Synchrophasor

A phasor is a complex number that represents both the magnitude and phase angle of a sine wave. Synchronized Phasors [synchrophasors] are phasors distributed across the power system synchronized from a common time source, usually GPS clock. Synchrophasor technology provides a tool for system operators and planners to measure the state of the electrical system. Synchrophasors measure voltages and currents, at diverse locations on a power grid, and can output accurately time-stamped voltage and current phasors. Because these phasors are truly synchronized,synchronized comparison of two quantities is possible, in time. These comparisons can be used to assess system conditions.

The technology has the potential to change the economics of power delivery. It is estimated that using synchrophasors to directly measure the power system will allow at least a 20% increase in efficiency of energy transmission in the United States.

History

In 1893, Charles Proteus Steinmetz presented a paper on mathematical techniques for analyzing AC networks which was believed to be the first concept of synchrophasors. Steinmetz’s technique of phasor calculation has evolved into the calculation of real time phasor measurements that are synchronized to an absolute time reference. Later IEEE, codified the phasors transmission mechanisms in standard IEEE 1344 and it's modification was later evolved as IEEE C37.118 standard.

Phasor Networks

The phasor network consists of Phasor Measurement devices (PMU), Phasor Data Concentrator (PDC) & SCADA system for achieving various functions based on the synchrophasors. The complete network should ensure the data transfer within the frequency of sampling of the phasor data.

Implementations

*The Bonneville Power Administration (BPA) is the first utility to implement a widespread adoption of synchrophasors in its wide-area monitoring system. Today there are several implementations underway.
*The Eastern Interconnect Phasor Project (EIPP) (now known as the North American Synchrophasor Initiative, or NASPI), has over 40 connected phasor measurement units collecting data into a "Super Phasor Data Concentrator" system centered at TVA.
*The DOE has sponsored several related research projects, including GridStat [http://www.gridstat.net] at Washington State University.

Applications

# Load shedding (i.e. Directing power where it is needed in real-time)
# Increase the reliability of the power grid by detecting faults early, allowing for isolation of operative system.
# Wide Area measurement and control.

Related standards

*IEEE C37.118
*IEEE 1344
*BPA PDCStream
* OPC-DA / OPC-HDA
* IEC 61850