General approach for accurate resonance analysis in transformer windings

In this paper, resonance effects in transformer windings are thoroughly investigated and analyzed. The resonance is determined by making use of an accurate approach based on the application of the impedance matrix of a transformer winding. The method is validated by a test coil and the numerical results are verified by an ATP-EMTP model. Further analysis is applied on a transformer winding for which the inductance and the capacitance matrix as well as the winding losses are previously determined. By having determined the amplification factor, it can be found the location where the most severe transients may occur. It is also shown that maximum resonance overvoltage depends on the duration of the excitation and its resonance frequency.