An adaptive droop voltage control for DC microgrid systems

Distributed energy resources and energy-storage units are parallel connected through converters in a DC bus microgrid. Current sharing is a basic requirement for microgrid and many current sharing methods are proposed. Distinct from those methods like the average current method, centralized method and master-slave method, the droop control method does not need any interconnections between the converters and has been widely adapted. However, in the traditional droop control, the system deals with the tradeoff between voltage regulation and current sharing, and it results in the voltage drop in case of good current sharing. In this paper, in order to improve the system performance, we propose a novel droop control method, such that the system adaptively updates the output voltage set-point for each of converters. As demonstrated with simulations, the proposed method greatly improves the output voltage regulation without significant compromise of current sharing performance.