基于PTP协议的列车通信网络时间同步优化研究

Research on time synchronization optimization of train communication network based on PTP protocol

目前列车通信网络支持的网络时钟协议,时间同步精度只能达到亚微秒,无法满足当前列车各节点时间同步精度的需求。针对上述问题,本文提出将精确时钟协议应用在列车通信网络中。为了实现低偏差范围情况下的高同步精度,本文在传统PI控制算法基础上,在改进的时钟伺服系统中提出多模型PI控制优化算法,设定比例系数KP和积分系数KI的阈值极限值,推导阈值极限值与PI输出补偿值的定量关系,进而补偿从节点的时间偏差。最后,以某列车通信网络场景为研究对象在OMNeT++仿真平台进行建模仿真,分析主从节点时间偏差值。与传统PI控制算法得到的时间偏差值相比,列车通信网络中各节点的时间偏差的改进值均在30 ns以内,同步偏差最低可达1.38 ns,验证了所提算法的优越性。

The traditional network clock protocol supported by the current train communication network can only achieve sub-microsecond time synchronization accuracy,which cannot meet the needs of the time synchronization accuracy of each node of the current train.Aiming at the above problems,this paper proposes to apply the precise clock protocol to the train communication network.In order to achieve high synchronization accuracy under the condition of low offset range,based on the traditional PI control algorithm,this paper proposes a multi-model PI control optimization algorithm in the improved clock servo system,and sets the threshold limit values of the proportional coefficient KP and the integral coefficient KI,The quantitative relationship between the threshold limit value and the PI output compensation value is derived to compensate for the offset of the slave node.Finally,taking a train communication network scene as the research object,modeling and simulation is carried out on the OMNeT++simulation platform,and the offset value of the master and slave nodes is analyzed.Compared with the offset value obtained by the traditional PI control algorithm,the improvement value of the offset of each node in the train communication network is all within 30 ns,and the offset can be as low as 1.38 ns,which verifies the superiority of the proposed algorithm.