Characteristic information extraction and developing process recognizing method of surface discharge in oil immersed paper insulation

Based on the platform for testing development characteristics of partial discharge in laboratory, typical surface discharge model was built up at first. Constant voltage testing on the model was performed to research the development process of surface discharge. The variation of total partial discharge energy per unit of time (W_total) was analyzed and the results show that the surface discharge development process is divided into 5 stages. Three-dimensional spectra and grayscale images in different discharge stages were also built in order to make the process more comprehensive and visual. As traditional moment parameter has its shortages, the wavelet theory was introduced to extract the moment characteristics of partial discharge grayscale images. According to the wavelet moment features extracted at different discharge times, under the condition of no prior knowledge, the Euclidean distance clustering method was used to divide the whole surface discharge process.