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We have modeled underground isolated power cables by using magnetic eddy-current (EC) and thermal coupled formulations solved by the finite-element method (FEM). The magnetic field equation expressed in terms of magnetic vector potential (MVP) is strongly coupled with the total current density equation, which includes the source and the EC densities for taking into account skin and proximity effects. The model uses the computed EC density of losses with electric conductivity temperature dependence introduced as a heat source in the free transient thermal equation completed by the convection heat transfer. We studied single and multicircuit three-phase arrangements at various cable spaces in order to analyze the magnetic flux density and the time-space temperature evolution. Index Terms--Finite element, magnetic eddy-current thermal models, underground isolated power cables.

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The aim of the present paper is to develop methods that would be able to predict transient voltage distribution along the insulated-multiconductor windings of electric equipment fed by frequency converters. Several electromagnetic (EM) challenges are presented with this desire. First, the resistance (R) and self-/mutual inductances (L,M) frequency-dependent parameters are accurately computed using the enforced electric total current process based on the finite-element (FE) formulation of the strongly coupled time-harmonic magnetic field and total current density equations model including skin and proximity effects. Second, the coupling capacitances (C) are computed from the FE electrostatic analysis using the floating electric scalar potential process. Finally, a realistic high-frequency electric circuit of the distributed (R, L, M, C) EM parameter matrices is formed in order to predict the turn-to-ground and turn-to-turn voltage transients. The numerical results obtained from the proposed models implemented under the MATLAB code are successfully verified by the corresponding laboratory test measurements. [ABSTRACT FROM AUTHOR]