Anisotropy in three-phase transformer circuit model

Abstract

Abstruct-In this paper, an important discussion of transformer design and modeling is given. Afterwards, the anisotropy effects of the transformer laminations have been stressed in light of the investigation of a three-phase three-limb transformer Tjoint. Three simple T-joint modeling schemes accounting for the lamination anisotropy are proposed. The fundamental result is that the flux lines remain almost parallel to the rolling direction (RD), except in a small area around the T-joint. Therefore, transformer yokes and limbs have been divided into longitudinal elements according to the RD. Reluctances related to these elements are connected according to the magnetic circuit coupling and yield a new transformer circuit model. A good agreement is obtained between computed and measured transients currents. Furthermore, the new transformer model enables some localized analysis. The computed localized fluxes and loci of flux density vectors near to the T-joint exhibit a satisfactory agreement with many results based on FEM or experimental investigations.Zndex Terms-Grain-oriented steels, transformer.

Time-Frequency Analysis of Barkhausen Noise for the Needs of Anisotropy Evaluation of Grain-Oriented Steels

“…The steel with anisotropic magnetic properties is manly used in the machinery industry for construction e.g. transformers or electric motors [6][7][8][9][10]. Considering the relationship between magnetic and mechanical properties of steel, the evaluation of magnetic anisotropy is also used in the process of mechanical state assessment [8].…”

Use of Time-Frequency Representation of Magnetic Barkhausen Noise for Evaluation of Easy Magnetization Axis of Grain-Oriented Steel

“…Determining the axis of easy magnetization is particularly important in the process of designing electrical machines, in essence the transformer cores or electric motors. Anisotropic properties allow optimizing their constructions and in consequence increasing effectiveness and reduce the costs of transformation and distribution of energy [20,21]. The resultant easy magnetization axis is influenced by a number of factors, including: residual stress, grain shape and size, etc.…”

New equivalent circuit model of UHVDC converter transformer winding for surge propagation investigation

“…Another method [6] is based on an empirical description of the various components of the iron loss. The iron core loss during transformer operation can be divided into three parts: hysteresis loss, eddy current loss, and additional loss, which are functions of frequency and maximum magnetic flux density [7–10].…”