Analysis and solution of frequency difference in IEEE1588 clock synchronization systems

In smart power substations, the application of precision time protocol defined in IEEE1588 becomes more and more popular. As a distributed network application, PTP is a perfect service to unify all the clocks of smart subsystems in the power substation. It will make great sense to research and improve PTP protocol in order to let it be practical and applicable for power automation applications. This paper focuses the performance of PTP. For convenience to analyze the performance of PTP, the basic elements, the messages, and protocol procedures are detailedly described in this paper. Formulas related with PTP performance are deduced. Frequency difference is the main factor to degrade the accuracy of PTP. Frequency difference among master clock, slave clock and transparent clock is fully discussed in this paper. The influence in directly connected PTP system and in transparent clock participated PTP system is analyzed from various aspects. In the end of the paper, some countermeasures to cope with degradation of PTP performance are suggested.