ABB RELION REX640 Technical Manual page 1427

1MRS759142 C
REX640
Technical Manual
• If governor lower limit alarm GOV_ALM_LO is TRUE, it resets the
frequency lower command LOWER_F. If governor high limit alarm
GOV_ALM_HI is TRUE, it resets the frequency raise command RAISE_F.
• If the output MATCH_OK is TRUE, the raise and lower commands are reset.
• If the frequency difference reaches the target value "± Smax/2" with the
hysteresis band specified by the settings Freq Diff Ov Synch and Freq Diff
sub Synch, the raise and lower commands are reset.
• During matching of network CB synchronization
• If any of the governor limit alarms GOV_ALM_HI or GOV_ALM_LO is
TRUE, the raise and lower commands are reset.
• When the generator is selected for fine tuning, if the frequency difference
reaches to target value "± Smax/2" with the hysteresis band specified by the
settings Freq Diff Ov Synch and Freq Diff sub Synch, the raise and lower
commands are reset.
• When the generator is selected for coarse tuning, if the frequency difference
reaches within the limits of Coarse Freq Diff Ov and Coarse Freq Diff sub,
the raise and lower commands are reset.
When the matching is done for its own CB synchronization, the output MATCH_OK is
activated if the measured voltage and frequency differences are within the set synchro
check limits. The MATCH_INPRO output is active while the matching is in progress.
When the matching is done for network CB synchronization, the monitored data
NTWMATCH_OK is activated if the network breaker voltage and frequency differences
are within the set match limits. NTWMATCH_PRO is active while the matching is in
progress. NTWMATCH_OK and NTWMATCH_PRO are available in the Monitored data
view.
Frequency rate of change tuning
When the control command parameter Tune V and F match is set to "Freq match
rate", the function calculates the generator frequency matching rate (dF/dt). The
calculated frequency matching rate is stored to the nonvolatile memory output
FREQ_CHG_RTE and is available in the Monitored data view. Once stored, the value
from FREQ_CHG_RTE can be used to set the setting Freq rate of change.
This tune frequency matching rate proceeds as follows:
1. The slip is adjusted until this lies in the range of +1...+3%, then the adjusting pulse
is discontinued.
2. Ten seconds after the first adjusting pulse, the slip s0 is measured, then a
frequency raise command RAISE_F lasting 3 s is given. Ten seconds after the
end of the pulse, the slip s is measured and df/dt is calculated according to the
formula
Section 9
Control functions
1421