On the Choice Between Transmission Line Equations and Full-Wave Maxwell's Equations for Transient Analysis of Buried Wires
On the Choice Between Transmission Line Equations and Full-Wave Maxwell's Equations for Transient Analysis of Buried Wires
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DOI：
10.1109/temc.2008.919040
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发表时间：
2008-05
影响因子：
2.1
通讯作者：
N. Theethayi;Yoshihiro Baba;F. Rachidi;R. Thottappillil
中科院分区：
文献类型：
--
作者：
N. Theethayi;Yoshihiro Baba;F. Rachidi;R. Thottappillil
在本文中，我们评估了输电线（TL）解在研究雷电瞬变与埋地电线相互作用中的有效性。所考虑的瞬态频率在几千赫兹到几兆赫之间，上升时间为0.1-10 μ s。本文用TL方程和全波麦克斯韦方程进行了比较模拟，两个方程的解都是基于时域有限差分法。结果表明，TL解对于埋地导线的雷电暂态分析具有足够的精度。它还声称，TL的方法仍然有效的频率低于闪电的所有瞬态。TL解决方案计算效率高，特别是在处理分布式电源和铁路系统时。只要横电磁模（TEM）占主导地位，TL方法就是有效的。然而，根据激励源的类型、其位置、频率和相关介质，可能存在被分类为天线模式的其他传播模式。基于场在土壤中的穿透深度的概念，提出了一个可能的频率近似公式，在该频率以上，埋地系统的TL解的有效性是有疑问的。本文的讨论可以激励TL解决方案的电力，铁路和电信系统的埋地导体的电磁暂态分析的应用。
In this paper, we evaluate the validity of transmission line (TL) solutions in the study of interaction of lightning transients with buried wires. The considered transients have frequencies between a few kilohertz to a few megahertz with risetimes 0.1-10 mus. Comparative simulations using TL equations and full- wave Maxwell's equations are carried out in the paper, and the solutions to both the equations are based on the finite-difference time-domain method. It is found that TL solutions are sufficiently accurate for lightning transient analysis of buried wires. It is also claimed that the TL approach remains valid for all transients having frequencies lower than those of lightning. TL solutions are computationally efficient, particularly when dealing with distributed power and railway systems. The TL approach is valid as long as the transverse electromagnetic mode (TEM) is dominant. However, other modes of propagation, classified as antenna modes, might be present depending upon the type of excitation source, its location, frequency, and the associated media. A possible approximate formula for the frequency above which the validity of TL solutions for buried systems is questionable is proposed based on the concept of penetration depth of fields into the soil. Discussions presented in the paper could motivate the application of TL solutions for electromagnetic transient analyses of the buried conductors of power, railway, and telecommunication systems.