ABB REC650 Applications Manual page 201

1MRK 511 286-UUS A
Application manual
The setting FreqDiffMin is the minimum frequency difference where the system are
defined to be asynchronous. For frequency difference lower than this value the systems
are considered to be in parallel. A typical value for the FreqDiffMin is 10 mHz. Generally,
the value should be low if both, synchronizing and synchrocheck function is provided as
it is better to let synchronizing function close as it will close at the exact right instance if
the networks run with a frequency difference.
Note! The FreqDiffMin shall be set to the same value as FreqDiffM
respective FreqDiffA for SESRSYN (25)irrespective of whether the
functions are used for manual operation, autoreclosing or both.
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 the Beat time A typical value for the 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.
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
Setting for the duration of the breaker close pulse.
tMaxSynch
The 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 a setting of 10 ms 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 start a margin needs to be added. Typical setting 600 seconds.
tMinSynch
Section 10
Control
195