Ma Zhiqin

Partial discharge developing stages identification based on cluster-hierarchical decision SVM in oil-paper insulation

Based on rod-plane electrodes in oil-paper insulation, the experiments for developing characteristics of partial discharge (PD) were performed using constant voltage method. Four statistical spectra and 29 characteristic values were extracted on the basis of the phase-resolved partial discharge (PRPD) pattern. Then 8 new parameters were extracted from the 29 characteristic values by using kernel principal component analysis and the different developing stages of PD were divided with system clustering. According to the clustering results, the PD stages hierarchical identification method was established based on clustering-multistage Support Vector Machine. Identification results show that the proposed method can identify discharging stages well and the obtained results are basically consistent with the results of system clustering analysis for the same data.

Air-gap discharge energy change characteristics in oil-paper insulation and the research on the correlation with the variation of gas

A test platform was built for the research on airgap discharge and its development characteristics which based on the air-gap discharge model in oil-paper insulation, and repeated carried out 36 hours partial discharge experiments using constant voltage method under the same conditions. Calculated the maximum discharge energy Wmax and the average discharge energy Wavg of the different discharge time. At the same time, average discharge energy per second Wasec was proposed as a new feature in which the discharge repetition was considered, the analysis showed that Wasec can characterize the the development characteristics of partial discharge very well. One the other hand, the dissolved gases in the oil were analyzed, the correlation analysis between six kinds of characteristic gas and Wasec showed that the content of H2 has the highest correlation with Wasec during the development of air-gap discharge in oil-paper insulation, followed by CO and CH4. The changes in the contents of these three gases can roughly reflect the variation of the Wasec. It has great significance in engineering practice.