A negative sequence voltage control strategy based on adaptive virtual impedance implementation for microgrid inverter under three-phase unbalanced load

Due to the unbalanced load in microgrid, the control performance of inverter will be degraded, such as three-phase unbalanced voltage and negative sequence current circulation between the paralleled inverters. By comparing the traditional virtual impedance and droop control method, a negative sequence voltage control strategy based on adaptive virtual impedance implementation is proposed. In this paper, the voltage amplitude and frequency of inverter is controlled by the positive sequence control loop. The negative sequence control strategy is designed by adaptive negative sequence virtual impedance to eliminate negative voltage and the negative current circulation. The simulation results verify the effectiveness of the control strategy.