International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
Application of Sparse Matrix Converter for
Microturbine-Permanent Magnet Synchronous
Generator output Voltage Quality Enhancement
N.Vinay Kumar1, A.Bhaskar2
1
2
PG Scholar, Department of Electrical and Electronics Engineering, Narayana Engineering College, Nellore. AP, India.
Associate professor, Department of Electrical and Electronics Engineering, Narayana Engineering College. Nellore, AP,
India.
Abstract— The progress of distributed generation set is
an important energy option in the present scenario
because distribution generation or cogeneration can be
used as a backup option to the load for the continuity of
the supply or it can be used as peak shaving load. Here
Microturbine-Permanent magnet synchronous generator
is used as distributed generation set. In which the
permanent magnet synchronous generator is having high
output frequency. So, there is a necessity to convert High
frequency to low frequency (50) Hz, conventional
rectifier-inverter or sparse matrix converter can be used
as frequency converter. In this paper, simulation results
of sparse matrix converter are compared with
conventional rectifier-inverter.
Keywords---Microturbine-Permanent magnet synchronous
generator, sparse matrix converter, filters, Harmonics.
I.
INTRODUCTION
Distributed generation sets have received
significant attention as a mean to improve the
performance and reliability of electrical power
system. They can provide low-cost energy and
increase energy efficiency. Moreover, through
combined heat and power (CHP) mode of
operation and their application can also reduce
transmission and distribution (T&D) losses, relieve
T&D assets, reduce constraints, and improve
overall power quality and reliability. Nowadays,
there is a growing interest in deploying
Microturbine
in
distribution
generation
application, because of their quick start capability
and easy controllability useful for efficient peak
shaving [1]. In the past few years the uses of
ISSN: 2231-5381
Distributed generation sets have increased
significantly. MTG’s are small, high speed power
plants that usually include the turbine, compressor,
generator, and power electronics to deliver the
power to the load. MTG’s [2] have a high- speed
gas turbine engine driving an integral electrical
generator that produces 25-300Kw power while
operating at a high speed, generally in the range of
30,000-80,000 rpm. Electric power frequency is
produced about 10,000 of Hz and this has to be
converted in standard frequency (50) Hz by the
application of sparse matrix converter [3].
Microturbine-Generator is having single-shaft and
split-shaft. Single shaft is having high speed
synchronous machine with the compressor and
turbine mounted on the same shaft while the shaft
used for power turbine rotating at 3000rpm and a
conventional generator connected via a gear box
for speed multiplication [3].
In this paper, the Single–shaft is usually
composed of gas turbine electric power generators.
The main advantage of using the single-shaft
configuration with Permanent magnet synchronous
generator (PMSG) or asynchronous generator is
that it is simpler in design. Moreover there is no
need for a gear reducer as power electronics sparse
matrix converter is used to supply standard
frequency to the load.
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
The disadvantages of using high speed
Permanent magnet synchronous machine are
thermal stress, demagnetization phenomenon
centrifugal forces, rotor loses because of fringing
effects, high cost etc.
The main advantage of coupling a synchronous
generator with the split-shaft Microturbine is that
it eliminates the use of the rectifier and power
converter. These generators are robust and less
costly as compared to permanent magnet
synchronous generator and all other problem with
high speed is eliminated. The use of power
electronic interface for power conversion
introduces harmonics in the system which reduces
the output voltage quality. These harmonics are
eliminated if synchronous generator is used with a
gearbox. However, the main drawback of a gear
box is that it requires maintenance along with its
lubricating system.
Frequency converter and protection and control
system (fig.1) [4]. The interface converter is used
to convert permanent magnet synchronous
generator
output
voltage-frequency (High
frequency) to power frequency (50/60Hz).
In this paper, sparse matrix converter is
proposed and this sparse matrix converter is
compared with the conventional rectifier-Inverter.
II.
MICROTURBINE-MODELLING
In this paper proposed model [5] is considered
for Microturbine, and modeling of Microturbine
has been done in Matlab/Simulink (fig.2). The
model consist of speed controller, accelerator
controller, Temperature controller, and fuel
(including valve positioned and actuator)
The exhaust temperature function is given by:
(
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)
(
)…. (1)
The torque function is given by:
(
)
(
)………. (2)
Where,
= speed or the turbine
Wf1, Wf2 = fuel flow signals
TR
= Rated exhaust temperature.
Fig.1 Block diagram of a single-shaft Microturbine-Generator
III.
SPARSE MATRIX CONVERTER
The sparse matrix converter is an AC/AC
converter which offers a reduced number of
components, a low-complexity modulation
scheme, and low realization effort. Sparse matrix
converters avoid the multistep commutation
procedure of the conventional matrix converter
improving system reliability and output voltage
quality at the load. Characteristics of the sparse
matrix converter topology are having 15 IGBT’s
and 18 Diodes and 7 isolated driver potentials.
Compared to the matrix converter, this topology
provides identical functionality, but with a reduced
numbers of switches and the option of employing
an improved zero dc-link current commutation
scheme, which provides lower control complexity
and higher safety and reliability. Sparse matrix
converter is shown in fig. 3
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
The sparse matrix converter is fed by voltage
source and, for this reason; the input terminal
should not be short circuited. On the other hand
the load has an inductive nature and for this nature,
an output phase must never be opened.
120000 rpm. They can supply customer’s baseload requirements or can be used for standby, peak
shaving, and cogeneration applications. The block
diagram of Microturbine is shown in fig.4
Fig.2 Microturbine model.
Fig. 4 Block diagram of Microturbine .
V.
SIMULATION RESULTS
In this section the Microturbine-Generator is
simulated in Matlab. The model of permanent
magnet synchronous generator is available in
Simulink library and is used for generator
simulation
Fig.3 Sparse matrix converter
IV.
MICROTURBINE
Microturbines are small and simple cycle gas
turbines. The output of the Microturbine range
typically from around 25 to 300 Kw. Performance
improvement
technique
incorporated
in
Microturbine include recuperation, low emission
technologies, and the use of advanced materials,
such as ceramic for the hot section parts.
Microturbines are available in single-shaft or splitshaft unit. Single-shaft unit is a high-speed
synchronous machine with the compressor and
turbine mounted on the same shaft. For these
machines, the turbine speed ranges from 50000 to
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In this simulation the focus will on the
comparing the sparse matrix converter with
conventional rectifier-inverter. The block diagram
of the simulated system is shown in fig.5. The
reference speed of the Microturbine-Generator is
set to 4500 rpm. And at t=14 sec. load is increased
from 0.2 Pu to 0.8 Pu.
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
Fig.5 Simulated system
(a)
Fig.6 Speed of Microturbine-Generator
(b)
Fig.8 Permanent magnet synchronous generator output voltage at (a) 0.2 Pu
and (b) 0.8 Pu
Sparse matrix converter and conventional
converter operates on these load voltages to
construct a 50 Hz. Output wave form of these
converters before filtering is shown in fig.9 and
fig.10.
Fig.7 Mechanical torque of Microturbine-Generator
At this speed the frequencies of the output
frequency of the permanent magnet synchronous
generator is 3000Hz, and must be converted to
power system frequency (50 Hz), This can be done
by using Sparse matrix converter.
In fig.8 shows the permanent magnet
synchronous generator output voltage of phase-a
(a)
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
(b)
Fig.10. Conventional rectifier-Inverter output voltage at (a) 0.2 Pu (b) 0.8Pu
(b)
Fig.9 Sparse matrix converter output voltage at (a) 0.2 Pu and (b) 0.8 Pu
These voltages are filtered by using filter to
construct the load terminal voltages. The filtered
output voltages of the sparse matrix converter and
conventional rectifier-Inverter are shown in fig. 11
and fig.12.
(a)
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(a)
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
(b)
Fig. 11 Load terminal voltage of sparse matrix converter at (a) 0.2 Pu (b) 0.8
Pu
Selected FFT signals for the sparse matrix
converter and Conventional rectifier-Inverter at 0.2
Pu and 0.8 Pu is shown in fig.13 and the total
harmonic distortion (THD %) at the load terminal
voltage of sparse matrix converter and
conventional rectifier-Inverter is shown in fig.14
and fig.15. The total harmonic distortion for the
load terminal voltage of sparse matrix converter at
0.2 Pu and 0.8 Pu are 5.50% and 4.50% and the
Total harmonic distortion for the load terminal
voltage of conventional rectifier-Inverter are
7.50% and 6.50%. From these values (THD%), we
can observe that the total harmonic distortion of
load terminal voltage using sparse matrix
converter is less than the load terminal voltage of
conventional rectifier-Inverter and the output
voltage of Microturbine-permanent magnet
synchronous generator is improved.
(a)
(a)
(b)
(b)
Fig. 12 Load terminal voltage of conventional rectifier-Inverter at (a) 0.2 Pu
(b) 0.8 Pu
Fig. 13 Selected signals of both sparse matrix converter and conventional
rectifier-Inverter at the load terminal voltage at (a) 0.2 Pu (b) 0.8 Pu.
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
(a)
Fig.15: Total harmonic distortions of the load terminal voltage of
conventional rectifier-Inverter at (a) 0.2 Pu (b) 0.8 Pu
VI.
(b)
Fig. 14: Total harmonic distortion of the load terminal voltage of sparse
matrix converter at load (a) 0.2 Pu and (b) 0.8 Pu
CONCLUSION
In this paper Microturbine-permanent magnet
synchronous generator is used as distributed
generation set. Here the application of sparse
matrix converter is used as frequency converter
for the Microturbine-Generator for improvement
of output voltage quality at the load and
simulation results of sparse matrix converter is
compared with the conventional rectifier-inverter
and larger dc-link capacitor which is common in
conventional rectifier-inverter is omitted and
hence, output voltage quality of the MicroturbinePermanent magnet synchronous generator
converter is enhanced.
REFERENCES
[1]
A.K.Saha, S.Chowdhury, S.P.Chowdhary, and P.A.Crossley,
“Modeling and performance of a Microturbine as a distributed energy
resource”, IEEE Trans. Energy Conv., vol. 24, no. 2, pp. 529-538, Jun.
2009.
[2]
Stephanie L.Hamilton, Southern California Edison, “Project title:
Microturbine generator program”, Proceedings of the 33 rd Hawaii
International conference on system science. 2000
[3]
Johann W.Kolar, Frank schafmeister, Simon D. Round, Hans Ertl, “
Novel three phase Sparse matrix converter”, IEEE Trans. on power
electronics, vol. 22, no.5, pp.1649-1661, Sept.2007.
(a)
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International Journal of Engineering Trends and Technology (IJETT) – volume 5 number 4 - Nov 2013
[4]
E.F.Pavinatto, M.B.Peres, P.D. Reis, L.S. Pereira, and F.P.Salles, “Use
of Microturbine in remote isolated oil and gas facilities in Brazil”,
IEEE Ind. Appl. Mag., pp.62-68, Nov/Dec.2008.
[5]
R. Norooizian, M.Abedi, G.B.Gharehpetian, and S.H.Ossein,
“Modeling and simulation of Microturbine-Generator system for ongrid and off-grid operation modes”, Int. Conf. on Renewable Energies
and Power Quality (ICREPQ’09), Apr.2009.
About Authors
N.Vinay Kumar received B.Tech. Degree from AVS
College of Engineering and technology, Venkatachalam affiliated to
JNTU ANANTHAPUR, At present he is perceiving M.Tech in
Electrical Power Engineering from Narayana Engineering College,
Nellore, Andhra Pradesh, India.
A.Bhaskar received Master degree in Power Electronic
in Industrial Drives (PE & ID) from Sathyabhama University,
Chennai. And B.Tech degree from Visvodaya Institute of Technology
and science, Kavali. At present he is an Associate Professor in EEE
department, Narayana Engineering College, Nellore, Andhra Pradesh,
India.
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