A new droop control method for the autonomous operation of distributed energy resource interface converters

Microgrid is widely accepted as an effective mean of integrating various distributed energy resources (DERs) through their interface converters to provide electric power of high quality and reliability. These distributed resources interface converters (DICs) are required to operate in an autonomous fashion without any communication for enhanced reliability. Conventionally, the real power-frequency droop control and the reactive power-voltage droop are adopted as the de-centralized control strategies in these DICs for the autonomous power sharing operations. However, the reactive power sharing of Q-V droop control often deteriorates if there are mismatched transmission line impedance characteristics. In this paper, a Q-V dot droop control method with V dot restoration mechanism is proposed to improve the sharing of reactive power. Its operation principle and control method are explained and analyzed. In addition, simulation and experimental results are presented to validate the effectiveness of the proposed method.