Research On Dynamic Risk Analysis And Evaluation Method Of High Speed Railway Power Supply System

In recent years,with the vigorous development of high-speed railway industry in China,the problem of high-speed railway operation safety has become increasingly prominent.In order to achieve safe operation of high-speed rail,scientific risk assessment of high-speed rail power supply systems is needed to reduce the losses caused by abnormal operation of high-speed railway.The actual operating environment of the high-speed rail power supply system is harsh and changeable.But the traditional static risk assessment cannot reflect the impact on the system risk caused by changes in the external environment and equipment status,and it cannot describe impact of the evolution of the risk of the high-speed rail power system to the transport system.In order to carry out more accurate dynamic safety risk estimation for high-speed railway power supply systems under different operating conditions,this thesis develops a dynamic risk assessment method for high-speed rail power supply system based on the traditional risk.In this thesis,the concept of risk propagation chain is used based on the theory of fault development of high-speed rail power supply system,and the results of traditional static risk assessment are deeply researched and mathematically modeled.Finally,a dynamic risk analysis assessment method that takes into account changes in equipment status,changes in external environment and cross-system risk is formed.Firstly,based on the operation mechanism of high-speed rail power supply system,the modelling simulation based on MATLAB/Simulink is carried out,and the short-circuit fault mechanism and fault characteristics of high-speed rail power supply system are analyzed.Secondly,the two main parts of the high-speed rail power supply system,the traction substation and the catenary system,are taken as the main analysis objects.Combined with historical data and related data,the risk of whole system is identified and analyzed by using the failure mode and influence analysis(FMEA)method.According to the results of FMEA analysis,this thesis extracts several typical risk propagate chains in the whole system,and applies the risk propagation chain to the improved risk priority number(RPN)method.Each calculation factor in RPN is given a new definition based on the risk propagate chain.Then,the expert scoring mechanism is introduced,and the DUOWA algorithm is used to unify and aggregate the opinions of various expert decisions.Then the relative static risk values are calculated and sorted for each risk chain,and the weak links in the system can be obtained and then advice aimed at risk reduction could be given.Then,in order to make a more accurate risk assessment of the high-speed rail power supply system in real-time operation,this thesis refines the risk chain with higher risk value derived from the static risk analysis process,and the mathematical model of dynamic probability in the process of risk propagation is given.Then the functional relationship between the characteristic quantity and the risk probability is established by using the fault mechanism of risk propagation and it is used as the dynamic condition probability of the Bayesian network to calculate the dynamic probability of the overall risk of the system.In order to draw the impact of risk propagation on passenger flow,the passenger flow intensity index is introduced to analyze the risk consequences and determine the severity,and the dynamic risk analysis and evaluation method of this risk chain was finally established.Based on the background of the project,the method is verified by Chengdu-Chongqing high-speed railway.By comparing the operating environment parameters of the high-speed railway power supply system,the simulation results can be used to obtain the difference of the dynamic risk level of the whole system under different operating conditions,and the simulation results are in line with the actual situation.According to the risk matrix,the countermeasures under different risk levels is given,which shows that the dynamic risk assessment method proposed in this thesis can achieve the dynamic risk assessment of the high-speed railway power supply system in operation,and provide theoretical reference to control risk.