CF3I has been widely considered as a potential alternative for SF6,because it has low global warming potential(GWP)but an insulation capability that is 1.2 times greater than that of SF6.In this paper,the electron swa...CF3I has been widely considered as a potential alternative for SF6,because it has low global warming potential(GWP)but an insulation capability that is 1.2 times greater than that of SF6.In this paper,the electron swarm parameters of CF3I and its gas mixture with N2,including the effective ionization coefficient and electron drift velocity,are examined theoretically through the Boltzmann equation method in the condition of steady-state Townsend(SST)experiments.Based on the derived data of the limiting field strength of CF3I-N2gas mixture,taking into consideration of environmental aspects such as GWP,ozone depletion potential(ODP),liquefaction temperature and toxicity,we studied the possibility of applying the gas mixture as the insulation medium in gas-insulated switchgears(GIS)or cubic type gas-insulated switchgears(C-GIS).It is found that CF3I-N2gas mixtures contained 30%～70%CF3I perform comprehensively better than pure SF6and compressed N2,and especially in medium and low voltage environments,the boiling point of CF3I-N2gas mixture meets the domestic and global requirements in mid-low latitude regions.Therefore we conclude that the gas mixture is acceptable for replacing SF6as the insulation medium in C-GISs.展开更多
It is necessary to find an efficient selection method to pre-analyze the gas electric strength from the perspective of molecule structure and the properties for finding the alternative gases to sulphur hexafluoride （...It is necessary to find an efficient selection method to pre-analyze the gas electric strength from the perspective of molecule structure and the properties for finding the alternative gases to sulphur hexafluoride （SF6）. As the properties of gas are determined by the gas molecule structure, the research on the relationship between the gas molecule structure and the electric strength can contribute to the gas pre-screening and new gas development. In this paper, we calculated the vertical electron affinity, molecule orbits distribution and orbits energy of gas molecules by the means of density functional theory （DFT） for the typical structures of organic gases and compared their electric strengths. By this method, we find part of the key properties of the molecule which are related to the electric strength, including the vertical electron affinity, the lowest unoccupied molecule orbit （LUMO） energy, molecule orbits distribution and negativeion system energy. We also listed some molecule groups such as unsaturated carbons double bonds （C=C） and carbonitrile bonds （C=N） which have high electric strength theoretically by this method.展开更多
An online partial discharge(PD) measurement performed on a high voltage direct current(HVDC) wall bushing successfully identified the presence of internal discharges.The wall bushing is a sulfur hexafluoride gas-insul...An online partial discharge(PD) measurement performed on a high voltage direct current(HVDC) wall bushing successfully identified the presence of internal discharges.The wall bushing is a sulfur hexafluoride gas-insulated bushing,rated for 500 kV dc and terminated on a thyristor-controlled HVDC converter bridge.The measurement of PD within the HVDC station environment is particularly challenging due to the high levels of electromagnetic noise caused by thyristor switching events and external air-corona from the neighboring high-voltage equipment.An additional challenge is the""mixed"voltage stress on the bushing insulation,which has both ac and dc high-voltage components.There are also fast transients during the firing of thyristors in the HVDC conversion process that cause added stress to the insulation.As a result,the analysis and interpretation of PD data for HVDC equipment is more complex;PD pulses may occur in response to the ac,dc,or switching transient voltage stresses.In this paper,an online PD measurement strategy for noise filtering and isolation of PD sources within the bushing are discussed.The PD measurement data is plotted on a phase-resolved diagram where the line supply power cord voltage was used as a reference. The phase-resolved diagram appears to suggest that the fast transients,caused during switching,trigger some PD events.Measurements were also performed with the aid of a modern PD measurement instrument having noise separation capabilities.The findings from the online PD measurements are verified with physical evidence,found after the bushing was removed from service,suggested internal PD had occurred inside the bushing.展开更多
SF_6因具有良好的绝缘效果而被广泛地应用于电力系统中。但同时,SF_6也是一种温室气体,随着环境问题日益恶化,人们迫切需要找到替代SF_6的绝缘气体。为此,通过实验研究了环境友好气体c-C_4F_8及c-C_4F_8/N_2混合气体替代SF_6的可行性。...SF_6因具有良好的绝缘效果而被广泛地应用于电力系统中。但同时,SF_6也是一种温室气体,随着环境问题日益恶化,人们迫切需要找到替代SF_6的绝缘气体。为此,通过实验研究了环境友好气体c-C_4F_8及c-C_4F_8/N_2混合气体替代SF_6的可行性。通过调节电极间隙(1~6 mm)和气压(150~350 k Pa),测量了气体在不同条件下的击穿电压及击穿电流波形,得到了气体的绝缘特性并与SF_6气体进行了对比分析。实验结果表明:纯净的c-C_4F_8气体的绝缘强度约为SF_6的1.3倍,体积比为1:1的c-C_4F_8/N_2混合气体的绝缘强度约为与SF_6的0.9倍。通过计算,c-C_4F_8/N_2混合气体的液化温度可以达到电力系统使用要求。考虑到c-C_4F_8气体对于环境的影响较小,使用c-C_4F_8/N_2混合气体作为替代SF_6的绝缘气体,有着良好的应用前景。展开更多
±1100 k V直流纯SF_6气体绝缘穿墙套管(以下简称±1100 k V直流穿墙套管)为目前世界电压等级最高的直流设备,也是直流输电系统中的关键设备。依托昌吉至古泉±1100 k V特高压直流输电工程,以±1100 k V直流穿墙套管为...±1100 k V直流纯SF_6气体绝缘穿墙套管(以下简称±1100 k V直流穿墙套管)为目前世界电压等级最高的直流设备,也是直流输电系统中的关键设备。依托昌吉至古泉±1100 k V特高压直流输电工程,以±1100 k V直流穿墙套管为研究对象,建立了套管的三维物理模型,从直流绝缘材料、电场强度、机械强度及温度场等方面进行优化设计,并制造了±1100 k V直流穿墙套管样机。该样机顺利通过了全套型式试验验证,其各项性能指标均满足工程要求。通过该套管的研制,掌握了特高压直流SF_6气体穿墙套管的关键技术,并可以推广应用到其他电压等级产品中。展开更多
基金Project supported by National Natural Science Foundation of China （51177101）
文摘CF3I has been widely considered as a potential alternative for SF6,because it has low global warming potential(GWP)but an insulation capability that is 1.2 times greater than that of SF6.In this paper,the electron swarm parameters of CF3I and its gas mixture with N2,including the effective ionization coefficient and electron drift velocity,are examined theoretically through the Boltzmann equation method in the condition of steady-state Townsend(SST)experiments.Based on the derived data of the limiting field strength of CF3I-N2gas mixture,taking into consideration of environmental aspects such as GWP,ozone depletion potential(ODP),liquefaction temperature and toxicity,we studied the possibility of applying the gas mixture as the insulation medium in gas-insulated switchgears(GIS)or cubic type gas-insulated switchgears(C-GIS).It is found that CF3I-N2gas mixtures contained 30%～70%CF3I perform comprehensively better than pure SF6and compressed N2,and especially in medium and low voltage environments,the boiling point of CF3I-N2gas mixture meets the domestic and global requirements in mid-low latitude regions.Therefore we conclude that the gas mixture is acceptable for replacing SF6as the insulation medium in C-GISs.
基金supported by National Natural Science Foundation of China(Nos.51177101 and 51337006)
文摘It is necessary to find an efficient selection method to pre-analyze the gas electric strength from the perspective of molecule structure and the properties for finding the alternative gases to sulphur hexafluoride （SF6）. As the properties of gas are determined by the gas molecule structure, the research on the relationship between the gas molecule structure and the electric strength can contribute to the gas pre-screening and new gas development. In this paper, we calculated the vertical electron affinity, molecule orbits distribution and orbits energy of gas molecules by the means of density functional theory （DFT） for the typical structures of organic gases and compared their electric strengths. By this method, we find part of the key properties of the molecule which are related to the electric strength, including the vertical electron affinity, the lowest unoccupied molecule orbit （LUMO） energy, molecule orbits distribution and negativeion system energy. We also listed some molecule groups such as unsaturated carbons double bonds （C=C） and carbonitrile bonds （C=N） which have high electric strength theoretically by this method.
基金Manitoba Hydro for funding and supporting this research
文摘An online partial discharge(PD) measurement performed on a high voltage direct current(HVDC) wall bushing successfully identified the presence of internal discharges.The wall bushing is a sulfur hexafluoride gas-insulated bushing,rated for 500 kV dc and terminated on a thyristor-controlled HVDC converter bridge.The measurement of PD within the HVDC station environment is particularly challenging due to the high levels of electromagnetic noise caused by thyristor switching events and external air-corona from the neighboring high-voltage equipment.An additional challenge is the""mixed"voltage stress on the bushing insulation,which has both ac and dc high-voltage components.There are also fast transients during the firing of thyristors in the HVDC conversion process that cause added stress to the insulation.As a result,the analysis and interpretation of PD data for HVDC equipment is more complex;PD pulses may occur in response to the ac,dc,or switching transient voltage stresses.In this paper,an online PD measurement strategy for noise filtering and isolation of PD sources within the bushing are discussed.The PD measurement data is plotted on a phase-resolved diagram where the line supply power cord voltage was used as a reference. The phase-resolved diagram appears to suggest that the fast transients,caused during switching,trigger some PD events.Measurements were also performed with the aid of a modern PD measurement instrument having noise separation capabilities.The findings from the online PD measurements are verified with physical evidence,found after the bushing was removed from service,suggested internal PD had occurred inside the bushing.
文摘SF_6因具有良好的绝缘效果而被广泛地应用于电力系统中。但同时,SF_6也是一种温室气体,随着环境问题日益恶化,人们迫切需要找到替代SF_6的绝缘气体。为此,通过实验研究了环境友好气体c-C_4F_8及c-C_4F_8/N_2混合气体替代SF_6的可行性。通过调节电极间隙(1~6 mm)和气压(150~350 k Pa),测量了气体在不同条件下的击穿电压及击穿电流波形,得到了气体的绝缘特性并与SF_6气体进行了对比分析。实验结果表明:纯净的c-C_4F_8气体的绝缘强度约为SF_6的1.3倍,体积比为1:1的c-C_4F_8/N_2混合气体的绝缘强度约为与SF_6的0.9倍。通过计算,c-C_4F_8/N_2混合气体的液化温度可以达到电力系统使用要求。考虑到c-C_4F_8气体对于环境的影响较小,使用c-C_4F_8/N_2混合气体作为替代SF_6的绝缘气体,有着良好的应用前景。
文摘±1100 k V直流纯SF_6气体绝缘穿墙套管(以下简称±1100 k V直流穿墙套管)为目前世界电压等级最高的直流设备,也是直流输电系统中的关键设备。依托昌吉至古泉±1100 k V特高压直流输电工程,以±1100 k V直流穿墙套管为研究对象,建立了套管的三维物理模型,从直流绝缘材料、电场强度、机械强度及温度场等方面进行优化设计,并制造了±1100 k V直流穿墙套管样机。该样机顺利通过了全套型式试验验证,其各项性能指标均满足工程要求。通过该套管的研制,掌握了特高压直流SF_6气体穿墙套管的关键技术,并可以推广应用到其他电压等级产品中。
