of transformers are defined by setting
TnRXOP
to
On
or
Off
. The following rules are applicable for
the settings of T1RXOP – T8RXOP.
•
In each instance of TR8ATCC, set all
TnRXOP
parameters corresponding to the connected
IEDs to
On
except the parameter corresponding to the IED itself. For example, do not set
T1RXOP
to
On
in IED T1 or
T2RXOP
to
On
in IED T2.
For example, if IEDs T1, T2 and T3 are connected,
•
In instance 1 of TR8ATCC, set
T2RXOP
and
T3RXOP
to
On
.
•
In instance 2 of TR8ATCC, set
T1RXOP
and
T3RXOP
to
On
.
•
In instance 3 of TR8ATCC, set
T1RXOP
and
T2RXOP
to
On
.
12.1.3
Minimum Circulating Current (MCC) method
SEMOD176327-195 v5
Voltage control of parallel transformers with the circulating current method means minimizing the
circulating current at a given voltage target value. The busbar voltage (UB) is measured individually
for each transformer in the parallel group by its associated TR8ATCC function. These measured
values are then exchanged between the transformers, and in each TR8ATCC block, the mean value
of all UB values is calculated. The resulting value UBmean is then used in each IED instead of UB for
the voltage regulation.
1.
Check the overcurrent blocking level (
Iblock
) in
Main menu /Settings/IED Settings /Control/
TransformerVoltageControl(90, U↕) /TR8ATCC(90, U↕||):x/TCCtrl/Iblock
.
2.
Check that the circulating current blocking (
OperCCBlock
) is set
On
, and the check the correct
settings for circulating current limit (
CircCurLimit
) in
Main menu/Settings /IED Settings/
Control /TransformerVoltageControl(90, U↕)/TR8ATCC(90, U↕||):x/ParCtrl/CircCurrLimit
.
IEC13000252-1-en.vsd
3.
Connect all transformers in the parallel group to the same busbar on the secondary side.
4.
Open the test display for Transformer Voltage Control on the LHMI in
Main menu /Test/
Function status /Control/TransformerVoltageControl(90, U↕)
.
5.
Manually execute Raise commands to step up the tap changer for transformer T1 to two steps
above the setting for the other transformers in the parallel group.
6.
Check that the value of
IPRIM
is below the overcurrent blocking level (
Iblock
)
7.
Check that the value of
ICIRCUL
is below the circulating current limit (
CircCurLimit
).
8.
Set the control mode to
Automatic
for all transformers.
9.
For transformer T1, adjust the parameter
Comp
on the local HMI in
Main menu/Settings/IED
Settings/Control/TransformerVoltageControl(90, U↕) /TR8ATCC(90, U↕||):x/ParCtrl /
Comp
so that the LOWER output is activated due to circulating current.
Comp
is a setting for circulating current Compensating Factor, and it is effectively a multiplier
value to change the sensitivity of the voltage regulation function to measured values of
circulating current. A nominal value of 200 for
Comp
should be appropriate to achieve sensitive
1MRK 511 403-UEN Rev. L
Section 12
Primary injection testing
Bay control REC670
209
Commissioning manual
© 2017 - 2022 Hitachi Energy. All rights reserved
Summary of Contents for REC670
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