Parameter 6141 F SYNCHRON serves as an automatic threshold between synchronous and asynchronous
switching. If the frequency difference is below the specified threshold, the power systems are considered to
be synchronous and the regulations for synchronous switching apply. If it is above the threshold, the
switching is asynchronous with consideration of the time left until the voltages are in phase.
A raising of the threshold may be necessary if drives (e.g. reciprocating compressor) burden the power system
differently in each half cycle and thus negatively influence frequency measurement accuracy.
Parameters 6142 dU SYNC U2>U1 and 6143 dU SYNC U2<U1 allowed the admissible voltage differences to
be set asymmetrically also. The setting value can actually be selected higher than for asynchronous condi-
tions. This is dictated by the system conditions (e.g. greater voltage drops due to current limiting reactor).
Parameters 6144 dα SYNC α2> α1 and 6145 dα SYNC α2< α1 restrict the operating range for synchro-
nous switching with regard to admissible angle difference. These two parameters allow an asymmetrical
switching range to be configured (see also Figure 2-33).
The preset value for the angle must possibly be increased if current limiting reactors cause a larger phase shift.
This however increases the compensation current when switching near the limits.
Moreover, the enable time delay T SYNC-DELAY (address 6146) can be set after which all synchronous
conditions must at least be fulfilled for the closing command to be generated. A particular degree of power
system quiescence is then awaited. The default setting of 10 s has proven to be a good value.
[zuschaltenbeisynchronennetzbedingungen-150502-kn, 1, en_GB]
Figure 2-33 Switching under synchronous system conditions
Ranges in the U,f Diagram
Figure 2-34 shows the setting parameters both for synchronous as well as asynchronous conditions, in the U, f
diagram. With synchronous power systems the frequency band is in principle very narrow.
Functions
2.2 Paralleling Functions
68 SIPROTEC 4, 7VE61 and 7VE63, Manual
C53000-G1176-C163-3, Edition 10.2017
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