Fast repetitive control Scheme for shunt active power filter in Synchronous Rotational Frame

This paper proposes a fast repetitive control (FRC) scheme for the shunt active power filter (SAPF) in the three-phase three-wire system, which can improve the dynamic response performance of the SAPF compared with the conventional RC strategy (CRC). The FRC is designed in the synchronous rotational frame (SRF) which can reduce the repetitive period to one-sixth of the fundamental cycle. A fractional delay (FD) filter is employed to eliminate the tracking error due to the grid frequency variations. To improve the performance of the SAPF in weak grid situation, this paper also proposed a close loop harmonic detection scheme so that the reference value can track the varied harmonic currents rapidly. Compared with the conventional open loop detection scheme, the compensation performance is highly improved. Simulations and experiments verified the proposed scheme.