Reliability Analysis And Risk Assessment Of Traction Substation For High-speed Railway

According to the “medium and long-term railway planning”,high speed railway is the focus of the national engineering construction based on major infrastructure and livelihood project in the future.The traction substation is the key to the power supply system conversion control of high speed railway,it can transport the stable power from the external power system to the overhead lines.It is particularly important to study the reliability of the traction substation for high speed railway and the potential risks.Meanwhile,the reliable operation of the traction substation for high speed railway is also the guarantee for the safety operation of high speed railway.Once the traction substation power supply failure occurs,it will cause the train delayed or even suspension,a large number of passengers stranded and huge economic losses to society.There are some dynamic characteristics in the traction substation for high speed railway such as repairable nature,redundancy and so on.Traditional reliability research methods are mostly based on static research,and these methods did not take into account the repairable feature.Aiming at the above problems,in the aspect reliability research,FMEA and DFTA methods are adopted for qualitative and quantitative analysis.First of all,according to the structural characteristics of the traction substation for high speed railway,the form of the main electrical connection and electrical equipment,the failure modes of each of primary power equipments are classified carefully based on the actual operation of the site and reference materials.Finding out the corresponding fault reasons,fault consequences and solutions through the failure mode and establishing the FMEA table.Secondly,the failure modes in FMEA table is bottom event of DFTA and combining with the characteristics of DFTA,the independent dynamic module and static module are founded,the reliability index is calculated based on known data,such as availability and mean time to first failure.Finally,the weak primary equipment in the traction substation for high speed railway could be found by analyzing the calculation results.In the aspect of risk assessment,the risk assessment model of the traction substation for high speed railway is constructed by considering the four influencing factors of personal,environment,management and equipment and the principle of risk assessment.An improved fuzzy hierarchy analysis and entropy method are proposed with the risk assessment method to calculate the subjective and objective weight through the theory of the fuzzy mathematics in the thesis,the final comprehensive weight vector can be solved.The risk level and score value of the system could be calculated by using the scoring mechanism to replace the maximum membership principle which is the traditional method of fuzzy evaluation.In the thesis,the traditional 1-9 scale language is changed to 3 scale language in the improved fuzzy comprehensive evaluation which simplifies the calculation of difficulty.Compared to the maximum membership degree principle,the scoring mechanism could overcome some shortages of the maximum membership degree principle and reflect the risk level of the traction substation for high speed railway preferably.The results of two analysis examples show that the method of reliability analysis and risk assessment is simple and effective,which lays a good foundation for the practical application of engineering.