Analysis of Short Circuit Performance of Split-Winding Transformer Using Coupled Field-Circuit Approach

Abstract

Abstract-The split-winding arrangement requires special short-circuit design considerations. During short-circuit conditions, there is a considerable distortion of the leakage field, which in turn produces high axial short-circuit forces. This paper deals with the computation and analysis of electromagnetic forces in windings of split-winding transformers. A nonlinear-transient field-circuit coupled finite element model is used to simulate the split-winding transformer. A 70-MVA, three-phase, 220/6.9/6.9-kV split-winding transformer is modeled under preset and postset short-circuit test conditions. Under the preset condition, the transformer is analyzed with one as well as both the LV windings short circuited to compare the axial forces produced in the windings for these two cases. The results show that there is a considerable rise in the axial forces when one winding is short circuited as compared with the case when both windings are short circuited. The effect of initial magnetization of core on axial short-circuit forces is calculated and discussed. It is also shown that even though postset method eliminates inrush related problems there is not much respite in short-circuit forces.Index Terms-Field-circuit coupling, finite-element method (FEM), nonlinear transient, split-winding transformer.

Analysis of electromagnetic forces in high voltage superconducting fault current limiters with saturated core

“…Several authors have developed formulations to compute the average and maximum values of these forces in round-core power transformers. Both the analytical formulations [9,10,12] and the 3D numerical analysis Finite-Element-Method analysis [15,20,21] obtained similar force patterns within the windings of a power transformer.…”

“…These electromagnetic forces present as radial and axial forces [9][10][11]. Analysis of electromagnetic forces within a power-transformer is well established [9][10][11][12][13][14][15][16][17][18][19]. It was shown that such forces are potential sources for damage.…”

“…The problem faced when applying the models used in the analysis of power transformer on FCL design is that transformer models are generally based on round core-coil arrangement [9][10][11][12][13][14][15][16][17][18][19], whereas FCL cores and coils often have different geometries. Since fault current limiting for high voltage applications is a relatively new technology, the effects of electromagnetic forces in HTS FCL coils have never been reported.…”

Transformer Winding Deformation Profile using Modified Electrical Equivalent Circuit

“…Sweep Frequency Response Analysis (SFRA) is a powerful method for the detection and diagnosis of defects in the active part of power transformer which can deliver valuable information about the mechanical as well as the electrical changes in the windings parameters. Kulkarni and Kumbhar (2007) have computed the force distribution due to short-circuit current in a splitwinding transformers using Finite Element Analysis (FEA). Faiz et al (2008) have analyzed the radial and axial electromechanical forces developed by the inrush and short circuit currents using 2D and 3D Finite Element Method (FEM) models.…”