Study on wavelet theory for selecting faulty line

According to the favorable frequency property of wavelet packet, this paper advanced to eliminate the band of resonance process and decompose transient zero sequence current occurred in fault line with a proper bandwidth, so as to obtain zero sequence current in different frequency range. Then, to confirm the bandwidth with the most obvious fault signature based on the view of maximum energy. With the reference to the principle: when all lines have the same characteristic bandwidth, the faulty feeder can be found out by comparing the polarity of the transient zero sequence current, which based on wavelet packet decomposition within the characteristic band; when the characteristic bandwidth is differ in all lines, the faulty feeder can be found out by this way: to select the characteristic band for each line in turn, contrast scope and polarity of zero sequence current of each linepsilas within the characteristic bandwidth, finally, the conclusion can be obtained by synthetizing the foregoing comparing result. And the way to select faulty line is also given when the breakdown occurs nearby phase voltage zero, the transition process is not obvious.