矿用分布式采集系统时钟同步方案设计与实现

Design and implementation of clock synchronization scheme for mine distributed acquisition system

单一的时钟同步技术由于其精度及应用局限性,无法满足矿用分布式采集系统高精度、高可靠性的时钟同步性能要求。针对上述问题,提出了基于北斗+IEEE 1588V2+本地后备时钟的三级协同时钟同步方案。选用部署在地面的T600-BDGOCXC型北斗授时服务器作为主时钟,为系统提供纳秒级精度的绝对时钟;采用STM32F407+DP83848及PTPd协议栈实现支持IEEE 1588V2协议的采集节点,通过井下工业环网将北斗的绝对时钟同步到各采集节点;本地后备时钟采用STM32F407内部RTC(实时时钟)实现,给各采集节点提供秒级精度的时间戳初值,便于各采集节点用最短时间实现与主时钟的同步。测试结果表明,北斗授时服务器与采集节点通过交换机直连的情况下,1 min后时钟同步精度达162 ns;北斗授时服务器与采集节点通过三级交换机连接的情况下,时钟同步精度为565 ns;在北斗授时服务器失效的情况下,优先级高的采集节点升级为主时钟并为其余采集节点授时,具有较强的可靠性。

Due to its accuracy and application limitations,single clock synchronization technology can not meet the high-precision and high-reliability clock synchronization accuracy requirements of the mine distributed acquisition system.In order to solve the above problems,a three-level coordinated clock synchronization scheme based on Beidou+IEEE 1588V2+local backup clock is proposed.The T600-BDGOCXC Beidou timing server is selected to be deployed on the ground as the master clock to provide absolute clock with nanosecond precision for the system.The STM32F407+DP83848 and PTPd protocol stack are used to implement the acquisition nodes that support IEEE 1588V2 protocol.The absolute clock of Beidou is synchronized to each acquisition node through the mine ring network.The local backup clock is implemented by using the STM32F407 internal RTC(Real-time Clock),which provides each acquisition node with time stamp initial value with second-level precision,so that each acquisition node can synchronize with the master clock in the shortest time.The test results show that the clock synchronization precision is 162 ns after 1 min when the Beidou timing server and the acquisition nodes are directly connected through the switch.The clock synchronization precision is 565 ns when the Beidou timing server and the acquisition nodes are connected through the three-level switch.When the Beidou timing server fails,the acquisition node with high priority is upgraded to be the master clock and provides timing for the remaining acquisition nodes with strong reliability.