A Low-pass Filter Method to Suppress the Voltage Variations Caused by Introducing Droop Control in DC Microgrids

Small-scale DC microgrids have been popular in recent years due to their flexibility and wide applications. Droop control is one of the most widely applied control method in interface converters for a DC microgrid. However, methods to select proper droop coefficients or droop coefficient zones are rarely discussed in reported literatures. This paper analyzes the impact caused by large droop coefficients from loop-gain perspective, and proposes a low pass filer method to avoid the significant DC bus voltage variations, which is harmful to the power quality and voltage-based control strategies. Also, a droop coefficient zone is defined according to the current sharing and DC bus voltage variations. A simulation study has been implemented to validate the proposed droop coefficient zone and feasibility of the proposed low pass filer method.