A Droop Control Strategy for Improving Reactive Power Sharing and Suppressing Frequency and Voltage Deviation in Islanded Microgrids

Conventional droop control strategies use a fixed droop coefficients, which creates a contradiction between dynamic response speed and power output range. To address this problem, a variable droop coefficient control strategy based on sigmoid function is proposed. With the characteristics of the curve of the sigmoid function, this strategy can change the droop coefficient synchronously and smoothly with the increase of frequency/voltage deviation, thus effectively suppressing the frequency or voltage deviation. In addition, to address the issue of decreased accuracy in reactive power sharing caused by the proposed strategy, this paper introduces a reactive power sharing method. By comparing the reactive power outputs of different inverters and distributing power to each inverter through an integral regulator, the accuracy of reactive power sharing is improved. Finally, the effectiveness of the proposed control strategy is demonstrated through both simulation analysis and experimental validation.