Computer-Assisted Modeling of Magnetic Fluxes of Power Transformer Affected by Quasi Direct Currents

Abstract

A technique has been developed for modeling the magnetic fields of power transformers in electric power systems using FEMM 4.2 software environment taking into account the structural design and real geometric dimensions of the magnetic system and the transformer tank, quasi direct current components in high-voltage windings, experimental magnetization properties for electrical and structural steel. Magnetic fields in magnetic systems with shell-core and shell designs have been modeled using a sample mass-produced TDC-400000/220/20 power transformer, as well as AODCTN-267000/500/220 autotransformer. The dependencies have been found of the average induction values in the central limb sections and side yokes on the quasi direct currents. It was shown that the saturation of a shell-core magnetic system starts (side yokes) at a quasi direct current close to the rated value of the no-load current, and ends (side yokes and all limbs) at a quasi direct current value close to the rated phase current of the high-voltage winding. The saturation of a shell-type magnetic system occurs when the quasi direct current comes close to the no-load current.