Ladder Network Parameters Determination Considering Nondominant Resonances of the Transformer Winding

In order to accurately model the transient behavior of transformer windings, we need models with a large number of nodes and parameters. This paper proposes a model that has fewer nodes and can accurately predict the behavior of a transformer in a wide range of frequencies. In the proposed method, based on the terminal measurements, N dominant resonances are determined, and it is experimentally shown that the winding has N-1 hidden resonances. Using this idea, we suggest the use of a 2N-1 section ladder network, which has a minimum number of nodes and can accurately model the behavior of the transformer winding. The parameters of this model are determined by minimizing the error function by using the genetic algorithm. The close agreement between the simulation and measurement results on the windings of a 20/0.4-kV and 1600-kVA transformer verifies the accuracy of the proposed method.