19.12
SEL-400 Series Relays Instruction Manual Date Code 20171006
Remote Data Acquisition
IEC 61850-9-2 Sampled Values (SV)
SV Subscriber Diagnostics and Testing
Once SV subscriptions are configured and enabled, new commands are available
to verify configuration, diagnose and troubleshoot SV communications, and aid
in commissioning and testing: COM SV and TEST SV.
The COM SV command displays information about the SV streams to which the
unit has been configured to subscribe. The data includes the SV destination MAC
address, Application ID, message name, dataset name, VLAN ID, and priority if
the information is available. If information is not available, the field remains
blank. The COM SV command also provides statistics for individual subscribed
SV streams and any error conditions that are currently present or were present
during the previous 30 seconds. For more information on the COM SV com-
mand, see Section 9: ASCII Command Reference in the product-specific manual.
As the SV subscriber receives subscribed SV messages, it places them into a buf-
fer that has a capacity of about 3 ms for each subscribed stream. The Port 5
CH_DLY SV channel setting determines how long the subscriber waits to receive
data from all subscribed streams and will use the channel data from its buffer that
corresponds to this instant in its past. If a subscribed message arrives so late
(> 3 ms) that the SV subscriber does not have a place for it in its buffer, or it
never arrives, the message is considered lost. If SV messages are delayed by
more than CH_DLY but arrive in time to be received into the buffer of the sub-
scriber, these messages are not considered lost, but their data are not used. The
COM SV command uses the warning CH_DLY EXCEEDED to indicate this
condition. If one to three consecutive messages are delayed or lost, the SEL SV
subscriber interpolates the missing data. The COM SV command uses the
INTERPOLATED warning code to indicate when it has had to interpolate for
missing or lost data. If more than three consecutive SV packets are delayed or
missing, the COM SV command uses the error message SV STREAM LOST to
indicate any subscriptions in this condition.
If any subscribed SV streams are lost, the SV subscriber can still be able to pro-
vide some subset of metering and protection functionality, depending on what
data are in the missing stream(s). For example, consider an SV subscriber that
has two active subscriptions with the first one providing one set of terminal cur-
rents and voltages, and the other providing another set of currents. If the second
subscription is lost, the SV subscriber can still provide metering data and some
degree of overcurrent and LOP protection with the data available from the first
stream. Refer to the product-specific instruction manual for available protection
features.
The TEST SV command places the SV subscriber into TEST SV mode. In this
mode, it accepts any subscribed messages with or without the test bit of the qual-
ity attribute set. The data that the SV subscriber receives while in TEST SV mode
are processed as valid data, so take care to ensure that outputs are blocked to pre-
vent any undesired operations. The MET command reflects the received data as
actual data, even with the test bit asserted. The COM SV command indicates
whether the SV subscriber is in TEST SV mode by displaying the information at
the top of the response. Refer to the TEST SV command description in Section 9:
ASCII Command Reference of the product-specific manual for more information.
The health of the incoming SV subscription data channels can be monitored with
the SV subscription Relay Word bits SVSALM, SVSmmOK, and SVCC, and the
SVNDmm (where mm is the SV stream number 01–07) analog quantities. The
SVSmmOK Relay Word bits are asserted when subscription mm is configured
and data conforming with the 9-2LE guideline is being actively received from it.
The SVCC (SV coupled clocks mode) Relay Word bit is asserted when the SV
subscriber is synchronized with the same smpSynch value as the subscription ref-
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