王伟峰,范建华,麻吕斌.AMI终端校时策略的优化与仿真[J].电测与仪表,2015,52(9):. WANG Wei-feng,FAN Jian-hua,MA Lv-bin.A High Precise Time Synchronization Strategy for Electric Energy Data Acquire Terminal[J].Electrical Measurement & Instrumentation,2015,52(9):.
AMI终端校时策略的优化与仿真
A High Precise Time Synchronization Strategy for Electric Energy Data Acquire Terminal
为了在集中器、专变终端等嵌入式系统中更高效地完成校时任务,本文基于网络时间协议(Network Time Protocol, NTP)的基本工作原理,结合智能用电信息采集系统(Advanced Metering Infrastructure , AMI)的网络延时特点,给出了AMI的终端NTP基本校时算法。文章针对NTP 时间同步算法在处理网络延时中的不足,提出了几种改进的校时策略,不仅提高了校时的准确性和稳定性,而且大幅度降低了工程计算量,从而可以更好的应用于嵌入式系统。本文首先使用最大似然估计法得出了多次NTP校时的时间偏差最优估计,然后分别介绍了去边缘值、均值滚动筛选和样本滤波方法来进一步改进校时策略。经实验验证,使用本文所提出的校时策略进行校时,校时误差最大仅为525毫秒,完全能把校时精度控制在1秒以内,并有较好的校时准确性和稳定性,能充分适配嵌入式系统并满足了AMI终端的校时要求。
英文摘要:
In order to better complete the clock synchronization in embedded system (such as concentrator and specific terminal), based on the principle of the Network Time Protocol (NTP) and the network delay characteristics of Advanced Metering Infrastructure (AMI), we propose a basic NTP time synchronization strategy for AMI. By analyzing the shortcomings of the network delay treatment of NTP strategy, improved time synchronization strategies are derived. The new strategies in this paper improve the accuracy and stability in time synchronization and reduce the computational complexity, thus they can be more efficiently applied to embedded system. First, maximum likelihood estimation method is used to get an optimal estimation for time error from several NTP procedures. Moreover, we introduce a large-deviation points cutting method, mean value filtering method and a sample filtering method to optimize clock synchronization. Finally, we verify the synchronization strategy through experiments and prove that the maximum synchronization error is 525 milliseconds, which is less than 1 second. The strategies have a better accuracy and stability, which are more suitable for embedded system and fully meets time synchronization requirements of AMI.
