ABB RELION REX640 Technical Manual page 1213

1MRS759142 F
3.5
2.5
1.5
0.5
Figure 692: Example impedance diagram of an electrically non-homogeneous feeder
(left), and the resulting error in fault distance if the measured fault loop reactance
is converted into physical fault distance by using only one line section parameters
(right).
Figure 692
In
parameters given in
Table 1155: Impedance settings
Parameter
R1 line section A
X1 line section A
Line Len section A
R1 line section B
X1 line section B
Line Len section B
R1 line section C
X1 line section C
Line Len section C
Figure 692
into physical fault distance. The fault location is varied from 1 km to 10 km in 1 km
steps (marked with circles). An error of nearly eight per cent at maximum is created
by the conversion procedure when modeling a non-homogenous line with only one
section. By using impedance model with three line sections, there is no error in the
conversion.
The previous example assumed a short circuit fault and thus, only positive-sequence
impedance settings were used. The results, however, also apply for earth faults.
REX640
Technical Manual
3
2
1
0
0 2 4 6
R (ohm)
the feeder is modelled either with one or three line sections with
Table 1155
illustrates the error when converting the measured fault loop reactance
Swan
Raven
PAS150
8
.
Impedance model with one
section
0.660 Ω/pu
0.341 Ω/pu
10.000 pu
N/A
N/A
0.000 pu
N/A
N/A
0.000 pu
Protection related functions
3.5
3
2.5
2
1.5
1
0.5
0
0 2 4 6
Fault Distance Error (%)
Impedance model with three
sections
0.236 Ω/pu
0.276 Ω/pu
4.000 pu
0.536 Ω/pu
0.369 Ω/pu
3.000 pu
1.350 Ω/pu
0.398 Ω/pu
3.000 pu
8
1213