Research On Reliability Of Traction Power Supply System Based On Gray Theory And PSO

In recent years, the state investment into the development of electrified railway is increasing constantly, the electrified railway transportation becomes the trend of road transportation industry. With the continuous development of electrical railway, the requirements of safe operation for traction power supply system are also increasing. However,the problems are becoming prominent which affect the safe and reliable operation of traction power supply system. Therefore, in order to meet the needs of the rapid development of china's railway, it becomes very necessary to improve the system's reliability.Firstly, this thesis states the structure characteristics of traction power supply system and explains the basic theoretical knowledge of reliability, introducing the characteristics of the Weibull-distribution mainly which is a common life distribution model. Meanwhile, detailed introductions to reliability research methods for the series and parallel system, the theory of fault tree analysis and minimal cut sets are also given.Secondly, gray GM(1,1) model and unbiased gray GM(1,1) model are used to predict the long-term failure data of the associated equipments, then the simulation errors under two different model are analyzed. Considering the different types of data collected in the working field, the Weibull distribution models, which are used to carry out the reliability assessments for different key equipments in traction power supply system, are established by the intelligent fitting method based on Particle Swarm Optimization(PSO) and piece-wise polynomial method respectively.Finally, this thesis analyses qualitatively the fault tree models of two subsystems called as traction substation and Overhead Contact Lines to find out the minimal cut sets which cause system failure easily. Combined with the Weibull distribution model of different equipments in two subsystems, the quantitative analysis of reliability degree for the two fault tree models are finished, and then the reliability model of the whole traction power supply system is gotten, the system's reliability degree and average lifespan are calculated. In addition, in order to research the influences of the each equipment on the reliability of the whole system, the gray relational analysis model is established, and the key equipment which may affect the whole system's reliability is discovered by this model.The reliability analysis for each single equipment and the whole traction power supply system show that the application of gray system theory and PSO algorithm in the system not only enriches the reliability research theory, but also brings convenience to the course ofreliability research and calculation with establis hment of a good foundation for theoretical applicati on.