Aspects of Computations of 3D Electromagnetic Fields near Power Overhead Lines

Published in 2015

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Summary

Computations of three-dimensional (3D) electromagnetic fields can presently be performed by means of a whole range of professional programs, such as COMSOL Multiphysics, ANSYS and Opera. These programs employ the finite-element method (FEM) requiring division of the computed area into volume elements of various sizes. However, a 3D mesh generation and its computation in these programs can sometimes be a problem due to a possible disproportion between the dimensions of conductors in focus and the whole computed area. In such cases, professional programs are either unable to generate a 3D mesh for the input data, or they create a 3D mesh consisting of a great number of elements, resulting in numerous degrees of freedom. This can make the computations considerably time-consuming. The aim of this paper is to demonstrate one possible way to cope with the difficulties described above, namely the application of the integral method. As opposed to the finite method, which requires the generation of a 3D mesh, the integral method only requires the use of a surface mesh on the individual parts, thus significantly reducing the number of degrees of freedom. The paper demonstrates the application of the integral method for the computation of 3D electromagnetic fields near a power overhead line and lists the advantages and disadvantages of this method. Although the illustrative example suffered a significant disproportion between the dimensions of some parts of the power overhead line (for example, the individual conductors and the beams of the tower) and the whole computed area, the integral method made it possible to compute the following electromagnetic field quantities: the electric field strength distribution, magnetic flux density distribution, Pointing vector distribution, electric potential distribution and the distribution of the surface charge density. However, in order to apply the integral method, it was necessary to code special procedures within the MATLAB software.