Power Coordination Strategy for Hybrid Energy Storage in AC/DC Microgrids Based on Virtual Impedance-Fuzzy Algorithm

A hybrid energy storage system consisting of batteries and supercapacitors can be integrated into the microgrid, to mitigate the power fluctuations on both sides of the source and load sides, which is a common issue in AC/DC hybrid microgrids. This paper proposes a power coordination strategy for hybrid energy storage in AC/DC microgrids based on virtual impedance and fuzzy algorithm optimization. First, the initial power allocation for hybrid energy storage is autonomously determined using composite virtual impedance. Then, a comprehensive analysis is conducted to assess the influence of composite virtual impedance parameters and filtering time constant on power distribution. Based on this, a power distribution adjustment method is proposed, and fuzzy control rules are derived. The fuzzy algorithm is used to adaptively optimize the output power of hybrid energy storage based on the state of charge and the power demond on the supercapacitor. Finally, the power in the AC/DC interlinking converter is adaptively adjusted to enhance the regulation ability of hybrid energy storage. The simulation results in MATLAB/Simulink experiments demonstrate that the proposed strategy can effectively suppress power fluctuations on both the source and load sides, eliminate DC bus voltage deviation, and prevent the issues such as over-charging and over-discharging of supercapacitors, thereby extending the service life of the equipment.