Power Line Tower Lightning Surge Impedance Computation, a Comparison of Analytical and Finite Element Methods.

Abstract

The aim of this work is to compare methods for the computation of transmission line tower surge impedance, that are: traditional analytical method using simplified equations; and the Finite Element Method for the mapping of electromagnetic fields surrounding the tower[9]. In the latter were used two different software, the public domain FEMM, and the commercial software FLUX3D. The first is able to perform calculations based in a 2D representation of the problem while the second uses a 3D representation of the problem to perform computations. It is also verified the impedance variation along the tower height, phenomenon that most of the time is not considered, and that can provide a direct impact in the performance of transmission lines facing the atmospheric discharges. With this purpose it was used the software ATP-EMTP, where it was modeled a simple case who brought results for immediate comparison.