Models And Algorithms On Optimum Maintenance Scheduling Of Railway Power Systems

Electrified railway has played an important role in modern transportations and social development in China because of its huge capacity, high efficiency, high speed and low pollution. Railway power systems, as the core of electrified railway, are required highly reliable, highly available and lowly dissipative in maintenance. Thus, studies on reliability evaluations and optimum maintenance scheduling of them have come to more attention. However, detailed studies are not adequate and satisfied.Optimisation methods of maintenance scheduling of railway power systems based on their reliability analysis are presented in this dissertation from the existing studies.The contributions of this dissertation mainly summarised as following.In this dissertation, Type I Extreme Value Distribution Approximation and Piecewise Polynomial Function Approximation are proposed to estimate the parameters of reliability distribution under only known lifetime mean and deviation of components from manufacturers. When the ratio to mean lifetime and its standard deviation is larger than 0.446, the parameters of Weibull can be well estimated by a group of piecewise polynomial functions given in the disseration. The maximum estimation errors are about 5% in computation tests. In addition, the case study of Type I Extreme Value Distribution (TIVED) Approximation is carried out. The reliability models of 12 kinds of components are tested byχ~2 and K - S tests. Of all components, 6 kinds of them satisfy both two tests and 2 kinds satisfy one of the two tests. The results denote that TIVED Approximation is a simple and feasible method to estimate the relaiblity of components in railway power systems.FTA models of traction substations, catenaries and supply sections are respectively constructed in this thesis after the analysis of railway power systems. The reliability and cost models affected by maintenance activities are also proposed in this dissertation. The BDD algorithm is employed to calculate the minimum cut sets and reliability function of fault trees. To find the critical components in the systems, the importance order and sensitivity of the components are carried out. The following conclusion can be drawn from the case studies: The failures of railway power systems mostely generate from catenaries. Of all components in catenaries, contact wires and insulators are most critical to the reliability of the overall system.Optimal maintenance scheduling of components, traction substations and catenaries is formulated for minimum cost, maximum reliability and both. The constraints of the minimum cost model include minimum reliability and availability, as well as total runtime. Those of the maximum reliability model include maximum cost, minimum availability and total runtime.