Digital relays for smart grid protection

Power system protection in electrical power engineering aims at eliminating a faulted part in an electric network from an otherwise healthy power system. Protection coordination involves a process of best timing any faulted currents so as to reduce the extension of outage areas to a minimum after a fault clearance. In the paper, innovative protection methods and devices widely based on computer relaying techniques and reporting are presented and discussed. Moreover, some procedures for the coordination and setting of protection relays are suggested. The main kinds of microprocessor-operated electronic releases analyzed in the study were overcurrent, directional overcurrent and undervoltage. Finally, possible future developments of digital protections are presented and discussed.