Damping of subsynchronous oscillations using STATCOM - A FACTS device

Analysis and damping of torsional oscillations in series compensated transmission systems is presented in this paper. The presence of series capacitors has given rise to the phenomena of sub synchronous resonance (SSR). Many countermeasures to SSR problem have been reported in the literature, which makes e of signals available at the generator station. The use of Flexible AC Transmission System (FACTS) devices like Static Compensator (STATCOM) is increasing in the network for enhancing power transfer, voltage stability and damping of power oscillations. In this paper the damping of sub synchronous oscillations using STATCOM, which is provided, at the middle of the transmission line is presented. A new auxiliary control signal designated as Computed Internal Voltage (CIV) is proposed to control STATCOM, which involves the computation of internal voltage of the remotely located generator utilising locally measurable STATCOM bus voltage and transmission line current signals. The IEEE second benchmark model system-1 is considered for the analysis. It is demonstrated that, the system is effectively damped under SSR conditions.