An Efficient Method for the Computation of Electromagnetic Fields Associated With Tortuous Lightning Channels

Lightning electromagnetic (EM) fields are typically computed by assuming the current propagation within a straight vertical channel of negligible cross section. However, it is well known that the lightning path is tortuous and this can significantly affect the radiated fields and the lightning-induced voltages on power lines. Lupò et al. (2000) proposed an analytical method evaluating the EM fields radiated by a tortuous channel assuming a step current source; to consider an arbitrary (realistic) current source, a slow-converging convolution integral was applied. The aim of this article is to reduce the computation time of such procedure by extending to the tortuous channel case the approach proposed by Brignone et al. (2021) for the evaluation of the lightning EM fields with arbitrary current source, originally developed for a straight vertical channel. The performances of the present method are evaluated by means of comparison with the solution proposed by Lupò et al. (2000), showing an excellent agreement with a significant reduction of the CPU effort. This in principle will allow the computation of lightning-induced overvoltages at both individual and statistical level without a prohibitive computational effort.

I. Introduction

Lightning is one of the most dangerous natural phenomena, able to produce high impacts and damage even though its hazard perception is low. For this reason, both ground and air discharges have been intensively studied. In particular, cloud-to-ground discharges have received great interest in the scientific literature, since they represent a significant risk for human beings, animals, civil structures, and power and communication infrastructures. On the other hand, intracloud and cloud-to-cloud events are important issues affecting aircraft safety; actually, lightning hazard is expected to increase with the development of aircraft technology, i.e., ever-more sophisticated on-board electronics and low-conducting carbon-fiber composite reinforcements reducing the shielding effect [1].