Detection of minor axial winding movement within power transformers using finite element modeling

In order to estimate effective frequency-dependent inductances of transformer windings considering diamagnetic properties, this paper presents an accurate computational model of a transformer, using finite-element method (FEM). Therefore, accurate frequency dependent inductances can be applied into a winding model for frequency response analysis (FRA). This research uses a hybrid winding model to investigate minor axial winding movement in both low (<;1 MHz) and high frequency ranges. Meanwhile, FEM models with respect to several scenarios of minor axial winding movement are constructed, so that corresponding inductances in accordance with specific cases can be obtained by FEM. Therefore, the influence of variations of electrical parameters can be taken into account for FRA in broad frequency ranges. Three scenarios of minor axial winding movement are analyzed in simulation studies.