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.

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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.

In this paper special attention is given to the mitigation of the magnetic field originated by underground power transmission cables. The mitigation system analyzed is composed by a set of n m conductors, parallel to the power cables, forming a grid. An optimization algorithm was developed in order to obtain the best location to install the grid conductors. In order to reduce the number of the unknowns, the algorithm was developed taking into account the symmetry of the system. Results are presented showing the influence of the number of the grid conductors and its cross-section dimensions on mitigation grid performance.

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