Most multi circuit lines have two parallel operating circuits. The application guide mentioned
below recommends in more detail the setting practice for this particular type of line. The basic
principles also apply to other multi circuit lines.
Parallel line applications
SEMOD154680-168 v2
This type of networks are defined as those networks where the parallel transmission lines
terminate at common nodes at both ends. We consider the three most common operation
modes:
1.
parallel line in service.
2.
parallel line out of service and earthed.
3.
parallel line out of service and not earthed.
Parallel line in service
SEMOD154680-175 v2
This type of application is very common and applies to all normal sub-transmission and
transmission networks.
A simplified single line diagram is shown in figure
ph
ph
0
1
ph
N
ph
0
1
0
V
V
Z
Z
I
3
K
I
3I
3 Z
I
Z
=
=
-
+
×
+
×
×
EQUATION1275 V3 EN-US
(Equation 215)
Where:
Vph
is phase-to-earth voltage at the IED point
Iph
is phase current in the faulty phase
3I0
is earth to fault current
Z1
is positive sequence impedance
Z0
is zero sequence impedance
Z0m
A
B
Z<
Z<
en05000221.vsd
IEC05000221 V1 EN-US
Figure 153: Class 1, parallel line in service.
The equivalent circuit of the lines can be simplified, see figure
.
1MRK 505 343-UEN B
Section 7
Impedance protection
249
Application manual
Содержание Relion 670 series
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