Extraction Method of PD Acoustic Emission Signal for Solid Insulated HVDC Equipment

The failure of Solid insulated high voltage DC equipment occurs from time to time. Due to the complexity and particularity of the insulation structure of it, there is no effective detection means. Acoustic emission technology can effectively detect the early fault of PD. Aiming at PD acoustic emission signals with different Signal-to-noise ratio (SNR), a method combining EEMD (EEMD) and wavelet adaptive threshold is proposed in this paper to denoise PD acoustic emission signals, and then EEMD is performed on the processed signals. The EEMD energy entropy of each eigenmode function (IMF) is obtained as the characteristic quantity, and the PD acoustic emission signal is effectively extracted. The results of PD AE simulation and measured signal processing for Solid insulated high voltage DC equipment show that the error of the proposed method is obviously smaller than that of the EMD method under the condition of low signal-to-noise ratio, which verifies the effectiveness of the proposed method.