A Phasor measurement unit is an important tool that is used to monitor and study electric power systems. These devices measure the voltage, frequency and phase angle at buses within the power system. PMU can provide a timestamp type pdf frequency disturbance recorder each measurement.
This allows measurements taken from different PMUs to be accurately compared. This process can be quite expensive and time-consuming, costing tens of thousands of dollars per device and requiring several months of effort. The high cost of installing PMUs has limited their use in the electric power industry. In 2000, researchers led by Virginia Tech faculty member Yilu Liu began the development of a low-cost phasor measurement network that could be installed at the low-voltage distribution level of the power grid. The FNET the system went online in 2004. The Frequency Disturbance Recorder, or FDR, is a GPS-synchronized single-phase PMU that is installed at ordinary 120 V outlets.