Detection of winding deformation in power transformers

Abstract

The winding is modeled using finite element method (FEM) based software and parameters such as capacitance and inductance are calculated for 10 section healthy coil. Using these parameter values, SFRA plots are obtained which are a set of reference for deformation analysis. The winding is modeled as radially and axially deformed coils using FEM software. The parameters change with deformation in the winding. The deformation is carried at five consecutive sections, and affected parameters are calculated for the same. The main purpose of doing so is to find the location of deformation corresponding to a similar deformation in an actual transformer. The main advantage of the FEM modeling is we can deform the sections as desired unlike in an actual case and obtain the fingerprint graphs from the modified parameter values. The SFRA plots are obtained for the deformations at five sections for axial and radial deformations. A comparison is carried between the SFRA plots for deformed cases with the reference set. The deviations observed are in resonant frequencies, peak current magnitude and bandwidth. From the observations, the type and location of deformation can be found corresponding to a similar deformation in an actual transformer.