With the increase of DC system application scenarios and DC loads ratio, the advantages of DC microgrid are increasingly prominent. To address the contradiction of classical droop control in terms of DC bus voltage stability and improved efficiency of current distribution , an improved droop control strategy based on bus voltage compensation and droop coefficient calibration is proposed in this paper. The stability of the parallel BOOST converter system using this control strategy is analyzed. A hierarchical control strategy is designed to solve problems of the bus voltage stability and current distribution of DC microgrid cluster. Three layers are included in this control strategy: the top layer is the sub-microgrid coordination control, the middle layer is the voltage compensation control and droop coefficient calibration control, and the bottom layer is the droop control and voltage closed-loop control. The effectiveness and reliability of the proposed hierarchical control strategy are verified by simulation and experiment results.

DC microgrid cluster, hierarchical control strategy, bus voltage, droop control