Voltage - Current Waveforms of Single-phase Power Transformer Due to DC Bias

Abstract

The exist of direct current (DC) component in an alternating current (AC), known as DC bias (or DC Off-set) has undesirable effects, particularly on the power transformer, due to the problem of core saturation (half-cycle saturation). An investigation of magnetizing current waveforms of single-phase power transformer due to DC bias injection through MATLAB simulation is present in this paper. The simulation and study are done by injected AC and DC currents simultaneously. The value of AC is fixed and DC is adjusted (variable) in magnitude and also in the directions (positive and negative). The results show that the waveforms (displayed in magnetic flux) are distorted when the DC bias exists. The pulsated waveforms are pushed to half-cycle in the same direction as DC current injected (positive and negative half-cycle saturation). For comparative necessity, the result without DC bias is also provided.