11.1.2
Voltage control of Parallel Transformers
In parallel operation, each transformer protection IED must be connected to the station
communication bus for data exchange. The following procedure assumes that the
necessary pre-configuration in the Parameter Setting tool and the Signal Matrix tool
has been performed and 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
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
.
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
(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/General
settings/Control/TransformerVoltageControl(ATCC,90)/TR8ATCC: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/General settings/Control/
TransformerVoltageControl(ATCC,90)/TR8ATCC:x/ParCtrl/
CircCurrLimit
.
1MRK 511 360-UEN A
Section 11
Primary injection testing
Bay control REC670 2.1 IEC
193
Commissioning manual
