Fractional-Order Model Predictive Control Strategy for Hybrid Energy Storage Systems in DC Microgrids Considering Model Mismatch

Hybrid energy storage system (HESS) in DC microgrid is used for balancing the power mismatch between load demand and renewable energy sources (RESs). Supercapacitor (SC) of HESS is responsible for high-frequency charging and discharging behaviors, however, the model mismatch of DC-DC converter connected with SC and time delay of controller may leads to non-optimal control laws, which can result in high frequency large voltage fluctuation and current ripple. This paper proposes a fractional-order model predictive control (FOMPC) to compensate model mismatch, and the control actions of converters is optimized through parameter tuning. The verification of the proposed method is done by Simulation and hardware-in-loop (HIL) experiments. Experimental results show that the fluctuation of bus voltage in dynamic response is reduced by around 20% compared with traditional MPC.