An improved droop control strategy for parallel inverters in microgrid

摘要

In this paper an improved droop control strategy for parallel inverters in microgrid was proposed. Aiming at the voltage sags problem caused by the introduction of virtual impedance, a double closed loop control method based on measured voltage feedback was employed for inverter control in the microgrid. Firstly, the frequency response character of the closed loop transfer function with virtual impedance and the inductive variation was analyzed in the frequency domain, indicating that the improved droop control method is necessary. Secondly, an improved droop control strategy based on inductive virtual impedance with measured voltage feedback was proposed. Lastly, the Matlab/Simulink simulation results show that the improved droop control strategy can not only solve the output voltage sags of the inverter, but also improve the accuracy of power allocation of droop control, maintain the system voltage and frequency stability. It is proved that the improved droop control strategy is effective.