A novel repetitive control scheme for three-phase grid-connected inverter with LCL filter

Grid voltage distortion gives rise to extra grid current harmonics in grid-connected inverter system. To damp these harmonics, this paper proposes a novel control strategy in which inverter output current is regulated by PI controller and grid current is controlled by repetitive controller (RC) for three-phase grid-connected voltage source inverter (VSI) with LCL filter under d-q rotating frame. This paper implements RC to regulate grid current based on the stability of the system under inverter output current control loop. This paper discusses the design of RC and analyzes the stability and effectiveness of the proposed control strategy in damping the grid current harmonics arising from grid voltage distortion. At last, proposed scheme is verified on a 100 kW three-phase grid-connected PV inverter prototype. Simulation and experimental results show that the proposed scheme has a good performance.