Damping Subsynchronous Resonance by Phase Shifters

A method is presented to damp subsynchronous resonance (SSR) using a thyristor-controlled phase shifter to modulate the generator real power. A control approach is proposed in which generator speed and/or modal speed deviations are used as the control signals for the phase shifter. Location of the phase shifter in the network to damp subsynchronous oscillations effectively is also investigated. An eigenvalue analysis method is used to study the effectiveness of this approach. It is shown that all torsional modes of system-1 of the second IEEE benchmark can be successfully suppressed by the use of the phase shifter with proper control signals and location. To verify the analytical results, a digital computer study on the second IEEE benchmark for SSR studies was conducted using a detailed nonlinear generator model. Results of the study are reported. >