Shiyou Wu

This paper proposes a method to localize multiple partial discharge (PD) sources in air-insulated substation by using radio frequency (RF) antenna sensors combining with clustering algorithm, which solves the problem that multiple PD or interference sources are difficult to localize in air-insulated substation (AIS). Our research group made four omnidirectional RF antenna sensors, the detection frequency band was 250 MHz-3 GHz, the voltage standing wave ratio (VSWR) of the RF antenna in the detection frequency band was less than 2, which meets the detection requirements. The scenes of multiple PD sources in AIS were simulated in the laboratory, the time difference of arrival (TDOA) was collected through four RF antennas, and the clustering effects of K-means and Two Step algorithms were compared. Based on the normal distribution characteristics of TDOAs and the better Two Step algorithm, a $3\sigma $ -Two Step algorithm was proposed to process TDOAs and output the centers of TDOAs. Newton iterative algorithm was used to solve the localization equations. The results show that the average localization error of two PD sources was 0.21 m and that of three PD sources was 0.45 m. The PD localization tests were carried out in an actual AIS in China, the proposed method localized a corona discharge on a post insulator and a corona discharge on a disconnector. Through the verifications with an ultraviolet camera, it was obtained that the localization errors at each position were within the range of 0.6-2 m.

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.

Partial discharge (PD) is a common phenomenon in high voltage (HV) equipment, which will radiate light signals outward in the process of discharge, by detecting this optical signal, we can judge whether the HV equipment have PDs or not, the conventional detection methods under impulse voltage are very complex due to the interference of electromagnetic (EM) wave, but optical method does not have this problem. Fluorescent optical fiber is not affected by numerical aperture problem, so the sensitivity of fluorescent optical fiber sensor is much higher than that of traditional quartz optical fiber sensor. In this work, the fluorescent optical fiber sensor was manufactured and applied to the PD detection in gas insulated switch (GIS) and transformer, fluorescent optical fiber was used as a probe, which was connected with the transmission optical fiber by coupler, and the photomultiplier tube was used to convert the optical signal into electrical signal for displaying by oscilloscope. The discharge signal can be detected by the sensor when the impulse voltage was applied to the GIS and transformer, and it was less affected by the interference of EM wave signals. As the PD source at different positions in GIS, we found that the optical signal attenuates greatly when the optical was blocked by some internal structures, and the attenuation was increase with the increase of distance between PD source and the sensor. The optical signals of PDs can also be detected by the sensor in the transformer, but the attenuation of the optical signal in the transformer was greater than that in GIS, it was greatly affected by the blocking of windings. The two experiments were verified in the TracePro simulation software, and the average deviations between results of experiments and simulations were less than 10%.