Communication Hardware Solutions - Hitachi Relion 670 Series Applications Manual

Section 20
Remote communication
Link forwarding
If it is not possible to have a communication link between each station, the solution has been to set the
protection up in a slave-master-slave configuration. This means that in Figure 124, only IED-B has
access to all currents and, therefore, this is the only place where the differential current is evaluated. If
the evaluation results in a trip, the trip signal will be sent over the two communication links.
IEC16000077 V1 EN-US
Figure 124:
If the LDCM is in 2Mbit mode, you can send the three local currents as well as the three remote currents
from the other links by configuring the transmitters in IED-B:
1. Ldcm312 transmitter sends the local currents and the three currents received by Ldcm313.
2. Ldcm313 transmitter sends the three local currents and the three currents received from Ldcm312.
As a result, six currents are received in IED-A and IED-C. These currents can be connected to the
protection function together with the local three currents.
This setup results in a master-master-master configuration, but without the benefit of reverting to a slave-
master-slave configuration in case of a communication link interruption. In case of a communication link
interruption, all three IEDs would be blocked.
20.1.2.1

Communication hardware solutions

The LDCM (Line Data Communication Module) has an optical connection such that two IEDs can be
connected over a direct fiber (multimode), as shown in figure 125. The protocol used is IEEE/ANSI
C37.94. The distance with this solution is typical 110 km/68 miles.
300
Doing so will affect all protections for the connected cycle time.
LDCM 64kbit will increase trip time about 5 - 15 ms during normal conditions.
LDCM 2Mbit will increase trip time about 2-3 ms during normal conditions.
In addition IED can get transmission delay from communication either from direct fiber or
other equipment such as MUXs etc. Maximum supported communication delay is 40 ms.
3-end differential protection with two communication links
Ldcm312
IED-A
Ldcm312
Three-end differential protection with two communication links
In order to forward the logic signals (for example, inter-trip or inter-block) between IED-A and
IED-C, the setting LinkForwarded should be defined. In IED-B, it is set to LDCM313 for
Ldcm312 and to LDCM312 for ldcm313.
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Ldcm312
IED-B
Ldcm313
1MRK511407-UUS Rev. N
GUID-DD3CF47C-A202-4416-954A-EFC0F8BEBCB7 v2
IED-C
IEC16000077-1-en.vsd
Phasor measurement unit RES670
Application manual
M12844-11 v7