PWMSC Controller Design for Damping Electromechanical Oscillations

Pulse Width modulated based Series Compensator (PWMSC), a newly FACTS device, can modulate the impedance of a transmission line through the variation of the duty cycle of a train of pulses with fixed frequency, resulting in improvement of system performance. In this study, a current injection model of PWMSC is proposed and incorporated in the transmission system model. The purpose of the work reported in this paper is to design an oscillation damping controller for PWMSC to damp low frequency oscillations. We have used the residue method to the linearized equations of the power system for multiple operating conditions and obtained a generalized form which is suitable for different damping controller input-output channels and therefore suitable for different control devices. The case study results show that the proposed controller is very effective to mitigate the power system critical modes of oscillation.