Phasor measurement unit
Therefore, PMUs equip utilities with enhanced monitoring and control capabilities and are considered to be one of the most important measuring devices in the future of power systems.
[3] In 1893, Charles Proteus Steinmetz presented a paper on simplified mathematical description of the waveforms of alternating current electricity.
With this change it is imperative that transmission and distribution networks are continuously being observed through advanced sensor technology, such as ––PMUs and uPMUs.
The θ is the phase angle offset from some defined starting position, and the ω is the angular frequency of the wave form (usually 2π50 radians/second or 2π60 radians/second).
In most cases PMUs only measure the voltage magnitude and the phase angle, and assume that the angular frequency is a constant.
The less sinusoidal the waveform is, such as grid behavior during a voltage sag or fault, the worse the phasor representation becomes.
A phase-locked oscillator along with a Global Positioning System (GPS) reference source provides the needed high-speed synchronized sampling with 1 microsecond accuracy.
However, PMUs can take in multiple time sources including non-GPS references as long as they are all calibrated and working synchronously.
The resultant time-stamped phasors can be transmitted to a local or remote receiver at rates up to 120 samples per second.
Now, with the invention of micro-synchronous phasor technology, many more of them are desired to be installed on distribution networks where power can be monitored at a very high degree of precision.
This high degree of precision creates the ability to drastically improve system visibility and implement smart and preventative control strategies.
A phasor is a complex number that represents both the magnitude and phase angle of the sine waves found in electricity.
[clarification needed] The monitored points are preselected through various studies to make extremely accurate phase angle measurements to indicate shifts in system (grid) stability.
[clarification needed] Synchrophasor technology will usher in a new process for establishing centralized and selective controls for the flow of electrical energy over the grid.
These controls will affect both large scale (multiple-states) and individual transmission line sections at intersecting substations.
Transmission line congestion (over-loading), protection, and control will therefore be improved on a multiple region scale (US, Canada, Mexico) through interconnecting ISO's.
PMUs often use phone lines to connect to PDCs, which then send data to the SCADA or Wide Area Measurement System (WAMS) server.
Typically an electrical engineer designs the installation and interconnection of a PMU at a substation or at a generation plant.
Substation personnel will also install "shunts" in all Current transformer (CT) secondary circuits that are to be measured.
[14] This standard was not comprehensive- it did not attempt to address all factors that PMUs can detect in power system dynamic activity.
M class is close in performance requirements to that in the original 2005 standard, primarily for steady state measurement.
