Detection Of SF₆ Partial Discharge Decomposition Gas Based On Nano-composite Materials

SF₆ gas is widely used in power equipment because of its excellent insulation performance,but in the long-term operation process,there are partial discharge,high temperature and other faults in the equipment,which will cause the decomposition of SF₆ gas to produce SOF₂,SOF₄,SO₂F₂,SO₂,H₂S and other gases,greatly reducing the insulation performance of SF₆gas,affecting the safe operation of equipment.H₂S gas content can reflect the insulation performance of SF₆ gas inside the gas insulation equipment,so as to timely diagnose the internal discharge faults of the gas insulation equipment.Therefore,the detection of H₂S in SF₆ decomposition gas has become one of the important means of internal discharge fault detection in gas insulation equipment.In this paper,gas sensor method was adopted to detect SF₆ decomposition gas H₂S,and relevant research work is as follows:（1）The characteristics and decomposition of SF₆ gas are described in detail through literature review.The reasons why SF₆ gas can be an insulating gas are explained from the physical and chemical characteristics and electrical characteristics of SF₆ gas.The decomposition mechanism and decomposition products of SF₆ gas were studied,and the factors affecting the decomposition of SF₆ gas were analyzed in detail.Finally,it is pointed out that H₂S gas is the characteristic gas of partial discharge and the warning gas of high temperature failure of SF₆ gas insulation equipment,and is the necessary gas to detect the decomposition gas products of SF₆.（2）The BiVO₄-Cu O sensor for detecting H₂S gas was developed through specific experiments.Decahedral BiVO₄ nanoparticles were synthesized by hydrothermal method.Cu O nanoparticles were loaded onto the surface of BiVO₄ by calcination method,and bivo4-Cu O gas sensitive materials were successfully prepared.The material was characterized by XRD and SEM,and its microstructure,particle size,element and substance composition were analyzed,and the existence of BiVO₄-Cu O heterostructure was confirmed.Gas sensitivity study results show that at the optimal operating temperature of 180℃,its detection limit for H₂S gas is very low as 100 ppb,and its sensitivity response to H₂S concentration of 100 ppm is as high as 110.9,and the response time is only 45s.（3）The Bi₂Mo O₆-Cu O sensor for H₂S gas detection was prepared by upgrading the gas sensitivity of the sensor.Bi₂Mo O₆ spherical particles were successfully synthesized by hydrothermal method,and Bi₂Mo O₆-Cu O gas sensitive materials were obtained by calcination of Cu O nanoparticles with different mole ratios on the surface of Bi₂Mo O₆.The Bi₂Mo O₆-Cu O gas sensitive material was characterized by XRD,XPS,SEM and TEM.The phase structure,chemical valence state and microstructure of the material were studied,and the existence of Bi₂Mo O₆-Cu O heterostructure was confirmed.The gas sensitivity study results show that when the composite molar ratio of Cu O and Bi₂Mo O₆ is 1:20,the sensor has the best gas sensitivity to acetone,and its detection limit reaches 5 ppb.The gas sensor responds sensitively to 100ppm H₂S as high as 1150.64 with a response time of only 21s.The research work in this paper is a positive exploration of the application of gas sensor method in the on-line monitoring of SF₆ insulated electrical equipment,and the research results provide theoretical support and experimental basis for the state evaluation of SF₆insulated electrical equipment.