Transient overvoltage study and model for shell-type power transformers

In order to calculate winding resonances of shell-type power transformers under lightning impulses, an accurate RLC model of the transformer taking into account frequency dependence, is presented. RLC parameters are calculated using analytical and finite element methods. An interactive computer model has been developed and allows automatic generation and calculation of the network elements. The classical network method is used for the frequency study. Transient overvoltages of the transformer are calculated from the frequency response by Fourier transform. Good agreement between experimental and numerical results shows that the model is well adapted to predict windings overvoltages