Comparison and Analysis of On-line Partial Discharge Measurement Methods for Gas Insulation Substation

In this paper, we compare and analyze the signals of acoustic emission (AE) sensor, high-frequency current transformer (HF-CT) and capacitive coupled (CC) sensor inspection methods when they are used to detect the partial discharge (PD) in gas isolation substations (GIS). The PD location feasibility of the AE method is also studied. In general, the leakage currents are measured by using the HF-CT. And the electric fields are measured by using the CC sensors. However, the PD signals measured from the electric methods are usually hard to judge their accurate location while the AE method has good direction ability. Since the frequency of PD signals from AE measurements is usually less than 100 kHz, within the specific location, we can use AE sensors with frequency response range from 23 ~ 80 kHz to do the on-site, long-term observation. From the practically measured results, we definitely obtained the PD signals in a 161-kV GIS for all three different sensors.