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Ma Z.,China Academy of Railway Sciences | Cheng J.,Shuohuang Railway Development Co.
Zhongguo Tiedao Kexue/China Railway Science

With the increase of axle load, the load of heavy haul train acting on track will increase significantly. Under the temperature force and dynamic train load, “bouncing” instability will occur on the CWR of sharp curve. In allusion to the stability problem of CWR on Shuo-Huang Railway under 30 t axle load, the method of unequal wavelength for calculating CWR stability was adopted to study the CWR stability of sharp curve on Shuo-Huang Railway and the safety reserve for CWR with different strengthening methods. Results show that the maximum temperature rise of CWR on R=400 m curve has exceeded the allowable temperature rise, and the stability is unable to meet the requirements under the operating conditions of heavy axle load freight car. The actual safety reserve for CWR on R=450 m curve and R=500 m curve has been significantly decreased. The CWR stability of sharp curve can be significantly improved by different strengthening methods, such as, increasing the number of sleepers, replacing heavy haul sleepers and fasteners. After the strengthening method of replacing heavy haul sleepers being adopted, the stability of CWR on R=400 m curve can be enhanced obviously and its safety factor can reach 1.43 under the condition of the brake temperature rise of 10℃. ©, 2015, Chinese Academy of Railway Sciences. All right reserved. Source

Yu G.-W.,Shuohuang Railway Development Co. | Zhang J.-Q.,Beijing Jiaotong University | Wu M.-L.,Beijing Jiaotong University
Journal of Railway Engineering Society

Research purposes: The traction network in an electric railway is a single-phase unbalance network with the earth, so there is an earth return current when it operates normally. A large earth return current indicates the impeded return current in the overhead contact system. The current is forced to return to the substation through the earth. It may bring a large current in the grounding grid of the substation, which causes overheat or even burning. It may also raise the rail potential, and threaten the safe running of the signal devices beside the rail. The operating performance of the traction power supply system and the driving safety can be worsened. The earth return current in a direct feeding network is calculated with the simulation software developed by the authors. The influences of different structures and parameters on the magnitude of the earth return current are compared and analyzed. Research conclusions: (1)The results reveal that the impedance relationship between the return network and the earth is the main factor influencing the earth current. To decrease the earth current, we can decrease the impedance of the return circuit, increase the grounding resistance, and reduce the leakage loop. (2)For the T-R feeding system without the return conductor, adding the overhead return conductor is an effective method. (3)To resolve the excessive large earth current problem, we should ensure the traction current return to substation freely and there should be no break or tortuous loop in the return circuit. (4)The research conclusions can be the references to the analysis of traction substation earth return current and resolving the excessive large earth current problem. ©, 2015, Editorial Department of Journal of Railway Engineering Society. All right reserved. Source

Yu G.-W.,Shuohuang Railway Development Co.
Journal of Railway Engineering Society

Research purposes: Currently, railway passenger dedicated line adopts up and down AT all-paralleling feeding system, which uses short-circuit test (man-made short-circuit point) to check its protection reliability and distance measurement accuracy. As the destructiveness and fatalness of the short-circuit test, it is very difficult to operate, the cost is very high, there are also limit for test times and flexibility. This paper analyzes the feasibility to adopt locomotive load monitoring and imitating short-circuit test to measure distance, to explore a safe and reliable test scheme.Research conclusions: The research proves that the locomotive load current distribution ratio is the same to the current distribution ration under short-circuit condition. So it is workable to make research with locomotive load current value instead of short-circuit parameters. The verified parameters calculated with locomotive load apply to the protective value of the failure distance and locate the actual failure point. Establish the T-R short-circuit ratio curve graph of each section of the whole line by using a large amount of data, and then confirm the failure point location by seeking table method. This technology could be applied to up and down all-paralleling AT feeding systems distance measurement accuracy verification and formulas of newly built and operational railway passenger dedicated line to verify parameters. Source

Yin H.,Beijing Jiaotong University | Meng X.-H.,Shuohuang Railway Development Co. | Li B.-L.,Shuohuang Railway Development Co. | Huang H.,Beijing Jiaotong University | Gao L.,Beijing Jiaotong University
Journal of Railway Engineering Society

Research purposes: Along with the wide application of regional Continuously Welded Rail (CWR) on heavy-haul railway, it is urgent to apply advanced information management tools for the safety and controllability of heavy-haul freight transportation. This paper mainly focuses on the framework of Heavy-haul Regional CWR Management Information System (HRC-MIS) and the solution of its critical technical issues by taking Shuohuang Railway as an example. The implementation of this system intends to offer powerful technical support to the scientific, informational and networked management of regional CWR on heavy-haul railway. Research conclusions: (1) The framework and functional modules of HRC-MIS are presented according to the theory of design and maintenance of heavy-haul regional CWR. (2) By studying the type, management scope, observation cycle and record method of the data, the calculating method with correction factor for actual neutral temperature and the algorithm for track section load which is based on aggregated traffic pushback are presented. (3)By deeply discussing about the internal correlations among all kinds of data and their influence on the status of the railway, the methods for statistical comparison analysis considering both space and time are proposed. (4)A prediction algorithm for actual neutral temperature by using the General Dynamic Fuzzy Neural Network is presented. And the assistant decision methods including regular and real-time over-limit alarming, early warning and maintenance instruction are proposed. (5) The results of this paper are worth popularizing in other regional CWR on heavy-haul railway and have reference value for the research on the variation law and status evaluation of CWR. Source

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