Suppression of common-mode torsional oscillations of nonidentical turbine-generators using SMES

This paper presents the analyzed results of damping improvement of common-mode torsional oscillations of a power system containing series-capacitor compensation using a superconducting magnetic energy storage (SMES) unit. The studied power system consists of two sets of nonidentical turbine-generators connected to an infinite bus through a common series-capacitor compensated line. A unified approach based on modal control theory is employed to design a proportional-integral-derivative (PID) damping controller using speed deviations of both generators as stabilizing signals. Frequency-domain approach based on eigenvalue analyses and time-domain approach based on nonlinear model simulations under disturbance conditions are both performed. It can be concluded from the simulated results that the proposed SMES can effectively stabilize common-mode torsional oscillations.