Delay margin computation of generator excitation control system by using fractional order controller

This article is devoted to stability analysis of generator excitation control system that has some time delay with fractional order proportional integral derivative controller by using direct method. When the time delay exceeds certain critical values, the excitation control system becomes unstable. In order to obtain more delay margin, in control part of the system, fractional order proportional integral derivative controller is used. A formulation is obtained to find out the maximum time delay which is known as delay margin with which the system can tolerate without any loss in its stability. All the possible stability regions analytically in the parametric space of the time delay is obtained by using an exact method and it is presented in this study. The method is formulated in frequency domain. The time-domain simulations are implemented to validate theoretical delay margin results in Matlab/Simulink. When it is compared with previous researches in literature, better stability margin is obtained. The results have shown that fractional order PID controller gives wide stability area than integer order PID controller.