ABB Relion 670 Series Applications Manual page 283

1MRK 505 370-UUS Rev. K
VDiffSynch
Setting of the voltage difference between the line voltage and the bus voltage. The difference is set
depending on the network configuration and expected voltages in the two networks running
asynchronously. A normal setting is 0.10-0.15 p.u.
FreqDiffMin
The setting FreqDiffMin is the minimum frequency difference where the systems are defined to be
asynchronous. For frequency differences lower than this value, the systems are considered to be in
parallel. A typical value for FreqDiffMin is 10 mHz. Generally, the value should be low if both
synchronizing and synchrocheck functions are provided, and it is better to let the synchronizing function
close, as it will close at exactly the right instance if the networks run with a frequency difference.
FreqDiffMax
The setting FreqDiffMax is the maximum slip frequency at which synchronizing is accepted. 1/
FreqDiffMax shows the time for the vector to move 360 degrees, one turn on the synchronoscope, and is
called Beat time. A typical value for FreqDiffMax is 200-250 mHz, which gives beat times on 4-5
seconds. Higher values should be avoided as the two networks normally are regulated to nominal
frequency independent of each other, so the frequency difference shall be small.
FreqRateChange
The maximum allowed rate of change for the frequency.
CloseAngleMax
The setting CloseAngleMax is the maximum closing angle between bus and line at which synchronizing
is accepted. To minimize the moment stress when synchronizing near a power station, a narrower limit
should be used. A typical value is 15 degrees.
tBreaker
The tBreaker shall be set to match the closing time for the circuit breaker and should also include the
possible auxiliary relays in the closing circuit. It is important to check that no slow logic components are
used in the configuration of the IED as there then can be big variations in closing time due to those
components. Typical setting is 80-150 ms depending on the breaker closing time.
tClosePulse
The setting for the duration of the breaker close pulse.
tMaxSynch
The setting tMaxSynch is set to reset the operation of the synchronizing function if the operation does not
take place within this time. The setting must allow for the setting of FreqDiffMin, which will decide how
long it will take maximum to reach phase equality. At the setting of 10 mHz, the beat time is 100 seconds
and the setting would thus need to be at least tMinSynch plus 100 seconds. If the network frequencies
are expected to be outside the limits from the start, a margin needs to be added. A typical setting is 600
seconds.
tMinSynch
Busbar protection REB670
Application manual
To avoid overlapping of the synchronizing function and the synchrocheck function the
setting FreqDiffMin must be set to a higher value than used setting FreqDiffM, respective
FreqDiffA used for synchrocheck.
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Section 12
Control
277