ABB REC670 Applications Manual page 421

1MRK 511 401-UUS A
Bay control REC670 2.2 ANSI
Application manual
Line voltage drop
The purpose with the line voltage drop compensation is to control the voltage, not at
the power transformer low voltage side, but at a point closer to the load point.
Figure 172 shows the vector diagram for a line modelled as a series impedance with
the voltage V at the LV busbar and voltage V
B
the line is I , the line resistance and reactance from the station busbar to the load point
L
. The angle between the busbar voltage and the current, is j. If all these
are R and X
L L
parameters are known V
Values for R and X are given as settings in primary system ohms. If more than one
L L
line is connected to the LV busbar, an equivalent impedance should be calculated and
given as a parameter setting.
The line voltage drop compensation function can be turned Enabled/Disabled by the
setting parameter OperationLDC. When it is enabled, the voltage V
the Automatic voltage control for tap changer function, TR1ATCC (90) for single
control and TR8ATCC (90) for parallel control for voltage regulation instead of V
However, TR1ATCC (90) or TR8ATCC (90) will still perform the following two
checks:
1. The magnitude of the measured busbar voltageV
range, (setting Vmin and Vmax). If the busbar voltage falls-out of this range the
line voltage drop compensation calculations will be temporarily stopped until the
voltage V comes back within the range.
B
2. The magnitude of the calculated voltage V
that it is only allowed to be equal to or smaller than the magnitude of V
otherwise V will be used. However, a situation where V
B
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 Enabled.
at the load center. The load current on
L
can be obtained by simple vector calculation.
L
L
Section 14
will be used by
L
, shall be within the security
B
at the load point, can be limited such
>V can be caused by a
L B
Control
SEMOD159053-105 v6
.
B
,
B
415