A Novel SOC Distributed Equalization Control Strategy for Energy Storage Units in DC Microgrids

In the microgrid, the difference of SOC between different energy storage devices will cause power distribution errors. In order to solve this problem, a SOC equalization control strategy is proposed. The method utilizes the state of charge of the energy storage unit and the change rate of voltage as information carriers. Each energy storage unit can adaptively adjust the equivalent output impedance of itself without a communication network to transmit information. Firstly, the underlying control is transplanted into the distributed energy storage control system, and the equalization algorithm based on the state of charge is embedded into the zero-return controller. Secondly, in order to control the speed of charge state equilibrium, the rate factor is added to the algorithm. Then, the equivalent model of DC microgrid is established, and the comprehensive principle of power allocation for distributed energy storage system is proposed, and the condition with AC component is also discussed. Finally, the effectiveness of the proposed strategy is analyzed by Matlab/Simulink simulation.