ABB Relion REC670 Applications Manual page 308

Section 13
Control
IEC06000488 V2 EN-US
Figure 152: Inverse time characteristic for TR1ATCC and TR8ATCC
The second time delay,
direction as the first command). It can have a definite or inverse time characteristic according
to the setting
follows the similar formulas as for the first time delay, but the
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 153
voltage U
the line resistance and reactance from the station busbar to the load point are R
angle between the busbar voltage and the current, is j. If all these parameters are known U
can be obtained by simple vector calculation.
Values for R
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
OperationLDC . When it is enabled, the voltage U
for tap changer function, TR1ATCC for single control and TR8ATCC for parallel control for
voltage regulation instead of U
following two checks:
1. The magnitude of the measured busbar voltage U
(setting
compensation calculations will be temporarily stopped until the voltage U
within the range.
2. The magnitude of the calculated voltage U
only allowed to be equal to or smaller than the magnitude of U
However, a situation where U
wish is to allow for a situation like that, the limitation can be removed by setting the
parameter
302
t1=180
t1=150
t1=120
t1=90
t1=60
t1=30
t2 , will be used for consecutive commands (commands in the same
t2Use (Constant/Inverse). Inverse time characteristic for the second time delay
shows the vector diagram for a line modelled as a series impedance with the
at the LV busbar and voltage U
B
and X are given as settings in primary system ohms. If more than one line is
L L
. However, TR1ATCC or TR8ATCC will still perform the
B
Umin and Umax ). If the busbar voltage falls-out of this range the line voltage drop
OperCapaLDC to On .
IEC06000488_2_en.vsd
at the load center. The load current on the line is I
L
will be used by the Automatic voltage control
L
, shall be within the security range,
B
at the load point, can be limited such that it is
L
>U can be caused by a capacitive load condition, and if the
L B
1MRK 511 358-UEN A
t2 setting is used instead of t1 .
and X
L
On / Off by the setting parameter
comes back
B
, otherwise U will be used.
B B
Application manual
SEMOD159053-105 v6
,
L
. The
L
L