Detection of Partial Discharge in GIS and Transformer Under Impulse Voltage by Fluorescent Optical Fiber Sensor

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%.