ABB Relion 670 Series Applications Manual page 340

Section 22
Basic IED functions
shown being in the test mode, the input signal IED_TEST on the TESTMODE function block is
activated in the configuration.
Forcing of binary input and output signals is only possible when the IED is in IED test mode.
22.13 Time synchronization TIMESYNCHGEN
22.13.1 Application
Use time synchronization to achieve a common time base for the IEDs in a protection and control
system. This makes it possible to compare events and disturbance data between all IEDs in the
system. If a global common source (i.e. GPS) is used in different substations for the time
synchronization, also comparisons and analysis between recordings made at different locations
can be easily performed and a more accurate view of the actual sequence of events can be
obtained.
Time-tagging of internal events and disturbances are an excellent help when evaluating faults.
Without time synchronization, only the events within one IED can be compared with each other.
With time synchronization, events and disturbances within the whole network, can be compared
and evaluated.
In the IED, the internal time can be synchronized from the following sources:
• GPS
• IRIG-B
• IEEE 1588 (PTP)
For IEDs using PMU functionality, only PTP, GPS or IRIG-B or a combination of both GPS and IRIG-B
is allowed.
For IEDs using IEC/UCA 61850-9-2LE in "mixed mode" a time synchronization from an external
clock is recommended to the IED and all connected merging units. The time synchronization from
the clock to the IED can be PTP, optical PPS or IRIG-B. For IEDs using IEC/UCA 61850-9-2LE from
one single MU as analog data source, the MU and IED still need to be synchronized to each other.
This could be done by letting the MU supply a PPS signal to the IED or by supplying a PPS signal
from the IED to the MU, by using a GTM.
The selection of the time source is done via the corresponding setting.
It is possible to select more than one time source, in which case one is backup for the other. The
time synchronization source with the best calculated time-quality is automatically selected. For
instance, if both GPS and IRIG-B are selected and both sources have the required accuracy, optical
IRIG-B with IEEE1344 will be automatically selected as the time synchronization source. Or if GPS
and SNTP are selected, when the GPS signal quality is bad, the IED will automatically choose SNTP
as the time-source.
If PTP is activated, the device with the best accuracy within the synchronizing group will be
selected as the source. For more information about PTP, see the Technical manual.
IEEE 1588 (PTP)
PTP according to IEEE 1588-2008 and specifically its profile IEC/IEEE 61850-9-3 for power utility
automation is a synchronization method that can be used to maintain a common time within a
station. This time can be synchronized to the global time using, for instance, a GPS receiver. If PTP
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