Advanced static compensator for flexible AC transmission

An advanced static VAr compensator capable of operating in all four quadrants of the P-Q plane is presented. It is realized by combining a GTO-controlled inverter with a battery energy storage system and a GTO-switched damping resistor. A hierarchically structured control system that fully utilizes the capabilities of the compensator to provide reactive power support in steady-state operation and both real and reactive power modulation in the event of power oscillations is developed. Results from simulation studies are presented to demonstrate the effectiveness of this compensator in improving the loadability of long transmission lines and in providing damping in interarea oscillations. >