ABB Relion 670 Series Applications Manual page 354

Section 13
Control
TR8ATCC (90) in adapt mode will continue the calculation of V
measured busbar voltage, it will compare it with the deadband DV. The following control rules are
used:
1. If V
di
Tapping will then take place after appropriate
2.
If V
di
Tapping will then take place after appropriate
3.
If V
di
The binary output signal ADAPT on the TR8ATCC (90) function block will be activated to indicate
that this TR8ATCC (90) is adapting to another TR8ATCC (90) 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 (90) 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
Enabled , 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
OperationAdaptEnabled , 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 (90) 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 171. 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 will in this case not be the same,
and they will not reach a minimum at the same time. This might result in a situation when
minimizing of the calculated circulating current will not regulate the tap changers to the same tap
positions even if the power transformers are equal.
However if the capacitive current is also considered in the calculation of the circulating current,
then the influence can be compensated for.
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is positive and its modulus is greater than DV, then initiate an VLOWER command.
is negative and its modulus is greater than DV, then initiate an VRAISE command.
modulus is smaller than DV, then do nothing.
, but instead of adding V
di
t1/t2 timing.
t1/t2 timing.
1MRK 511 358-UUS A
to the
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SEMOD159053-234 v5
OperationAdapt is
SEMOD159053-238 v4
Application manual