ABB REG670 Applications Manual page 574

Section 15
Control
568
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
information between TR8ATCC functions"
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
58.
T1
T2
IEC99000952 V1 EN
Figure 291: 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 TrfId = Tx, then the
TxPG signal will always be set to 1. The parallel function will consider
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
for more details). Figure
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