Selective harmonic active tuning control method for hybrid active power filters

摘要

This paper proposes a selective harmonic active tuning control method for hybrid active power filters (HAPFs). A HAPF is composed of a voltage source inverter (VSI) and an LC filter. With this method, the VSI in the HAPF is controlled as a virtual capacitance that varies with the dominant harmonic frequencies. Thus, the LC filter can be forced to be tuning at these frequencies, which significantly improves the harmonic filtering characteristic of the LC filter. Meanwhile, to enhance the filtering performance in the case of a small power grid impedance or to damp the resonances between an LC filter and the grid impedance, the harmonics in the grid source current are detected and proportionally fed back to the controller, which brings about an effect equivalent to adding a series harmonic resistance on the grid source side. The proposed control method has the advantages of a simple control structure and easy implementation. Simulation and experimental results confirm the effectiveness and feasibility of the proposed method.