Load Sharing and Voltage Restoration Improvement in DC Microgrids with Adaptive Droop Control Strategy

Abstract

DC microgrid is a connecting network between distributed DC generators. The converter control on DCMG is used to obtain proportional load sharing and voltage restoration of DC bus. The traditional droop control is a common control technique in DC microgrid networks with multiple unit converters. However, this technique has limited performance when the difference of the line resistance is considered. In this paper, the intelligent adaptive droop control is proposed to improve the accuracy of load sharing, while the distributed secondary loop is utilized to minimize the DC bus voltage deviation. The droop resistance is tuned using fuzzy logic controller so that the load power sharing error compensation is obtained, while the DC bus voltage deviation is reduced by the PI controller. The exchange of output currents between converter units through communication lines is considered to obtain the actual load current conditions. The proposed droop control strategy can guarantee the load power sharing balance between three sources with a ratio close to 1:1:1. The results of the comparison analysis between the proposed technique and the traditional droop control are simulated completely using Matlab/Simulink, even under fluctuating loads and the line resistance changes.