9.8.5 Application
A circuit breaker is used to connect two different power networks. It is essential
to ensure that these power networks are synchronized before closing the CB,
otherwise it may lead to disturbances in the power system, causing stress and
damage to the connected equipment.
The synchronization of any bus coupler or tie feeder is not feasible if the voltage and
frequency differences across the circuit breaker are not within the allowed limits. In
this case, the sources which are part of the power network connected across this
bus coupler or tie feeder CB have to adjust their voltage and frequency. ASCGAPC
can be used as coordinator for selection and coordination with the sources, during
the synchronization of any bus coupler or tie feeder circuit breaker. The function
allows the synchronization of only one circuit breaker at a time. In case of any
conflict, the synchronization process is stopped.
As a coordinator the function assists in the participating sources selection based
on the network topology and interacts with the sources to initiate the voltage and
frequency matching for the bus coupler or tie feeder CB to be synchronized.
When selected for synchronization, any NSCB communicates with ASCGAPC for
matching of voltage and frequency difference. ASCGAPC passes the required
information to the participating sources along with their active status. An NSCB
synchronization is described with one typical example in
Figure 890
.
Source
2
ASNSCSYN
(NSCB2)
ASCGAPC
ASGCSYN
(SCB2)
ASGCSYN
(SCB1)
ΔU, ΔF
Synchronize
Start Matching
Bus1
Bus2
Source
1
ASNSCSYN
(NSCB3)
ASCGAPC
ASNSCSYN
(NSCB1)
ASCGAPC
ASCGAPC
ASCGAPC
ΔU, ΔF
Figure 890: NSCB2 synchronization
In this application example, breaker NSCB2 must be closed so the synchronizing
conditions between Bus1 and Bus2 are checked by ASNSCSYN. ASNSCSYN sends the
autosynchronization request and voltage and frequency difference (ΔU, ΔF) between
the Bus1 and Bus2 to the Autosynchronization coordinator functions ASCGAPC.
ASCGAPC transfers the voltage and frequency difference sent by ASNSCSYN to the
ASCGAPC of source 1 ASGCSYN function as well as to the ASCGAPC of source 2
ASGCSYN function. It also sends the permission to the source to start matching the
voltage and frequency. The matching process is carried out so that the voltage and
frequency difference between Bus1 and Bus2 measured by ASNSCSYN reduces and
comes within the synchrocheck limits. This satisfies the synchrocheck conditions
for breaker NSCB2 which can then be synchronized by ASNSCSYN.
1MRS759142 F
Control functions
REX640
Technical Manual
1619
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