Abstract：The IEC 61850 standard network transmission scheme of sampling-values (SV) completely depends on the synchronous network, which reduces the reliability of digital substations. Although the point to point transmission scheme of SV eliminates the synchronous source dependence, it makes the secondary wiring complex , loses the data sharing advantages, and reduces the maintainability of digital substations.This paper uses a new network transmission scheme which doesn’t rely on the synchronized merging units’ (MU) SV. In this scheme, the network transmission delays are recorded by special switches and filled in the specific field of the data packet, then the SV Synchronization calculations implement. After testing, this scheme’s networking real-time is quite similar to traditional scheme, while its time synchronous accuracy error, under ns level, meets the accuracy requirement of sampling. This scheme eliminates the synchronous source dependency of cross-interval sampling, improves the overall reliability of intelligent digital systems, and also considers the digital substation’s maintainability. So it has good prospects in practical application of smart grids and digital substations.
2014, Vol. 15 
