R.7.20
SEL-421 Relay Reference Manual Date Code 20111215
Synchrophasors
Synchrophasor Analog Quantities
When received, synchrophasor messages contain digital data. This data is
stored in the Remote Synchrophasor Relay Word bits in Table 7.12.
Synchrophasor Analog Quantities
The synchrophasor measurements in Tab le 7.13 are available whenever
Global setting EPMU := Y. When EPMU := N, these analog quantities are set
to 0.0000.
It is important to note that the synchrophasors are only valid when the relay is
in HIRIG timekeeping mode, which can be verified by monitoring the TSOK
Relay Word bit. When TSOK = logical 1, the SEL-421 timekeeping is
synchronized to the high-accuracy IRIG-B signal, and the synchrophasor data
is precisely time-stamped.
RTCDLYB This bit is asserted when the last received valid message on channel B is
older than MRTCDLY.
RTCSEQA This bit is asserted when the processed received message on channel A is
the expected next-in-sequence. It is deasserted if it is not. The deassertion
implies that one or more packets of information were lost.
RTCSEQB This bit is asserted when the processed received message on channel B is
the expected next-in-sequence. It is deasserted if it is not. The deassertion
implies that one or more packets of information were lost.
RTCCFGA Indicates channel A is successfully configured.
RTCCFGB Indicates channel B is successfully configured.
Table 7.12 Remote Synchrophasor Data Bits
Name Description
RTCAD01–RTCAD16 First sixteen digitals received in synchrophasor message on
channel A. Only valid when RTCROKA is asserted.
RTCBD01–RTCBD16 First sixteen digitals received in synchrophasor message on
channel B. Only valid when RTCROKB is asserted.
Table 7.11 Synchrophasor Client Status Bits (Sheet 2 of 2)
Name Description
Table 7.13 Synchrophasor Analog Quantities (Sheet 1 of 3)
Name Description Units
Frequency
FREQ_PM Measured system frequency
a
Hz
DFDT Rate-of-change of frequency, df/dt
a
Hz/s
Synchrophasor Measurements
IAWPMM, IBWPMM,
ICWPMM
Synchrophasor current magnitude
(I_W terminals)
A
b
IAWPMA, IBWPMA,
ICWPMA
Synchrophasor current angle
(I_W terminals)
degrees
IAWPMR, IBWPMR,
ICWPMR
Synchrophasor current, real component
(I_W terminals)
A
b
IAWPMI, IBWPMI,
ICWPMI
Synchrophasor current, imaginary
component (I_W terminals)
A
b
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