Magnetization current waveforms and harmonic performance of single phase power transformer under DC bias

Abstract

This paper presents an investigation of voltage-magnetizing current waveforms of single phase power transformer due to DC bias injection through simulation and experimental study. A method base on MATLAB simulation that is capable of predicting of magnetizing current without and with DC bias is used. The experimental study is done by the DC bias current injected simultaneously with AC source to primary winding of transformer. The input AC voltage to primary winding is maintained constant during investigation and the DC currents increased gradually. The results show that the waveforms distorted when the DC bias exist. The pulsated waveforms are pushed to half cycle in which the bias current is in the same direction as magnetizing current (unsymmetrical pulsated) and even harmonics are significant. The simulated waveforms has good agreement with the measured one.