Research On Fault Location Method Of Gas-insulated Equipment Based On Gas Diffusion Effect

Gas insulated fully enclosed combined electrical equipment,also known as GIS equipment,has been widely used in high voltage and ultra high voltage fields.Sulfur hexafluoride(SF₆)gas is filled into GIS equipment as insulation and arc extinguishing medium.When discharging fault occurs inside the equipment,SF₆ gas will decompose and produce characteristic component gas that characterizes the fault.At present,the gas detection technology of characteristic components is becoming more and more mature,but the gas diffusion effect inside the equipment will affect the detected gas content of fault characteristic components,resulting in insufficient equipment fault detection.In order to further improve the accuracy of gas detection technology to judge whether the equipment is faulty or not and the fault location,it is necessary to study the diffusion effect and influencing factors of characteristic component gas in GIS equipment.First of all,this paper introduces the common fault types of GIS equipment by reference,and gives the characteristic gas components generated by SF₆ gas decomposition when insulation failure occurs in the equipment.Based on computational fluid dynamics(CFD)method,FLUENT simulation software was used to simulate the gas diffusion effect of fault characteristic components in GIS equipment.Secondly,the diffusion characteristics of four characteristic components of SO₂,H₂S,HF and CO are analyzed by simulation,and the time and concentration of the four gases to reach uniform diffusion can be obtained,which can be combined with the existing gas detection technology to help guide the time and period of field GIS equipment to detect gas components.It provides a theoretical basis for judging the latent fault inside the equipment.Under the conditions of 10 different initial concentrations,the function relation between the initial concentration and the concentration with uniform diffusion is obtained,which provides a theoretical basis for judging the severity of the fault and deducing the total amount of the initial gas in the fault.Three different fault locations were selected to study the variation of gas concentrations of four characteristic components diffused to the inlet with time.The study on gas diffusion effect of four characteristic components lays a foundation for fault location of GIS equipment.Finally,based on gas diffusion effect and CNN-LSTM,fault partition of GIS equipment is proposed.The gas diffusion data of GIS equipment in different fault areas obtained from gas diffusion effect were classified by combining CNN,LSTM and CNN-LSTM respectively,and the classification accuracy was 92.8%,96.3%and 98.6%,respectively.After fault partition of GIS devices,the scope of faults can be reduced and the initial fault location can be realized.