Broadband UHF Sensor And Its Application In GIS Online Monitoring

Because GIS has been operating under high voltage,high current and complex electromagnetic environment for a long time,and the damage caused by its production and transportation,such as cracking of basin insulator,internal air gap of basin insulator,etc.,it will cause the internal insulation strength of GIS to decrease or even lead to its internal insulation breakdown,and then cause GIS power outage accident.GIS partial discharge fault on-line monitoring system can effectively monitor GIS partial discharge faults,give early warning of its internal insulation status,and effectively reduce the occurrence of power outages caused by partial discharge in GIS.Currently,the sensors used for GIS partial discharge UHF detection have detection frequency bands,narrow,single detection frequency band,affect the air tightness of GIS,and the size of the structure is too large,so it is of great significance to carry out the research of broadband UHF sensor and its GIS partial discharge fault online monitoring system.First of all,this paper analyzes the UHF sensor theory used for GIS partial discharge UHF signal detection.With the aid of HFSS three-dimensional electromagnetic field simulation software,the radiation characteristics of UHF sensor are simulated and analyzed,and a partial discharge detection frequency range of300MHz～3000MHz is designed.Broadband UHF sensor,used CAD to draw its engineering documents,and made the actual partial discharge broadband UHF sensor model.In the laboratory,use a network analyzer to measure and analyze its voltage standing wave ratio,and discharge it with a needle board.The model simulates the insulation defects inside the GIS,and builds a 252 k V GIS partial discharge experiment platform.The partial discharge broadband UHF sensor is packaged and placed outside the GIS pot-type insulator pouring hole,and its ability to couple GIS partial discharge UHF signals is actually tested;Secondly,the UHF signal conditioning unit for partial discharge broadband UHF sensor output signal processing is designed and manufactured.The UHF signal conditioning unit designed in this article integrates a broadband filter unit,a broadband low-noise amplifier unit and a detection circuit unit.Among them,the broadband filter unit is a Chebyshev I-type bandpass filter,and the broadband low-noise amplifier unit is a two-stage cascaded TQP3M9008 low-noise amplifier.The detection circuit unit is implemented by a high-frequency envelope detection diode HSMS2852,using Altium Designer Draw its schematic file and PCB board diagram file,make the actual UHF signal conditioning unit,and debug and analyze the actual UHF signal conditioning unit of GIS partial discharge;Finally,the software unit of the GIS partial discharge fault online monitoring system is developed.Based on the industrial computer with built-in Windows system,this paper uses Lab VIEW software to develop the software unit of the GIS partial discharge fault online monitoring system,which mainly includes user management functions,local Discharge fault online monitoring function,historical data query function and system exit function,a partial discharge detection experiment platform was built in the laboratory,and the operating status of the software unit was actually tested.