Abstract:To solve the problems of unreasonable power allocation and unbalanced state of charge (SOC) control among energy storage units in DC power supply systems, an adaptive power allocation control strategy considering SOC is proposed for energy storage systems. Firstly, the power allocation characteristics of energy storage units adopting droop control are analyzed, and on this basis, an adaptive droop control considering SOC and charging/discharging balance factors is propose, and the basis for parameter setting is provided. The proposed adaptive power allocation control method can enable energy storage units with higher initial SOC to allocate more discharge power, and energy storage units with lower initial SOC to allocate more charging power. In addition, the proposed control method can dynamically adjust the droop coefficient and the charging or discharging power allocated by energy storage unit based on SOC, which can achieve reasonable power allocation of energy storage units and fast balancing control of SOC. Finally, a simulation example is built in PSCAD/EMTDC to verify the effectiveness of the proposed adaptive power allocation control method for energy storage systems considering SOC.