A reliability assessment method for traction transformer of high-speed railway considering the load characteristics

Reliability assessment of traction transformers is critical to reliability research of the entire high-speed rail traction power supply system. In this paper the impact of high-speed rail load characteristics on the reliability of traction transformer is analyzed, and reliability assessment of traction transformers is proposed. Considering the imbalance, impact and nonlinearity of high-speed rail traction load in this method, transformer derating rate was calculated based on the standard IEEE C57.110 procedures, and thermal circuit model and its differential equations were applied to obtain transformer hot-spot temperature and quantify the traction load characteristics. Then Arrhenius-Weibull model was utilized for transformer reliability assessment. In the example the feasibility of this method was validated by the measured data, and traction transformer reliability index was calculated for reliability assessment. The results show that the impact of the traction load characteristics of high-speed rail on transformer reliability can´t be ignored. The assessment results can assist reasonable decision to reduce the operation risk of traction transformer and meet the demand of safety and reliability.