A Coordinated Droop Control Method using a Virtual Voltage Axis for Power Management and Voltage Restoration of DC Microgrids

Abstract

In this paper, a coordinated droop control method through virtual voltage axis is proposed for voltage restoration and energy management of dc microgrids (MGs). Droop control is a control method that operates a dc MG using only local information. However, there are several drawbacks in that output voltage deviations occur, and the utilization priorities of various sources are not considered. To solve these problems, the voltage compensation term is defined as the virtual axis voltage value. It can minimize the voltage deviation of the dc MG and enable energy management by determining the operation band. However, the value of the virtual voltage axis is affected by communication delays. Therefore, its influence on the values of the virtual voltage axis was analyzed. The reference voltage and the droop gain of the droop control were designed, and the validity of the proposed method was verified using a lab-scale dc MG.