Cooperative Control Strategy of Hybrid Energy Storage System under Isolated Operation of Micro-grid

Wind and photovoltaic(PV) power generation have strong randomness, fluctuation and intermittence, so it is necessary to configure energy storage devices in micro-grid to suppress its output fluctuation. Aiming at the characteristics of islanded operation mode of micro-grid, a coordinated control strategy of hybrid energy storage system with lithium batteries (Li-b) and super capacitors (SC) is designed. The two-stage filter structure of the first-order low-pass filter and the second-order high-pass filter is adopted to distribute the load power gap. On this basis, considering the state of charge (SOC) of Li-b and the voltage of SC, a cooperative control strategy of hybrid energy storage system is designed. Then, according to the coordinated control strategy, the control structure of the two-stage energy storage converter (including DC/DC converter and DC/AC converter) is designed. Finally, a simulation model is built in MATLAB/Simulink to verify the effectiveness of the control strategy of the hybrid energy storage system designed in this paper.