A new approach to distribution system protection-adaptive relaying

The authors outline the design of an adaptive relaying system for the distribution network of the City of Saskatoon. Overcurrent and directional overcurrent relays are used to protect the network. Important design aspects of the system are emphasised. The developed software and hardware are described. The scheme, implemented in the Power System Research Laboratory at the University of Saskatchewan, is briefly outlined. Also examined are the consequences of partial and total failure of communications between relays and the station computers, and the station computers and the central computer. Measures to alleviate such situations are discussed