An accurate power-sharing control method based on circulating-current power model for voltage-source-inverter parallel system

This paper analyzes the voltage-source-inverter parallel system as a multi-input & multi-output system, and proposes the circulating-current mathematical model, the steady-state model and small-signal model of parallel system. Then the phasor models of the circulating-current and the circulating-current power are proposed. Subsequently, the mathematical model of traditional droop control is built and analyzed based on the circulating-current power model. According to the analysis of droop control, this paper proposes an accurate parallel control strategy (ω-P_cir and V-Q_cir control), which can eliminate the circulating-current power and the bias of output voltage frequency and amplitude. Finally, simulation and experiment result are presented, which validates the performance of the proposed method.