Enhanced DC Series Arc-Fault Detection in LVDC Systems With Capacitor-Assisted Impedance Shaping

초록

A DC grid can achieve high power conversion efficiency by reducing conversion stages between DC energy resources and loads. However, as system complexity increases, DC distribution systems face series arc faults due to damaged power cables and loose connectors, which can induce a fire hazard. Unlike AC grids, DC grids lack natural current and voltage zero crossings, which complicates arc-fault detection. This paper investigates series arc fault detection in LVDC systems with auxiliary DC-link/feeder capacitance for impedance shaping. The proposed capacitor-assisted impedance shaping increases the magnitude of arc-induced current variation and strengthens the frequency-spectrum change of the line current used by the FFT-based detector, thereby improving DC series arc-fault detectability. The operational principle is analyzed to derive capacitance-based impedance-shaping design guidelines for such LVDC systems. Also, a hybrid detector combines time-domain and frequency-domain analyses to detect DC series arc faults, which utilizes the arc characteristics of DC and AC components. Experimental validation of the proposed structure and detection algorithm is performed on a 30-kW laboratory LVDC testbed.

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