Research On Designs And Applications Of A Partial Discharge Ultrasonic Detection Test Device

Gas Insulation Switchgear?GIS?is mostly used in substations of 110k V and above for its compact structure,high reliability,good safety and convenient maintenance.SF₆gas is used as insulation and arc extinguishing medium of GIS.It could lead to large scale blackout once a GIS equipment insulation accident happened,which could cause serious social impact and major economic losses.Insulation defects and faults can be found in time by the application of live detection technology,which has important theoretical and practical value for ensuring the safe operation of GIS.It is summarized that the characteristics,generation mechanism and classifica-tion of partial discharge,and it is introduced that five typical types defects of partial discharge inside GIS equipment.It is described that three partial discharge detection methods frequently applied in the field,and with their basic principle and application range,such as pulse current method,ultra-high frequency method and ultrasonic method.Based on the ultrasonic method,a partial discharge ultrasonic detecting device is developed.The hardware part and the software part of the device are explained in principle,and the structural part of the detecting rod is designed.Combined with the ultrasonic testing method,detailed testing steps are developed based on relevant standards and actual conditions on site.The detection device is used to detect GIS equipment of different voltage levels in two 500k V substations.The results are showed that from the pulse mode map and phase mode map,and the signal is obviously formed into two clusters in a cycle.Combined with the typical actual case spectrum reference are given by the relevant ultrasonic testing standards,the spectrum analyzed and detected preliminarily is compliance with the characteristics of the floating potential discharge,and is verified by the device disintegration inspection.In summary,the partial discharge ultrasonic detecting device is developed in this dissertation and the sensor can be stably fixed on the tank of the GIS equipment.The test interference caused by the hand shake during the test are reduced,the test range are broaded by the test rod with the telescopic expansion,It can not only be avoided that the climbing operation of the test points at the high point of the GIS equipment,but also the difficulty that the GIS equipment of the 220k V voltage level cannot be detected due to the compact structure and some test points are solved.In addition,defects can be accurately located and identified by the partial discharge ultrasonic detecting device according to the detection data,and defects are eliminated in time to ensure safe and reliable operation of the device.