Detecting and localizing series arc fault in photovoltaic systems based on time and frequency characteristics of capacitor current

•A dc arc fault detection method using parallel capacitor current is proposed.•The difference of integrated spectrum of capacitor current has a certain range.•The polarity of the capacitor current pulse can localize the series arc fault.•Arc fault in a PV string can be localized comparing capacitor current amplitudes. A dc series arc fault is difficult to detect and localize due to the lack of a current zero crossing point. Unless there is an adequate protection, these faults can pose a threat to the stable operation of a photovoltaic (PV) system. A detection method for series dc arc faults in a PV system based on time and frequency characteristics of a parallel capacitor current is proposed. Series and parallel solar panel array systems are constructed, and a capacitor is paralleled with the load. Series arc faults are generated at different locations in the PV system, including locations between panels, on the PV bus and the load side. When a series arc is generated in the system, the high frequency components of the current will pass through the dc bus capacitor. The polarity and amplitude of capacitor currents as well as the integration of the frequency spectrum of capacitor currents are analyzed and identified as key attributes to differentiate dc series arc faults from other system changes. The impact of the harmonics generated by a converter is analyzed. The results indicate that the proposed approach and apparatus could be used to detect and localize series arc faults.