Research On Reliability Of AC Traction Powre Supply System In Urban Rail Transit

Urban rail transit is one of the main choices for many people to travel,not only because of its fast speed,safety and reliability,but also because it has the comfort and punctuality that other ground transportation does not have.Therefore,urban rail transit is It plays an increasingly indispensable role in modern urban life.The lack of power supply capacity of the DC power supply scheme,the large investment in the initial stage of construction,and the existence of turbulence have seriously affected the rapid development of urban rail transit.The AC power supply scheme has the advantages of low construction cost,strong power supply capability,and high power supply reliability.It is also applicable to urban rail transit,and the reliability of the power supply system is a key factor to ensure the normal operation of the entire system.This paper introduces the structure and principle of the two power supply schemes,and expounds the shortcomings and advantages of both the DC power supply scheme and the AC power supply scheme.In order to ensure the normal operation of the urban rail transit AC power supply system,reliability analysis of the entire system is essential.This paper gives the urban rail transit AC traction power supply system.The basic framework of reliability research and its reliability indicators,and the entire power supply system is divided into the following four levels: central substation layer,cable layer,traction substation layer and contact network layer.Firstly,according to the power supply characteristics of urban rail transit,the single-phase combined power supply is used for the central substation,and the corresponding reliability analysis model is established by the GO method and the Bayesian network method for the central substation,and then simplified.MATLAB programming is used for quantitative analysis and qualitative reliability analysis.On the basis of qualitative analysis,find out the weak links of the central substation and propose improvement measures for these weak links.Then,for the power cable,three standby situations of no standby,50% standby,and 100 standby are considered respectively,and corresponding reliability models are respectively established for the three standby situations,and then the specific reliability parameters of the cable are calculated.For the traction substation along the line,the Bayesian network method is used to calculate the reliability of the three fault conditions: single feeder fault,single power arm fault and all faults.For the contact network along the line,the reliability parameters of the whole-contact network are calculated from the aspects of whether or not the state measurement and control technology is considered.Finally,on the basis of this,the urban rail transit AC traction power supply system adopts the fuzzy comprehensive evaluation theory based on the expert scoring method to distribute the reliability,and the system reliability index is reasonably distributed to the four subsystems that constitute the urban rail transit AC traction power supply system.In order to improve and optimize the reliability of the system.