Minimum Circulating Current (Mcc) Method - ABB RET670 Commissioning Manual

1MRK 504 154-UUS B
tested to enable data exchange between IEDs or between instances of voltage control in the same
IED.
For parallel operation, it is also recommended to confirm the setting for the general parallel
arrangement of transformers in Main menu/Settings/Setting group N/Control/
TransformerVoltageControl(ATCC,90)/TR8ATCC:x/ParCtrl. General parallel arrangement of
transformers are defined by setting
the settings of T1RXOP – T8RXOP.
• In each instance of TR8ATCC, set all
Enabled except the parameter corresponding to the IED itself. For example, do not set
to
T1RXOP to Enabled in IED T1 or T2RXOP to Enabled in IED T2.
For example, if IEDs T1, T2 and T3 are connected,
• In instance 1 of TR8ATCC (90), set
• In instance 2 of TR8ATCC (90), set
• In instance 3 of TR8ATCC (90), set
11.1.3

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 (VB) 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 VB values is calculated. The resulting value VBmean is then used in each IED instead of VB 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.
Commissioning manual
TnRXOP to On or Off . The following rules are applicable for
TnRXOP parameters corresponding to the connected IEDs
T2RXOP and T3RXOP to Enabled .
T1RXOP and T3RXOP to Enabled .
T1RXOP and T2RXOP to Enabled .
Iblock ) in Main menu/Settings/General settings/
OperCCBlock ) is set On , and the check the
CircCurLimit ) in Main menu/Settings/General
IEC13000252-1-en.vsd
Section 11
Primary injection testing
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