DISC on TR8ATCC block is activated by open LV CB. If now the setting parameter
OperHoming
=
On
for that transformer, TR8ATCC will act in the following way:
• The algorithm calculates the “true” busbar voltage, by averaging the voltage
measurements of the other transformers included in the parallel group (voltage
measurement of the “disconnected transformer” itself is not considered in the
calculation).
• The value of this true busbar voltage is used in the same way as U
set
for control of a single
transformer. The “disconnected transformer” will then automatically initiate URAISE or
ULOWER commands (with appropriate
t1
or
t2
time delay) in order to keep the LV side of
the transformer within the deadband of the busbar voltage.
Homing (operation with the master follower method)
SEMOD159053-216 v3
If one (or more) follower has its LV circuit breaker open and its HV circuit breaker closed, and if
OperHoming
=
On
, this follower continues to follow the master just as it would have made
with the LV circuit breaker closed. On the other hand, if the LV circuit breaker of the master
opens, automatic control will be blocked and TR8ATCC function output MFERR will be
activated as the system will not have a master.
Adapt mode, manual control of a parallel group
SEMOD159053-219 v2
Adapt mode (operation with the circulating current method)
SEMOD159053-221 v5
When the circulating current method is used, it is also possible to manually control the
transformers as a group. To achieve this, the setting
OperationAdapt
must be set
On
, then the
control mode for one TR8ATCC shall be set to “Manual” via the binary input MANCTRL or the
local HMI under Main menu/Control/Commands/TransformerVoltageControl(ATCC,90)/
TR8ATCC:x whereas the other TR8ATCCs are left in “Automatic”. TR8ATCCs in automatic mode
will then observe that one transformer in the parallel group is in manual mode and will then
automatically be set in adapt mode. As the name indicates they will adapt to the manual
tapping of the transformer that has been put in manual mode.
TR8ATCC in adapt mode will continue the calculation of U
di
, but instead of adding U
di
to the
measured busbar voltage, it will compare it with the deadband DU. The following control rules
are used:
1.
If U
di
is positive and its modulus is greater than DU, then initiate an ULOWER command.
Tapping will then take place after appropriate
t1/t2
timing.
2.
If U
di
is negative and its modulus is greater than DU, then initiate an URAISE command.
Tapping will then take place after appropriate
t1/t2
timing.
3.
If U
di
modulus is smaller than DU, then do nothing.
The binary output signal ADAPT on the TR8ATCC function block will be activated to indicate
that this TR8ATCC is adapting to another TR8ATCC in the parallel group.
It shall be noted that control with adapt mode works as described under the condition that
only one transformer in the parallel group is set to manual mode via the binary input MANCTRL
or, the local HMI Main menu/Control/Commands/TransformerVoltageControl(ATCC,90)/
TR8ATCC:x.
In order to operate each tap changer individually when the circulating current method is used,
the operator must set each TR8ATCC in the parallel group, in manual.
Adapt mode (operation with the master follower method)
SEMOD159053-234 v5
When in master follower mode, the adapt situation occurs when the setting
OperationAdapt
is
On
, and the master is put in manual control with the followers still in parallel master-follower
control. In this situation the followers will continue to follow the master the same way as when
it is in automatic control.
Section 13 1MRK 511 358-UEN A
Control
310
Application manual
To Next Page
Loading...
