Harmonics generated from a DC biased transformer

Abstract

Harmonic characteristics of transformer excitation currents under DC bias caused by geomagnetically induced currents (GICs) are presented. A saturation model for a single phase shell-form transformer based on 3-D finite-element analysis is used to calculate the excitation currents. As a consequence, the variation of excitation current harmonics over an extended range of GIC bias is determined. The results of this study are useful in understanding transformers as harmonic sources and their impact on power systems during a solar magnetic disturbance