Abstract:The traditional IEC 61850 networking mode has the disadvantages of synchronous source dependency and low reliability. The pointtopoint transmission scheme can help to solve the problem of synchronous source dependence, but the process layer data cannot be shared that makes the maintainability of digital station reduced. This paper proposed a new scheme using switches that have the function of delay recording to realize digital sampling transmission, and verified this scheme by the methods of comparing the samplingvalue(SV)data between direct message and network transmission, network cascading change and network traffic interference, etc. In addition, the network delay performance of SV and the delay recording accuracy of switches are also tested in this study. The results show that the maximum SV data delay of the new scheme is less than 1ms in condition of three cascaded network with full load. Furthermore, if using gigabit cascade network, the network delay and its precision are less than 500μs and 250ns, respectively. All the results are completely satisfied the requirement of IEC 61850 that is the synchronous sampling precision of process level should be less than 1μs. This study proved that the new scheme has a
comparative realtime performance as the traditional networking scheme and solved the dependence of crossinterval sampling on synchronous source. Moreover, this paper also proposed improvements to solve the delay interpolation synchronization algorithm and the Reserved field conflict in order to improve the reliability of the new scheme, which makes the new scheme has a better application prospect in smart grids and digital substations.
