Research On Dynamic Risk Analysi’s And Evaluation Method Of Metro Train Traction System

In recent years,China’s rail transit industry has developed rapidly,and a large number of metro train lines have been opened for operation.As the "heart" of the train,the tec hnical content and complexity of the metro train traction system continue to increase,making the probability of metro train failures greatly improved.Traditional risk assessment methods cannot dynamically assess the operational status of a system because of excessive historical statistics on faults.Therefore,it is very important to analyze the impact of faults on the traction system of metro trains and evaluate the dynamic risk,to find out the faults and their chain reaction as soon as possible,and to ensure the safe and efficient operation of metro trains.In order to complete the risk assessment of the metro train traction system,this thesis first introduces the basic structure of the metro train traction system,and analyzes the operation mode,working characteristics and fault conditions of the metro train traction system.Based on the basic electrical parameters of the Chengdu Metro B-type vehicle,the model of the metro train traction system was established based on the Matlab/Simulink platform.Based on this,the vehicle accident occurred in the Guangzhou Metro Line 2 was selected as a typical fault case to simulate the fault.At the fault mechanism level,the analysis of the causes and related effects of typical faults is completed.Secondly,in order to establish a complete risk assessment system for the metro traction system,the risk analysis of the key equipment VVVF inverter of the traction system was carried out by using the FMEA analysis(Failure Mode Effect Analysis)in the static risk analysis method,and the RPN value of each failure mode was calculated.By calculating the RPN value of each failure mode,the risk ranking of each failure mode is completed,and the weak links existing in the safe operation of the train traction system are found out.Then,for the weak links found in the static risk analysis,the fault events that the traction motor is difficult to work normally due to the short circuit of the traction support capacitor breakdown are selected,and the risk propagation chain is established.Through the analysis of the failure mechanism of the risk chain,the observable risk feature quantity is extracted to obtain the influence of the filter support capacitor breakdown short circuit on the traction motor failure rate.Combined with the evaluation factors of metro operation and maintenance,cluster analysis is used to complete the dynamic risk assessment of the safety weak link of the metro train traction system.Based on the above content,this thesis establishes a dynamic risk analysis and evaluation method for the metro traction system.Compared to traditional methods,this method pays more attention to the overall risk probability of the overall system and the risk propagation process which caused by the changes of operating state of the electrical equipment.It can provide a theoretical basis for the online risk assessment of the running metro train traction system,so as to achieve the purpose of timely detecting risks and effectively avoiding risks.