Systems and methods for under-frequency blackout protection

A system for detecting a rotor speed condition on an electric power delivery system, comprising:

• a plurality of generators each in electrical communication to supply electrical power to the electric power delivery system,
• a plurality of generator rotor position detection devices, each in communication with one generator of the plurality of generators, configured to output a signal corresponding with a rotor position of the generator;
• a plurality of intelligent electronic devices (IEDs), each IED of the plurality of IEDs in communication with one of the generators and with one of the generator rotor position detection devices, the plurality of IEDs each configured to detect a rotor speed condition using the output of the generator rotor position detection device in communication therewith and to communicate the rotor speed condition;
• and
• a central IED communicatively coupled with the plurality of IEDs, the central IED configured to
• determine which generators of the plurality of generators are connected on a common isolated sub-grid based on:
• the rotor speed conditions communicated from the plurality of IEDs;
• and, times associated with the rotor speed conditions communicated from the plurality of IEDs;
• and
• determine which loads of a plurality of loads are connected on the common isolated sub-grid based on electric power delivery system information communicated from IEDs associated with the plurality of loads;
• wherein the system provides operational control of the electric power delivery system by signaling appropriate IEDs of the plurality of IEDs to modify associated generation or load based on the determination of which generators are connected on a common isolated sub-grid and which loads are connected on the common isolated subgrid.