Phasor Measurement Unit (PMU) is a vital component of Wide Area Monitoring Systems (WAMS) capable of measuring the voltage magnitude and phase angle at every system bus in the power system, and the current magnitude and phase angle at every branch (lines, transformers and other series elements), simultaneously and continuously. Using Phasor Measurement Units the WAMS can produce synchrophasors, or derived time-synchronized phasor values, to complete the picture of the functioning electricity grid.
The data in each PMU is time-synchronized via Global Positioning System (GPS) receivers – to an accuracy of one microsecond – and aggregated in the Phasor Data Concentrator (PDC) several times a second. The phasors measured simultaneously provide snapshots of the conditions at monitored nodes. By comparing these snapshots, the steady state, and also the dynamic state of critical nodes, can be observed across transmission and sub-transmission networks.
RES670 is a Phasor Measurement Unit that provides power system AC voltages and currents as synchrophasors, providing real and imaginary parts or magnitude and phase angle. The communication capabilities of RES670 include IEEE C37.118 for WAMS solutions and IEC 61850 for easy integration in an existing substation automation system. Further, along with the phasor data measurement functionality, several protection and control functions of the Relion® 670 series IEDs are available in RES670.