Fault passage protection based on IDMT relaying with IEC61850-90 inter-substation communications

Protecting electricity distribution networks is becoming increasingly challenging with continual demands to improve performance. Invariably, the solution involves capitalizing on the developments in digital relaying and communications. This paper describes the findings of an investigation into extending IEC61850 beyond the substation in order to provide network wide communications. It introduces the basis for Fault Passage Protection for protecting distribution feeders using an associated internet communications scheme. This protection builds on widely established techniques based on instantaneous and IDMT overcurrent relaying and provides reduced tripping times for faults on the protected feeder while retaining the advantages of the inherent remote back-up protection.