Adaptive Wavelet de-noising method based on segmented processing technology for PD location

It is possible to carry out PD location using the time difference of PD pulses received by a UHF antenna array. In practical applications, the electromagnetic interference within the substation will pollute these received signals and make it difficult to calculate the time difference of the PD pulses, which, thus, reduces the reliability of the PD source locating. Based on the segmented processing technology, an adaptive Wavelet de-noising method is proposed in this paper. Considering that the level and the time-frequency characteristic of the background noise differ little in microsecond time period of sampling, each waveform acquired by PD detecting system are divided into two sections, the one without PD pulse is used for the calculation of the wavelet coefficients which are used to estimate the de-noising thresholds of the signal. The influence of this adaptive wavelet de-noising process on the PD pulse time delay calculation is analyzed in details. The results of simulation and application show that this method can suppress noise effectively and extract the PD pulse accurately, which contribute to the reliability of the PD source locating.