Application; Operation Principle - ABB RELION 630 Series Technical Manual

Section 3
Basic functions
3.8.4
3.8.5
62
only if the current measuring SMAI is used as a frequency reference
for the adaptive DFT. This is not recommended, see the Setting
guidelines.

Application

Signal matrix for analog inputs function (SMAI), also known as the preprocessor
function, processes the analog signals connected to it and gives information about all
aspects of the analog signals connected, like the RMS value, phase angle, frequency,
harmonic content, sequence components and so on. This information is used by the
respective functions in Application Configuration, for example, protection,
measurement or monitoring.
The SMAI function is used within PCM600 in direct relation with the Signal Matrix
or the Application Configuration tools.

Operation principle

Every Signal matrix for analog inputs function (SMAI) can receive four analog
signals (three phases and one neutral value), either voltage or current, see
and Figure 32. SMAI outputs give information about every aspect of the 3ph analog
signals acquired (phase angle, RMS value, frequency and frequency derivates etc. –
244 values in total). The BLOCK input will reset all outputs to 0.
The output signals AI1 to AI4 in SMAI_20_x function block are direct outputs of the,
in SMT or ACT, connected input group signals to GRPxL1, GRPxL2, GRPxL3 and
GRPxN, x=1-12. GRPxN is always the neutral current. If GRPxN is not connected,
the AI4 output is all zero. The AIN output is the calculated residual sum of inputs
GRPxL1, GRPxL2 and GRPxL3 and is equal to output AI4 if all inputs, including
GRPxN, are connected. Note that function block will always calculate the residual
sum of current/voltage if the input is not connected in SMT or ACT. Applications with
a few exceptions shall always be connected to AI3P.
Value group 1 to 3 for setting GlobalBaseSel refers to phase and
phase-to-phase global base value function instances. Value group 4 to
6 refer to residual global base value function instances and are not
intended for most applications.
More detailed explanation of some of the settings and example of using frequency
adaptive DFT.
DFTRefExtOut: Parameter valid for function block SMAI_20_1:1, SMAI_20_1:2
and SMAI_80_1 only. Reference block for external output (SPFCOUT function
output).
DFTReference: Reference DFT for the block.
1MRS757256 F
PML630/Compact Load-Shedding Solution
Technical Manual
Figure 31