Phasor Measurement Unit (PMU) / synchrophasor

A Phasor Measurement Unit is a device installed on the grid that takes highly precise, time-synchronized measurements of voltage and current many times per second, producing data called synchrophasors. These measurements let grid operators see the grid's actual dynamic behavior in near real time across wide geographic areas, which is far more detailed than traditional SCADA data alone provides, and is used to detect emerging instability before it leads to a wider disturbance.