III. THE CONCEPT OF PHASOR MEASUREMENT
PMUs are installed at all important locations of the
network to be observed. These PMUs are accurately time
synchronized, typically through the Global Positioning System
(GPS). Based on this time reference, the magnitudes and
phases of voltages and currents at the PMU locations are
measured, at exactly the same times in all locations.
The measured quantities are transferred over fast
communication links to a monitoring center. In the monitoring
center, the data from the connected PMUs are collected,
aligned, archived and provided to the SCADA applications.