Computing the electromagnetic field of the system of arbitrarily positioned conductors in horizontally stratified multilayer medium

Abstract

SUMMARYThis paper presents a novel computational methodology, based on the finite element technique, for the analysis of electromagnetic field due to system of arbitrarily positioned current-carrying conductors in horizontally stratified multilayer medium, having arbitrary number of layers with different characteristics (including air). Each soil layer is horizontally unbounded, homogenous and isotropic, whereas conductors can penetrate different layers and extend into the air. The effect of the stratified multilayer medium is taken into account by using the originally developed fixed image method. Complete electromagnetic coupling between grounding system conductors (satisfying thin-wire approximation) is taken into account, whereas attenuation and phase shift effects are approximated. The electric and magnetic field in stratified multilayer medium are computed from the scalar electric and vector magnetic potentials, using the said fixed image method and approximations to the attenuation and phase shift effects.

Fixed-Image-Method-Based Transient Electromagnetic Model of Grounding System in Horizontally Stratified Multilayer Medium

“…The effect of medium heterogeneity is taken into account by using the fixed image method originally developed in [17] and used in [3,13,14]. Basically, this fixed image method utilized the imaging method to take into account various earth layer configurations.…”

“…This transient model introduces improvements to previously published time-harmonic model of the grounding system [3,13,14] and features a novel algorithm for transformation purposes between the time and frequency domain and vice versa. These algorithms for continuous numerical Fourier transform (CNFT) [15] and inverse continuous numerical Fourier transform (ICNFT) [16] are robust, accurate and versatile which is clearly demonstrated in the aforementioned papers.…”

“…In the time-harmonic electromagnetic model published in [3,13,14] and improved in this paper, conductors of the grounding system are subdivided into straight segments which satisfy the thin-wire approximation. Longitudinal current of the conductor segment is in the improved model approximated using a linear approximation instead of a constant as used in [3,13,14].…”

“…Longitudinal current of the conductor segment is in the improved model approximated using a linear approximation instead of a constant as used in [3,13,14]. Complete electromagnetic coupling between segments is taken into account.…”

“…Complete electromagnetic coupling between segments is taken into account. Computation of Sommerfeld integrals is circumvented using an effective approximation of the attenuation and phase shift effects which significantly contributes to the execution speed of the model [3,13,14]. Segments of the grounding system can be situated in any layer of the horizontally stratified multilayer medium which includes the air layer and an arbitrary number of ground layers.…”