目前在电力行业中广泛应用的SF6气体具有严重的温室效应,寻找一种绝缘性能优良的环保型替代气体成为研究热点。近年来,C3F7CN及其混合气体凭借出色的绝缘性能和环保特性得到了国内外学者的广泛关注。目前针对其放电分解机理的研究较少...目前在电力行业中广泛应用的SF6气体具有严重的温室效应,寻找一种绝缘性能优良的环保型替代气体成为研究热点。近年来,C3F7CN及其混合气体凭借出色的绝缘性能和环保特性得到了国内外学者的广泛关注。目前针对其放电分解机理的研究较少。首先,基于ReaxFF反应分子动力学方法和密度泛函理论,从微观层面模拟研究了C3F7CN/CO2混合气体的分解机理。基于构建的C3F7CN/CO2混合气体模型,研究了温度对C3F7CN分解过程的影响,分析了其可能的分解路径、产物类型及分布等。计算结果表明,C3F7CN在局部过热或放电等故障条件下分解容易产生CF3·、C3F7·、C·、CF3CFCN·、CF2·和F·等各类自由基,上述自由基复合将产生CF4、C2F6、C3F8、CF3CN、CO等产物。其次,利用气体绝缘试验平台和气相色谱质谱联用仪(gas chromatography mass spectrometer,GC-MS),试验分析了其多次击穿后的分解产物。试验结果表明,混合气体多次击穿后的主要分解产物是CF4、C2F6、CF3CN。这些产物分子均具有比较好的绝缘能力,保障了C3F7CN/CO2混合气体的绝缘性能不被破环。相关结论为进一步探究C3F7CN/CO2混合气体的绝缘特性及协同效应等课题提供理论依据和工程指导。展开更多
Heptafluoroisobutyrontrile(C_(3)F_(7)CN)performs well in dielectric properties and environmental protection,which has the potential to replace SF6 gas.The decomposition characteristics of C_(3)F_(7)CN mixture under fa...Heptafluoroisobutyrontrile(C_(3)F_(7)CN)performs well in dielectric properties and environmental protection,which has the potential to replace SF6 gas.The decomposition characteristics of C_(3)F_(7)CN mixture under fault conditions directly affect the possibility of its replacement for SF6 gas.However,the number of studies on the decomposition characteristics of C_(3)F_(7)CN mixture under overheating fault is less.In this paper,the decomposition characteristics of C_(3)F_(7)CN/CO_(2) mixture under an overheating fault are studied by gas chromatography-mass spectrometry(GC/MS)and quantum chemical calculations.Byproducts CO,C_(3)F_(6) and HF are detected at 200℃.At 550℃,the C_(3)F_(7)CN molecule begins to decompose and produces CHF_(3),C_(2)F_(4),CF_(3)CN and CNCN.Moreover,the results of GC/MS show that the insulation medium C_(3)F_(7)CN contains an impurity,which is C3HF7(HFC-227ea).Combined with the results of GC/MS and quantum chemistry calculations,it can be concluded that the decomposition by-product C_(3)F_(6) at 200℃ mainly comes from the decomposition of C_(3)HF_(7).C_(3)HF_(7) reduces the decomposition temperature of the C_(3)F_(7)CN/CO_(2) mixture.Therefore,it is very important to improve the purity of the insulation medium C_(3)F_(7)CN.展开更多
文摘目前在电力行业中广泛应用的SF6气体具有严重的温室效应,寻找一种绝缘性能优良的环保型替代气体成为研究热点。近年来,C3F7CN及其混合气体凭借出色的绝缘性能和环保特性得到了国内外学者的广泛关注。目前针对其放电分解机理的研究较少。首先,基于ReaxFF反应分子动力学方法和密度泛函理论,从微观层面模拟研究了C3F7CN/CO2混合气体的分解机理。基于构建的C3F7CN/CO2混合气体模型,研究了温度对C3F7CN分解过程的影响,分析了其可能的分解路径、产物类型及分布等。计算结果表明,C3F7CN在局部过热或放电等故障条件下分解容易产生CF3·、C3F7·、C·、CF3CFCN·、CF2·和F·等各类自由基,上述自由基复合将产生CF4、C2F6、C3F8、CF3CN、CO等产物。其次,利用气体绝缘试验平台和气相色谱质谱联用仪(gas chromatography mass spectrometer,GC-MS),试验分析了其多次击穿后的分解产物。试验结果表明,混合气体多次击穿后的主要分解产物是CF4、C2F6、CF3CN。这些产物分子均具有比较好的绝缘能力,保障了C3F7CN/CO2混合气体的绝缘性能不被破环。相关结论为进一步探究C3F7CN/CO2混合气体的绝缘特性及协同效应等课题提供理论依据和工程指导。
基金supported by the National Key R&D Program of China(2017YFB0902500)Science&Technology Project of State Corporation of China:The Environment-Friendly Gas-Insulated Transmission Line(GIL)and National Natural Science Foundation of China(51877203)。
文摘Heptafluoroisobutyrontrile(C_(3)F_(7)CN)performs well in dielectric properties and environmental protection,which has the potential to replace SF6 gas.The decomposition characteristics of C_(3)F_(7)CN mixture under fault conditions directly affect the possibility of its replacement for SF6 gas.However,the number of studies on the decomposition characteristics of C_(3)F_(7)CN mixture under overheating fault is less.In this paper,the decomposition characteristics of C_(3)F_(7)CN/CO_(2) mixture under an overheating fault are studied by gas chromatography-mass spectrometry(GC/MS)and quantum chemical calculations.Byproducts CO,C_(3)F_(6) and HF are detected at 200℃.At 550℃,the C_(3)F_(7)CN molecule begins to decompose and produces CHF_(3),C_(2)F_(4),CF_(3)CN and CNCN.Moreover,the results of GC/MS show that the insulation medium C_(3)F_(7)CN contains an impurity,which is C3HF7(HFC-227ea).Combined with the results of GC/MS and quantum chemistry calculations,it can be concluded that the decomposition by-product C_(3)F_(6) at 200℃ mainly comes from the decomposition of C_(3)HF_(7).C_(3)HF_(7) reduces the decomposition temperature of the C_(3)F_(7)CN/CO_(2) mixture.Therefore,it is very important to improve the purity of the insulation medium C_(3)F_(7)CN.
