequency spectrum of 8-kV, 75-A, 600-kVA bus voltage in a twobus system with a three-level CNT.
stages shown in Fig. 11. The filter capacitors are necessary to
prevent the 25-kHz electromagnetic interference caused by the
CNT from propagating back to the source. Through experimental data gathered by varying the size of the filter capacitors,
the equivalent source inductance was calculated to be initially
30 mH from the following equation:
1
.
(4)
Lsource =
(3ω0 )2 C2F
Fig. 19. Leading-reactive power demonstration of an 8-kV, 75-A, 600-kVA
two-bus system with a three-level CNT.
The third and fourth waveforms in Figs. 16–19 show the
synthesized converter output voltage and the voltage across
each of the two parallel AC-PEBB-based converters. These two
waveforms depict the 25-kHz VQS-based PWM technique used
in this experiment and show the parallel modules successfully
operating in unison.
B. Issues With Harmonics and Resonances
Note the third-harmonic ripple seen in the waveforms in
Figs. 16–19. This is a byproduct of the VQS modulation
method, as explained in [17], and would need to be filtered out
in a practical application, as demonstrated in [22]. As shown
in Fig. 20, a third harmonic at 41% of the fundamental is seen
on converter and bus voltages in addition to the current. This
phenomenon was not noticeable at the lower power level tests
performed in [12] and is due to the voltage drop across the
impedance of the source and power transformers from the thirdharmonic current. Filtering of the third-harmonic current as in
[22] will also solve the voltage harmonic issue.
In addition to harmonics, resonances at the third harmonic
were experienced. These resonances were found to be occurring
between the filter capacitors, i.e., CF , and input transformer
By lowering the number of input transformer stages, the
tap ratio of the bus transformers (from 17% to 9.5%), and
the amount of filter capacitance (from 200 to 50 μF), the
resonant frequency of the system was able to be moved far
enough away from 60 Hz to eliminate interference with system
operation; without these steps, the source current drawn at
higher power levels due to resonances would have overloaded
the POWERSTAT and system transformers. Higher order (5th
through 11th) harmonics were also seen in the system, caused
by the filter capacitors interacting with various smaller parasitic
elements present in the system. While smaller in magnitude,
these harmonics increased the number of zero-crossings for
voltage and current under certain operating conditions; spending more time around zero-crossings resulted in more missed
commutations. To damp higher order harmonics, resistors RF
were placed in series with the filter capacitance values. Fig. 11
shows the final configuration used for higher current and higher
power testing.
C. Converter Efficiency
With the AC-PEBB configuration in Fig. 14, the input and
output voltages and currents of the AC-PEBB system were
measured in order to estimate system efficiency. Table II shows
the results of this measurement at 400 kVA, where the CNT
is over 99% efficient, neglecting transformer core and winding
losses. This high efficiency is mainly due to the converter’s
ability to gain full control range without being exposed to the
full bus voltage.
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TABLE II
CNT C ONVERTER E FFICIENCY AT 6.7 kV, 60 A, 400 kVA
Fig. 22. Demonstration of voltage sharing between individual IGBTs in a
CNT at 5 kV, 10 A, and 50 kVA.
Fig. 21. Real power demonstration of an 11-kV, 15-A, 165-kVA two-bus
system with a three-level CNT.
D. High-Voltage Testing
Testing was performed at lower current and higher voltage
levels to ensure that a single AC-PEBB was able to handle its
full voltage rating of 565 V (RMS), 800 V (peak). Fig. 21 shows
these results at 11 kV, 15 A, and 165 kVA. The fourth waveform
in this figure shows an individual IGBT voltage peaking at
750 V, demonstrating successful operation of the AC-PEBB at
near its rated value of 800 V. Note that at higher voltages and
lower currents, the third-harmonic currents do not significantly
affect bus voltage, as explained in Section V-B.
E. Series Operation
The series-stacking capability of AC-PEBBs was examined
by validating their voltage-sharing capabilities. Fig. 22 shows
successful voltage sharing at a 5-kV (RMS) bus voltage, where
770 V (peak) is impressed across each AC-PEBB. The purple
waveform shows an individual device voltage being held to
about 335 V (peak) by the green waveform, which is the active
snubber voltage and exactly half of the voltage across an ACPEBB cell, demonstrating equal voltage sharing and seriesstacking capabilities of the cell.
VI. C ONCLUSION
This paper has outlined the construction and testing of an
AC-PEBB unit built for operation at MV levels. Important
design considerations were highlighted, and viability of the
concept has been shown successful experimental results at up
to 11-kV and 600-kVA levels and low-voltage prototyping. The
PEBB proved to be compact, easy to interconnect, and highly
efficient.
Practical issues relating to medium-voltage ac/ac converter
design were also examined and uncovered during the course of
this work. Harmonic and resonance issues showed themselves
to be significantly worse at higher power levels and will be a
major challenge in any practical MV or HV application. Additionally, series stacking of cells became difficult as the tuning of
each analog active snubber circuit was cumbersome when many
cells were used. A more robust active snubber control design is
recommended for true plug-and-play capability to be achieved.
ACKNOWLEDGMENT
The authors would like to thank Dr. J. Rhett Mayor,
B. Loeffler, and A. Semidey of the Department of Mechanical
Engineering, Georgia Institute of Technology, Atlanta, GA,
USA, for their contributions to this project relating to the
construction and thermal management of the CNTs used in this
research. The authors would also like to thank T. Parker and the
engineers/technicians of the National Electric Energy Testing
Research and Applications Center for their assistance in the
construction and operation of the medium-voltage test bed used
in this research.
R EFERENCES
[1] “National electric transmission congestion study,” U.S. Department of
Energy, Washington DC, USA, Dec. 2009.
[2] P. Fairley, Germany Takes the Lead in HVDC, IEEE Spectrum, New York,
NY, USA. (2013, Apr. 29). [Online]. Available: http://spectrum.ieee.org/
energy/renewables/germany-takes-the-lead-in-hvdc
[3] F. Kreikebaum, D. Das, and D. Divan, “Reducing transmission investment
to meet renewable portfolio standards using controlled energy flows,” in
Proc. ISGT, Jan. 19–21, 2010, pp. 1–8.
[4] Y. Xiao, Y. Song, L. Chen-Ching, and Y. Sun, “Available transfer capability enhancement using FACTS devices,” IEEE Trans. Power Syst., vol. 18,
no. 1, pp. 305–312, Feb. 2003.
[5] P. Fairley, Flexible AC Transmission: The FACTS Machine, New York,
NY, USA. (2010, Dec. 30). [Online]. Available: http://spectrum.ieee.org/
energy/the-smarter-grid/flexible-ac-transmission-the-facts-machine
[6] C. Schauder et al., “Operation of the unified power flow controller (UPFC)
under practical constraints,” IEEE Trans. Power Del., vol. 13, no. 2,
pp. 630–639, Apr. 1998.
[7] M. Fotuhi-Firuzabad, R. Billinton, and S. Faried, “Transmission system
reliability evaluation Incorporating HVDC links and FACTS devices,” in
Proc. IEEE Power Eng. Soc. Summer Meet., 2001, vol. 1, pp. 321–326.
[8] A. Rajabi-Ghahnavieh, M. Fotuhi-Firuzabad, and R. Feuillet, “Evaluation
of UPFC impacts on power system reliability,” in Proc. IEEE/PES T&D,
Apr. 21–24, 2008, pp. 1–8.
IYER et al.: VALIDATION OF THE PLUG-AND-PLAY AC-PEBB FOR GRID CONTROL APPLICATIONS
[9] M. G. Bennet, N. S. Dhaliwal, and A. Leirbukt, “A survey of the reliability
of HVDC systems throughout the world during 2009–2010,” CIGRE,
Paris, France, 2012.
[10] IEEE Guide for Electric Power Distribution Reliability Indices, IEEE Std.
1366-2003, May 14, 2004.
[11] D. Das and D. Divan, “Power flow control in networks using controllable network transformers,” IEEE Trans. Power Electron., vol. 25, no. 7,
pp. 1753–1760, Jul. 2010.
[12] A. Iyer, R. Moghe, R. Kandula, J. Hernandez, and D. Divan, “Plugand-play AC/AC power electronics building blocks (AC-PEBBs) for grid
control,” in Proc. ECCE, Sep. 15–20, 2012, pp. 1354–1361.
[13] T. Ericsen, N. Hingorani, and Y. Khersonsky, “PEBB power electronics
building blocks—From concept to reality,” in Proc. IEEE IAC PCIC,
2006, pp. 1–7.
[14] R. Feldman et al., “A hybrid modular multilevel voltage source converter
for HVDC power transmission,” IEEE Trans. Ind. Appl., vol. 49, no. 4,
pp. 1577–1588, Jul./Aug. 2013.
[15] C. Klumpner, F. Blaabjerg, and P. Nielsen, “Speeding-up the maturation
process of the matrix converter technology,” in Proc. IEEE Power Electron. Spec. Conf., 2001, pp. 1083–1088.
[16] D. Divan, J. Sastry, A. Prasai, and H. Johal, “Thin AC converters—A new
approach for making existing grid assets smart and controllable,” in Proc.
IEEE PESC, Jun. 15–19, 2008, pp. 1695–1701.
[17] D. Divan and J. Sastry, “Voltage synthesis using dual virtual quadrature
sources—A New Concept in AC Power Conversion,” in Proc. IEEE
PESC, Jun. 2007, pp. 2678–2684.
[18] A. Iyer, R. Kandula, R. Moghe, F. Lambert, and D. Divan, “Scaling
the controllable network transformer (CNT) to utility-level voltages with
direct AC/AC power electronic building blocks (PEBBs),” in Proc. ECCE,
Sep. 15–19, 2013, pp. 3049–3056.
[19] A. Prasai and D. Divan, “Active AC snubber for direct AC/AC power
converters,” in Proc. ECCE, Sep. 17–22, 2011, pp. 507–514.
[20] A. Iyer, R. Moghe, R. Kandula, A. Prasai, and D. Divan, “Experimental
validation of active snubber circuit for direct AC/AC converters,” in Proc.
ECCE, Sep. 15–20, 2012, pp. 3856–3861.
[21] B. H. Loeffler, “Modeling and optimization of a thermosiphon for passive thermal management systems,” M.S. thesis, Dept. Mech. Eng.,
Georgia Inst. Technol., Atlanta, GA, USA, 2012. [Online]. Available:
https://smartech.gatech.edu/handle/1853/45960
[22] D. Das et al., “Design and testing of a medium voltage controllable
network transformer prototype with an integrated hybrid active filter,” in
Proc. IEEE ECCE, Sep. 17–22, 2011, pp. 4035–4042.
Amrit R. Iyer (S’11) received the B.S.E.E. degree from the University of Illinois at UrbanaChampaign, Champaign, IL, USA, in 2003, with
an emphasis in power electronics. He is currently
working toward the Ph.D. degree in electrical engineering with the Electrical Energy Group, Georgia
Institute of Technology, Atlanta, GA, USA, under
Prof. D. Divan.
He spent several semesters working with the Illinois Tiny Satellite Initiative, including serving as the
lead for the group’s power management team. He has
published over a dozen papers and has two patents pending in his areas of
interest. His current research interests include power electronic converter design
for medium- and high-voltage applications and smart sensing technologies for
utility applications, where his work has been sponsored by General Electric,
Advanced Research Projects Agency—Energy, the National Electric Energy
Testing Research and Applications Center, and Georgia Tech’s Intelligent
Power Infrastructure Consortium.
Rajendra Prasad Kandula (S’10) received the
B.Tech. degree from the National Institute of Technology, Nagpur, India, in 2002 and the M.Tech. degree from the Indian Institute of Science, Bangalore,
India, in 2004. He is currently working toward the
Ph.D. degree at the Georgia Institute of Technology,
Atlanta, GA, USA.
For three years, he was a Design Engineer with
Bharat Heavy Electricals Ltd. R&D, New Delhi,
India, working with high-power drives and gridconnected solar inverters. His research interests include power electronics for utility applications such as active filters and power
routers for meshed systems.
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Rohit Moghe (S’07–M’12) received the B.Tech.
degree in electrical engineering from the Indian Institute of Technology, Roorkee, India, in 2007, and the
M.S. and Ph.D. degrees from the Georgia Institute of
Technology, Atlanta, GA, USA, in 2010 and 2012,
respectively.
During May–August 2008 and 2009, he was a
summer intern with the ABB U.S. Corporate Research Center and Siemens Energy & Automation,
respectively. He is currently a Principal Engineer
with Varentec Inc., San Jose, CA, USA. His research
focuses on power electronic converters for utility applications such as VAR
support, power flow controllers, medium-voltage solid-state transformers, and
energy harvesting for wireless sensors.
Dr. Moghe was awarded the Best Undergraduate Research Award by the
Indian Institute of Technology. He was one of the founding members of the
Energy Club at the Georgia Institute of Technology and served as President
during 2010–2011.
Jorge E. Hernandez (S’10) received the B.S. degree
in electrical engineering from the Technological University of Panama, Panama City, Panama, in 2006
and the M.S. degree in electrical engineering from
the Georgia Institute of Technology, Atlanta, GA,
USA, in 2009. He is currently working toward the
Ph.D. degree in the School of Electrical and Computer Engineering, Georgia Institute of Technology.
From January to July 2007, he was a Research Engineer with the Technological University of Panama,
overseeing renewable integration projects for rural
communities. His research interests include power electronics for utility applications, and power system operation/control and electricity markets, under
current practices and under scenarios with high wind and electric vehicle
penetration.
Frank C. Lambert (S’70–M’73–SM’87) received
the B.S. and M.S. degrees in electrical engineering
from the Georgia Institute of Technology, Atlanta,
GA, USA.
He is currently the Associate Director of the National Electric Energy Testing Research and Applications Center, Georgia Institute of Technology. He is
responsible for interfacing with the members of the
National Electric Energy Testing Research and Applications Center to develop and conduct research projects dealing with transmission and distribution issues.
For 22 years, he was with Georgia Power Company, engaged in transmission/
distribution system design, construction, operation, maintenance, and automation.
Mr. Lambert participates in the IEEE Power and Energy Society Distribution
Subcommittee and the PES Switchgear Committee and is serving on the PES
Governing Board as the Vice President for Chapters.
Deepak Divan (S’78–M’78–SM’91–F’98) received
the B.Tech. degree from the Indian Institute of
Technology, Kanpur, India, in 1975 and the M.Sc.
and Ph.D. degrees from the University of Calgary,
Calgary, AB, Canada, in 1979 and 1983, respectively.
He is the President and CTO of Varentec Inc.,
San Jose, CA, USA, which is a company funded
by the green-tech venture capital firm Khosla Ventures, providing innovative solutions to achieve a
smart and dynamically controllable grid. He has over
35 years of experience in industry and academia
in the areas of power electronics applied to utility and industrial systems,
with Varentec being his third entrepreneurial venture. From 2004 to 2011,
he was a Professor of electrical and computer engineering and the Founding Director of the Intelligent Power Infrastructure Consortium with the
Georgia Institute of Technology, Atlanta, GA, USA. Prior to that, he led
Soft Switching Technologies as Founder and CEO. He was also a Professor of electrical engineering with the University of Wisconsin–Madison,
Madison, WI, USA. He has over 250 papers and 50 issued and pending patents.
He combines unique perspectives on the changing landscape of the Transmission and Distribution grid and the need for a transition to dynamic grid control,
including advanced power electronics solutions. His research interests include
dynamic grid control, sustainable energy, and advanced power electronics.
Dr. Divan was a recipient of the 2006 IEEE Newell Award and is a past
President of the IEEE Power Electronics Society.