Suppression of subsynchronous resonance using robust H∞ TCSC damping controllers

This paper presents the analyzed results of using H^∞ thyristor controlled series compensation (TCSC) damping controllers for the damping enhancement of common torsional mode interactions of a power system containing series-capacitor compensation. The studied power system consists of two sets of nonidentical turbogenerators connected to an infinite bus through a series-capacitor compensated line. A set of TCSC modules is proposed to properly connect in parallel with part of the series capacitor of the transmission line. A unified approach based on robust control theory is employed to design H^∞ TCSC damping controllers, which sense both shaft speed deviations of the studied generators as stabilizing signals. A frequency-domain approach based on eigenvalue analyses and a time-domain approach based on nonlinear model simulations under disturbance conditions are both performed. The analyzed results show that the proposed H^∞ TCSC damping controllers can effectively stabilize common mode torsional oscillations.