ABB Relion 670 series, Техническое руководство

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10.3.6 Monitored data
PID-3862-MONITOREDDATA v1
Table 395: SAPFRC (81R) Monitored data
Name Type Values (Range) Unit Description
STARTDUR REAL - % Start duration in percents of the total
operation time
10.3.7 Operation principle
M14970-3 v8
Rate-of-change frequency protection SAPFRC (81) is used to detect fast power system frequency
changes at an early stage. SAPFRC (81) has a settable definite time delay. If the rate-of-change of
frequency remains below the set value, for negative rate-of-change, for a time period equal to the
chosen time delay, the TRIP signal is issued. If the rate-of-change of frequency remains above the
set value, for positive rate-of-change, for a time period equal to the chosen time delay, the TRIP
signal is issued. To avoid an unwanted trip due to uncertain frequency measurement at low
voltage magnitude a voltage controlled blocking of the function is available from the
preprocessing function. If the voltage is lower than the set blocking voltage in the preprocessing
function the function is blocked and no PICKUP or TRIP signal is issued. If the frequency recovers,
after a frequency decrease, a restore signal is issued.
10.3.7.1 Measurement principle
M14970-6 v7
The rate-of-change of the fundamental frequency of the selected voltage is measured
continuously, and compared with the set value, PUFreqGrad. Rate-of-change frequency protection
SAPFRC (81) is also dependent on the voltage magnitude. If the voltage magnitude decreases
below the setting
MinValFreqMeas in the preprocessing function, which is set as a percentage of a
global base voltage parameter, SAPFRC (81) is blocked, and the output BLKDMAGN is issued. The
sign of the setting
PUFreqGrad, controls if SAPFRC (81) reacts on a positive or on a negative
change in frequency. If SAPFRC (81) is used for decreasing frequency that is, the setting
PUFreqGrad has been given a negative value, and a trip signal has been issued, then a 100 ms
pulse is issued on the RESTORE output, when the frequency recovers to a value higher than the
setting
RestoreFreq. A positive setting of PUFreqGrad, sets SAPFRC (81) to PICKUP and TRIP for
frequency increases.
To avoid oscillations of the output PICKUP signal, a hysteresis has been included.
10.3.7.2 Time delay
M14970-10 v6
Rate-of-change frequency protection SAPFRC (81) has a settable definite time delay,
tTrip. .
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,
1MRK 502 066-UUS B Section 10
Frequency protection
677
Technical manual