ABB Relion 670 Series Applications Manual page 372

Section 14
Control
is to allow for a situation like that, the limitation can be removed by setting the parameter
OperCapaLDC to Enabled .
~
ANSI06000487 V2 EN-US
Figure 177: Vector diagram for line voltage drop compensation
The calculated load voltage V
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 (90) and parallel control TR8ATCC (90):
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.
In the second case, a voltage adjustment of the set point voltage can be made in four discrete
steps (positive or negative) activated with binary signals connected to TR1ATCC (90) or TR8ATCC
(90) function block inputs LVA1, LVA2, LVA3 and LVA4. The corresponding voltage adjustment
factors are given as setting parameters
inputs are activated with a pulse, and the latest activation of anyone of the four inputs is valid.
Activation of the input LVARESET in TR1ATCC (90) or TR8ATCC (90) block, brings the voltage
setpoint back to
With these factors, TR1ATCC (90) or TR8ATCC (90) adjusts the value of the set voltage
according to the following formula:
Vsetadjust
EQUATION1978-ANSI V2 EN-US
366
R
V
B
V
B
jX I
V
L L
L
R I
L L
is shown on the local HMI as value ULOAD under Main menu/Test/
L
Vset .
I
L
= + × +
Vset S S
a ci
I Base 2
© Copyright 2017 ABB. All rights reserved
X
L
L
Re
ANSI06000487-2-en.vsd
LVAConst1 , LVAConst2 , LVAConst3 and LVAConst4 . The
1MRK 511 401-UUS F
SEMOD159053-118 v6
Vset
(Equation 123)
Bay control REC670
Application manual