Fast and efficient calculation of lightning-induced voltages in frequency-dependent transmission lines over lossy ground

This paper presents a fast and efficient algorithm for the calculation of electromagnetic fields radiated from lightning return-stroke channel as well as lightning-induced voltages in frequency-dependent transmission lines. The algorithm developed in this paper employs a mixed time-frequency macro-model that is based on tracing the poles and residues of the transfer function of the lightning-transmission-line system. Accurate and fast calculation of electromagnetic field data along the excited transmission line is critical to obtain the source terms (or forcing functions) in field-to-transmission-line coupling equations. Using the proposed method, we are able to obtain a closed form solution for the lumped sources required for the analysis of a two-conductor transmission line exposed to nonuniform electromagnetic fields. The algorithm provides high accuracy as well as significant speed gain for multiconductor transmission lines (MTL) as well. To demonstrate the application of the proposed method, we will compare our results with those obtained using other methods or measurements. (C) 2013 Elsevier B.V. All rights reserved.