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

Abstract

SUMMARYThere has been a great controversy about the possible connection between magnetic field and human health over the past few years.Electric and magnetic fields exist due to the presence of electric devices, in general, and in particular, of any power system, in generation, transmission or distribution lines or cables. In this paper special attention is given to the magnetic field created by underground power cables. Results for different values of frequency and soil magnetic permeability are presented giving importance to both effects acting together. It will be also analysed the influence of the sheath grounding for soils having different values of permeability in magnetic field distribution. The model formulation and assumptions are described in a previous work on where this paper is based on.

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

“…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].…”

Series Impedance and Losses of Magnetic Field Mitigation Plates for Underground Power Cables

“…In these works, either Pollaczek's integrals or the generalized ones [12], [13] are evaluated using power series developments in parallel with numerical methods. In [15], [16], and [18], Pollaczek's integrals are evaluated using purely numerical techniques, and in [17], approximations using the first two terms of the power series developments are taken for frequencies less than 1 MHz. Finally, Pollaczek's approximation has been also extended to treat power cables buried in multilayered soils [18].…”

Calculation of losses and ampacity derating in medium-voltage cables under harmonic load currents using finite element method

“…Moreover, the effect of sheath is not considered, and steel shield is considered to carry only eddy current losses with special cradled configuration cables. Magnetic field produced by power cable in different frequencies and soil magnetic permeability is investigated in 1 study . Some studies are carried out for analytical determination of harmonic current effect on power cable conductor losses, temperature rise, and insulation life that are for low‐voltage cable without metallic layer and based on International Electrotechnical Commission standard formulations …”

“…Magnetic field produced by power cable in different frequencies and soil magnetic permeability is investigated in 1 study. 18 Some studies are carried out for analytical determination of harmonic current effect on power cable conductor losses, temperature rise, and insulation life that are for low-voltage cable without metallic layer and based on International Electrotechnical Commission standard formulations. 19,20 As was explained, precise calculation of cable losses is necessary especially for sheathed cables and by considering the grounding method and current waveforms.…”