Consensus-based Distributed Coordinated Control for Islanded DC Microgrids

In this paper, a distributed coordinated control strategy between the energy storage units (ESUs) and the photovoltaic (PV) units in a dc microgrid has been proposed. Hierarchical control for the multiple ESUs has been adopted. In the primary level, an adaptive droop control is introduced, with the droop gains automatically regulated according to the state of charge (SOC) and the rated power of the ESUs. In the secondary level, distributed cooperative control based global de voltage recovery and current sharing improvement has been presented. As another main contribution, a strategy for the coordinated operation of the ESUs and the PV units is proposed. Based on this strategy, the PV unit can change its control mode smoothly and flexibly to guarantee the stable operation of the de microgrid in case of emergency conditions. The proposed distributed cooperative control strategy for the de microgrid has been verified by a low-voltage islanded de microgrid prototype.