铁路时间同步网综合原子时标的研究

Research on Distributed Ensemble Time Scale for Railway Time Synchronization Network

铁路时间同步网为铁路各系统提供统一的标准时间量值,其精确、稳定与否对铁路系统安全、高效地运营具有重要影响。根据调研,当前铁路时间同步网的潜在问题有:各时间节点时间溯源参考不一致,且未精确溯源至协调世界时(UTC);仅设置1处的1级时间节点故障时,2,3级时间节点受其影响大、鲁棒性不足;监测手段仅针对单个节点,缺乏整体层面的自动监测方法。针对以上潜在问题,该文提出可精确溯源至UTC的铁路时间同步网综合原子时标(TE)作为网内统一的时间溯源参考的解决方案,通过建立铁路时间同步网仿真模型,研究设计了综合原子时标算法,基于1级、2级时间节点19台母钟设备形成了TE。仿真结果表明,TE与UTC的溯源偏差可优于30 ns,溯源不确定度可优于5 ns;1级时间节点正常运行时,引入TE可提高2级时间节点时间稳定度约40%;1级时间节点故障时,TE仍可持续生成并作为网内统一的时间溯源参考,TE同步架构下的2级时间节点与传统同步架构下的相比,其频率、时间稳定度提高约35%;基于TE可获取任意节点间时差,通过分析时差数据,可实现整体层面的所有时间节点、精确时间协议(PTP)链路通断的自动监测。

The railway time synchronization network provides the standard time quantity value for various railway systems.The accuracy and stability of the time quantity value have an important impact on the safe and the efficient operation of the railway systems.There are three potential problems with the current railway time synchronization network.The traceability references of each time node are inconsistent,and the time of each node is not accurately traced to Coordinated Universal Time(UTC).Only one primary time node is set.The secondary and the tertiary time nodes are greatly affected by the failure of the primary time node,and lack of robustness.Monitoring methods are only used a single time node.There is no automatic monitoring method at the overall level.In view of the above potential problems,the distributed Ensemble Time scale(TE)for railway time synchronization network that can accurately trace to UTC is proposed.A simulation model of railway time synchronization network is established,and a TE algorithm is designed.TE is generated by 19 atomic clocks from the primary and the secondary time nodes.The results show that the time differences between TE and UTC can be better than 30 ns.The uncertainty of TE-UTC is better than 5 ns.When the primary time node works normally,the time stability of the secondary time node can be improved about 40%by introducing TE.When the primary time node fails,TE can be continuously generated and used as a unified traceability reference.The frequency and time stability of the secondary time node under the TE synchronization architecture is about 35%higher than that under the traditional synchronization architecture.The time differences between any time nodes can be obtained based on TE.By analyzing the time differences data,automatic monitoring of all time nodes and the continuity of Precision Time Protocol(PTP)links at the overall level can be realized.