Decentralized Multiple Control for DC Microgrid with Hybrid Energy Storage

For a microgrid with hybrid energy storage system , unreasonable power distribution, significant voltage deviation and state-of-charge (SOC) violation are major issues. Conventionally, they are achieved by introducing communication into centralized control or distributed control. This paper proposes a decentralized multiple control to enhance the performance of the system. A low-pass filter based on droop control is applied to battery energy storage system (BESS), and a low-pass difference filter based on proportional-integral (PI) voltage regulation is employed for supercapacitor (SC). The cooperation between them realizes power distribution, in which the average power is compensated by BESS and the high-frequency fluctuation is suppressed by SC. Meanwhile, the voltage deviation is diminished through mode re-division. Considering the SOC imbalance of BESSs and SOC violation of SC, current correction and voltage compensation methods based on local information are proposed to optimize the current sharing of BESSs and ensure the availability of SC, respectively. The advantage of voltage compensation is that, the SC is still available in process of SOC recovery. The simulation model is established on the MATLAB/Simulink environment and the feasibility of proposed strategy is verified by simulation analysis in different scenarios.