Fractional Order PID Frequency Control in Islanded AC Microgrid Concerning Demand Response

The intermittent characteristic of distributed generators in AC microgrid threaten the frequency stability of microgrid system and even affect power quality seriously. The imbalance of generation and demand may also cause frequency fluctuations of microgrid system. In this paper, in order to effectively control the stability of secondary frequency for islanded AC microgrid system, the demand response control loop considering time delay effect is introduced to participate in the secondary frequency regulation of microgrid system. The fractional order PID (FOPID) controller based on optimal control rules is proposed and applied to secondary frequency regulation of islanded microgrid. Simulation experiments are carried out for islanded AC microgrid to demonstrate the effectiveness of the proposed FOPID control strategy.