A Hybrid Model of Transformer Windings for Very Fast Transient Analysis Based on Quasi-stationary Electromagnetic Fields

Abstract Based on the principle of a quasi-stationary electromagnetic field, a hybrid lumped parameter model of transformer winding under very fast transient over-voltage (VFTO) is proposed in this article. The hybrid model consists of a single-turn model combined with a two-coil model. The single-turn model can be used to calculate the inter-turn over-voltage under a steep-front impulse. The simulation time can be significantly reduced with the help of the two-coil model in the proposed hybrid model. The calculation method for the model parameters is given, and the simulation study for the voltage distribution of a practical transformer winding under a chopped-wave impulse has been performed. The simulation result has been compared with the actual data measured at the Chongqing ABB Transformer Factory to verify the effectiveness of the model. The result shows that the model can predict the voltage distribution inside a transformer winding correctly.