Damping electromechanical oscillations of a power system with SMES

A method of damping electromechanical oscillations of synchronous generators through Super-Conducting Magnetic Energy Storage (SMES) systems is proposed. The strategy is derived from the simple principle that, following a perturbation in a power system, the SMES should compensate for any changes in the power balance of the system. The firing angle control of the thyristors in the SMES unit is obtained in terms of the current supplied/absorbed by the converters. The strategy developed was tested on the nonlinear model of a single-machine infinite bus system with an SMES unit connected to the generator bus. Simulation studies show that proper sequences of current injection from the SMES provides excellent damping to the system, bringing back even a transiently unstable system within normal levels of operation very quickly. The proposed control strategy is simple and requires little hardware to implement.