ABB Relion 670 Series Applications Manual page 403

1MRK 511 401-UUS F
Comp : When parallel operation with the circulating current method is used, this setting increases
or decreases the influence of the circulating current on the regulation.
If the transformers are connected to the same bus on the HV- as well as the LV-side,
calculated with the following formula which is valid for any number of two-winding transformers
in parallel, irrespective if the transformers are of different size and short circuit impedance.
= ´
Comp a
EQUATION1984-ANSI V1 EN-US
where:
•
DV is the deadband setting in percent.
n denotes the desired number of difference in tap position between the transformers, that
•
shall give a voltage deviation V
p is the tap step (in percent of transformer nominal voltage).
•
a is a safety margin that shall cover component tolerances and other non-linear
•
measurements at different tap positions (for example, transformer reactances changes from
rated value at the ends of the regulation range). In most cases a value of a = 1.25 serves well.
This calculation gives a setting of
transformers have n tap positions difference.
OperSimTap : Enabling/disabling the functionality to allow only one transformer at a time to
execute a Lower/Raise command. This setting is applicable only to the circulating current method,
and when enabled, consecutive tap changes of the next transformer (if required) will be separated
with the time delay
OperUsetPar : Enables/disables the use of a common setting for the target voltage VSet . The
common setting for target voltage is mainly used for the circulating current method, but can also
be applied to the master follower method. When enabled, a mean value of the
transformers in the same parallel group will be calculated and used.
OperHoming : Enables/disables the homing function. Applicable for parallel control with the
circulating current method, as well for parallel control with the master-follower method.
VTmismatch : Setting of the level for activation of the output VTALARM in case the voltage
measurement in one transformer bay deviates to the mean value of all voltage measurements in
the parallel group.
tVTmismatch : Time delay for activation of the output VTALARM.
T1RXOP.......T8RXOP : This setting is set Enabled for every transformer that can participate in a
parallel group with the transformer in case. For this transformer (own transformer), the setting
must always be
TapPosOffs : This setting gives the tap position offset in relation to the master so that the
follower can follow the master's tap position including this offset. Applicable when regulating in
the follow tap command mode.
Bay control REC670
Application manual
´ D
2 V
´
100%
´
n p
which corresponds to the dead-band setting.
di
Comp that will always initiate an action (start timer) when the
t2 .
Disabled .
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Section 14
Control
Comp can be
(Equation 131)
VSet values for the
397