Enhancement of power system transient stability using a nonlinear coordinated excitation and TCPS controller

A robust nonlinear coordinated generator excitation and thyristor-controlled phase shifter (TCPS) controller is proposed to enhance the transient stability of a multimachine power system. To eliminate the nonlinearities and interconnections of the multimachine power system, a direct feedback linearization (DFL) compensator through the excitation loop is designed. Considering the effects of plant parametric uncertainties and remaining nonlinear interconnections, a robust decentralized generator excitation controller is proposed to ensure the stability of the DFL compensated system. Only the bounds of the generator parameters are necessary to be known in the design of the proposed controller, while the transmission network parameters, system operating points or the fault locations need not be known. Since the proposed controller can ensure the stability of large-scale power system within the whole operating region for all admissible parameters, the transient stability of the overall system can be enhanced significantly. Digital simulation studies were conducted on a three-machine power system to show the effectiveness of the proposed control scheme in enhancing the transient stability of the system regardless of the network parameters, operating points and fault locations. (C) 2002 Published by Elsevier Science Ltd.