A new control strategy combing PI and quasi-PR control under rotate frame for three phase grid-connected photovoltaic inverter

In this paper, a new control strategy that combines Proportion Integrity (PI) with quasi-Proportion Resonant (PR) control under d-q rotate frame is proposed for three phase grid-connected photovoltaic inverter to achieve the zero error tracking of fundamental current as well as to suppress the selected harmonics current. Also, grid voltage feed forward is used to enhance the dynamic response and disturbance rejection capability. Finally, the proposed strategy is implemented on a 100 kW PV array grid-connected inverter with 1.21% THD of grid current at 80kW output and 7th harmonics reduced by more than half. The experimental result shows that the proposed control strategy has good performance in fundamental current tracking and harmonics current rejection.