Study On The Reliability Of Combined Co-Phase Power Supply System

Compared with the existing co-phase power supply system, combined co-phase power supply system can eliminate split phases in exit points of the electric traction substations, at the same time, the whole system can be optimized. In order to make the capacity utilization of single-phase traction transformer maximized and the capacity of the co-phase compensation device minimized, single phase traction transformer and co-phase compensation device can be selected according to the requirements of the traction load and the voltage unbalance degree. The stable operation of the co-phase power supply system is an important premise to the realization of nationwide engineering, so it has very important practical significance to assess the reliability of traction power supply system.First of all, in this paper, the structure, components, working principle and technical superiority of combined co-phase power supply system is analyzed and the general approaches used in studying the reliability of the system are presented. With the reliability index and the basic framework of combined co-phase power supply system proposed, the scheme to analyze the reliability of the combined co-phase power supply system from the aspects of device and system is confirmed.Secondly, for the co-phase power supply device, it’s reliability is calculated based on the failure rates and reliability of the high power electronic elements. Then, the module consist of components, the unit consist of modules and the whole device are analyzed based on a k/n(G) reliability model and the failure rate and Mean Time To Failures (MTTF) of the two optimized schemes, which include increasing internal modules of converter cells and increasing the units of the device, are quantificationally evaluated and presented. Furthermore, the relationship between the promotion of the reliability and the improvement of the backup capacity is evaluated and the reasonable proportion of the backup capacity is proposed based on the analysis of economy.Finally, a commonly used AT traction power supply system that based on single-phase and single-three phase combined co-phase power supply system is analyzed. A Bayesian Network method is taken to analyze the reliability of the traction substation main wiring, and the Fault Tree analysis method is taken to verify the correctness of the conclusion of the Bayesian Network method. In the last part, the weak link of the combined co-phase power supply system is presented and the feasible optimized schemes that can improve the reliability of the whole system are proposed.