PD pattern recognition based on transient earth voltage (TEV) pulse amplitude-frequency of occurrence diagrams for switchgears

Metal-enclosed switchgears are widely used in power distribution networks. According to the statistical data, the main reason of the switchgears' accident is the partial discharge in the switchgears. PD detection based on transient earth voltage (TEV) has been used widely. However, the accuracy of the pattern recognition results is unsatisfactory because of this method's recognition measure mainly according to the phase-amplitude diagrams, and the difficulty of obtaining the reference phase on site. In this paper, a pattern recognition method based on the amplitude-frequency diagrams was presented, which can be carried out without reference phase. Four typical PD models was set up and there amplitude-frequency diagrams were measured, the similarity of these diagrams for the same model under different voltages and different models were calculated and compared. The results indicate that under different voltages, the diagrams of the same defect model have high consistency; the TEV signal amplitude-frequency of occurrence diagrams of different models have significant differences. It is possible to carry out pattern recognition of the switchgears' PD without the reference phase based on amplitude-frequency diagrams.