Mitigation of Subsynchronous Oscillations with Common Controller Based Statcom and SSSC

This paper proposes a powerful common controller to mitigate the Turbine-generator shaft oscillations due to Subsynchronous resonance (SSR) with Statics synchronous compensator (STATCOM) and Static synchronous series compensator (SSSC). The mitigation of SSR is achieved by increasing the network damping at frequencies which are close to the torsional mode frequency of the turbine-generator shaft. The increase of network damping is done by the extraction of subsynchronous component of voltage and current from the measured signal of the system. From the knowledge of subsynchronous components, a shunt current is injected by STATCOM and a series voltage is injected by SSSC into the transmission line to make the subsynchronous current to zero which is the main cause of turbine oscillations. To analyze the effectiveness of the proposed common control scheme, IEEE first benchmark model has taken. The results show the accuracy of the proposed control scheme to mitigate the Torque amplification of SSR.