Modified Harris Hawks Optimization-Based Fractional-Order Fuzzy PID Controller for Frequency Regulation of Multi-Micro-Grid

Load frequency control of a multi-micro-grid (MMG) including renewable energies is presented in this work. A hybrid system consisting of a wind turbine generator (WTG), solar photovoltaic panel (PV), diesel engine generator (DEG), aqua electrolyzer (AE), fuel cell (FC), battery energy storage system (BESS) and electric vehicle (EV) is considered. As renewable energies are erratic and have higher intricacy, the problem of frequency regulation is more challenging. The system frequency is influenced significantly due to fluctuations in wind power, solar irradiation and changes in load. Large fluctuation is experienced in a hybrid power system if the frequency control mechanism is not effective and robust enough to handle the deviation in generation-load balance. Here, a fractional-order-fuzzy-PID (FOFPID) controller is suggested for frequency control. To tune the FOFPID parameters, a nature-inspired, population-based optimization paradigm called modified Harris Hawks optimizer (mHHO) is proposed, which is an improved version of the original HHO with enhanced global search potential. The supremacy of the proposed mHHO over HHO along with various state-of-the-art optimization techniques is established via statistical analysis with benchmark test functions. The stability of the proposed system is verified using Bode plot. The robustness of mHHO on scalability for different dimensions over existing approaches is also established. The feasibility of the proposed approach and its effectiveness is validated in a real-time simulation. It is seen that the mHHO-based FOFPID controller offers upgraded frequency regulation service as compared to PID and FPID.