Study On Subway Main Control System Reliability Evaluation Method Based On DFTA

Subway is the vitals of city track traffic, its stable and reliable operation is especially important. Subway main control system, SMCS is the substantial guarantee of the reliable operation of subway system, so the reliability methods study on SMCS are helpful to the design, maintenance. It has significant academic and applied value to study and select an efficiencal reliability method.The structure and function of subway main control system are introduced in the paper, and the deficiency of traditional FTA method using in SMCS is discussed. Considering SMCS with the characteristics of fault-tolerant, order-related and redundant, dynamic fault tree analysis has been introduced to analysis the SMCS reliability.When evaluating the reliability of DFTA, it's converted into Markov Process to be analyzed, which is divided into non-repairable in third paragraph and repairable models in fourth paragraph to assess the SMCS' reliability in this paper. In repair aspect, Markov chain method is used, and its solving formula is improved to be applied extensively. In non-repairable aspect, first reliability index such as Availability,Ateady-state Failure Frequency,Mean Time To First Failure,Mean Up Time,Mean Down Time and Mean Cyclic Time are introduced, and then analytical method and transfer matrix measure are expounded to acquire them, at last hierarchy iterative method is introduced to improve DFTA model, which makes calculation quantity decreased and dynamic reliability indicators applied to whole dynamic fault tree of SMCS.DFTA software including various dynamic models of reliability analysis of SMCS has been developed, so that the users can evaluate the system reliability conveniently and manage reliability data efficiently. As introducing Markov arithmetic, this software includes the following functions: computer assistant dynamic fault tree modeling function, system auto reliability analysis function and dynamic indicators outputting function. Dynamic fault tree model of SMCS and analysis result can be gained for users which avoid complex account. Finally, applying the software to station monitoring system and center monitoring system proves that DFTA method can analysis reliability of the SMCS and this software are usable.