Multi-energy body DC micro-grid parallel operation energy management strategy

The DC microgrid has become an important development direction of the microgrid because of its advantages of easy coordination control, low line cost and no reactive power loss. Energy storages with different power characteristics are solutions to improve the effectiveness and economy of isolated DC microgrid systems. In order to suppress the voltage fluctuation of DC bus and optimise the running status of battery and super capacitor, the hybrid energy storage system (HESS) distributed droop control strategy was adopted. Among them, both the battery unit and the super capacitor unit are set as droop controlled slack terminals. In order to solve the problem of drooping controlling the inconsistency of power characteristics of various terminals, different droop coefficients are selected for different types of energy storage units. Without exceeding the power response range of each energy storage power source, the capacity of each energy storage unit is utilised to the maximum extent. In view of the state of charge (SOC) equilibrium of multi-battery energy storage units, a SOC-based variable droop coefficient control strategy was designed to adjust the power distribution twice, so that the multi-cell energy storage units with higher SOC could bear the burden. Larger power output tasks to achieve a balanced goal. In order to verify the feasibility of the proposed method, a MATLAB/SIMULINK model was built. The simulation results show that compared to the traditional droop control, the improved variable droop coefficient control strategy can effectively suppress the DC bus voltage fluctuation and achieve multi-cell SOC equalisation and supercapacitor Rapid recovery of SOC.