Research On Time Synchronization Of Information Transmission Network In Smart Grid

Smart grid is a modernized power and information network, in which communications technology is employed to connect power supply information and end-user consumption information that is collected through analog or digital signals. By using this information, power generation, transmission and consumption of industry and household can be adjusted to achieve power loss reduction, energy saving and improvement of power grid reliability. Real-time and efficiency of the communications technology directly impact value and security of the entire power system. Compared with foreign countries, China’s research on communications security of smart grid started relatively late. Improving accuracy of link latency in power grid communications process and practical networking design to achieve time synchronization of the whole network and accuracy requirement of power grid communications have become one of the most critical parts in development of smart grid in China. Therefore, it is very significant to study the information security of the communications network to achieve efficient operation of the whole power system.Currently, the optical networks for power system communications spread all over the world. Different countries use different optical communications standards. SONET (Synchronous Optical Networking) and SDH (Synchronous Digital Hierarchy) are two technology systems that are widely used. The United States and Canada use the SONET while other countries such as China use the SDH. Time messages are critical for time synchronization of the whole power grid, and most of the time messages are transmitted through the SDH optical networks. Thus, it is important to study accuracy of the PTP (Precision Time Protocol) transmission process via SDH networks.The contributions of this thesis are as follows:1.Factors of producing latency in communications links are analyzed based on a lot of survey. Theoretical derivation is conducted, and an algorithm for optimized time-synchronization transmission protocol is proposed.2.The existing communications network deployment in the pilot area of Guangzhou is analyzed, and the overall planning of the time synchronization system is designed. Substations in the pilot area use the communications devices where the proposed modified algorithm is embedded.3.By collecting real data in devices, reliability of the algorithm is analyzed and ensured to meet the requirement of communications link latency in the China Southern Power Grid. Further, the algorithm is extended into other areas to achieve the time synchronization of link security in the entire power grid.