Transformer core modeling as applied to slow transients and protective studies

Magnetic core has major effects on the response of transformers at low frequencies. For better understanding of transformer behaviors and modeling them accurately, it is necessary to study core behaviors and their effects on transformer current and voltage waveforms. For better studying core behaviors, it is possible to divide total flux of windings into core and air fluxes. In this paper, modeling of core fluxes by employing the principle of duality method is discussed. At the end, a real 230/63 kV, 125 MVA transformer with two winding and three-legged core has been simulated. Obtained simulation results are compared with test results and good agreement between these results are obtained