Date Code 20111215 Reference Manual SEL-421 Relay
Section 7
R.Reference Manual
Synchrophasors
The SEL-421 Relay provides Phasor Measurement Unit (PMU) capabilities
when connected to a suitable IRIG-B time source. Synchrophasor is used as a
general term that can refer to data or protocols.
This section covers:
➤ Introduction on page R.7.1
➤ Synchrophasor Measurement on page R.7.6
➤ Settings for Synchrophasors on page R.7.9
➤ Synchrophasor Relay Word Bits on page R.7.19
➤ Synchrophasor Analog Quantities on page R.7.20
➤ View Synchrophasors by Using the MET PM Command on
page R.7.24
➤ C37.118 Synchrophasor Protocol on page R.7.25
➤ SEL Fast Message Synchrophasor Protocol on page R.7.31
➤ Synchrophasor Protocols and SEL Fast Operate Commands on
page R.7.37
See Configuring High-Accuracy Timekeeping on page U.4.71 for the
requirements of the IRIG-B time source. Synchrophasors are still measured if
the high-accuracy time source is not connected, however, the data is not time-
synchronized to any external reference, as indicated by Relay Word bit
TSOK = logical 0.
Introduction
The word synchrophasor is derived from two words: synchronized phasor.
Synchrophasor measurement refers to the concept of providing measurements
taken on a synchronized schedule in multiple locations. A high-accuracy
clock, commonly a Global Positioning System (GPS) receiver such as the
SEL-2407 Satellite-Synchronized Clock, makes synchrophasor measurement
possible.
The availability of an accurate time reference over a large geographic area
allows multiple devices, such as a number of SEL-421 relays, to synchronize
the gathering of power system data. The accurate clock allows precise event
report triggering and other off-line analysis functions, which are described in
Section 4: Time-Synchronized Measurements in the Applications Handbook.
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