Reliability Evaluation Of Key Electrical Equipment In Co-phase Power Supply System

The traction power supply system adopts a single-phase power frequency AC system in China.There are negative sequence-based power quality problems and electric locomotive over-phase problems.Nowadays,under the development requirements of high-speed and heavy-duty electrified railways,the co-phase power supply system will gradually replace the traditional traction power supply system.Over the years,the co-phase power supply technology has developed steadily,and the reliability of the system has also attracted more and more attention.In particular,the currently used co-phase power supply systems are based on power and power electronic devices.The random fluctuation and impact of traction load have a great impact on their life.Based on the measured load,the analysis of the reliability of the co-phase power supply system is not only helpful to ensure the accuracy of the reliability evaluation,but also convenient to propose corresponding optimization measures for the characteristics of the traction load.This paper first conducts a reliability evaluation of the core device of the co-phase power supply system,the in-phase power flow controller(PFC).According to the characteristics of the device,the reliability evaluation method based on the physical failure mechanism is used,the loss rate of the IGBT module is calculated by combining the measured data with the loss calculation,junction temperature calculation,life prediction,etc.,and the evaluation method based on the reliability prediction manual is used to determine the DC power Failure rate of capacitors,reactors and other devices.Based on PFC’s special multi-module cascade topology,from small to large,from components to power unit modules to the whole device,the reliability is evaluated step by step,and the k/n(G)model is used to establish the device reliability evaluation model.On this basis,the GO method is used to analyze the reliability of the in-phase power supply system.According to the main wiring of the in-phase power supply system,draw the corresponding GO diagram,perform operator calculation,and quantitatively analyze the system reliability.Finally,consider that PFC is the core equipment of the in-phase power supply system,and the failure rate is relatively large.Taking it as an object,a reliability optimization method for the in-phase power supply system is proposed.According to the structure of PFC,the impact of the number of spare modules and spare strategies on reliability is analyzed,and the optimal number of cascaded modules with excellent reliability and economy of PFC is determined,as well as the spare strategy suitable for PFC.