Study On Partial Discharge Characteristic Of Insulated Tie Rod In GIS Arc Extinguishing Chamber

Insulated tie rod in disconnector of gas insulated switchgear(GIS)is one of the key components in the whole equipment,it will bear great voltage drop and rotating force in operation,which will lead to a series of defects such as wear and tear on its interior and surface,these defects will lead to distortion of electric field distribution on the surface of insulated tie rod,partial discharge and eventually flashover along the surface.At present,the research on the characteristics of partial discharge spectra of GIS insulating tie rod is still unclear at home and abroad.In order to discover the fault of GIS insulated tie rod in time,it is necessary to study the characteristics of partial discharge spectrum.By investigating the typical defects of insulating tie rods in production and operation,the following four typical defects are set up:surface metal tip?surface scratch?surface conductive powder adhesion?Internal air gap.The distribution of electric field on the surface of insulated tie rod with different defect types is analyzed by three-dimensional finite element simulation,and the distortion rule of electric field distribution on insulated tie rod with defect is obtained,the results show that the electric field enhancement coefficient is the largest when metal particles adhere to the surface,which means that the electric field distortion is the greatest;the other two defects have higher electric field enhancement coefficient when the defect is far from the central guide rod.A partial discharge test platform for GIS insulated tie rod was built,after comparing the advantages and disadvantages of partial discharge detection methods,UHF method and ultrasonic method are chosen to detect partial discharge.In the experiment,three kinds of defects were set up according to the actual operation conditions,and two groups of variables,voltage value and surface humidity,were set to compare.In order to eliminate the interference signal as far as possible,and solve the problem of signal attenuation caused by the loss of UHF and ultrasonic signals in the process of transmission to sensors,in the experiment,the chaotic detection model of partial discharge pulse signal under strong noise background is constructed by using the double-coupled Duffing oscillator system with transient synchronous catastrophe under the excitation of partial discharge signal pulse,which effectively improves the detection accuracy of UHF and ultrasonic signals.By comparing the experimental maps,it can be found that the UHF maps and ultrasonic data of partial discharge caused by different defects have different characteristics,and,UHF method is more sensitive to metal tip defect and surface scratch defect with higher voltage level;ultrasound detection is more sensitive to the adhesion reaction of graphite powder on the surface of tie rod;the higher the voltage and humidity,the more obvious the phenomenon of partial discharge is.The research results of this paper can provide technical support for partial discharge live detection of GIS insulated tie rod,favorable for timely detection of insulation defects of GIS insulated tie rod,it provides technical support for improving the maintenance strategy of GIS equipment and reducing the operation cost of power grid.