Recently, static var generators (SVGs) or static synchronous compensators based on self-commutated converters have been put into practical use for the purpose of compensation for reactive power, power swings damping, and/or voltage control in power systems. The SVGs have also been applied to reduce voltage fluctuations appearing at high-speed train substations. When parallel resonance occurs between passive filters installed at a point of common coupling (PCC) and the power-system impedance existing upstream of the PCC, voltage/current harmonics are significantly amplified in the power system. This paper describes the control and performance for a self-commutated gate-turn-off (GTO) converter operating in parallel with conventional line-commutated thyristor converters. This hybrid power conversion system rated at more than dozens of MVA has an inductive load at the dc side. A bank of passive filters is connected not only for harmonic compensation of the line-commutated converters, but also as a constant leading reactive-power source. The GTO converter can control either leading or lagging reactive power so as to achieve unity power factor operation. In addition, it has the capability of damping out parallel resonance between the passive filters and the power-system impedance. This paper confirms the viability and effectiveness of the hybrid system by means of theory and computer simulation.
[1]
Hirofumi Akagi.
Control Strategy and Site Selection of a Shunt Active Filter for Damping of Harmonic Propagation in Power Distribution Systems
,
1997
.
[2]
H. Akagi,et al.
Analysis and design of an active power filter using quad-series voltage source PWM converters
,
1988,
Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting.
[3]
Fujio Ishiguro,et al.
Development of a large static VAr generator using self-commutated inverters for improving power system stability
,
1991
.
[4]
Thanh-Nam Le,et al.
Active damping of resonances in power systems
,
1994
.
[5]
M. Takeda,et al.
Harmonic current and reactive power compensation with an active filter
,
1988,
PESC '88 Record., 19th Annual IEEE Power Electronics Specialists Conference.