Abstract: We consider the possibility of proposed high-frequency (HF) models of transformers past power transformersforming part of an electrical grid. We first model a transformer, their application to power quality (PQ) studies. The models are classified according their structure, including its laminated core, toobtain asymptotic behavior of currents and voltages in the secondary circuit. we are able to determine the effects of different by-pass mechanisms which might be tried to getthe high-frequency signal from the primary to the secondary circuit. This research work is devoted to the comparisonof some proposed high-frequency (HF) models of transformers.

Keywords: high frequency transients, high frequencymodelling.