BPF based Estimation and Mitigation of SSR with SSSC

Abstract

The risk of Subsynchronous Resonance (SSR) may reduce with the hybrid of active and passive series compensations. The hybrid series compensation can be done with Static Synchronous Series Compensator (SSSC) (an active FACTS device) and fixed series capacitor (passive compensation). In this paper, we propose a Band Pass Filter (BPF) based Subsynchronous Damping Controller (SSDC) with SSSC. The aim of the paper is to increase the damping of all critical TMs with minimum number of highly frequency selective BPFs. The BPFs are used to extract the subsynchronous frequency components from electrical network. The extracted subsynchronous frequency components are used to modulate the reference value of SSSC injected voltage. Thereby, the SSSC injecting voltage can suppress the subsynchronous currents flowing in the transmission network. The linear (DQ) model is developed in MATLAB-Simulink using the differential and algebraic equations of the system. The damping torque, eigenvalue and transient simulation methods are performed with the linear model to carry out the analysis of SSR. The eigenvalue analysis is used to select the number of filters. The number of BPFs is selected in view of suppressing the torsional vibrations at all critical frequencies. The outcomes of the paper show that the negative damping is considerably diminished with the proposed SSDC in the entire range of torsional mode frequencies and mitigate SSR.