Determination of the high frequency parameters of the power transformer used in the railway substation

The paper deals with the modeling method of the power transformers (three phases) used in the railway substation. In order to propose a high frequency model, which will be valid in the frequency band varying from 10 kHz to 30 MHz, it is necessary to identify the various impedances with a good accuracy. Often, these impedances are measured with an impedance analyzer, but for high power transformers, like those used in railway substation, these measurements are more difficult to carry out due to low power level delivered by the impedance analyzer. In this paper, we propose to use measurements in the time domain to identify the transformer impedances. These impedances can be obtained through measurements in various test configurations of the transformer. In the second part of the paper, a high frequency model, using the electrical equivalent circuit, is proposed and validated by the measurement data.