Performance Evaluation of TCSC and GCSC for Damping of Torsional Oscillations

This paper presents the mathematical modeling of a thyristor-controlled series compensator (TCSC) and gate-controlled series capacitor (GCSC) in a turbine generator system to dampen torsional oscillations due to sub-synchronous resonance (SSR). The parameters of transmission line and turbine generator unit are adapted from IEEE first benchmark model (FBM) for examining stability analysis. The system is found potentially unstable when frequency of SSR mode meets the frequency of torsional modes due to change in fixed compensation of transmission line. Thus, this paper shows the application of TCSC and GCSC to demonstrate the damping of torsional modes in IEEE FBM. The eigenvalue analysis and time-domain results verify the effectiveness of TCSC and GCSC for damping of torsional mode oscillations under unstable conditions. MATLAB/Simulink is used for simulation studies.