ABB REG670 Applications Manual page 561

1MRK 502 071-UEN -
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
Automatic voltage control for tap changer function, TR1ATCC for single control and
TR8ATCC for parallel control for voltage regulation instead of U
TR1ATCC or TR8ATCC will still perform the following two checks:
1. The magnitude of the measured busbar voltage U
range, (setting Umin and Umax). If the busbar voltage falls-out of this range the
line voltage drop compensation calculations will be temporarily stopped until the
voltage U comes back within the range.
B
2. The magnitude of the calculated voltage U
that it is only allowed to be equal to or smaller than the magnitude of U
otherwise U will be used. However, a situation where U
B
a capacitive load condition, and if the wish is to allow for a situation like that, the
limitation can be removed by setting the parameter OperCapaLDC to On.
~
U
L
IEC06000487 V2 EN
Figure 284: Vector diagram for line voltage drop compensation
The calculated load voltage U
Main menu/Test/Function status/Control/TransformerVoltageControl(ATCC,
90)/TR1ATCC:x/TR8ATCC:x.
Load voltage adjustment
Due to the fact that most loads are proportional to the square of the voltage, it is
possible to provide a way to shed part of the load by decreasing the supply voltage a
couple of percent. During high load conditions, the voltage drop might be
considerable and there might be reasons to increase the supply voltage to keep up the
power quality and customer satisfaction.
It is possible to do this voltage adjustment in two different ways in Automatic voltage
control for tap changer, single control TR1ATCC and parallel control TR8ATCC:
1. Automatic load voltage adjustment, proportional to the load current.
2. Constant load voltage adjustment with four different preset values.
In the first case the voltage adjustment is dependent on the load and maximum voltage
adjustment should be obtained at rated load of the transformer.
L
R X
L L
U
B
U
B
jX I
L L
Re
R I
L L
IEC06000487-2-en.vsd
is shown on the local HMI as value ULOAD under
L
Section 15
. However,
B
, shall be within the security
B
at the load point, can be limited such
>U can be caused by
L B
Control
,
B
555