Application of modified modal theory in the modelling of practical transformers

Abstract

The paper is concerned with validating a new form of transformer model aimed at efficient and accurate representation of power transformers in the calculation of electromagnetic transients arising under service and test conditions, where the duration of interest may be as short as tens of microseconds or as long as 5 ms or more. The principal concern is to confirm that modal models, based on a modified theory of modal analysis, retain their efficient structure when proper account is taken of the effects of transient-flux penetration into a practical core, and consequent frequency dependence of inductive and resistive parameters. This is done by modelling representative test windings on a commercial laminated core and comparing computed results with test results.