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Article

Cristian Demian, Raphael Romary, Gilles Vogt and Valentin Costan

The axial magnetic field occurs in the end-region of large turbo-generators is known to induce hot points or voltages between laminations, that may cause insulation…

Abstract

Purpose

The axial magnetic field occurs in the end-region of large turbo-generators is known to induce hot points or voltages between laminations, that may cause insulation breakdown and thus stator faults.

Design/methodology/approach

It is important to dispose of simple methods for estimating the axial flux rapidly with regard to the operating point of the machine.

Findings

The authors provide a practical model of the axial magnetic field based on a simplified vector diagram. The parameters required to build the vector composition of the flux densities are assessed with a limited number of finite element method simulations of the whole end-region of the machine. These simulations were validated by an experimental test on a real turbo-generator. Then the axial flux density was simply estimated for various operating points.

Originality/value

The originality of the paper concerns the practical model of the axial magnetic field based on a simplified vector diagram.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Virginie Majchrzak, Guillaume Parent, Jean-François Brudny, Valentin Costan and Philippe Guuinic

For the proposed coupling transformer, a magnetic bypass based on the virtual air gap principle is realized by inserting auxiliary windings in a return leg added to a…

Abstract

Purpose

For the proposed coupling transformer, a magnetic bypass based on the virtual air gap principle is realized by inserting auxiliary windings in a return leg added to a standard transformer. With such a setup, it is able to act as a voltage regulator as well as protect the power electronics of the dynamic voltage restorer from electrical grid fault currents. This paper focuses on the electrical design part of the coupling transformer. It aims to explain how the behavior of the auxiliary windings electrical circuit of the magnetic bypass impacts the performances of the device.

Design/methodology/approach

The influence of the electrical auxiliary windings circuit configurations on the operation of the coupling transformer is studied by finite element analyses with nonlinear and isotropic magnetic materials.

Findings

A configuration for the realization of the electrical circuit of the auxiliary windings is determined according to the finite element simulation results to achieve the design of the coupling transformer whose magnetic core was previously designed.

Originality/value

By studying the operation of a special coupling transformer with nonlinear saturation phenomenon by finite element analyses, a to-do list of the electrical circuit parameters is described to design this device well.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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