Research On High Frequency Modeling And Simulation Methods Of Transformer Windings Under Very Fast Transient Overvoltages

Switching operations in Gas Insulated Substations (GIS) may generate Very Fast Transient Overvoltage (VFTO) which is very dangerous for the power system, especially for the transformer which is directly connected to GIS. For a real transformer winding, if each turn is simulated as one transmission line, a system of very large-scale equations will be obtained. Multi-conductor Transmission line (MTL) model based on the representation of the winding by its individual turns of several coils and some turns combinated are used to analyze the transient response of transformer windings under VFTO. This paper presents a model based on MTL using order-reduced method to simplify the calculation. Using the different methods of calculating the transformer winding parameters compared its impact on the simulation results. For validation, the calculated results are compared with the measurements on a transformer winding model and the result is satisfactory.