Design And Realization Of Linux-based Network Time Synchronization System

With the social and economic development, China’s power industry is playing an increasingly important role, and the scale of the power supply system is gradually expanding. In large power supply system, an accurate time reference of the system failure is needed to facilitate the analysis of maintenance personnel, especially when power operation changing. Furthermore, the development of the smart grid arises with a higher requirement of the time synchronization. The NTP protocol network time synchronization system can be a good solution for time and failure analysis in high-precision grid.Firstly, extensive research situation has been carried out. Then, according to the basic principle of NTP protocol and timing and design requirements of satellites, combined with design specifications of the power system time synchronization system, adhering to the modular design concept, the Linux-based set of network time synchronization system for the power system is designed. The time synchronization system supports Network Time Protocol. The system can process satellite packets and network message. The system also has E2E and P2P two timing patterns at the same time. The system adopts the modular design. Various modules work together to guarantee the stability and reliability of the system. In this paper, both hardware and software aspects is described in detail.On the hardware side, the designed system includes three parts:satellite time receiver module, NTP core implementation module and network time output module. The satellite time receiver module is based on GPS/Compass satellite receiver; the NTP core implementation module is based on the form of a combination between ARM and CPLD module; NTP Network Time output module uses a dedicated network chip, satellite packets is firstly collected by GPS/Compass satellite receiver. And then, through the unified scheduling of high performance processor ARM and the professional processing CPLD, the system time can reach high precision. In addition, the perfect peripheral interface circuit is designed to provide driver support and protection, and through the high precision temperature compensated crystal oscillator design scheme, the Automorphic Functions can be achieved.On the software side, as the open-source Linux system entirely and perfectly supports NTP protocol embedded Linux systems, ARM processors are used in the program. This paper firstly describes the specific methods and procedures of Linux systems transplant; secondly, introduces the NTP protocol specific method module, BOA server modules, network and serial communication modules and other software; finally, gives the software watchdog modules to ensure safe and reliable operation of the system.A large number of experiments and test data show that the designed network time synchronization system can achieve high precision, easy application, good reliability, which will meet the requirements of the power system for the NTP clock synchronization, and has good application value.