Performance analysis of time synchronization precision of PTP in smart substations

Abstract

The precision time protocol (PTP) is fundamentally recommended in smart substations, which could potentially result in further weakening the power system. However, defects of domestic PTP devices restrict the spread of the application of PTP in smart substations. In this paper, the computation of the PTP offset in different clock modes from the two editions of 1588 standards is analyzed theoretically. Test platforms are built to study the timing accuracy of PTP performance under certain circumstances. Especially, a time synchronizing precision test is conducted under the network dataflow including certain messages like PTP, Generic Object Oriented Substation Event (GOOSE) and Sampled Value (SV). In terms of synchronizing precision and stability, the “PTP straight link” test shows that P2P is better than E2E, and that ETH is better than UDP. And the effect of boundary and transparent clock shows that the one-step “P2P-ETH” transparent clock will fulfill the application requirement in smart substation. The last test indicates that the network traffic which consists of such messages enlarge the jitter of PTP synchronization. And comprehensively, the one-step “P2P-ETH” transparent clock is suitable in smart substation.