SoC Balancing Strategy for Distributed Energy Storage System Based on Event-Triggered Mechanism in DC Microgrids

Distributed energy storage systems (DESSs) are often used to improve energy efficiency in DC microgrids. However, the life of DESSs will be degraded when energy storage units (ESUs) charged with unbalanced state-of-charge (SoC). Besides, the periodical updating mechanism for control parameters could bring a communication burden among converters, especially when DESSs reach balance. To solve the above issues, a SoC balancing control strategy of DESS based on event-triggered mechanism is proposed in this paper. Firstly, a SoC-based droop control method is designed to adjust the discharge current of each ESU in order to achieve the SoC balance. Secondly, a event-triggered control (ETC) is proposed to achieve the same discharge rate of SoC when DESSs reach balance. Meanwhile, the unnecessary communication times of the DESSs are reduced through event-triggered mechanism. Finally, the effectiveness of the proposed strategy is verified by Matlab/environment. The simulation results show that the proposed control strategy could realize the SoC balance and the communication burden could be significantly reduced in contrast to the time-triggered control (TTC).