Adaptive relaying for protecting a distribution system-a feasibility study

The feasibility of an adaptive relaying system for a distribution network is examined. A reduced version of the City of Saskatoon distribution network has been selected for this study. Overcurrent and directional overcurrent relays are used to protect the system. The scope of the work includes changing relay settings and relay pick-up currents in an online mode as operating conditions of the system change. The system changes considered are the loads and generation level changes and line and transformer outages over a period of several days. Relay coordination and communication software which are essential for implementing an adaptive relaying system are discussed. A laboratory model for an adaptive relaying system is presented. It is shown that by using microprocessor-based relays and appropriate software, as well as communication aids, an adaptive relaying concept can be implemented