Accurate Current Sharing in a DC Microgrid Using Modified Droop Control Algorithm

TL;DR

This paper introduces a modified droop control algorithm for DC microgrids that improves current sharing accuracy among parallel converters, addressing cable resistance issues and ensuring efficient power distribution.

Contribution

It proposes a simple, locally-measured, modified droop control method that enhances current sharing accuracy in DC microgrids with unequal cable resistances.

Findings

Simulation results confirm improved current sharing accuracy.

Experimental tests validate the effectiveness of the modified control.

The method performs well across different converter ratings.

Abstract

Due to the increasing popularity of DC loads and the potential for higher efficiency, DC microgrids are gaining significant attention. DC microgrids utilize multiple parallel converters to deliver sufficient power to the load. However, a key challenge arises when connecting these converters to a common DC bus: maintaining voltage regulation and accurate current sharing. Unequal cable resistances can cause uneven power sharing and lead to power losses. Conventional droop control methods, which employ a virtual resistor to address this issue, have limitations in achieving good performance across the entire converter operating range. This paper proposes a modified droop control algorithm to address this issue. This method modifies the virtual resistor in a way that ensures power sharing aligns with each converter-rated capacity. The algorithm is simple to implement and uses local measurements to update the droop gain. This paper presents simulation studies and experimental tests to analyze the performance of the proposed method, considering scenarios with equal and unequal converter ratings. The results successfully validate the accuracy and effectiveness of this innovative approach.