ABB Relion REC670 Applications Manual page 319

1MRK 511 358-UEN A
With the four outputs in the function block available, it is possible to do more than just
supervise a level of power flow in one direction. By combining the outputs with logical
elements in application configuration, it is also possible to cover for example, intervals as well
as areas in the P-Q plane.
Busbar topology logic
Information of the busbar topology that is, position of circuit breakers and isolators, yielding
which transformers that are connected to which busbar and which busbars that are connected
to each other, is vital for the Automatic voltage control for tap changer, parallel control
function TR8ATCC when the circulating current or the master-follower method is used. This
information tells each TR8ATCC, which transformers that it has to consider in the parallel
control.
In a simple case, when only the switchgear in the transformer bays needs to be considered,
there is a built-in function in TR8ATCC block that can provide information on whether a
transformer is connected to the parallel group or not. This is made by connecting the
transformer CB auxiliary contact status to TR8ATCC function block input DISC, which can be
made via a binary input, or via GOOSE from another IED in the substation. When the
transformer CB is open, this activates that input which in turn will make a corresponding
signal DISC=1 in TR8ATCC data set. This data set is the same data package as the package that
contains all TR8ATCC data transmitted to the other transformers in the parallel group (see
section
shows an example where T3 is disconnected which will lead to T3 sending the DISC=1 signal to
the other two parallel TR8ATCC modules (T1 and T2) in the group. Also see table 32.
T1
IEC99000952 V1 EN-US
Figure 160: Disconnection of one transformer in a parallel group
When the busbar arrangement is more complicated with more buses and bus couplers/bus
sections, it is necessary to engineer a specific station topology logic. This logic can be built in
the application configuration in PCM600 and will keep record on which transformers that are
in parallel (in one or more parallel groups). In each TR8ATCC function block there are eight
binary inputs (T1INCLD,..., T8INCLD) that will be activated from the logic depending on which
transformers that are in parallel with the transformer to whom the TR8ATCC function block
belongs.
TR8ATCC function block is also fitted with eight outputs (T1PG,..., T8PG) for indication of the
actual composition of the parallel group that it itself is part of. If parallel operation mode has
been selected in the IED with setting
The parallel function will consider communication messages only from the voltage control
functions working in parallel (according to the current station configuration). When the parallel
voltage control function detects that no other transformers work in parallel it will behave as a
single voltage control function in automatic mode.
Exchange of information between TR8ATCC functions
Each transformer in a parallel group needs an Automatic voltage control for tap changer,
parallel control TR8ATCC function block of its own for the parallel voltage control.
Application manual
"Exchange of information between TR8ATCC functions"
T2 T3
U
U
1
2
Z
Z
I
2
1 1
TrfId = Tx , then the TxPG signal will always be set to 1.
SEMOD159053-259 v3
for more details). Figure
U
3
I Z I =0
3 3
2
I =I +I
L 1 2
99000952.VSD
SEMOD159053-267 v6
Section 13
Control
160
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