Research On WS₂ Based Sensor And Detection System For Partial Discharge Characteristic Gases In Air Insulated Equipments

Air insulated equipment uses air as a natural insulating medium,and is widely used in manufacturing,transportation,gas fields,mines,and other industries that require high reliability in power supply.However,the operating environment of such equipment is relatively harsh.During installation and maintenance,long-term operation,or overload,it is inevitable that insulation degradation will cause electric field distortion,and partial discharge may occur,leading to insulation failure and causing safety accidents.After partial discharge faults break through air,two characteristic gases,nitrogen dioxide（NO₂）and carbon monoxide（CO）,will be generated.Timely and effective monitoring of the concentration of two fault characteristic gases is an important way to detect partial discharge faults in air insulated equipment,and has important significance for ensuring the safety of production in factories and enterprises and the safety of people’s property.Based on the project of the National Natural Science Foundation of China,a tungsten disulfide（WS₂）based gas sensor based on intrinsic and metal modified tungsten disulfide（WS₂）was prepared by hydrothermal method according to the components of partial discharge fault gases in air insulated equipment.The gas sensitivity of the sensor to NO₂ and CO gases was tested,and a gas sensitive detection system for detecting partial discharge fault gases in air insulated equipment was proposed.The main research work and results are as follows:（1）In this paper,five kinds of intrinsic WS₂,Ni-WS₂,Pd-WS₂,Pt-WS₂,and Au-WS₂ materials were prepared using a hydrothermal method using sodium tungstate dihydrate as the tungsten source and thioacetamide as the sulfur source.The morphology,structure,and elemental composition of the materials were investigated using various characterization methods such as XRD,SEM,EDS,and XPS.The prepared WS₂ based samples all exhibit a layered nanosheet structure,with uniform distribution of elements,complete grain growth,and high crystallinity.Doped metals increase the specific surface area and porosity of the substrate material,providing more diffusion paths and micro reaction chambers for the target reaction gas.At the same time,a planar thermal gas sensor with small size and low power consumption was selected and coated with the material to construct a hexagonal base gas sensor.（2）Based on the established gas sensor testing platform,experiments were conducted to test the gas sensitivity of the sensor to NO₂ and CO gases,including response sensitivity,response concentration fitting relationship,response/recovery time,repeatability,and long-term stability.The Ni metal doped WS₂ sensor exhibits higher response sensitivity in NO₂gas environments,with a sensitivity of about 3.08 times that of the intrinsic WS₂ sensor to 5 ppm NO₂.The response sensitivity of the Pt-WS₂ sensor to 10 ppm CO gas is 4.03,approximately 3.52 times that of the intrinsic WS₂ sensor;The response/recovery speed of the Au-WS₂ sensor to CO gas is 20 to 30 seconds faster than that of the Pt-WS₂ sensor.Based on the energy band structure,density of states,adsorption distance,adsorption energy,and charge transfer calculated by density functional theory,the sensitivity mechanism of metal modified tungsten disulfide materials was discussed from multiple perspectives.（3）The overall scheme of the gas sensing detection system based on STM12C5A60S2 is designed.The main control chip is a STC12C5A60S2 single chip microcomputer equipped with a high-speed voltage input type A/D converter.The signal processing circuit of the gas sensor is an in-phase proportional amplification circuit,and a voltage follower circuit is provided to improve the load carrying capacity.Select PT100 platinum thermistor to constitute a contact temperature sensor,test the resistance value of the thermistor through a Wheatstone bridge,and introduce a differential proportional amplification circuit with high input resistance to amplify the output signal.Use Multisim simulation software to build corresponding models to verify the rationality of the system circuit design,and complete the system board design and physical production with the reasonable layout of other modules.Based on the constructed gas sensing detection system simulating the application environment,various concentrations of the two target gases were tested,and the detection system achieved accurate detection and fault alarm of air partial discharge characteristic gases.