The Research On The Partial Discharge Detection Methods Of GIS Based On Ultrasonic And UHF

Gas Insulated Switcher,which is also called GIS power supply device,has the advantages of compact structure,high reliability of power supply system,low maintenance and repair cost,and less influence from various external factors,etc,and has been widely developed and applied in power systems of many countries in the world.However,considering that GIS power supply equipment is fully closed structure,When there is an internal malfunction,it will take longer time for maintenance and processing,which will bring more severe fault impact compared with open power substation.According to the research results,partial discharge is a phenomenon of insulation defects in GIS equipment.In this paper,the partial discharge signal is analyzed by the combination of ultrasonic wave and UHF to clarify the defect type,complete the accurate positioning and eliminate hidden dangers,and ensure the equipment can be safely,stably and efficiently operated.The paper is dedicated to analyze the partial discharge mechanism of GIS equipment and its representative insulation defects,and compare some conventional detection technologies.The paper mainly includes the following points,Firstly,the paper builded an experimental platform for partial discharge in the laboratory,and artificially set four typical insulation defect discharge models: metal tip discharge,floating potential discharge,air gap inside insulation discharge and metal free particles discharge.Secondly,the paper detected the defects one by one with the ultrasonic and UHF detection method,analyzed the detection result spectrum of the ultrasonic detection method in the continuous and the phase mode,at the same time did the further research on the phase of the UHF detection method.Thirdly,the paper also studied when the metal tip discharge and the floating potential discharge occur simultaneously,to sum up the characteristics of the discharge spectrum for GIS fault pattern recognition.Finally,the ultrasound-electric combination method was used to locate the position of the discharge source for insulation defects accurately.With the study of partial discharge on GIS by ultrasonic and UHF detection method,and a comprehensive study combining these two detection methods,the author also studied on-site to combine the detection principle and positioning technology.The method was used to detect a floating potential discharge defect in a current transformer of 110 k V GIS substation of Gansu Lanzhou Power Supply Company,and then disassembled for inspection,the validity of the method was proved,so that the power equipment can operate safely and stably.