Digital communication for current differential protection schemes

摘要

The overwhelming majority of the more than 200,000 differential relays that are in worldwide operation today use pilot cables as their communication media. The advances in telecommunications frequently make a change of the complete protection system concept necessary. Modern digital communications have entered the substation. Fibre optic cables and enterprise digital communication networks replace more and more traditional pilot wires. The majority of today's telephone networks have now been upgraded from analogue to digital, with the result that there are hardly any rentable wire pilot wires available anymore for analogue differential relays. This paper deals with the relay requirements on digital communication links and new opportunities for a further enhancement of line differential schemes.