Current Control of Shunt Active Power Filter Based on Repetitive Control

The current control of single-phase shunt active power filter (SAPF) adopts a dual-loop control structure. The inner loop PI controller modifies the frequency response of LCL filter, simplifies the design of outer loop repetitive controller, and achieves a fast transient response. A plus-in repetitive controller is adopted as the outer loop controller to eliminate steady-state error. The disturbance caused by the grid voltage, is attenuated by feed forward control The analysis of the performance of feed forward control, the stability and robustness of the dual-loop control system is detailed in this paper. All the analysis and experimental results show that the dual-loop control system has well steady-state performances, fast transient response, good attenuation of grid voltage, and is robust to variation of LCL filter parameters.