ABB RELION 630 Series Technical Manual page 69

1MRS757256 F
PML630/Compact Load-Shedding Solution
Technical Manual
These DFT reference block settings decide DFT reference for DFT calculations
(InternalDFTRef will use fixed DFT reference based on set system frequency.
DFTRefGrpn will use DFT reference from the selected group block, when own group
selected adaptive DFT reference will be used based on calculated signal frequency
from own group.ExternalDFTRef will use reference based on input DFTSPFC.
MinValFreqMeas: The minimum value of the voltage for which the frequency is
calculated, expressed as percent of "Voltage base Val PP" (of the selected BASEPH
group).
Settings DFTRefExtOut and DFTReference shall be set to default
value "InternalDFTRef" if no VT inputs are available. If, however, it
is necessary to use frequency adaptive DFT (DFTReference set to
other than default, refering current measuring SMAI) when no
voltages are available, one must note that the MinValFreqMeas
setting is still set in reference to "Voltage base Val PP" (of the selected
BASEPH group). This means that the minimum level for current
amplitude is based on Voltage base Val PP. For example, if Voltage
base Val PP is 20000, the resulting minimum amplitude for current is
20000 * 10% = 2000.
Section 3
Basic functions
63