A program for harmonic modeling of distribution network transformers and determination of loss in the transformers and the amount of decrease of their life

Abstract

Harmonic modeling of power network transformers is dealt with. The input of the electromagnetic model, voltages and distorting currents and the output of this model are harmonic losses. By using the thermal model and the input of losses temperature distribution is obtained. By using the temperature distribution the amount of transformer's loss of life and the related cost are calculated. For thermal modeling of the transformer existing experimental formulas in the other papers that have been obtained by experimental results have been used. About the presented harmonic model for the transformer's equivalent circuit the following points have been considered: 1) considering the shell and the juxtaposition effect in the modeling of loss. 2) Modeling of the core's saturation effect by adding the current source which is dependant on the voltage. 3) The core's loss as a function of the frequency. 4) Adding leakage and stray capacitors in the model.