For the line differential protection relays, sampling synchronization is one of the most critical factors to affect the protection performance. Previously, sampling synchronization using voltage phase difference was proposed. In this paper, simulations for more complex, but actually existing, systems such as transmission line consisting of underground cable and over-head line and multi-terminal line are carried out and the proposed method is verified through these simulations.

Sampling synchronization,Propagation delays,Line current differential relay,Line parameters