Accurate magnetic field evaluation due to underground power cables

Abstract

SUMMARYExposure to low frequency magnetic fields has been a matter of health concern and controversy over the past years. These aspects motivated the development of methods and algorithms for the magnetic field evaluation due to power transmission lines and cables. In this paper special attention is given to buried power transmission cables. Results for different values of frequency and different values for the magnetic permeability of the soil are obtained, presented and compared with a standard approximation. Results confirm the importance of the method developed in this paper, not only as a reference method but also as a mandatory method for higher values of the soil magnetic permeability and higher values of the frequency.

Mitigation of the magnetic field due to underground power cables using an optimized grid

“…Under these conditions Reference [4] shows that similar results are obtained using accurate or standard models to evaluate the induction magnetic field. Therefore, the ordinary procedures based on Ampère's law will be used.…”

“…Considering the reference system represented in Figure 1 for an underground power transmission system in flat configuration, the magnetic induction intensity presents a maximum value at point (x ¼ 0, y ¼ 0) and a curve profile, along the ground surface, which is almost symmetrical to the y-axis [3,4]. Therefore, in order to mitigate the field intensity along the ground surface using a grid it is natural to assure that the mitigation conductors have a symmetrical arrangement related to y-axis.…”

“…The current distribution can be obtained applying a matrix based multi-conductor transmission line (MTL) model [1][2][3]. To calculate the series-impedance matrix relevant theories and results are described in References [3][4][5][6][7][8][9][10]. The methodology followed here is based on the model described in previous works [8,9].…”

The influence of frequency and soil permeability on the magnetic field due to underground power cables

“…In this case, the global solution for axial components of the magnetic potential in the soil may be obtained as in Reference [6] A s ðx; yÞ ¼ Z 1…”

“…Significant theories and results are described in References [1][2][3][4][5]. As indicated in the previous work [6], the model is developed, first through a general field formulation based on Fourier integrals and series developments [7] and later applying the Pollaczek approach. References [2] and [3] present the appropriate conditions to obtain enough accuracy (errors below 1%) by using this approach.…”