Nonlinear co-ordinated excitation and TCPS controller for multimachine power system transient stability enhancement

A robust nonlinear co-ordinated generator excitation and thyristor-controlled phase shifter 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 linearisation (DFL) compensator through the excitation loop is designed. Considering the effects of plant parametric uncertainties and remaining nonlinear interconnections, a robust decentralised generator excitation controller is proposed to ensure the stability of the DFL compensated system. Only the bounds of the generator parameters need to be known in the design of the proposed controller. while the transmission network parameters, system operating points or the fault locations do not need to be known. As the proposed controller can ensure the stability of a 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 that the proposed control scheme can enhance the transient stability of the system significantly, regardless of the network parameters, operating points and fault locations