Research On Modeling Of Windings Of Transformer Based On Unequal-Length Multi-Conductor Transmission Line Theory

In order to calculate voltage distribution in transformer windings under the very fast transients, a new unequal-length model is proposed in this paper considering the actual configuration of the transformer. The single-input multi-output model is also deduced in this paper. Based on the fact that the dielectric breakdown is always located near the entrance of the winding, the whole winding is divided into several parts. In order to ensure the calculation accuracy, the principle of the partition is introduced in this paper. According to the principle, a new hybrid model of the windings is established, which is composed of three parts: firstly the coils of the entrance of the winding are represented by the unequal-length multi-conductor model, then a single transmission line model is used to represent the middle part of the winding, and the coupling of the mentioned two parts is approximated by applying the single transmission line model; the rest coils of the winding is modeled by an equivalent impedance. For validation, the calculated results are compared with the measurements on a transformer winding model and the result is satisfactory.