Accurate Harmonic Current Control for Large-Capacity LCL-Type Active Power Filter with Inverter-side Current Feedback

초록

Due to the difference between inverter-side and grid-side currents in the LCL filter, an Active Power Filter (APF) with an Inverter-side Current Feedback (ICF) configuration may struggle to accurately supply harmonic currents caused by nonlinear loads. In a large-capacity APF operating at low switching frequencies (5 kHz or less), the resonant frequency of the LCL filter is typically designed to be 2.5 kHz or less, which is below the recommended maximum harmonic current order of the 50th (3 kHz) to meet harmonic regulations specified by grid standards. As a result, meeting these grid standard recommendations becomes challenging for a large-capacity APF with ICF configuration. To address this issue, this paper proposed a method for modifying the harmonic current reference based on the transfer function of the difference between inverter-side and grid-side currents, enabling accurate harmonic current supply even with the ICF configuration. Since the proposed method depends on LCL filter parameters, a detailed performance evaluation accounting for parameter variations was conducted, and the effectiveness of the proposed method was validated. Through simulations and experiments, it was confirmed that applying the proposed method effectively improves both Individual Harmonic Distortion (IHD) and Total Harmonic Distortion (THD). © 1972-2012 IEEE.

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