Adaptive Low-Order Harmonic Currents Suppression in AC Power System Using Fractional-Order Circuit

This paper proposed an innovative fractional-order circuit LC (FOC-LC) based resonant filtering method to suppress low-order harmonic currents in AC power system. By constructing the FOC-LC harmonic suppression branch and applying a corresponding modulation strategy, the impedance complex plane maintains symmetrical resonance inductance and capacitance. This leads to an extremely low equivalent impedance for different harmonic currents, effectively suppressing harmonics with diverse frequencies and magnitudes. The proposed method demonstrates robustness to device parameters and maintains reliable harmonic suppression performance within an acceptable error range. The utilization of fractional-order circuits allows for auxiliary charging, modifying output port capacitance, adjusting equivalent resistance, and even achieving negative resistance characteristics. This results in minimal resonance equivalent resistance in the harmonic suppression branch. To verify feasibility, a 1.2 kW prototype was implemented, yielding promising results. The experimental validation validates the practical applicability and effectiveness of this method.