Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have prove...Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have proven their operational reliability and functional assurance.In the past,cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables.New developments of high voltage XLPE cables make it possible to use this technology for EHV level applications in transmission networks.Within this paper,mixed network configurations,consisting of overhead lines and high voltage cables,are investigated.An exemplary EHV transmission line with a total length of about 100 km,which is quite typical for Central Europe,has been studied.Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice.The length of the cable sections are ranging from several kilometers up to lengths of 100 km.In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts.A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system.Numerical programs like ATP/EMTP have been used for these simulations.Peak values and wave shapes of the transient voltage stress have been evaluated,based on different systems and within possible combinations.In respect of the insulation coordination and transient stress at network nodes,the voltage-time trends are also analyzed.The combination of high voltage overhead and cable transmission systems,especially such with lengths of more than about 50 km,are making tightened and extended demands to the network design,to the operational management and of course to the network protection also.As an output of this investigations,the results might influence the strategy in running this new type of combined transmission systems.展开更多
绝缘子自然积污特性研究对架空输电线路的外绝缘配置具有重要意义。为研究特高压直流输电线路积污特性,准确设计线路绝缘配置。笔者通过对±800 k V楚穗直流输电线路沿线绝缘子串进行人工污秽取样分析,结合线路沿线的气候特征及污染...绝缘子自然积污特性研究对架空输电线路的外绝缘配置具有重要意义。为研究特高压直流输电线路积污特性,准确设计线路绝缘配置。笔者通过对±800 k V楚穗直流输电线路沿线绝缘子串进行人工污秽取样分析,结合线路沿线的气候特征及污染源,研究气象条件、污染源以及材质对外绝缘积污的影响。研究表明,特高压直流线路绝缘子积污受大气环境与污染源的影响;复合绝缘子表面污秽度远大于玻璃和陶瓷绝缘子。展开更多
文摘Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have proven their operational reliability and functional assurance.In the past,cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables.New developments of high voltage XLPE cables make it possible to use this technology for EHV level applications in transmission networks.Within this paper,mixed network configurations,consisting of overhead lines and high voltage cables,are investigated.An exemplary EHV transmission line with a total length of about 100 km,which is quite typical for Central Europe,has been studied.Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice.The length of the cable sections are ranging from several kilometers up to lengths of 100 km.In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts.A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system.Numerical programs like ATP/EMTP have been used for these simulations.Peak values and wave shapes of the transient voltage stress have been evaluated,based on different systems and within possible combinations.In respect of the insulation coordination and transient stress at network nodes,the voltage-time trends are also analyzed.The combination of high voltage overhead and cable transmission systems,especially such with lengths of more than about 50 km,are making tightened and extended demands to the network design,to the operational management and of course to the network protection also.As an output of this investigations,the results might influence the strategy in running this new type of combined transmission systems.
文摘绝缘子自然积污特性研究对架空输电线路的外绝缘配置具有重要意义。为研究特高压直流输电线路积污特性,准确设计线路绝缘配置。笔者通过对±800 k V楚穗直流输电线路沿线绝缘子串进行人工污秽取样分析,结合线路沿线的气候特征及污染源,研究气象条件、污染源以及材质对外绝缘积污的影响。研究表明,特高压直流线路绝缘子积污受大气环境与污染源的影响;复合绝缘子表面污秽度远大于玻璃和陶瓷绝缘子。
