Effect of control circuits on power system optimization

Non-linear power system optimization studies commonly deal with optimal control of field excitation only and neglect the effect of regulator time constants and the presence of feedback loops. Studies reported in this paper show that the time constants of the regulators and the exciter circuits render the control of the field excitation less effective in obtaining an improved optimal response and that the closed loop operation provides only a limited improvement. Optimization studies of a power system simulated to different degrees of sophistication are described here. From these studies it is concluded that the effective method of obtaining a markedly improved dynamic response is the optimal control of input power. The desired level of improvement in system response can be obtained despite the governor loop time lag, particularly in systems incorporating doubly excited synchronous machine.