ABB Relion REC670 Applications Manual page 323

1MRK 511 358-UEN A
Setting
RevActPartBk(aut
omatically reset)
CmdErrBk
(manually reset)
TapChgBk
(manually reset
Table continues on next page
Application manual
Values (Range) Description
Alarm The risk of voltage instability increases as
Auto Block transmission lines become more heavily loaded in an
attempt to maximize the efficient use of existing
generation and transmission facilities. In the same
time lack of reactive power may move the operation
point of the power network to the lower part of the P-
V-curve (unstable part). Under these conditions, when
the voltage starts to drop, it might happen that an
URAISE command can give reversed result that is, a
lower busbar voltage. Tap changer operation under
voltage instability conditions makes it more difficult
for the power system to recover. Therefore, it might
be desirable to block TR1ATCC or TR8ATCC
temporarily.
Requirements for this blocking are:
•
•
•
If all three requirements are fulfilled, TR1ATCC or
TR8ATCC automatic control will be blocked for raise
commands for a period of time given by the setting
parameter
will be set. The reversed action feature can be turned
off/on with the setting parameter
Alarm Typical operating time for a tap changer mechanism is
Auto Block around 3-8 seconds. Therefore, the function should
Auto&Man Block wait for a position change before a new command is
issued. The command error signal, CMDERRAL on the
TCMYLTC or TCLYLTC function block, will be set if the
tap changer position does not change one step in the
correct direction within the time given by the setting
tTCTimeout in TCMYLTC or TCLYLTC function block.
The tap changer module TCMYLTC or TCLYLTC will
then indicate the error until a successful command
has been carried out or it has been reset by changing
control mode of TR1ATCC or TR8ATCC function to
Manual and then back to Automatic. The outputs
CMDERRAL on TCMYLTC or TCLYLTC and TOTBLK or
AUTOBLK on TR1ATCC or TR8ATCC will be activated
depending on the actual parameter setting.
This error condition can be reset by the input
RESETERR on TCMYLTC function block, or
alternatively by changing control mode of TR1ATCC or
TR8ATCC function to Manual and then back to
Automatic.
Alarm If the input TCINPROG of TCMYLTC or TCLYLTC
Auto Block function block is connected to the tap changer
Auto&Man Block mechanism, then this blocking condition will be active
if the TCINPROG input has not reset when the
tTCTimeout timer has timed out. The output TCERRAL
will be activated depending on the actual parameter
setting. In correct operation the TCINPROG shall
appear during the URAISE/ULOWER output pulse and
disappear before the
This error condition can be reset by the input
RESETERR on TCMYLTC function block, or
alternatively by changing control mode of TR1ATCC or
TR8ATCC function to Manual and then back to
Automatic.
The load current must exceed the set value
RevActLim
After an URAISE command, the measured busbar
voltage shall have a lower value than its previous
value
The second requirement has to be fulfilled for
two consecutive URAISE commands
tRevAct and the output signal REVACBLK
tTCTimeout time has elapsed.
Section 13
Control
OperationRA .
317