In view of the inner-clock synchronization method normally used in the line current differential protection

the possibility of differential protection mal-operation is analyzed when there is an inconsistence of the sending and receiving routing in measuring the channel delay based on the Ping-Pong theory. By combining the synchronization criteria of the electrical variables on both sides of the line

an adaptive abnormal differential current monitoring method is proposed for identifying the synchronization abnormality in the line current differential protection. A self-correcting synchronization strategy is then given which combines the inner-clock system

external clock system and electrical variables criteria. The strategy is able to automatically realize the synchronization status identification and improve the capability in solving the routing inconsistency of differential protection. Testing results show that the proposed multi-dimensional cross-checking based self-correcting synchronization strategy can increase the robustness of line differential current in the routing inconsistency situation.