Temperature Rise Test And Simulation Study In Traction Transformer

As one of the most important electrical equipments in electrified railway power supply system, the performance of traction transformer has a decisive influence on the operation of electrified railway. Since traction transformer has very low average load rate, high demand for short-term overload capacity and significant impact load, so the rules of traction transformer winding hot-spot temperature and insulation aging are different from the power transformer. Calculating the winding hot-spot temperature and aging rate accurately can help to ensure the service life and reduce the capacity at the same time. Based on the structural characteristics and load characteristics of traction transformers, this article set up a traction transformer temperature rise test platform and the corresponding numerical calculation model, studied the distribution characteristics and change rules of temperature field and flow field in transformer under the steady state, step load and continuous impact load, analyzed the influence of baffles and the position of the radiator for the winding hot-spot temperature, and built DQY-31500/220 traction transformer numerical calculation model, explored the rules of winding hot-spot temperature rise and insulation aging under the typical load curve.This paper studied the influence of load state for the temperature field and flow field in transformer. First, a traction transformer temperature rise test platform was developed, On this platform, the temperature distribution and change rules as well as flow speed of radiator in transformer under different loads are measured, and by adjusting the pump valve size to change oil flow circulation speed, the effect of oil flow circulation speed on winding hot-spot temperature was also studied.Then,this paper created a corresponding numerical calculation model based on the temperature rise test platform to calculate the distribution of temperature field and flow field in traction transformer, and compared the simulation results with the test datas to validate the simulation model, studied the variation rules of winding hot spot temperature, winding average temperature, import and export oil temperature of radiator, the top oil temperature and average oil temperature under steady-state, the step load and the continuous impact load, analyzed the association of winding hot-spot temperature and flow rate under steady-state and step load, and explored the impact of former temperature field and flow field on the winding hot-spot temperature under impact load. In order to optimize the transformer structure and reduce the winding hot-spot temperature, it also studied the effects of baffles and the relative position of winding and radiator center on winding hot-spot temperature.Finally, building the DQY-31500/220 traction transformer simulation model based on the finite volume method to explore the rules of winding hot spot temperature rise and insulation aging under the typical load curve, and calculate the average daily life loss under this typical load curve.