SYSTEM FOR THE MEASUREMENT AND EVALUATION OF SYNCHRONIZATION CHARACTERISTICS OF IEEE 1588 PRECISION TIME PROTOCOL CLOCK NODES
Clock synchronization protocols provide a manner for synchronizing real-time measurement instruments to different degrees of precision in time. IEEE C37.238 is an IEEE 1588 Precision Time Protocol (PTP) profile for use in power system protection, control, automation and data communication applications utilizing an Ethernet communications architecture, and is capable of sub-microsecond synchronization accuracy. Accurate measurement and analysis of the synchronization of PTP clock nodes, either for interoperability testing or evaluation of individual node performance, is enabled by a special software testing tool, Power Profile GUI (PPGUI), which is presented in this thesis.
PPGUI utilizes the Pulse Per Second (PPS) timestamp logging capabilities of an existing measurement system, which was developed at the U.S. National Institute of Standards and Technology, but PPGUI significantly extends the capabilities of the existing system. An algorithm is presented for censoring and correctly aligning timestamp sequences to remove flaws in the original data, such as those arising from impulsive noise coupled onto the PPS signal lines, while preserving the valid and useful data. PPGUI automatically provides measurements of Timing Error, Holdover, and Convergence as specified in the IEEE 1588 protocol for up to 64 clock nodes and for continuous test durations in excess of 168 hours. Measurements of several PTP clock nodes operating in different network configurations are analyzed with PPGUI and results are presented for cases of correct and anomalous synchronization behaviors.