Research on Feed-forward Fast Repetitive Power Control for LCL type APF

Active power filters using repetition control (RC) with harmonic detection can effectively suppress harmonics in the system. However, there are accuracy and delay problems in the harmonic detection link, and there is an inherent delay link in the internal mode of the repetition control (FRC), while the actual frequency of the grid will fluctuate above and below 50 Hz, and the resonance frequency of the (FRC) deviates from the actual harmonic and fundamental frequencies of the grid, which reduces the control accuracy of the system. For this reason, a new fast repetitive power control (FFRC) with feed-forward channel is proposed with higher gain and wider resonant bandwidth, which still maintains a better compensation effect when the grid frequency fluctuates and has a faster dynamic response.