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Contribution à la modélisation électrique, électromagnétique et thermique des transformateurs: Application à l'étude de l'échauffement sur charges non linéaires

Abstract : The widespread use of nonlinear loads in the industry is the source of several disturbances in the electrical network. Thus the current harmonics leads to increase the losses due to proximity and skin effects in the transformer windings. Therefore, the transformers become more sensitive to overheating. In order to avoid a dielectric failure as well as a premature ageing, the hot spot temperature must not exceed the prescribed insulating value. However, for a given nonlinear load it is difficult to predict the electromagnetic and thermal state of the transformer. The main objective of this research is to characterize the harmonic behaviour of the power transformer to prevent, at the design stage, these unexpected troubles.

A first work presented in this thesis deals with an analytical and axisymetric method to compute the winding current density distribution. Then, the conductor layers are homogenised and a steady state thermal finite element calculation is applied to obtain the temperature map. Finally, the effectiveness of the proposed method is verified on a medium power dry type transformer loaded by an innovative experimental installation.

A second model is based on a new analytical and numerical method. First a 3D finite element method (FEM) is applied to compute the magnetic field in the free and the iron spaces. This non-linear calculation is combined with a mixed form of the electrical circuit equation. Then a 3D thermal FEM allows to show the temperature distribution in the transformer. Finally, this coupling model is applied to a small power distribution transformer with embedded sensors to verify the overheating effect of non sinusoidal currents.
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https://tel.archives-ouvertes.fr/tel-00116335
Contributor : Anthony Lefèvre <>
Submitted on : Saturday, November 25, 2006 - 8:29:51 PM
Last modification on : Wednesday, February 13, 2019 - 3:20:03 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 7:07:21 PM

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  • HAL Id : tel-00116335, version 1

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Anthony Lefèvre. Contribution à la modélisation électrique, électromagnétique et thermique des transformateurs: Application à l'étude de l'échauffement sur charges non linéaires. Energie électrique. Université de Nantes, 2006. Français. ⟨tel-00116335⟩

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