Comparison of Extraction Methods for Fundamental Frequency Positive Sequence Current in the APF

This paper analyzes the extraction strategies based on the low-pass filter, the second-order generalized integrator and the cascaded delay signal cancellation filter for the fundamental frequency positive sequence (FFPS) current of the source current, in order to solve the problem of voltage fluctuation when active power filter, which controlled by power balance method, is facing the load fluctuation. From the aspects of algorithm complexity, difficulty in parameter design, immunity to interference, dynamic characteristics and steady-state characteristics, the optimal scheme for extracting the FFPS current from source current and the applications of the remaining extraction schemes are obtained. Finally, the results were verified by simulation.