| SF6 gas is a kind of synthetic gas,which is widely used in high voltage technology because of its stable chemical properties,excellent insulation and arc extinguishing performance.However,its large amount of emission will produce super strong greenhouse effects.In order to reduce the use and emission of SF6 gas,the exploration of its alternative gas has become a research hotspot.A large number of studies show that new perfluorinated insulating gases such as C4F7 N and C5F10 O have excellent environmental performance and arc extinguishing performance,but their research and application are still in the initial stage.The mixed gas composed of SF6 and N2 can greatly reduce the consumption of SF6,and can significantly improve the liquefaction of SF6 and the sensitivity of electric field nonuniformity,which has great industrial potential in the high-voltage power equipment industry.Therefore,the research on arc extinguishing performance of SF6/N2 mixed gas has engineering significance and academic value.In order to ascertain the arc extinguishing performance of SF6/N2 mixed gas and successfully apply it to high speed grounding switch,the research mainly starts from the experiment and simulation calculation of high speed grounding switch of mixed gas.Test aspect: For the 550 k V SF6/N2 mixed gas high speed grounding switch,build a measuring platform for electromagnetic induction current arc characteristic,design an arc observation system and method,use an arc voltage sensor and a Rogowski coil to measure the arc voltage and current respectively,and analyze the SF6/N2 mixed gas arc volt-ampere characteristics of high speed grounding switch;Use high-speed cameras to capture and collect arc images,perform morphological processing on the arc images,analyze the evolution of the arc shape during the breaking process of the high speed grounding switch,extract geometric characteristics such as the diameter of the arc,and analyze the effects of arc voltage,current,and power on the arc shape evolution The influence of geometric characteristics,to further understand the arc characteristics of mixed gas;In terms of simulation calculation: establish a two-dimensional multiphysics coupling transient arc mathematical model of the high speed grounding switch,analyze the breaking performance of the high speed grounding switch,and obtain the law of breaking phase angle,gas pressure and mixing ratio on the breaking performance.The research results show that the minimum gas configuration scheme for successfully breaking the 200 A electromagnetic induction current is a 30%SF6/70%N2 mixed gas of0.5MPa or a 20%SF6/80%N2 mixed gas of 0.7MPa;the SF6 content in the mixed gas is combustible The arc voltage in the arc stage,its stability,and the rate of rise before zero crossing have obvious effects.When the arc is extinguished,the arc root on the moving contact side is disconnected first,regardless of the gas mixing ratio;the arc diameter is highly linearly correlated with the current and the injected power;when the SF6 content in the SF6/N2 mixed gas is 20%,the peak value The average arc diameter at the moment is 30.8mm,and when it increases to 30%,40%,and 100%,the average arc diameter decreases by 2.92%,52.17%,and 23.78%.The arc simulation obtained the dynamic change of the arc shape,which is basically consistent with the experimental results;the lower the SF6 content in the mixed gas,the worse the arc radial heat dissipation capacity,which will cause the diameter to become thicker. |
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