DAMPING OF POWER-SYSTEM OSCILLATIONS BY AN ACTIVE AND REACTIVE POWER MODULATION SUPERCONDUCTING MAGNETIC ENERGY-STORAGE UNIT

A method for repressing the low frequency oscillation of a synchronous generator is considered in this paper using a simultaneous active and reactive power (P-Q) control scheme of a superconducting magnetic energy storage (SMES) unit. In order to increase the damping of the generator, a proportional-integral (PI) controller is used to modulate the active and reactive power input/output of the SMES unit according to the speed deviation of the generator shaft. The SMES unit with the PI controller can provide sufficient damping torque for the electromechanical mode. The gains of the PI controller are determined by the least square error technique, where the weighted quadratic sum of the system states is minimized. Eigenvalue analysis and digital simulation are performed to demonstrate the damping effect of the SMES unit over a wide range of loading conditions.