Adaptive quasi-PRD control method of grid-connected PV inverter under weak grid

The high grid impedance in weak grid will lead to small bandwidth of control system and poor control performance of PV inverter. To solve this problem, this paper presents a quasi-PRD control method which can increase the bandwidth and dynamic response speed of control system. At first, the quasi-PRD controller was applied to replace the traditional PI controller. Then, the two harmonic injection method was used to detect grid impedance online which would be used to adjust the controller parameters adaptively. At last, some simulation and experiments were done to verify the validity of the novel control method.