Power Equalization and Frequency Recovery Control Strategy Based on Adaptive Virtual Impedance

Abstract

In the island AC microgrid system, suppressing the circulating current to achieve power sharing is a necessary condition for the stable operation of the AC microgrid system, however, in the actual system, there is an equivalent line impedance difference between different distributed generation units (DGs). Affected by this, the reactive power in the system cannot be equally divided. In addition, the traditional droop control strategy is poorly regulated, and the system frequency and voltage are biased. In this paper, based on the traditional droop control, an adaptive virtual impedance control strategy is proposed to eliminate the line impedance difference and suppress the circulating current. At the same time, the frequency recovery and voltage compensation links are added to achieve the error-free adjustment, and the active power can also achieve a better equalization effect. Finally, the simulation results verify the correctness and effectiveness of the theoretical analysis.