di
i
cc _ i
i
V
C I
X
=
×
×
EQUATION1979-ANSI V1 EN-US
(Equation 119)
where X
i
is the short-circuit reactance for transformer i and C
i
, is a setting parameter
named
Comp
which serves the purpose of alternatively increasing or decreasing the
impact of the circulating current in TR8ATCC control calculations. It should be noted
that V
di
will have positive values for transformers that produce circulating currents and
negative values for transformers that receive circulating currents.
Now the magnitude of the no-load voltage for each transformer can be approximated
with:
i
Bmean
di
V
V
V
=
+
EQUATION1980-ANSI V1 EN-US
(Equation 120)
This value for the no-load voltage is then simply put into the voltage control function
for single transformer. There it is treated as the measured busbar voltage, and further
control actions are taken as described previously in section
. By doing this, the overall control strategy can be summarized
as follows.
For the transformer producing/receiving the circulating current, the calculated no-load
voltage will be greater/smaller than the measured voltage V
Bmean
. The calculated no-
load voltage will then be compared with the set voltage
VSet
. A steady deviation which
is outside the outer deadband will result in VLOWER or VRAISE being initiated
alternatively. In this way the overall control action will always be correct since the
position of a tap changer is directly proportional to the transformer no-load voltage.
The sequence resets when V
Bmean
is inside the inner deadband at the same time as the
calculated no-load voltages for all transformers in the parallel group are inside the
outer deadband.
In parallel operation with the circulating current method, different
VSet
values for
individual transformers can cause the voltage regulation to be unstable. For this reason,
the mean value of
VSet
for parallel operating transformers can be automatically
calculated and used for the voltage regulation. This is set
Enabled
/
Disabled
by setting
parameter
OperUsetPar
. The calculated mean
VSet
value is shown on the local HMI as
a service value USETPAR under
Main menu/Test/Function status/Control/
TransformerVoltageControl(ATCC,90)/TR8ATCC:x
.
The use of mean
VSet
is recommended for parallel operation with the circulating
current method, especially in cases when Load Voltage Adjustment is also used.
1MRK 511 401-UUS A
Section 14
Control
Bay control REC670 2.2 ANSI
423
Application manual
Summary of Contents for Relion REC670
Page 1: ...RELION 670 SERIES Bay control REC670 Version 2 2 ANSI Application manual ...
Page 2: ......
Page 26: ...20 ...
Page 42: ...36 ...
Page 96: ...90 ...
Page 274: ...268 ...
Page 292: ...286 ...
Page 298: ...292 ...
Page 308: ...302 ...
Page 470: ...464 ...
Page 514: ...508 ...
Page 608: ...602 ...
Page 646: ...640 ...
Page 656: ...650 ...
Page 657: ...651 ...