ABB Relion 670 Series RES670, Техническое руководство

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Trip signal issuing requires that the rate-of-change of frequency condition continues for
at least the user set time delay,
tTrip . If the PICKUP condition, with respect to the
measured frequency ceases during the delay time, and is not fulfilled again within a user
defined reset time,
tReset , the PICKUP output is reset, after that the defined reset time has
elapsed. Here it should be noted that after leaving the hysteresis area, the PICKUP
condition must be fulfilled again and it is not sufficient for the signal to only return back
into the hysteresis area.
The RESTORE output of SAPFRC (81) is set, after a time delay equal to the setting of
tRestore , when the measured frequency has returned to the level corresponding to
RestoreFreq , after an issue of the TRIP output signal. If tRestore is set to 0.000 s the
restore functionality is disabled, and no output will be given. The restore functionality is
only active for lowering frequency conditions and the restore sequence is disabled if a new
negative frequency gradient is detected during the restore period, defined by the settings
RestoreFreq and tRestore .
10.3.7.3 Blocking
Rate-of-change frequency protection (SAPFRC, 81) can be partially or totally blocked, by
binary input signals or by parameter settings, where:
BLOCK: blocks all outputs
BLKTRIP: blocks the TRIP output
BLKREST: blocks the RESTORE output
If the measured voltage level decreases below the setting of MinValFreqMeas in the
preprocessing function, both the PICKUP and the TRIP outputs are blocked.
10.3.7.4 Design
Rate-of-change frequency protection (SAPFRC, 81) measuring element continuously
measures the frequency of the selected voltage and compares it to the setting
PUFreqGrad . The frequency signal is filtered to avoid transients due to power system
switchings and faults. The time integrator operates with a definite delay time. When the
frequency has returned back to the setting of
RestoreFreq , the RESTORE output is issued
after the time delay tRestore , if the TRIP signal has earlier been issued. The sign of the
setting PUFreqGrad is essential, and controls if the function is used for raising or
lowering frequency conditions. The design of SAPFRC (81) is schematically described in
figure
107 .
1MRK 511 365-UUS A
Section 10
Frequency protection
Phasor measurement unit RES670 2.1 ANSI 311
Technical manual