The novel multiagent distributed SOC balancing strategy for energy storage system in DC microgrid without droop control

Abstract

For the distributed energy storage system (ESS) in a DC microgrid, the novel distributed control strategy based on multiagent control is designed to achieve state of charge (SOC) balancing. In the proposed scheme, the output current of the converter is not required, which is an attractive feature to avoid the measurement error. The voltage loop can stabilize the bus voltage and provide the original current reference for each ESS. The SOC information is introduced to design the current closed loop, so that the operating current of the ESS can be dynamically adjusted to realize SOC balance control according to the SOC and capacity of each ESS during the charging and discharging process. Furthermore, in order to avoid the circulating current in ESSs, an adaptive current segment regulation algorithm is designed to improve the SOC balance speed, especially in the case of low SOC difference among ESSs. The proposed control strategy not only can enhance the current regulation performance under steady and transient states, but also has favorable voltage control capability and stability. Finally, the real-time test results in OPAL-RT platform are presented to validate the effectiveness of the proposed method.