Distributed Secondary Control With an Event-Triggered Consensus-Based Observer for Energy Storage Systems in Islanded DC Microgrids

This paper proposes a distributed secondary control strategy with an event-triggered consensus-based observer. Firstly, a voltage-shifting term is introduced in the proposed control strategy to ensure accurate current sharing, faster state-of-charge (SOC) balancing and bus voltage restoration. Since the SOC balancing speed becomes very slow when the difference in SOC between battery energy units (BEUs) is small, and SOC balancing of BEUs with low power is difficult. Therefore, an adaptive SOC balancing factor to improve the balancing speed is proposed in this control strategy. In addition, communication delay can lead to large errors in traditional consensus-based observers, and continuous communication can bring a significant burden. Considering these issues, the event-triggered consensus-based observer is proposed. This observer can achieve accurate average consensus under communication delay and greatly reduce communication burden. The convergence of the proposed observer under communication delay is theoretically proven, and the Zeno behavior is excluded. At last, the effectiveness of the proposed control strategy has been verified in MATLAB/Simulink and RT-LAB experiments.