Backup Solution for Traveling Wave Differential Protection Under Synchronization Failure

Traveling wave differential protection (TWDP) has shown advantages over traditional current differential protection in terms of sensitivity, rapidity and immunity to distributed capacitive current. However, existing TWDP schemes depends heavily on data synchronization through either GPS or communication, of which the potential failure should be considered. This paper discusses the backup solutions for TWDP in condition of synchronization failure. Firstly, the influence of synchronization error to TWDP is analyzed. The results indicate that such error would lead to mal-operation under external faults. Secondly, a backup algorithm is proposed to handle the synchronization failure issus. Extensive simulation experiments based on the PSCAD/EMTDC software show that the proposed method could avoid mal-operation under external faults while maintain sensitivity to internal faults even if synchronization error is large.