Design of a DC series arc fault detector for photovoltaic systems protection

Because the line current decreases when a DC series arc fault occurs in a solar photovoltaic (PV) system, conventional overcurrent protection devices are unable to isolate such fault. A series arc generates extreme heat and can lead to fire incidents if the arc lasts long enough. The current components in the frequencies range of 48.83 kHz ~ 93.99 kHz in a series arc fault are much higher than in the pre-fault current, fast Fourier transform (FFT) can be applied to analyze the current signal and to detect a DC series arc fault. An experimental grid-connected solar PV system consisting of ten polysilicon modules connected in series is constructed in this study, and a new design of DC series arc fault detector (AFD) is proposed and tested under different operation conditions. Two commercial AFDs are also tested in this study for comparison. The result shows that the proposed AFD can detect DC series arc faults in a solar PV system with 100% accuracy.