Two Countermeasures for Damping Torsional Interactions and Transient Torques of Turbine-Generators

Two different schemes of thyristor-controlled static phase-shifters for damping torsional interaction and transient torques of turbine-generators, are investigated and compared. Generator speed deviation from the synchronous speed, is used as the control signal. The two schemes are the discrete step controlled phase-shifters and the point-on-wave controlled phase-shifters. The studies are carried out on the first IEEE benchmark for SSR studies, using the BPA´s Electromagnetic Transients Program (EMTP). The investigation results show that the two schemes of static phase-shifters can be used to provide effective damping for torsional interaction and transient torques of large turbine-generators. The results also indicate that as compared with the point-on-wave controlled phase-shifters, the discrete step controlled phase-shifters are more effective for damping torsional oscillations.