Damping of power system oscillation by active power and reactive power modulation SMES unit

An active power and reactive power (P-Q) simultaneous control scheme of superconducting magnetic energy storage (SMES) unit is designed to damp out the low frequency oscillation of power system. In order to increase the damping of the turbogenerator, a proportional-integral (PI) controller is used to modulate the active power and reactive power input/output of the SMES unit according to the speed deviation of the generator shaft. The gains of the PI controller are determined by pole assignment method by shifting the electromechanical mode to the prespecified position. Eigenvalue analysis and digital simulation are performed to demonstrate the damping effect of the SMES unit