Modified integrated congruence transform and its application in computation of VFTO distribution in transformer windings

The paper deals with the computation of very fast transient overvoltages (VFTOs) in transformer windings with frequency-dependent effect. For this purpose, a new technique that extends the idea of integrated congruence transform(ICT) is presented so that it can handle multi-conductor transmission lines(MTLs) with frequency-dependent per-unit-length(FD-PUL) parameters. Based on it, a fast frequency domain algorithm is developed for the calculation of VFTO distribution in transformer windings. For validation of the algorithm, the calculated results are compared with the measurements on a transformer winding model and the result is satisfactory.