Modeling of Axial Displacements of Transformer Windings for Frequency Response Analysis Diagnosis

The aim of the article is to present the method of modeling the frequency response of the transformer windings with axial displacements. Frequency response analysis (often referred to as FRA or SFRA) is a powerful and sensitive method for testing the mechanical integrity of transformer cores, windings, and press frames in power transformers. The proper interpretation of FRA results is crucial in assessing winding faults. Computer modeling of transformer active part deformations is one way to expand knowledge about the impact of mechanical faults on the shape of the frequency response (FR) curve. The data collected from these models can be used as training data sets for artificial intelligence tools. An automatic tool developed from this approach would significantly improve the accuracy of the FRA method and simplify the interpretation and evaluation of results. The described study utilizes new types of lumped parameter models with input data obtained from the FEM analysis. The research conducted shows the influence of the winding axial deformation on the frequency response curve and provides information on the sensitivity of the FR curve’s shape to this type of deformation. A series of tests, which involved measuring and simulating typical axial damages, were conducted to evaluate the effectiveness of the presented algorithms.