Time Synchronization Timesynchgen; Application - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
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 is enabled
on the IEDs and the switches that connect the station are compatible with IEEE 1588, the station will
become synchronized to one common time with an accuracy of under 1us. Using an IED as a boundary
clock between several networks will keep 1us accuracy on three levels or when using an HSR, 15 IEDs
can be connected in a ring without losing a single microsecond in accuracy.
Phasor measurement unit RES670
Application manual
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Section 22
Basic IED functions
IP1750-1 v2
M11345-3 v13
325