ABB Relion 670 Series Applications Manual page 81

1MRK 511 401-UUS F
Where:
1)
2)
3)
4)
5)
4.2.4.4 Example on how to connect a phase-to-phase connected VT to the IED
Figure 22
overview of the required actions by the user in order to make this measurement available to the
built-in protection and control functions within the IED. It shall be noted that this VT connection is
only used on lower voltage levels (that is, rated primary voltage below 40 kV).
Bay control REC670
Application manual
shows how to connect three secondary phase-to-ground voltages to three VT inputs on the IED
is the TRM where these three voltage inputs are located. For these three voltage inputs, the following
setting values shall be entered:
VTprim = 132 kV
VTsec = 110 V
Inside the IED, only the ratio of these two parameters is used. It shall be noted that the ratio of the
entered values exactly corresponds to ratio of one individual VT.
66
66
3
=
110
110
3
EQUATION1903 V1 EN-US
are three connections made in Signal Matrix Tool (SMT), which connect these three voltage inputs to
first three input channels of the preprocessing function block 5). Depending on the type of functions
which need this voltage information, more then one preprocessing block might be connected in
parallel to these three VT inputs.
shows that in this example the fourth (that is, residual) input channel of the preprocessing block is
not connected in SMT tool. Thus the preprocessing block will automatically calculate 3Vo inside by
vectorial sum from the three phase to ground voltages connected to the first three input channels of
the same preprocessing block. Alternatively, the fourth input channel can be connected to open delta
VT input, as shown in Figure 23.
is a Preprocessing block that has the task to digitally filter the connected analog inputs and calculate:
• fundamental frequency phasors for all input channels
• harmonic content for all input channels
• positive, negative and zero sequence quantities by using the fundamental frequency phasors for
the first three input channels (channel one taken as reference for sequence quantities)
These calculated values are then available for all built-in protection and control functions within the
IED, which are connected to this preprocessing function block in the configuration tool. For this
application most of the preprocessing settings can be left to the default values. However the
following settings shall be set as shown here:
VBase=66 kV (that is, rated Ph-Ph voltage)
If frequency tracking and compensation is required (this feature is typically required only for IEDs
installed in the generating stations) then the setting parameters
accordingly.
gives an example how to connect a phase-to-phase connected VT to the IED. It gives an
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Analog inputs
(Equation 2)
DFTReference shall be set
SEMOD55055-134 v7
Section 4
75