ABB REC670 Applications Manual page 403

1MRK 511 401-UEN A
Bay control REC670 2.2 IEC
Application manual
TR8ATCC in adapt mode will continue the calculation of U
to the measured busbar voltage, it will compare it with the deadband DU. The
U
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following control rules are used:
is positive and its modulus is greater than DU, then initiate an ULOWER
1. If U
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command. Tapping will then take place after appropriate t1/t2 timing.
is negative and its modulus is greater than DU, then initiate an URAISE
2. If U
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command. Tapping will then take place after appropriate t1/t2 timing.
modulus is smaller than DU, then do nothing.
3. If U
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The binary output signal ADAPT on the TR8ATCC function block will be
activated to indicate that this TR8ATCC is adapting to another TR8ATCC in the
parallel group.
It shall be noted that control with adapt mode works as described under the
condition that only one transformer in the parallel group is set to manual mode via
the binary input MANCTRL or, the local HMI Main menu/Control/Commands/
TransformerVoltageControl(ATCC,90)/TR8ATCC:x.
In order to operate each tap changer individually when the circulating current
method is used, the operator must set each TR8ATCC in the parallel group, in
manual.
Adapt mode (operation with the master follower method)
When in master follower mode, the adapt situation occurs when the setting
OperationAdapt is On, and the master is put in manual control with the followers
still in parallel master-follower control. In this situation the followers will continue
to follow the master the same way as when it is in automatic control.
If one follower in a master follower parallel group is put in manual mode, still with
the setting OperationAdaptOn, the rest of the group will continue in automatic
master follower control. The follower in manual mode will of course disregard any
possible tapping of the master. However, as one transformer in the parallel group is
now exempted from the parallel control, the binary output signal ADAPT on
TR8ATCC function block will be activated for the rest of the parallel group.
Plant with capacitive shunt compensation (for operation with the
circulating current method)
If significant capacitive shunt generation is connected in a substation and it is not
symmetrically connected to all transformers in a parallel group, the situation may
require compensation of the capacitive current to the ATCC.
An asymmetric connection will exist if for example, the capacitor is situated on the
LV-side of a transformer, between the CT measuring point and the power
transformer or at a tertiary winding of the power transformer, see figure 177. In a
situation like this, the capacitive current will interact in opposite way in the
different ATCCs with regard to the calculation of circulating currents. The
capacitive current is part of the imaginary load current and therefore essential in
the calculation. The calculated circulating current and the real circulating currents
Section 14
Control
, but instead of adding
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SEMOD159053-234 v5
SEMOD159053-238 v4
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