【作者】 周原；

【导师】 司马文霞；

【作者基本信息】 重庆大学 ， 电气工程， 2012， 硕士

【摘要】 特高压直流（UHVDC）在大容量、远距离输电方面比传统交流输电具有更大的优势，已成为当代电力技术发展的重要标志。随着我国电力系统全国联网、西电东送、南北互供工程的实施,我国电网将形成大容量交直流并列运行的格局。在特高压直流输电线路的建设过程中，由于直流输电线路跨度较大，架设新的输电线路面临越来越严重的走廊用地紧张以及生态环境态等问题，特别是在东部发达地区这一问题尤为突出。采用交直流同塔架设可以节约土地资源、降低工程对环境的破坏并有效降低工程成本。可以预见，交流输电线路与±800kV直流输电线路同塔架设的输电方式必将出现。迄今为止，我国乃至世界范围内尚无特高压直流与交流线路同塔架设的设计经验和运行经验。目前国外虽已有采用交直流同塔架设的输电线路，但电压等级、负荷均较低，交直流线路间的耦合作用不严重；国内对于平行架设交直流线路间的相互影响的研究多为同廊道架设下交直流线路间相互影响，而与同廊道架设相比，交直流同塔架设耦合作用更为严重。因此深入研究交直流同塔架设线路的相互影响并对其工程应用的可行性进行分析，在理论和工程方面均具有十分重要的意义。本文从理论上分析了交直流同塔架设线路耦合作用产生的机理，对直流线路耦合分量的不同成分及其影响因素、交流换位对直流线路工频耦合分量的抑制作用进行了计算分析。根据规划中的锡盟-上海交直流同塔多回输电线路相关数据，采用电磁暂态程序PSCAD/EMTDC建立了详细的直流换流站模型以及交直流同塔架设输电线路内部过电压仿真模型。运用模型对交直流线路间的基频耦合作用、过电压及其对同塔架设线路绝缘配合的影响进行了研究。主要内容包括：1)交流正常运行在直流线路产生的工频耦合分量及其影响因素；2)超高压交流线路工频过电压，交、直流线路操作过电压对交流线路以及同塔架设直流线路感应过电压及两侧换流站工频耦合分量的影响；3)计算了交直流同塔架设线路的感应电压、感应电流，以及交、直流重合闸（重启动）过程中的潜供电流，并提出了限制措施。通过仿真计算及分析，本文得到如下结论：1）交流线路对同塔架设直流线路的耦合作用较为严重，可采用耦合段内均匀换位对交流线路正常运行时直流线路上的工频耦合分量进行限制。2）交流线路换位对交流线路不对称故障时直流线路上的工频耦合分量没有限制作用，需要在设计中考虑其对换流变的影响；3）交流线路工频过电压，交、直流操作过电压对同塔架设线路绝缘不造成威胁；4）与交流线路上的潜供电流相比，直流线路潜供电流很小，可通过适当延长直流第一次重启动时延避免重启动失败。更多还原

【Abstract】 With the rapid development of electric power industry in China, UHVDCtransmission, with its advantages over long distance and high capacity transmission, isbecoming a promising developing direction in the UHV transmissiontechnology.Several EHV and UHV DC transmission project have been put intooperation in China and the power grid in China is forming a pattern of parallel operationof large-capacity AC/DC transmission. Facing the reality of corridor shortage in someregions and environmental restriction, siting of new transmission corridors has becomeincreasingly difficult, especially in southeast China. Adopting AC/DC hybridtransmission line provides an attractive solution to the problem of restrictedright-of-way，so it is predictable that AC/DC hybrid transmission lines will occur inChina.Thus far, no EHVAC and UHVDC hybrid line built on the same tower exists inChina and abroad. Very few hybrid AC/DC transmission lines have been constructedabroad, but the voltage and load level are relatively low compare with UHVDC/EHVAC hybrid line, so the coupling effect between the AC/DC conductors is lessserious. Research of AC/DC coupling in China mainly focus on AC/DC line built alongthe same right-of way, but UHVDC/EHVAC lines built on the same tower have closeproximity between conductors, which makes the coupling effect more serious. As such,a computer simulation of the AC and DC coupling effect of lines built on the sametower can serve as a reference for future designs.This thesis discussed the method of calculating electromagnetic coupling betweenDC and AC transmission lines,analyzed the formation mechanism of capacitive andinductive component of the fundamental coupling and its influencing factors,thecomputing method of AC/DC coupling with AC transposition is also put forward.Withthe analysis and results, acording to the parameters of planning Ximeng-ShanghaiEHVAC/UHVDC hybrid transmission project, the detailed simulating model of DCconverter station and hybrid transmission line with double circuits AC500kV and DC±800kV transmission line are presented.Base on the simulating model ofUHVDC/EHVAC hybrid transmission line, the study are carried out in the followingaspects:1) The fundamental frequency component of DC line with different AC/DCoperation conditions;2) AC/DC switching overvoltage and their influence on hybrid line insulation;3) Induced current and voltage during outage maintenance and secondary arccurrent during DC restart, their restricting methods are also analyzed.Through simulation and analysis, the following conclusions are obtained：1)Normally operating AC line can produce serious fundamental frequency component onDC line,Three-segment-transposition of AC line within the hybrid line can reduce theDC line induced component effectively；2) With AC asymmetric fault, there is norestricting role of AC line transposition on power frequency coupling component of DCline, which should be considered in the design of the converter transformers；3) ACpower frenquency overvoltage and AC/DC switching overvoltage within the hybrid linedoesn’t pose a threat to the insulation of adjacent circuits；4) Compare with thesecondary arc current on AC line, secondary arc current on DC line is very small, whichdoesn’t affect the DC line restart obviously,we may extend the first restarting delayappropriately to avoid DC restart failure.更多还原