Example On How To Connect A Phase-To-Phase Connected Vt To The Ied - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
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 21
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).
Phasor measurement unit RES670
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 22.
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 DFTReference shall be set accordingly.
gives an example how to connect a phase-to-phase connected VT to the IED. It gives an
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Section 4
Analog inputs
(Equation 2)
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