NONLINEAR EXCITATION AND PHASE-SHIFTER CONTROLLER FOR TRANSIENT STABILITY ENHANCEMENT OF POWER-SYSTEMS USING ADAPTIVE-CONTROL LAW

The highly nonlinear nature of the generator and system behaviour foll owing a severe disturbance precludes the use of classical linear contr ol techniques. In this paper, a nonlinear adaptive excitation and stat ic phase shifter controller is proposed to enhance the transient stabi lity of a power system. The phase shifter is located near the generato r terminal in a power system. A third-order generator model is used, w hich is in the standard form of the nonlinear system representation. T he phase shifter is represented by a first-order model. Nonlinear feed back control laws are found which linearize and decouple the power sys tem. An adaptive control law is used to design the controller for the excitation and phase shifter. The design of the resulting controller i s independent of the operating point. Our simulation results demonstra te that the proposed controller can ensure transient stability of the power system under a large sudden fault which may occur at the generat or bus terminal. (C) 1996 Elsevier Science Ltd.