A New Coordinated Operation Strategy for Unified Power Quality Conditioner (UPQC)

This paper proposes a new coordinated operation strategy to improve the low utilization rate of series inverter in traditional unified power quality conditioner (UPQC), and to fully optimize the total capacity of UPQC. When source voltage is in the normal range, the series inverter compensates part of reactive power by reducing the source power factor angle, so as to reduce the capacity demand of shunt inverter. In the case of deep voltage sags, the series inverter always decreases its active power exchange with the shunt inverter by injecting appropriate voltage, and thus lessens energy coupling between the two inverters. In addition, it also presents a capacity design scheme based on the new coordinated operation strategy, which has been proven effective in reducing the total capacity demand up to 27% of compensating device in the most range of load power factor. Finally, the new coordinated operation strategy is validated through an experimental study.