A proportion-feedback-integration control for the grid-connected inverter in distributed generation systems
分布式发电系统中并网逆变器的比例反馈积分控制技术

Current control for the grid-connected inverter of distributed power generation systems has a significant impact on the power quality. The conventional PI control can not achieve the null steady-state error for the ac grid current, and the underlying reason for that is rarely depicted at length in literature. In this paper, the linear model for the grid current control is built, and then, the causes for the steady-state error in the conventional PI control is revealed based on the superposition theorem and frequency-domain analysis. A novel proportion-feedback-integration(PFI) control is proposed to eliminate the steady-state error and reject the dc component. It is easy to implement and applicable to both single-phase systems and three-phase systems. The simulation results are in agreement with the theoretical analysis, thus, verifying the effectiveness of the proposed approach.