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燕山石化乙烯装置共有7套控制系统。虽然各控制系统的控制器都带有内部时钟,但其固有误差难以避免,长时间连续运行,会产生控制系统内部及各控制系统之间时钟不匹配的情况,导致系统时钟失去正确的计量作用。本文针对DCS控制系统内部时钟的时间一致性要求和各控制系统时钟固有误差难以避免的问题,并且考虑到控制系统的兼容性,采用2种方法来解决此类问题。首先,对于支持TCP/IP网络通讯的控制系统,实现了基于GPS授时原理的NTP/SNTP协议时钟同步网络服务器来同步控制系统时钟方法;然后,对不支持TCP/IP网络通讯的Triconex TMR系统,采用从DCS控制站DO卡件送出一个5S脉冲,TMR系统在接收到此脉冲后,把系统时间设定为凌晨2点的约定握手信号来解决。实施时钟同步后,各控制系统内部及控制系统之间的理论时钟误差在10 ms以下。在实际使用中,对DCS系统来说,同一个网络域的设备时钟误差在10 ms以下;不同域的设备由于经过网络转换单元BCV转换协议,时钟误差在20 ms以下。采用统一时钟管理,有利于事故原因的查找,有利于事故发生过程的明晰,为生产系统提供必要的控制调整指导措施和事故原因分析数据。通过这些措施的实施,时钟同步运行良好,保证各控制系统间数据的统一,为日常乙烯生产提供更加精确的仪表数据,便于系统控制的分析优化。
Yanshan Petrochemical ethylene plant a total of 7 sets of control system. Although the controller of each control system has an internal clock, its inherent error is hard to avoid. Continuous operation for a long time will result in a clock mismatch between the control system and each control system, resulting in the loss of the correct measurement function of the system clock . In this paper, DCS control system for the internal clock time consistency requirements and the control system clock inherent error is difficult to avoid the problem, and taking into account the control system compatibility, using two methods to solve this problem. First of all, for the control system supporting TCP / IP network communication, a clock synchronization network server of the NTP / SNTP protocol based on GPS timing principle is implemented to synchronously control the system clock method. Then, for a Triconex TMR system that does not support TCP / IP network communication, Send a 5S pulse from the DO card of the DCS control station. After receiving this pulse, the TMR system sets the system time as the agreed handshake signal at 2 am. After implementing clock synchronization, the theoretical clock error between each control system and the control system is below 10 ms. In actual use, for DCS systems, the device clock error in the same network domain is less than 10 ms; the clock error of the devices in different domains is less than 20 ms due to the BCV conversion protocol of the network conversion unit. The use of a unified clock management is conducive to finding the cause of the accident, which is conducive to the clarification of the accident occurrence process and provides the necessary control adjustment guidance measures and accident analysis data for the production system. Through the implementation of these measures, the clocks work well in synchronization to ensure the unity of data among control systems, provide more accurate instrument data for daily ethylene production, and facilitate the analysis and optimization of system control.