Active damping controller design for SSSC to mitigate subsynchronous resonance

Static Synchronous Series Compensator (SSSC) is one of the second generation Flexible AC Transmission System (FACTS) controllers. In this paper, an active damping control strategy for the SSSC is proposed to mitigate subsynchronous resonance (SSR) in the series compensated power system. A multimode controller design method is developed to suppress multiple unstable torsional frequencies separately. The modified IEEE first benchmark model with SSSC for subsynchronous resonance investigation is adopted to perform the studies. The simulation results show that, with a small rating of the SSSC, the proposed controller can provide positive electrical damping around the torsional frequencies and is effective to mitigate the torsional interaction between the electrical network and turbine-generator shafts.