Application of an Improved Multi-Conductor Transmission Line Model in Power Transformer

In this paper, a new multi-conductor transmission line (MTL) method is introduced to analyze the voltage distribution of power transformer windings, including inserted capacitance continuous winding and duplex winding, under lightning overvoltage excitation. This new MTL model may take into account electromagnetic induction between windings. The influences of copper screen tapes on the MTL parameters are discussed. The terminal conditions of single winding including screen tape differ from those of duplex windings, which have to be carefully considered. The results are compared with the traditional equivalent circuit model, revealing that the new model may provide detailed accurate voltage distribution on each turn of the windings.