A Modified Droop Control Algorithm for DC Microgrids to Achieve Accurate Current Sharing and Improved Voltage Regulation

Abstract

Droop control is a commonly used method for load current sharing among the converters in DC microgrid applications. However, in this method, the current sharing and load voltage regulation are affected by cable resistances and other non-idealities. The conventional droop control method’s performance can be improved using secondary control algorithms that involve low-bandwidth communication channels. In this paper, an improved secondary control algorithm is proposed for a multi-source, single load bus DC microgrid system. In the proposed algorithm, the load voltage information is communicated to the individual converters, and there are no communication channels between individual converters. Thus the proposed algorithm achieves accurate current sharing and improved load voltage regulation with reduced communication channels compared to several state-of-the-art approaches. All the controllers in the proposed algorithm are implemented locally, and hence a decentralized control is achieved. The proposed algorithm’s effectiveness is validated using circuit simulations and hardware-based experiments on a two converter single load bus DC microgrid system.