Finite-Element Modeling for Analysis of Radial Deformations Within Transformer Windings

This paper develops computational models for undeformed and deformed transformers, using the finite-element method (FEM) to calculate frequency dependent parameters accounting for diamagnetic properties. In this manner, properly estimated inductances and capacitances can be derived and applied into a winding model for frequency response analysis (FRA). This research uses a hybrid winding model, so that frequency responses in the high frequency range (> 1 MHz) can be explored for the investigation of radial winding deformation. Meanwhile, computational models with respect to winding radial deformation are constructed, so that corresponding inductances and capacitances in specific radial deformed cases can be obtained by FEM. Therefore, the influence of the capacitances as well as the inductances can be taken into account for FRA of radial deformation in high frequencies. The frequency response in the undeformed case is compared with the experimental data to verify the accuracy of the frequency dependent parameters and mathematical winding models. The analyzed results in radial deformed cases are compared with the fault features derived from experimental studies reported in relevant literatures.