ABB RELION 670 SERIES Applications Manual page 375

1MRK 506 369-UUS -
Line distance protection REL670 2.2 ANSI
Application manual
distance protection zone is reduced if, due to operating conditions, the equivalent zero
sequence impedance is set according to the conditions when the parallel system is out of
operation and grounded at both ends.
-
Z Z
0 0m
I
0
A
-
Z Z
0 0m
B
IEC09000255 V1 EN
Figure 180: Equivalent zero-sequence impedance circuit for a double-circuit line with
one circuit disconnected and not grounded
The reduction of the reach is equal to equation 122.
(
1
× × +
2 Z Z
1 0 E
3
=
K
U
( )
1
× × +
2 Z Z
1 0
3
EQUATION1284 V1 EN
This means that the reach is reduced in reactive and resistive directions. If the real and
imaginary components of the constant A are equal to equation
= × × +
Re( ) A R 0 (2 R 1
EQUATION1285 V1 EN
= × × +
Im( ) A X (2 R
0 1
EQUATION1286 V1 EN
The real component of the KU factor is equal to equation 125.
( )
Re
( )
Re 1
K
= +
u
( )
 
Re
A
 
EQUATION1287 V3 EN
The imaginary component of the same factor is equal to equation 126.
Z
0m
I
0
C
IEC09000255_1_en.vsd
)
+
R
Z
f
= -
1
(
× ×
Z 2 Z
+
R
1
0
f
+ × - ×
R 0 3 Rf ) X 0 ( 0 2 X
+ × + × ×
R 3 R ) R (2 X
0 1 0
2
A X
⋅
m 0
2 2
( )
 
Im
A
+
 
Impedance protection
2
m 0
)
+ +
Z 3 R
0
f
123 and equation 124.
+ ×
X 1)
+
X )
1 0
Section 8
(Equation 307)
(Equation 308)
(Equation 309)
(Equation 310)
369