Lightning strikes to tall objects: A study of wave interactions at the return‐stroke front using a nonlinear transmission line model

Abstract

A theoretical study is presented to investigate lightning strikes to towers, with focus on wave interactions occurring at the return-stroke front due to the arrival of current pulses that propagate upward on the channel after being transmitted from the tower. The lightning channel is represented as a transmission line including corona and nonlinear losses. Analyses for the hypothetical case of a lossless channel considering matched tower and channel impedances show that the arrival of current pulses at the upward moving return-stroke front leads to an increase in corona currents leaving the channel. This transient process generates current pulses whose arrival at the tower top can be interpreted as the effect of a current reflection at the upward moving front, even though no impedance discontinuity exists at that point if return-stroke and leader channel properties are assumed the same. In the more realistic case of a lossy channel considering unmatched channel and tower impedances, the nonlinear channel resistance modifies the current pulses that propagate along the channel so that they merge smoothly with the return-stroke front. In this case, the interaction of the current pulses transmitted from the tower to the channel with the upward moving return-stroke front does not lead to features that can be clearly interpreted as the result of current reflections at that point in the evaluated conditions. Finally, it is argued that the current reflection coefficient at the tower top should be viewed as a current dependent parameter as opposed to a constant, linear value.

An Extension of the Guided Wave M‐Component Model Taking Into Account the Presence of a Tall Strike Object

“…During the past decades, much attention has been paid to the modeling of return‐strokes to tall strike objects (e.g., Baba & Rakov, 2005a, 2005b, 2007; Bermudez et al., 2003, 2005; Pavanello, Rachidi, Rubinstein, et al., 2007; Pavanello, Rachidi, Janischewskyj, et al., 2007; Rachidi et al., 2001, 2002). Other studies have also taken into account the grounding conditions (Petrache et al., 2005), the presence of an upward‐connecting leader (e.g., Mosaddeghi et al., 2011; Shostak et al., 2000), and wave interactions at the return‐stroke wavefront (De Conti et al., 2015; Mosaddeghi et al., 2011;Shoory et al., 2011). Nonuniform, multiple‐section modeling of the struck tower was considered in Boev and Janischewskyj (2011), Rahimian and Hussein (2015).…”

3‐D Finite Difference Time Domain Simulation of Lightning Strikes to the 634‐m Tokyo Skytree

“…Several research groups have reported directly measured lightning currents and associated electric fields (e.g., Pavanello et al, 2007;Pichler et al, 2010;Saito et al, 2015;. Modeling attempts with varying degree of success were reported by Pavanello et al (2007), Kordi et al (2003), Saito et al (2015), , and Zhu et al (2018). As of today, no one formulated the problem in the framework of 3-D finite difference time domain (FDTD) method.…”