Enhanced droop controller for operating parallel-connected distributed-generation inverters in a microgrid

Abstract

Distributed generation (DG) is gaining popularity because of prevalent environmental issues and the need for better power quality. To address these concerns, the microgrid was introduced to utilize DG. Inverter controls are essential for improving power quality because DG units are connected to a grid through an inverter. In this paper, an enhanced droop control technique is proposed to properly operate parallel-connected inverters in an AC microgrid. The proposed control strategy is based on the droop control technique, which utilizes locally measurable feedback signals. The droop control method is used for power sharing because of the absence of critical communication links among parallel-connected inverters. The transient response of the conventional droop control of power sharing is slow, and its frequency and voltage deviations are high. These factors limit accurate power sharing among parallel-connected inverters. The enhanced droop control is introduced to mitigate this problem, through which the trade-off between voltage regulation and reactive power sharing decreases significantly. In addition, the proposed method improves the transient response and achieves higher output power without voltage and frequency deviations. The results indicate that the desired transient response and accurate reactive power sharing with the line impedance mismatch are achieved. The simulation results are analyzed using MATLAB/Simlink to verify the effectiveness of the proposed control strategy.