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.
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.
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
1MRK 505 370-UEN D Section 12
Control
Busbar protection REB670 261
Application manual
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