特高压气体绝缘开关设备套管的宽频等效电路建模
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摘要
气体绝缘开关设备(GIS)进出线套管处的电磁模型对特快速暂态过电压(VFTO)、暂态外壳电压(TEV)以及外部瞬态空间电磁场的建模计算有重要影响。特高压GIS系统的VFTO频率最高可达100MHz,此时套管屏蔽层导体的长度与电磁波波长可比拟,不能再用集总参数对套管建模。建立了具有双层屏蔽导体的特高压GIS复合套管宽频等效电路,分别采用传输线理论、分段传输线的级联和近似公式建立套管的三导体系统间均匀段、尺寸渐变段的双导体和导体间电磁泄漏阻抗的模型;用集总电容来等效导体尺寸不连续处激发的电磁波的高次模对主模传输的影响;分别提取套管顶部均压环、中间屏蔽层的对地电容,提取套管顶部均压环对中间屏蔽层的部分电容。综合上述传输线及各个部位的阻抗模型,计算1~100MHz频率范围内,从套管底部看进去的输入阻抗,并与全波电磁仿真的套管三维输入阻抗对比,二者一致性较好。
Electromagnetic model of bushing of gas insulated switchgear(GIS) is very important for the simulation of very fast transient over-voltage(VFTO), transient enclosure voltage(TEV) and transient electromagnetic field. The VFTO can contain frequency components up to 100 MHz. At such high frequencies, the length of the inner shielding conducting layer is comparable with the wavelength and hence the bushing can not be modelled as a lumped parameter element. The broadband circuit model of a gas insulated bushing with double layer shielding is investigated. The three-conductor system of bushing is modeled using transmission line theory. The influence of high order modes of electromagnetic waves excited in the discontinuities of bushing on transmission of the main mode is treated as a lumped capacitance. The two-conductor with tapered size is considered as the cascading of multiple segments of transmission lines. The electromagnetic leakage from bushing is handled with by using a radiation impedance obtained from the approximate formula. The ground capacitance parameters of top grading ring and the middle shielding layer as well as the capacitance parameter between top grading ring and the middle shielding layer are extracted respectively, by using numerical computation method. The input impedance observed at the bottom of the bushing is calculated using the circuit model of transmission line and impedance model built above within the frequency range from 1MHz to 100 MHz. The results from the broadband circuit model are in good agreement with those from the 3D full-wave simulations solver CST-MWS.
Electromagnetic model of bushing of gas insulated switchgear(GIS) is very important for the simulation of very fast transient over-voltage(VFTO), transient enclosure voltage(TEV) and transient electromagnetic field. The VFTO can contain frequency components up to 100 MHz. At such high frequencies, the length of the inner shielding conducting layer is comparable with the wavelength and hence the bushing can not be modelled as a lumped parameter element. The broadband circuit model of a gas insulated bushing with double layer shielding is investigated. The three-conductor system of bushing is modeled using transmission line theory. The influence of high order modes of electromagnetic waves excited in the discontinuities of bushing on transmission of the main mode is treated as a lumped capacitance. The two-conductor with tapered size is considered as the cascading of multiple segments of transmission lines. The electromagnetic leakage from bushing is handled with by using a radiation impedance obtained from the approximate formula. The ground capacitance parameters of top grading ring and the middle shielding layer as well as the capacitance parameter between top grading ring and the middle shielding layer are extracted respectively, by using numerical computation method. The input impedance observed at the bottom of the bushing is calculated using the circuit model of transmission line and impedance model built above within the frequency range from 1MHz to 100 MHz. The results from the broadband circuit model are in good agreement with those from the 3D full-wave simulations solver CST-MWS.
引文
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[9]Rao M M,Thomas M J,Singh B P.Electromagnetic field emission from gas-to-air bushing in a GIS during switching operations[J].IEEE Transactions on Electromagnetic Compatibility,2007,49(2):313-321.
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[12]张惠娟,韩叶,凌跃胜,等.变电站电磁干扰预测分析[J].电工技术学报,2015,30(1):412-417.Zhang Huijuan,Han Ye,Ling Yuesheng,et al.The forecast analysis in substation electromagnetic interference[J].Transactions of China Electrotechnical Society,2015,30(1):412-417.
[13]卢斌先,孟准.基于GIS制造特征的电磁波仿真模型简化的研究[J].电工技术学报,2013,28(1):119-125.Lu Binxian,Meng Zhun.The research of gas insulated switchgear model simplification and its influence on simulation result based on manufacturing feature[J].Transactions of China Electrotechnical Society,2013,28(1):119-125.
[14]钟建英,韩书谟,张友鹏.特高压复合套管的设计计算与分析[J].电气制造,2008(2):682-686.Zhong Jianying,Han Shumo,Zhang Youpeng.The design computation and analysis of the 1100k V ultra high voltage composite bushing[J].Electrical Manufacturing,2008(2):682-686.
[15]杨丽君,黄加佳,许佐明,等.高压交流套管的油纸绝缘热老化特性及寿命模型研究[J].电工技术学报,2016,31(5):144-151.Yang Lijun,Huang Jiajia,Xu Zuoming,et al.Investigation on thermal aging characteristics and lifetime model of oil-paper insulation for HV AC bushing[J].Transactions of China Electrotechnical Society,2016,31(5):144-151.
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[17]Whinnery J R,Jamieson H W.Equivalent circuits for discontinuities in transmission lines[J].Proceedings of the Ire,1944,32(2):98-114.
[18]Whinnery J R,Jamieson H W,Robbins T E.Coaxialline discontinuities[J].Proceedings of the IRE,1944,32(11):695-709.
[19]焦重庆,李明洋.同轴结构半径突变处补偿电容的计算分析[C]//2015中国电磁兼容大会,北京,2015:16-21.
[20]Marcuvitz N.Waveguide handbook[M].New York:Mc Graw-Hill,1951.
[2]杨昊,王丹,刘涤尘.特高压交流输电模型的建立与经济性优选分析[J].电力系统保护与控制,2015,43(3):91-96.Yang Hao,Wang Dan,Liu Dichen.Establishment of UHV AC transmission model and economical optimization strategy[J].Power System Protection and Control,2015,43(3):91-96.
[3]冯利民,王晓波,吴联梓,等.500k V GIS变电站VFTO对于电子式互感器的电磁骚扰研究[J].电工技术学报,2016,31(1):85-90.Feng Limin,Wang Xiaobo,Wu Lianzi,et al.Study on the impact of VFTO electromagnetic interference on electronic transformers in 500k V GIS substation[J].Transactions of China Electrotechnical Society,2016,31(1):85-90.
[4]计荣荣,周浩,易强,等.特高压交流系统合闸过电压特点研究[J].电力系统保护与控制,2011,39(14):86-93.Ji Rongrong,Zhou Hao,Yi Qiang,et al.Study on characteristic of switching surge due to closing lines in UHVAC system[J].Power System Protection and Control,2011,39(14):86-93.
[5]宋小会,杨建翔,郭志忠,等.交流特高压变电站站用变保护技术方案[J].电力系统保护与控制,2014,42(24):110-115.Song Xiaohui,Yang Jianxiang,Guo Zhizhong,et al.Protection of station transformer of UHV AC substation station technology solutions[J].Power System Protection and Control,2014,42(24):110-115.
[6]姜自强,刘建勇.南阳特高压断路器失灵保护的研究[J].电力系统保护与控制,2015,43(12):117-122.Jiang Ziqiang,Liu Jianyong.Study on Nanyang substation of UHV circuit breaker failure protection[J].Power System Protection and Control,2015,43(12):117-122.
[7]张宁,刘静琨.影响特高压电网运行的因素及应对策略[J].电力系统保护与控制,2013,41(1):109-114.Zhang Ning,Liu Jingkun.The ultra high voltage grid risk analysis and its assessment framework[J].Power System Protection and Control,2013,41(1):109-114.
[8]Smajic J,Holaus W,Kostovic J,et al.3D fullMaxwell simulations of very fast transients in GIS[J].IEEE Transactions on Magnetics,2011,47(5):1514-1517.
[9]Rao M M,Thomas M J,Singh B P.Electromagnetic field emission from gas-to-air bushing in a GIS during switching operations[J].IEEE Transactions on Electromagnetic Compatibility,2007,49(2):313-321.
[10]Rao M M,Dharani P,Rao T P.Computer aided identification of inter-layer faults in gas insulated capacitively graded bushing during switching[J].Journal of Electrical Engineering&Technology,2009,4(1):28-34.
[11]Rao M M,Rao T P,Ram S S T,et al.Simulation of capacitively graded bushing for very fast transients generated in a GIS during switching operations[J].Journal of Electrical Engineering&Technology,2008,3:36-42.
[12]张惠娟,韩叶,凌跃胜,等.变电站电磁干扰预测分析[J].电工技术学报,2015,30(1):412-417.Zhang Huijuan,Han Ye,Ling Yuesheng,et al.The forecast analysis in substation electromagnetic interference[J].Transactions of China Electrotechnical Society,2015,30(1):412-417.
[13]卢斌先,孟准.基于GIS制造特征的电磁波仿真模型简化的研究[J].电工技术学报,2013,28(1):119-125.Lu Binxian,Meng Zhun.The research of gas insulated switchgear model simplification and its influence on simulation result based on manufacturing feature[J].Transactions of China Electrotechnical Society,2013,28(1):119-125.
[14]钟建英,韩书谟,张友鹏.特高压复合套管的设计计算与分析[J].电气制造,2008(2):682-686.Zhong Jianying,Han Shumo,Zhang Youpeng.The design computation and analysis of the 1100k V ultra high voltage composite bushing[J].Electrical Manufacturing,2008(2):682-686.
[15]杨丽君,黄加佳,许佐明,等.高压交流套管的油纸绝缘热老化特性及寿命模型研究[J].电工技术学报,2016,31(5):144-151.Yang Lijun,Huang Jiajia,Xu Zuoming,et al.Investigation on thermal aging characteristics and lifetime model of oil-paper insulation for HV AC bushing[J].Transactions of China Electrotechnical Society,2016,31(5):144-151.
[16]Ramo S,Whinnery J R,Van Duzer T.Fields and waves in communication electronics[M].New Jersey:John Wiley&Sons,1994.
[17]Whinnery J R,Jamieson H W.Equivalent circuits for discontinuities in transmission lines[J].Proceedings of the Ire,1944,32(2):98-114.
[18]Whinnery J R,Jamieson H W,Robbins T E.Coaxialline discontinuities[J].Proceedings of the IRE,1944,32(11):695-709.
[19]焦重庆,李明洋.同轴结构半径突变处补偿电容的计算分析[C]//2015中国电磁兼容大会,北京,2015:16-21.
[20]Marcuvitz N.Waveguide handbook[M].New York:Mc Graw-Hill,1951.