Siemens 7SJ82, Manual

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Compensation for low-frequency oscillations
If you activate this option (parameter
(_:150) Suppr. frequ. oscillations
), low-frequency
oscillations, for example, as a consequence of power swings in the range of 0.8 Hz to 1.6 Hz are detected
and smoothed. This stabilizes the release checks in the presence of frequently changing violations of
upper and lower limits for the specified frequency threshold values. The option affects the frequency
check of the Synchrocheck stage types and the synchronous operating mode of the Synchronous/Asyn-
chronous stage type. It does not affect the asynchronous operating mode.
In the example of the following figure, the synchrocheck function would initiate energization, if the
allowed frequency difference was set to 10 mHz without the parameter
Suppr. frequ. oscilla-
tions
as soon as the frequency f2 enters the 10-mHz band. If the parameter
Suppr. frequ. oscil-
lations
is activated, energization is not initiated, since the average value of f2 is outside the band.
[dwsynfre-101013-01.vsd, 1, en_US]
Figure 8-69 Example: Frequency Difference between the Constant Frequency f1 and the Sinusoidal
Oscillating Frequency f2
With this option active, the range of function measured values is expanded by the smoothed frequency.
Release of switching in synchronous networks occurs after one second at the earliest. This time is needed
to smooth the frequency measured values.
The actual frequency can be larger or smaller than the smoothed value at any instant. The
Max. diff.
"f threshold"
parameter makes it possible to limit the increase in instantaneous frequency value in
relation to the respective frequency threshold value.
Closing at De-Energized Line/Busbar
Description
If at least one of 2 parts of an electrical power system is de-energized, the parts of the electrical power system
can be connected together via the following operating modes.
If the measured voltage is less than the threshold
V1, V2 without voltage
, the zero potential of the part
of the electrical power system is detected. In this case, all phases are compared to the parameter
V1, V2
without voltage
. The energized side must be in the defined operating range with respect to voltage and
frequency (see chapter 8.4.4.1 Description ) and all phases must exceed the threshold
V1, V2 with
voltage
.
The following additional closing conditions can be selected, which are then applied next to the closing condi-
tions for the synchronism:
Settings Description
Close cmd. at V1> & V2<
Closing release under the condition that the part V
1
of the power
system is energized and the part of the electrical power system
U
2
is de-energized.
8.4.10
8.4.10.1
Control Functions
8.4 Synchronization Function
1154 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017