| Combined co-phase power supply is developed on the basis of Meishan’s co-phase power supply scheme in recent years,and it can minimize the capacity of co-phase compensation device and achieve the goal of minimizing the one-time investment of the co-phase compensation device.In the case of combined co-phase power supply,the traction power supply and the negative sequence compensation can be mutually independent in structure,and the functions are mutually combined.As the core component of co-phase compensation device,the performance of the co-phase compensation converter has an important influence on the reliable operation of co-phase power supply system.The weak link of the energy conversion system is the co-phase compensation converter.In order to reduce the system’s failure rate,it is urgent to analyze the reliability of co-phase compensation converter,and propose the corresponding maintenance and repair strategy to ensure the stable operation of the co-phase compensation device.The existing literatures mainly use the electronic equipment reliability manual MIL-HDBK-217F and GJB/Z 299C to evaluate the reliability of co-phase compensation converter in a working state,and these manuals only focus on the effect of junction temperature on the device reliability under constant traction load,while ignoring the impact of junction temperature fluctuations.The failure of the device in the power converter is strongly related to the thermal stress experienced by the device,and more than fifty percent of the faults in the power converter are caused by the fatigue failure of the insulated gate bipolar transistor(IGBT)module.The fluctuation of the traction load causes the loss of the co-phase compensation converter to fluctuate,and then causes the junction temperature of IGBT module to fluctuate,and the speed of IGBT module failure is mainly determined by the mean of the junction temperature of the device and the fluctuation amplitude.First of all,the composition of co-phase power supply system and the structure and parameters of co-phase compensation converter are introduced in this paper.Then,the common methods of reliability evaluation of power converters are analyzed,and the reliability of co-phase compensation converter is evaluated based on the physical failure mechanism.Secondly,taking the 5MW modular co-phase compensation converter as an example,the simulation model of the junction temperature of the rectifier side and the inverter side of the IGBT module is established based on the relevant electric parameters of the converter,and the loss and junction temperature of co-phase compensation converter under rated operating conditions are analyzed.Then,combined with the measured traction load data of high-speed railway and heavy haul railway,the Bayerer model and the linear fatigue cumulative damage theory are used to evaluate the reliability of co-phase compensation converter under different operating modes.Finally,aiming at the traction load of heavy haul railway in this paper,the third operation mode which can improve the reliability of co-phase compensation converter is studied.Based on the power loss of the co-phase power supply system,the relationship between the failure rate of co-phase compensation converter and the system loss is analyzed under different output modes of the traction transformer and the co-phase compensation device. |
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