Minimum Circulating Current (Mcc) Method - ABB Relion 670 Series Commissioning Manual

1MRK 511 403-UEN E
TransformerVoltageControl(ATCC,90)/TR8ATCC:x/ParCtrl. General parallel arrangement of
transformers are defined by setting
for the settings of T1RXOP – T8RXOP.
• In each instance of TR8ATCC, set all
IEDs to
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
• In instance 2 of TR8ATCC, set
• In instance 3 of TR8ATCC, set
12.1.3

Minimum Circulating Current (MCC) method

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 (
Control/TransformerVoltageControl(ATCC,90)/TR8ATCC:x/TCCtrl/Iblock.
2. Check that the circulating current blocking (
correct settings for circulating current limit (
Settings/Control/TransformerVoltageControl(ATCC,90)/TR8ATCC:x/ParCtrl/
CircCurrLimit.
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(ATCC,90).
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
7. Check that the value of
8. Set the control mode to
9. For transformer T1, adjust the parameter
Settings/IED Settings/Control/TransformerVoltageControl(ATCC,90)/TR8ATCC:x/
ParCtrl/Compso that the LOWER output is activated due to circulating current.
Bay control REC670
Commissioning manual
On except the parameter corresponding to the IED itself. For example, do not set
T2RXOP and T3RXOP to On .
T1RXOP and T3RXOP to On .
T1RXOP and T2RXOP to On .
IPRIM is below the overcurrent blocking level ( Iblock )
ICIRCUL is below the circulating current limit ( CircCurLimit ).
Automatic for all transformers.
© Copyright 2017 ABB. All rights reserved
TnRXOP to On or Off . The following rules are applicable
TnRXOP parameters corresponding to the connected
Iblock ) in Main menu/Settings/IED Settings/
OperCCBlock ) is set On , and the check the
CircCurLimit ) in Main menu/Settings/IED
IEC13000252-1-en.vsd
Comp on the local HMI in Main menu/
Section 12
Primary injection testing
SEMOD176327-195 v4
191