Self-tuning Fuzzy PID Controller for Load Frequency Control in AC Micro-grid with Considering of Input Delay

A micro grid (MG) system that benefits from distributed generation (DG) resources has a non-linear and time-varying nature which encounters the control problem with some difficulties. Also, due to the fact that in the most MG systems the frequency controllers are centralized in the control room and, the DGs are located at distances from the control room, the occurrence of delay is undeniable and it should be considered in the design of the controller. For this purpose, a self-tuning fuzzy PID controller has been designed for load frequency control in a MG system in the presence of delay. The designed fuzzy PID controller is a nonlinear controller and can handle the nonlinearities. To deal with the delay in the input of the system, the Ziegler-Nichols like criteria has been utilized to derive the adaptive mechanism which tunes the scaling factors according to the maximum amount of delay in the online manner. The proposed self-tuning fuzzy PID controller has been applied for load frequency control of a time-delay MG system and the simulation results have been compared with the results of fixed structure fuzzy PID controller. The simulation results indicate the efficiency of the proposed controllers in dealing with time-varying delay.