Using phasor Measurement units in power system island restoration

System frequency is an indicator of system integrity. Bus frequencies are reliable indicators of power system islands and system separation points. Frequency information is also very important during the black-start and system restoration following break-ups; phasor data can be used to bring equipment back into service without risking stability or unsuccessful reclosing attempts. Phasor Measurement Units are vital in the identification and warning of islanding conditions during emergencies and can provide significant insight in managing an island.