K
N
Z
0L
Z
1L
–
3 Z
1L
×
------------------------
=
EQUATION99 V1 EN
(Equation 185)
D
I is the change in current, that is the current after the fault minus the current before
the fault.
In the following, the positive sequence impedance for Z
A
, Z
B
and Z
L
is inserted into
the equations, because this is the value used in the algorithm.
For double lines, the fault equation is:
FA
A
A
1L
F
0P
0M
A
I
V
I p Z
R
I
Z
D
= × ×
+
×
+
×
EQUATION1600 V1 EN
(Equation 186)
Where:
I
0P
is a zero sequence current of the parallel line,
Z
0M
is a mutual zero sequence impedance and
D
A
is the distribution factor of the parallel line, which is:
D
A
1 p
–
(
)
Z
A
Z
A L
Z
B
+
+
(
)
Z
B
+
×
2 Z
A
Z
L
2 Z
B
×
+
+
×
-----------------------------------------------------------------------------
=
EQUATION101 V1 EN
The K
N
compensation factor for the double line becomes:
K
N
Z
0L
Z
1L
–
3 Z
1L
×
------------------------
Z
0M
3 Z
1L
×
-----------------
I
0P
I
0A
-------
×
+
=
EQUATION102 V1 EN
(Equation 187)
From these equations it can be seen, that, if Z
0m
= 0, then the general fault location
equation for a single line is obtained. Only the distribution factor differs in these two
cases.
Because the D
A
distribution factor according to equation
is a function of p,
can be written in the form:
p
2
p K
1
K
2
K
3
R
F
×
–
+
×
–
0
=
EQUATION103 V1 EN
(Equation 188)
1MRK505222-UUS C
Section 15
Monitoring
943
Technical reference manual
Summary of Contents for Relion 670 series
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