High frequency FEM-based power transformer modeling: Investigation of internal stresses due to network-initiated overvoltages

This paper presents a method of how to obtain both terminal and internal high frequency models of power transformers using FEM. The model is established from construction information and the approach implements frequency-dependent phenomena on a physical basis. Eddy current effects are represented accurately even with a relatively coarse mesh by using a frequency-dependent complex permeability representation for the core and windings. The model can be employed in EMTP-like programs for a variety of applications, such as analysis for FRA, internal/terminal stresses and transformer network interaction. Analyses of internal stresses are elucidated in this paper.