The application of transient earth voltage in the partial discharge of power transformers

Partial discharge characteristics are extracted to analyze the potential shortcomings of transformers. And in order to better study the partial discharge characteristics of transformers, the detection performance of the two methods has been compared and analyzed. Using the method of transient earth voltage and pulse current to cooperate is very helpful to improve the accuracy of pattern recognition. In this paper, the method of transient earth voltage to detect the partial discharge of transformers is proposed. Then the parameters measured by this method are extracted and briefly analyzed. Four artificial partial discharge models of transformers have been set up, including needle-plate defect in oil, air gap defect in oil, surface defect in oil and sphere-plate defect in oil. The experiment uses the constant-voltage testing method to extract the characteristic parameters from phase spectrogram of maximum discharge capacity and discharge frequency by the method of transient earth voltage and pulse current based on phase analyze. Partial discharge characteristic parameters have been extracted by the method of phase-resolved partial discharge. The differences between each type of discharge characteristics and the relationship between the two methods are comparatively analyzed. And the method of pattern recognition has been used which based on support vector machines. The data have been analyzed for recognition which are obtained by the method of transient earth voltage, pulse current and the combination. According to the analysis of the two groups of data comprehensively, the accuracy of pattern recognition has been greatly improved.