Research On Reliability Of The Marshalling Station Operation System Based On Stochastic Petri Net

Marshalling station is in charge of the railway transportation system, and it`s task is about managing the wagon flow reorganization and transferr, is the key to limit the load capacity of the network of railway transportation. The reliability of marshalling station has a critiacal influence on the railway transportation system, much will depend on work capcacity of marshalling station, but the reliability of marshalling station operation is the main indieator of continuous work, while it is the objective criterion of appraising the wholly operation.In other words, the reliability of marshalling station impacts the reliability of the railway transportation system.From the perspective of system, this paper analysis the marshalling station operation is a discrete event dynamic system, which made up of three subsystems, Reach and Disintegration, Dissolution and Marshalling, Marshalling and Departure.In the past study of the marshalling station operation system, use traditional tools-queuing net model,the mathematical modle of its feature makes Product-Form Solutions for the system to solve complexity is greatly reduced, but ingeneral, a discrete time queuing net model is not the characteristics of PFS, solving only through converted into continuous time Markov chains, and description of synchronization, blocking, splitting insufficiently.According to characteristics of discrete event dynamic system, at the level of logic, Petri net has better description ability, the state of event-driven system in the Petri net model can correspond one-for-one; At the level of time, Petri net has the advantage of the introduction of time parameters, it can accurately describe the dynamic characteristics of the system; At the level of statistics, the model can be embedded Markov chain, to get the probability of the system in steady state.This paper adopts the stochastic Petri net of marshalling station operation system as the research method, traffic flow is a prerequisite for the stability of the system, so traffic resources as the vanguard to analysis the statistical distribution of the marshalling station technical operation time.Then for the sake of simplify the solving complexity to prove a necessary condition for embedding Markov chain of continuous random variable obeying exponential distribution. Finally, select Lanzhou North Marshalling Station to analysis reliability of Marshalling station operation system, it is in a higher level concluded, at the same time, there are some measures to deal with the unbalanced traffic flow while it is under the condition of the fluctuation.