In
this paper, a new control strategy of a three level 48-pulse static synchronous
compensator (STATCOM) is proposed with a constant dc link voltage and pulse
width modulation at fundamental frequency switching. The proposed STATCOM is
realized using eight units of three-level voltage source converters (VSCs) to
form a three-level 48-pulse STATCOM. The conduction angle of each three-level
VSC is modulated to control the ac converter output voltage, which controls the
reactive power of the STATCOM. A fuzzy logic controller is used to control the
STATCOM. The dynamic performance of the STATCOM is studied for the control of
the reference reactive power, the reference terminal voltage and under the switching
of inductive and capacitive loads.
KEYWORDS:
1. Fuzzy
logic control (FLC)
2. Static
synchronous compensator (STATCOM)
3. Voltage
source converter (VSC)
4. Flexible
ac transmission system (FACTS)
5. Power
frequency switching (PFS)
SOFTWARE: MATLAB/SIMULINK
Fig.
1 System configuration for simulation
Fig.
2 a Dynamic performance of STATCOM for varying the reference reactive power. b
Zoomed-in waveforms of the STATCOM ac current as well the dc current during a
floating, b capacitive and c inductive operations
Fig.
3 Dynamic performance of STATCOM for varying the reference terminal voltage
Fig.
4 Dynamic performance of STATCOM by switching on inductive and capacitive loads
Fig.
5 a ac terminal voltage without STATCOM on switching non-linear load. b Dynamic
performance of STATCOM and ac terminal voltage by switching on switching
non-linear load
Fig.
6 Dynamic performance of STATCOM by switching on large value of apparent power
Fig.
7 Dynamic performance of STATCOM under short circuit of the upper half of the dc
bus capacitance
Fig.
8 Dynamic performance of STATCOM under short circuit of the complete dc bus capacitance
Fig.
9 a Variation of the dc voltage with sudden load change using a PI and an FLC.
b Variation of the ac terminal voltage with sudden load change using a PI and
an FLC
CONCLUSION:
A
new control strategy of a three-level 48-pulse STATCOM has been proposed with a
constant dc link voltage and pulse width modulation at fundamental frequency switching. Its performance has been validated using MATLAB/Simulink.
Simulation results have validated the satisfactory dynamic and steady
performances of the proposed STATCOM operation. The harmonic content of the STATCOM
current is found well below 5 % as per IEEE 519 standard [27].
REFERENCES:
1.
T. Johns, A. Ter-Gazarian, D.F. Warne, Flexible ac transmission systems
(FACTS), IEE Power Energy Series, the Institute of Electrical Engineers,
London, UK, 1999
2.
N.G. Hingorani, L. Gyugyi, Understanding FACTS: Concepts and Technology of
Flexible ac Transmission Systems (IEEE Press, 2000)
3.
R.M. Mathur, R.K. Verma, Thyristor-Based FACTS Controllers for Electrical
Transmission Systems (Wiley-IEEE Press, 2002)
4.
K.R. Padiyar, FACTS Controllers in Power Transmission and Distribution (New Age
International (P) Limited Publishers, India, 2007)
5.
K.K. Sen, Introduction to FACTS Controllers: Theory, Modeling and Applications
(Wiley-IEEE Press, 2009)
