State-of-Charge Dynamic Balancing Control for Multi-Energy Storage Units in DC Distribution System

Due to the intermittent nature of renewable energy and the uncertainty of load fluctuations in DC distribution system, energy storage systems have become an important part of maintaining stable operation of power supply systems. Aiming at the problem of uneven power distribution caused by inconsistent states of multi-energy storage units, this paper proposes a state of charge (SOC) dynamic balancing control strategy based on arctangent function for multi-energy storage units under island operation mode, for sake of balancing differences among energy storage batteries and reducing system active losses. Considering the variation range of droop coefficient, the inverse tangent function is utilized to link droop coefficient with SOC to achieve adaptive adjustment. At the same time, the amplification factor is introduced to amplify differences of SOC between multi-energy storage units, which will achieve fast balancing control of SOCs. MATLAB/Simulink simulation analyzes SOC balancing effect of the proposed control strategy under different amplification factors. The simulation results verify the effectiveness of proposed method.