Distribution substation control and monitoring using numerical relays

In the past, protective relays have been autonomous devices whose sole purpose was to protect an electrical system against fault conditions. Where control and monitoring functions were required, they were normally implemented using an additional SCADA system or similar network. Recent technological advances have now made it feasible to add communication facilities to relays, enabling remote monitoring by direct extraction of system parameters and remote control of the items of plant connected to the relays. The authors describe a communication system developed specifically for remote monitoring and control of protective relays within the substation environment, particularly at distribution level