ABB RED650, Applications Manual

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21.12.2.3 Process bus IEC/UCA 61850-9-2LE synchronization
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When process bus communication (IEC/UCA 61850-9-2LE protocol) is used, it is
essential that the merging units are synchronized with the hardware time of the IED
(see Technical manual, section
Design of the time system (clock synchronization ) ).
To achieve this, PTP, PPS or IRIG-B can be used depending of the facilities of the
merging unit.
If the merging unit supports PTP, use PTP. If PTP is used in the IED and the
merging unit cannot be synchronized from the IED, then use GPS-based clocks to
provide PTP synch as well as sync to the merging unit.
If synchronization of the IED and the merging unit is based on GPS, set the
parameter
LostSyncMode to BlockOnLostUTC in order to provide a block of
protection functions whenever the global common time is lost.
If PTP is not used, use the same synchronization method for the HwSyncSrc as the
merging unit provides. For instance, if the merging unit provides PPS as
synchronization, use PPS as
HwSyncSrc . If LDCM in GPS-mode is used, that is,
the hardware and software clocks are connected to each other, HwSyncSrc is not
used and other means to synchronize the merging unit to the IED is required. For
instance,
FineSyncSource is set to the same source that the merging unit uses.
21.12.2.4 Time synchronization for differential protection and IEC/UCA
61850-9-2LE sampled data
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When using differential communication in conjunction with sampled data received
from merging units (MU) over the IEC/UCA 61850-9-2LE process bus, the MU
and the IED needs to be controlled by the same GPS synchronized clock. The
required accuracy is +/- 4 µs. The accuracy can be achieved by using a GTM, GPS-
based IRIG-B clock or PTP clock, and synchronizing MU from the same clock or
from the PPS output of the GTM card. If, for instance, IRIG-B is used, the settings
for time synchronization should be
CourseSyncSrc = Off , FineSyncSource = IRIG-
B , TimeAdjustRate = Fast . The setting for Encoding in SYNCHIRIG-B needs to be
set to 1344 .
1MRK 505 393-UEN B
Section 21
Basic IED functions
Line differential protection RED650 2.2 IEC 421
Application manual