A Method of Suppressing Circulating Current for Parallel Inverters Based on the Compensating Current

For improving the efficiency and characteristics of parallel grid inverter, the suppression of circulating current is needed. A parallel inverters system of average current control based on the compensating current control method is studied in this paper, in which the position and adjusted function of compensating current are optimized to make its response time constant small and current averaging effect not influenced by the delay and phase shift of the PI regulator, and it has better suppressing effect of fundamental circulating current. For the compensating current method is mainly used to suppress the circulation of fundamental circulating current, the low pass filter is applied to eliminate the effect of harmonic current in compensating circulation current, which make fundamental current component only be included in compensating current. While the high frequency harmonics circulation is suppressed by using LCL filter. The simulation results show that the proposed average current control scheme based on compensating current has superiority for suppressing fundamental circulating current, and LCL filter has the validity to suppress the high frequency harmonics circulation.