A new approach to reduce the leakage flux and electromagnetic force on distribution transformer under unbalanced faults based on finite element method

Abstract

Summary The short‐cırcuıt capacity design of a transformer is one of the most significant and challenging criteria. Electromagnetic forces in transformer winding regions are produced by interaction between the leakage flux and current density. Under short circuit condition when currents increase to 20 times, windings are exposed to very high electromagnetic force. This paper is focused on the reduction of leakage flux and electromagnetic force under fault condition of distribution transformer. This article is composed of two parts. First, Finite Element Methods (FEM) that improved in Ansoft‐Maxwell has been used to investigate the leakage flux and electromagnetic forces of three‐phase, three leg, 10/0.4‐kV, 1000‐kVA distribution transformer. Then, to optimal design of transformer under single phase to ground short circuit condition two auxiliary winding was chosen as an active shielding to reduce the radial and axial leakage flux. According to Lenz's law this windings produce a magnetic flux that is the apposite of the leakage flux from an iron‐core system. Results indicate that the proposed auxiliary winding remarkably decreased the leakage flux and electromagnetic force in the winding regions. It should be noted that the resultant of main flux is not affected by auxiliary winding. Copyright © 2015 John Wiley & Sons, Ltd.

Comparison of Effect Efficiency and Voltage Regulation Between Three-Phase Transformer Winding Connections

“…can be combined to find out the temperature and set the conditions temperature of the transformer [8]- [12]. Our experiment has limited by using the Fourier transform for accurate approximation of the hysteresis characteristics, and magnetization model that the magnetic field strength produced to the variation of the magnetic flux density [13] [14]. This research analyzed the effect of efficiency and voltage regulation between three-phase transformer to know a best performance on various windings.…”

Design optimization of distribution transformers by minimizing the total owning cost

“…This can be performed in a straightforward way by using proper optimization techniques . Recently, new insights on the design optimization of transformers have been dealt with . In Ref, an approach is proposed that focused on loss minimization while satisfying requirements related to short‐circuit impedance and electromagnetic stress.…”

“…[11][12][13][14] Recently, new insights on the design optimization of transformers have been dealt with. [15][16][17][18][19][20][21] In Ref, 15 an approach is proposed that focused on loss minimization while satisfying requirements related to short-circuit impedance and electromagnetic stress. In Ref, 16 the maximization of transferred power is carried out by taking into account thermal issues in the transformer.…”

A proposal of a qualitative index for mechanical withstand safety margin analysis of transformers

“…The principal effects arising as a result of the action of these forces on transformer windings are described in several studies . In addition, finite element studies of the forces arising as a result of the flow of short‐circuit current or energizing current through transformer windings are reported . Although such finite element studies are more precise than analytical methods, they require long simulation times.…”

“…[9][10][11][12] In addition, finite element studies of the forces arising as a result of the flow of short-circuit current or energizing current through transformer windings are reported. [13][14][15] Although such finite element studies are more precise than analytical methods, they require long simulation times. The combined conclusion of all of these studies is that electromechanical forces in transformers produce tensile and compressive radial stresses, buckling stresses, bending stresses, and tilting forces on windings.…”