Evaluation of Performance of FACTS based Phase Imbalance Schemes for Damping Torsional Oscillations and Power Swings

Recent investigations have focused on the use of active phase imbalance schemes using series connected FACTS devices for subsynchronous resonance (SSR) and power swing damping. This paper compares the effectiveness of TCSC and SSSC based single phase compensation schemes with the corresponding three phase schemes. Controllability of swing modes as well as torsional modes is compared by using a simplified, dynamic phasor based expression of the linearized electrical torque of a synchronous machine connected to a compensated transmission line. The analysis and simulation studies show that a single phase scheme is unlikely to be an attractive alternative to a three phase scheme from a cost and sizing perspective.