Novel Method for Partial Discharge Detection in Gas Insulated Substation

For the insulation diagnosis of electrical imaterials in power apparatus, partial discharge (PD) measurement has been recognized as an important tool. In this paper, electrical and mechanical methods were combined for the detection of the PD defect. To analyze the fundamental frequency vibration, the induced current including eddy current and circulating current in GIS was analyzed firstly. Then, PD pulses and vibrations on enclosure were measured on a 252kV GIS PD test system. PD faults included protrusion and insulator flashover. The phase of the pulse current of the two kinds of PD defects was analyzed. Meanwhile, the frequency spectrum of vibration on the GIS equipment was analyzed. In order to diagnose the partial discharge fault better, the relationship between the pulse current signals with the vibration signal was established. A more reliable PD detection method was proposed by combining with the electrical signal and the vibration signal.