Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

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18.42
SEL-400 Series Relays Instruction Manual Date Code 20171006
Synchrophasors
PMU Recording Capabilities
If the RTCCFGA Relay Word bit indicates a new configuration, you can issue the
RTC command to ensure that the data being received have not changed. The
RTC command displays a description of the synchrophasor data being received.
Use this command to ensure that the remote value that you chose for the
SEL
OGIC
equation (for example, RTCAP02 in Figure 18.13 ) is the correct value
to compare with the local synchrophasor value.
The RTCDLYA bit asserts when synchrophasor data have not been received
within the window you set with the local MRTCDLY setting (100 ms in this
example). If the RTCDLYA asserts, consider three options. First, the MRTCDLY
setting can be increased. However, the MRTCDLY setting is your way of guaran-
teeing operation within a certain time. Increasing MRTCDLY allows for commu-
nications channels with longer transmission delay, but at the cost of increasing
the maximum time of operation. A second option is to improve the communica-
tions channel so that it operates within the required MRTCDLY setting time. A
final option is available if the assertion of RTCDLY results from a temporary
communications channel disruption. In this case, putting RTCDLYA in the SER
provides warning.
The COM RTC command also provides information for monitoring system sta-
tus. Figure 18.19 shows a COM RTC command response. Use the maximum
packet delay field to monitor the communications channel delay. This informa-
tion can help you choose an appropriate value for the MRTCDLY setting.
PMU Recording Capabilities
The PMU can be configured to record synchrophasor data by setting EPMDR := Y.
Select one of the data configuration q you want to record using SPMDR setting
where
q = 1–NUMPHDC. Create a recording trigger using PMTRIG SEL
OGIC
setting. On the rising edge of PMTRIG, the PMU starts recording synchrophasor
data. The duration and the pretrigger duration of the recording are user settable.
NOTE:
Select PMTRIG trigger
conditions to assert PMTRIG only once
during a four-hour period if
EPMDR = Y (i.e., synchrophasor
recording is enabled).
The PMU stores these files in the SYNCHROPHASOR subdirectory with .PMU
extension. Use FILE READ or FTP to retrieve these stored data files. The file is
in binary format and IEEE C37.118 data format compliant.
The file starts with a Configuration 2 frame followed by the data frames as shown
below.
<Configuration 2 Frame>
<Data Frame 1>
<Data Frame 2>
.
Summary for RTC channel A
Port: 2
ID: 8
Present Status: Receiving
Max Packet Delay: 50 msec
Message Rate: 60 msgs/sec
Summary for RTC channel B
Port: 1
ID: 9
Present Status: Receiving
Max Packet Delay: 40 msec
Message Rate: 60 msgs/sec
Figure 18.19 Example COM RTC Command Response