Frequency Time Accumulation Protection Function Ftaqfvr (81A) - ABB REC670 Applications Manual

Section 10
Frequency protection
10.4
10.4.1
10.4.2
264
Frequency time accumulation protection function
FTAQFVR (81A)
Identification
Function description
Frequency time accumulation
protection
Application
Generator prime movers are affected by abnormal frequency disturbances. Significant
frequency deviations from rated frequency occur in case of major disturbances in the
system. A rise of frequency occurs in case of generation surplus, while a lack of
generation results in a drop of frequency.
The turbine blade is designed with its natural frequency adequately far from the rated
speed or multiples of the rated speed of the turbine. This design avoids the mechanical
resonant condition, which can lead to an increased mechanical stress on turbine blade.
If the ratio between the turbine resonant frequencies to the system operating frequency
is nearly equal to 1, mechanical stress on the blades is approximately 300 times the
nonresonant operating condition stress values. The stress magnification factor is shown
in the typical resonance curve in Figure 99.
IEC 61850 IEC 60617
identification identification
FTAQFVR f<>
1MRK 511 401-UUS A
GUID-124A1F91-44C0-4DB6-8603-CC8CA19AE2A6 v3
GUID-87605DA0-EAA6-4A6C-BF03-7FDB187E1B29 v2
ANSI/
IEEEidentification
81A
GUID-82CA8336-82BE-42AB-968A-D4F08941C9D0 v3
Bay control REC670 2.2 ANSI
Application manual