SSR mitigation using gate-controlled series capacitors

The subsynchronous resonance (SSR) phenomenon may occur when a steam turbine-generator is connected to a long transmission line with series compensation. The main purpose of this works is to verify the capability of the gate controlled series capacitor (GCSC) to mitigate SSR. For this study the GCSC was tested in conjunction with the first IEEE benchmark system. The actual possibility of controlling SSR was verified by digital simulation using the ATP/EMTP (alternative transients program/electromagnetic transients program). As a result it was shown that GCSC is a powerful device for controlled series compensation both for power flow control and SSR damping. It was shown also that in some case the GCSC can damp SSR even without a specific control. GCSC can also damp electromechanical power oscillations as shown in some simulations