Siemens SIPROTEC, Manual

Page: 353 / 776

Functions
2.18 Synchronism and Voltage Check (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
353
The closing check for manual reclosing is possible in one of the following operating modes:
MC SYNCHR Released at synchronism, that is when the critical values MC
maxVolt.Diff , MC maxFreq.Diff , MC maxAngleDiff are within the
set limits.
MC Usy1< Usy2> Released if measuring point Usy1< is de-energised and the measuring point
Usy2> is energised.
MC Usy1> Usy2< Released if measuring point Usy1> is energised and the measuring point
Usy2< is de-energised.
MC Usy1< Usy2< Released if measuring point Usy1< is de-energised and the measuring point
Usy2< is also de-energised.
MC OVERRIDE Released without any check.
Each of these conditions can be enabled or disabled individually; combinations are also possible, e.g. release
if
AR Usy1<Usy2> or AR Usy1>Usy2< are fulfilled. Combination of AR OVERRIDE with other parameters is,
of course, not reasonable (see also Figure 2-171).
The release conditions can be configured individually for automatic reclosing or for manual closing or for closing
via control commands. For example, manual closing and closing via control command can be allowed in cases
of synchronism or dead line, while, before an automatic reclose attempt dead line conditions are only checked
at one line end and after the automatic reclose attempt only synchronism at the other end.
Dead-line closing
To release the closing command to couple a dead overhead line to a live busbar, the following conditions are
checked:
• Is the feeder voltage below the set value
Dead Volt. Thr.
?
• Is the busbar voltage above the setting value Live Volt. Thr. but below the maximum voltage Umax ?
• Is the frequency within the permitted operating range f
N
±
3 Hz?
After successful check the closing command is released.
Corresponding conditions apply when switching a live line onto a dead busbar or a dead line onto a dead
busbar.
Closing under synchronous system conditions
Before releasing a closing command under synchronous conditions, the following conditions are checked:
• Is the busbar voltage above the setting value
Live Volt. Thr. but below the maximum voltage Umax ?
• Is the feeder voltage above the setting value
Live Volt. Thr.
but below the maximum voltage
Umax
?
• Is the voltage difference |U
sy1
– U
sy2
| within the permissible tolerance AR maxVolt.Diff or MC
maxVolt.Diff ?
• Are the two frequencies f
sy1
and f
sy2
within the permitted operating range f
N
±
3 Hz?
• Does the frequency difference |f
sy1
– f
sy2
| lie within the permissible tolerance AR maxFreq.Diff or MC
maxFreq.Diff ?
• Is the angle difference |
ϕ
sy1
–
ϕ
sy2
| within the permissible tolerance
AR maxAngleDiff
or
MC
maxAngleDiff
?
To check whether these conditions are fulfilled for a certain minimum time, you can set this minimum time as
T
SYNC-STAB
. Checking the synchronism conditions can also be confined to the a maximum monitoring time
T-
SYN. DURATION
. This implies that the conditions must be fulfilled within the time
T-SYN. DURATION
for the
duration of
T SYNC-STAB
. This the case, the closing release is granted.