The Research Of On-site Evaluation Technology Of UHF Online Monitoring Sensor

Since the large-scale use of Gas Insulated Substation（GIS）equipment in the 1980s,due to its low failure rate,high reliability and small footprint,GIS has been widely used in the current power system,so the safe and stable operation of GIS and its supporting equipment directly affects the normal operation of the power supply system.However,due to the complex internal structure of GIS,defects such as loose parts,dirt on the surface of the insulator,internal foreign objects,and conductor burrs will inevitably occur during the manufacturing and assembly process.Some defects will cause Partial Discharge（PD）in the GIS after being put into use,which is serious will cause insulation breakdown and accidents.Therefore,in order to ensure the safe and stable operation of power equipment,it is necessary to detect the PD of GIS equipment.In recent years,GIS PD Ultra High Frequency（UHF）detection technology has been rapidly developed and widely used due to its high sensitivity,wide detection bandwidth and strong anti-interference ability.However,in the field application of PD UHF detection method,the detection effect is not obvious due to incorrect sensor configuration,which limits the promotion and application of UHF detection technology to a large extent.Although the Conference International des Grands Reseaux Electriques（CIGRE）put forward a evaluation method for UHF sensors,there are many cases that the proposed method is not suitable for on-site evaluation.In view of the above problems,this dissertation does the following research.Based on the 110 kV GIS real platform,a set of GIS PD simulation device was processed,and the measurement control system was developed.On this basis,data collection and characteristic analysis were performed on the PD signals generated by the GIS PD simulation device;A high amplitude and steep front pulse generator based on HTS 30-08-UF high voltage electronic switch is designed and developed.The rising edge of the pulse signal can reachlevel,and the waveform repeatability is good.It is suitable for field verification of UHF sensor.At present,how to inject UHF electromagnetic wave calibration signals into the GIS without a built-in UHF sensor is one of the key problems faced the field sensitivity calibration of the GIS PD UHF online monitoring system.This dissertation is based on the development of a high amplitude and steep front pulse generator,proposed an external UHF electromagnetic wave transmitting method for GIS,that is,the calibration signal is injected via resin sprue on metal flange of basin-insulator.The propagation mode and the structure of electric field of UHF electromagnetic wave passing through the resin sprue is researched by simulation and theoretical analysis.Based on this,the propagation attenuation characteristics of injection pulse in GIS cavity are analyzed.It is proposed to calibration the UHF sensor of GIS by using the forward propagation coefficient in microwave network theory,often known as₂₁ parameter.The results show that the transfer function between the transmitter and receiver sensors can be obtained through the₂₁ parameter,and finally the signal output value of the sensor can be calculated,providing a basis for UHF sensor calibration.