Identification of Series Fault Arc of Low-voltage Power Cables in Substation Based on Wavelet Transform

Low-voltage cable in substation is easy to cause fire accident due to fault arc. The current of series fault arc is similar to the current under normal load fluctuation in waveform, so it is difficult to identify it directly. The AC load characteristic test of low-voltage cable was carried out in the UHV Lanjiang station of Zhejiang power grid, and the arc simulation test of series fault of low-voltage cable was carried out in the laboratory. Based on wavelet transform, the original current signals of the two working conditions are decomposed by 5-level wavelet transform and the key features are extracted. By comparing the wavelet details of each decomposition scale, it is found that the ratio of the maximum absolute value to the mean absolute deviation of the series fault arc current signal is significantly higher than that of the load characteristic current signal. Therefore, it can be used as the detection basis for the series fault arc of low-voltage power cables in Substation.