Lightning Electromagnetic Fields Computation: A Review of the Available Approaches

Abstract

Lightning represents one of the most critical issues for electrical infrastructure. In dealing with overhead distribution line systems, indirect lightning strikes can lead to induced voltages overcoming the critical flashover value of the line, thus damaging the insulators. The computation of lightning-induced voltages requires the modeling of the lightning current, the evaluation of the lightning electromagnetic fields and the solution of the field-to-line coupling equations. The numerical calculation of the lightning electromagnetic fields is time-consuming and is strongly dependent on the lightning channel modeling and soil properties. This article presents a review of the most widely adopted methods to calculate the lightning electromagnetic fields, starting from the classical formulation, which requires numerical integration, and highlighting the most effective approaches that have been developed to reduce computational effort. This is done first for the case of a perfectly conducting ground, then the available formulations to account for the ground finite conductivity are presented together with their possible implementations in both the frequency and time domains.

Electromagnetic Fields from Cloud-to-Cloud Horizontal Lightning Channel on Perfect Conducting Soil: Induced Potentials in Flying Aircraft

“…The problem of calculating the electric and magnetic fields generated by a vertical cloud-to-ground lightning channel has been widely investigated by various authors under the assumption that the ground is a perfect conductor [2]. In these works, two types of calculation methods can be found, the time-domain-based method [3,4] and the one that uses Fourier phasors as calculation elements in the frequency domain [5]. For the problem being studied, air is the medium in which the lightning channel develops.…”

“…This is a poor conductive medium for which a virtually null electrical conductivity must be assumed except when it is ionized, as is the case with the channel that carries the electrical charge between the cloud and the ground. Due to the null conductivity of air, the frequency-based method leads to equations for the induced electric field whose solutions have a singularity for zero frequency, that is, for the contribution to the induced electric field of the constant component of the source [5]. For this reason, calculations in the time domain are much more frequently found in the literature.…”