Detection Study on Propagation Characteristics of Partial Discharge Optical Signal in GIS

Optical detection of partial discharge (PD) has irreplaceable advantages, in order to study the propagation characteristics of PD optical signals in gas-insulated switch (GIS), and the effectiveness and sensitivity of the optical detection method of PD. First, the simulation model of GIS is built in TracePro7.3, and the total flux map (TFM) and the average value of relative flux (AVRF) of the detection planes (DPs) are obtained to analyze the intensity distribution of the optical signals. Through the simulation, it is concluded that, when the source is close to the inner conductor or the tank inner surface, the AVRF of the DP is smaller, and it is more difficult to detect the optical signal. With the increase in the distance between the PD source and the DP, the optical signals' intensity attenuates rapidly; when the distance reaches 1.4 m, the attenuation is about 99%. The turning point of the T-shaped GIS has a great influence on the optical signal propagation, the AVRF of DP attenuates by up to 72.5%, and it is difficult for the optical signals to incident into the vertical part of the tank. Then, we made a fluorescent optical fiber sensor for PD detection in GIS and compared it with the pulse current method and ultrahigh-frequency (UHF) method. The results show that the optical detection method has the highest sensitivity when the distance between the PD source and the optical sensor is small. The effects of defects at different positions and angles on the amplitude of the detected optical signal are further studied. Practical experiments are carried out in the actual running GIS to verify the effectiveness of the proposed method. The research results will provide a new method for PD detection in GIS and improve the detection accuracy of PD.