A networking transferring scheme of distributed synchronized sampled data for smart substation

The transfer method of sampled data in process-level network of smart substation is one of key technical problems in smart substation. At present, there are two sampled data transferring methods, namely the point-to-point transferring and networking transferring. The system structure can be simplified when networking transferring is used, however its operation depends on global synchronization system, so the failure in global synchronization system leads to the whole system out of service, so the networking transferring of sampled data should not depend on global clock. A new local synchronization scheme, in which the margin unit is used as local master clock and the protection, measuring and control devices as slave clocks, is proposed, and there are many slave clocks in a single measuring and control device, which are locally synchronized with local master clock in margin unit. By means of optimizing the clock selection and tracking mechanisms of IEEE1588, and utilizing interpolation the synchronous data sampling is implemented, and the dependence on global synchronization system is effectively avoided. Main advantage of the proposed scheme is that the networking transferring of sampled data is implemented without global synchronization system. Results of applying the proposed scheme to engineering practice show that the proposed scheme is more reliable and practicable than traditional networking scheme.