Dynamic Thermal Network Modeling for Disk-Type Winding Domain of On-Board Traction Transformer

Abstract

For on-board traction transformer (OBTT), due to its compact structure and continuous motion environment, in the period of design and maintenance, dynamic thermal characteristics were getting more attention. In this study, a dynamic thermal network model was proposed for the winding domain inside OBTT, where distributed thermal capacitance was introduced to reflect the heat storage process. The thermal resistance of stagnant oil was first modelled for the heat transfer occurring near boundary layers. Based on the real disc-type winding geometry from one 6.3-MVA OBTT, the proposed model was verified with CFD transient simulation and temperature-rise test. Then, the dynamic thermal characteristics could be easily obtained with the proposed model. The proposed model can be used for design optimization and basis for dynamic thermal rating.