ABB Relion 670 Series Applications Manual page 417

1MRK 511 401-UEN Rev. K
Table 62: Blocking settings
Setting
OCBk
(automatically
reset)
OVPartBk
(automatically
reset)
UVPartBk
(automatically
reset)
UVBk
(automatically
reset)
RevActPartBk(aut
omatically reset)
Table continues on next page
Bay control REC670
Application manual
Values (Range) Description
Alarm When any one of the three HV currents exceeds the
Auto Block preset value
Auto&Man Block temporarily totally blocked. The outputs IBLK and
TOTBLK or AUTOBLK will be activated depending on
the actual parameter setting.
Alarm If the busbar voltage U
Auto&Man Block
point voltage UVL) exceeds
alarm will be initiated or further URAISE commands
will be blocked. If permitted by setting in PST
configuration, Fast Step Down (FSD) of the tap
changer will be initiated in order to re-enter the
voltage into the range
function is blocked when the lowest voltage tap
position is reached. The time delay for the FSD
function is separately set. The output UHIGH will be
activated as long as the voltage is above
Alarm If the busbar voltage U
Auto&Man Block
point voltage U
figure204), an alarm will be initiated or further
ULOWER commands will be blocked. The output
ULOW will be activated.
Alarm If the busbar voltage U
Auto Block
blocking condition is active. It is recommended to
Auto&Man Block
block automatic control in this situation and allow
manual control. This is because the situation normally
would correspond to a disconnected transformer and
then it should be allowed to operate the tap changer
before reconnecting the transformer. The outputs
UBLK and TOTBLK or AUTOBLK will be activated
depending on the actual parameter setting.
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 TR1ATCCor TR8ATCC
temporarily.
Requirements for this blocking are:
•
•
•
If all three requirements are fulfilled, TR1ATCCor
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
© Copyright 2017 Hitachi Power Grids. All rights reserved
IBlock , TR1ATCCor TR8ATCC will be
(not the compensated load
B
Umax (see figure 204), an
Umin < U
B
(not the compensated load
B
Ublock and Umin (see
) is between
L
falls below
B
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
Section 15
< Umax . The FSD
Umax .
Ublock this
OperationRA .
Control
411