ABB Relion 670 series, Руководство по применению, Страница: 631 / 760

If there is a transmission line that is opened at the remote end or radial or remote end source
is weak, then a fault anywhere on the line can result into undervoltage at the remote end. There
can be undervoltage at remote end also due to heavy loading or poor power factor on lagging
side. A fault in a line connected beyond the remote end bus can also produce undervoltage at
remote end. The compensated voltage calculated at the local end can detect such
undervoltages. The undervoltage caused by a fault can be asymmetrical while that due to
overloading is symmetrical.
The trip signal issued by compensated over and under voltage function should be
accompanied by a transfer trip signal received from the remote end. The trip signal should be
used as a release signal which can permit a remote transfer trip to be used to trip the local
circuit breaker.
Setting of over voltage and under voltage levels for compensated voltage should be same as
the remote end over and under voltage levels. This will ensure proper operation of voltage
protection of the transmission line.
The definite delay time for compensated over and under voltage can be shorter than that at
remote end, but not too short. A short delay time would result in frequent operation of
compensated over and under voltage function without corresponding transfer trip received
from remote end.
Switchable shunt reactors located on both line terminals and substation bus-bars are
commonly used on long radial EHV transmission networks for the purpose of voltage control
during daily/seasonal load variations.
The function can internally correct for the current through the local shunt reactor. The setting
EnShuntReactor should be On if there is a shunt reactor on the line. Change in this setting will
be effected only when IED is restarted. Hence this setting should be configured during
installing and then connection and disconnection of shunt reactor breaker should be handled
by the input SWIPOS. In figure 390 , if the measured current I
S
is configured in the IED, then
internal shunt reactor correction should be used (The setting EnShuntReactor should be On if
there is a shunt reactor on the line. Change in this setting will reboot the IED to take effect of
X
SR
. Hence this setting should be configured during installing and then connection and
disconnection of shunt reactor breaker should be handled by the input SWIPOS). Also, for
shunt reactor connected through the breaker or disconnector, status of the same must be
configured in the IED as shown in figure 390 .
Frequently, the input current to the line protection IED is already corrected for the current
through the local shunt reactor. In figure 390 if the measured current I
L
is connected to the IED
then even if local shunt reactor is present its correction should not be done inside the function,
otherwise this will result into incorrect calculation for compensated voltage.
R
L
I
s
I
L
U
s
U
R
I
R
X
SR
IED
Breaker Status
IEC09000775-1-en.vsd
IEC09000775 V1 EN-US
Figure 390: Breaker status configured with IED
15.8.4.3 Setting guidelines
GUID-DE3963D6-016E-41AD-832F-1D10DD26AABA v2
1MRK 505 343-UEN B Section 15
Scheme communication
625
Application manual