L型GIS管道对电磁波传播的影响及等效电路建模
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摘要
在GIS管道中传播的电磁波,在诸如拐弯、盆式绝缘子及套管等结构改变的位置,其电磁场分布会产生局部的畸变。这种畸变通常以集总电路元件的形式补偿到描述电磁波的传输线模型中。本文针对管道L型拐弯讨论了由电感和电容组成的π型和T型两种等效补偿电路。基于电磁场仿真得到的L型管道的二端口网络参数,运用传输线理论导出了补偿电感和补偿电容的计算公式。结合某特高压GIS管道尺寸参数,计算得出π型补偿时补偿电容大约在15~40p F,补偿电感大约在0.08~0.23μH,且随频率变化;T型补偿时,电容值大约在15~32p F,电感值大约在0.1~0.2μH。比较了考虑和不考虑补偿电路两种情况下传输特性的差异,结果表明,两种情况下终端负载上的时域电压波形的差异与负载阻抗大小有关,总体来说终端开路和短路时差别大,匹配时差异小。
Field distribution of electromagnetic wave propagating in a gas insulated switchgear(GIS) can be distorted locally at the discontinuous/abrupt positions like elbows, spacers and bushings. The effect of such distortion is usually regarded as a lumped circuit element inserted into the transmission line model. For L-type elbow of GIS pipe, both π-type and T-type equivalent circuits consisting of compensation capacitance and compensation inductance are investigated in this paper. Based on the two-port network parameter obtained by electromagnetic simulation of the L-shaped pipe, the formulae of both the compensation capacitance and inductance are derived by using transmission line theory. For a 1100 k V GIS dimensions, the capacitance is about 15~32p F and the inductance is about 0.1~0.2μH when the T-type circuit adopted, and the capacitance is about 15~40p F and the inductance is about 0.08~0.23μH when the π-type circuit adopted. Both the capacitance and the inductance are changing with the frequency. A circuit including a terminal load on one end of the L-shape pipe and a pulse voltage source on the other end is established to compare the difference between the two cases: with and without the equivalent circuit inserted. It is shown that, the equivalent circuit has obvious effect on the load voltage waveform when the load matches badly with the pipe, but has few influence when the two match with each other well.
Field distribution of electromagnetic wave propagating in a gas insulated switchgear(GIS) can be distorted locally at the discontinuous/abrupt positions like elbows, spacers and bushings. The effect of such distortion is usually regarded as a lumped circuit element inserted into the transmission line model. For L-type elbow of GIS pipe, both π-type and T-type equivalent circuits consisting of compensation capacitance and compensation inductance are investigated in this paper. Based on the two-port network parameter obtained by electromagnetic simulation of the L-shaped pipe, the formulae of both the compensation capacitance and inductance are derived by using transmission line theory. For a 1100 k V GIS dimensions, the capacitance is about 15~32p F and the inductance is about 0.1~0.2μH when the T-type circuit adopted, and the capacitance is about 15~40p F and the inductance is about 0.08~0.23μH when the π-type circuit adopted. Both the capacitance and the inductance are changing with the frequency. A circuit including a terminal load on one end of the L-shape pipe and a pulse voltage source on the other end is established to compare the difference between the two cases: with and without the equivalent circuit inserted. It is shown that, the equivalent circuit has obvious effect on the load voltage waveform when the load matches badly with the pipe, but has few influence when the two match with each other well.
引文
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[14]丁登伟,高文胜,刘卫东.GIS中特高频电磁波模式转换及传播效率的仿真研究[J].高压电器,2014,6(6):13-20.
[15]孟准.GIS内部电磁波传播规律的研究[D].北京:华北电力大学,2011.
[16]刘君华,徐敏骅,黄成军.局部放电电磁波在GIS中的衰减特性[J].电工技术学报,2010,25(8):52-58.
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[2]唐炬,樊雷,张晓星,等.用谐波小波包变换法提取GIS局部放电信号多尺度特征参数[J].电工技术学报,2015,30(3):250-257.
[3]律方成,金虎,王子建,等.基于组合核多特征融合的GIS局部放电检测与识别[J].电工技术学报,2014,29(10):334-340.
[4]王娜,林莘,徐建源,等.特高压GIS变电站中快速暂态过电压仿真及其特性分析[J].高电压技术,2012,38(12):3310-3315.
[5]吴昊,李成榕,徐海瑞,等.用于VFTO测量的GIS窗口式传感器[J].电工技术学报,2012,27(9):210-217.
[6]陈维江,李志兵,孙岗,等.特高压气体绝缘开关设备中特快速瞬态过电压特性的试验研究[J].中国电机工程学报,2011,31(31):38-47.
[7]吴思扬,叶齐政,李兴旺,等.GIS浇注孔的尺寸与局部放电辐射出的UHF电磁波强度的关系的研究[J].电工技术学报,2014(S1):531-536.
[8]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.
[9]王娜,林莘,徐建源,等.特高压GIS变电站中快速暂态过电压仿真及其特性分析[J].高电压技术,2012,38(12):3310-3315.
[10]Povh D,Schmitt H.Voleker O,Witzmann R.Modelling and Analysis Guidelines for Very Fast Transients[J].IEEE Transactions on Power Delivery,1996.11.4.
[11]Ardito A,Iorio R.et al.Accurate modeling of capacitively graded bushings for calculation of fast transient overvoltage in GIS IEEE trans on Power delivery,1992.3.
[12]Witzmann R.Fast transients in Gas Insulated Substations(GIS)-Modeling of Different Gis Components[Z].1987.
[13]Lalot J,Sabot A,Kieffer J,Rowe S W.Preventing earth faulting during switching of disconnectors in GIS including voltage transformer[J].IEEE Trans.on Power Delivery,VOL.PWRD-1,No.1,Jan.1986.
[14]丁登伟,高文胜,刘卫东.GIS中特高频电磁波模式转换及传播效率的仿真研究[J].高压电器,2014,6(6):13-20.
[15]孟准.GIS内部电磁波传播规律的研究[D].北京:华北电力大学,2011.
[16]刘君华,徐敏骅,黄成军.局部放电电磁波在GIS中的衰减特性[J].电工技术学报,2010,25(8):52-58.
[17]Whinnery J R,Jamieson H W,Robbins T E.Coaxial-line discontinuities[J].Proceedings of the IRE,1944,32(11):695-709.
[18]Whinnery J R,Jamieson H W.Equivalent circuits for discontinuities in transmission lines[J].Proceedings of the IRE,1944,32(2):98-114.
[19]邱关源,罗先觉(修订).电路[M].5版.北京:高等教育出版社,2006.
[20]Tesche F M.EMC Analysis Methods and Computational Models[M].Wiley Publication,1986.