ABB REC670 Applications Manual page 591

1MRK 511 401-UEN A
Bay control REC670 2.2 IEC
Application manual
Application functions should be connected to a SMAI block with same task cycle
as the application function, except for e.g. measurement functions that run in slow
cycle tasks.
DFTRefExtOut: Parameter valid only for function block SMAI1 .
Reference block for external output (SPFCOUT function output).
DFTReference: Reference DFT for the SMAI block use.
These DFT reference block settings decide DFT reference for DFT calculations.
The setting InternalDFTRef will use fixed DFT reference based on set system
frequency. DFTRefGrp(n) will use DFT reference from the selected group block,
when own group is selected, an adaptive DFT reference will be used based on
calculated signal frequency from own group. The setting ExternalDFTRef will use
reference based on what is connected to input DFTSPFC.
The setting ConnectionType: Connection type for that specific instance (n) of the
SMAI (if it is Ph-N or Ph-Ph). Depending on connection type setting the not
connected Ph-N or Ph-Ph outputs will be calculated as long as they are possible to
calculate. E.g. at Ph-Ph connection L1, L2 and L3 will be calculated for use in
symmetrical situations. If N component should be used respectively the phase
component during faults I
Negation: If the user wants to negate the 3ph signal, it is possible to choose to
negate only the phase signals Negate3Ph, only the neutral signal NegateN or both
Negate3Ph+N. negation means rotation with 180° of the vectors.
GlobalBaseSel: Selects the global base value group used by the function to define
(IBase), (UBase) and (SBase).
MinValFreqMeas: The minimum value of the voltage for which the frequency is
calculated, expressed as percent of UBase (for each instance n).
Settings DFTRefExtOut and DFTReference shall be set to default
value InternalDFTRef if no VT inputs are available.
Even if the user sets the AnalogInputType of a SMAI block to
"Current", the MinValFreqMeas is still visible. However, using the
current channel values as base for frequency measurement is not
recommendable for a number of reasons, not last among them
being the low level of currents that one can have in normal
operating conditions.
Examples of adaptive frequency tracking
Preprocessing block shall only be used to feed functions within the
same execution cycles (e.g. use preprocessing block with cycle 1 to
feed transformer differential protection). The only exceptions are
/U must be connected to input 4.
N N
Section 23
Basic IED functions
585