Three-phase photovoltaic grid-connected inverter based on feedforward decoupling control

Abstract

Based on the analysis of operating principle of two-stage photovoltaic grid-connected inverter, the mathematical model of three-phase grid-connected inverter under dq synchronous rotating reference frame is set up, and the feed-forward decoupling control strategy of three-phase photovoltaic grid-connected inverter is deduced, and the overall control strategy of two-stage photovoltaic grid-connected inverter is proposed in this paper. The control strategy consists of MPPT(Maximum Power Point Tracking) loop, DC voltage outer loop, AC current inner loop. This control strategy not only realizes the decoupling control of active power and reactive power, but also has the characteristics of simple control and high control accuracy and so on. Finally, the control strategy proposed in this paper is applied in 5kW photovoltaic grid-connected inverter. The precision and effectiveness of this control strategy are verified by the experiments. The system is proved to be steady and dynamic.