ABB Relion 670 Series Technical Reference Manual page 950

Section 15
Monitoring
944
Where:
V Z
= +
K A B
1
× +
I Z Z Z
A L L ADD
EQUATION1601 V1 EN
æ
V Z
= ×
K A B
ç
2
× +
I Z Z Z
è
A L L ADD
EQUATION1602 V1 EN
I Z + Z
æ
F A A B
×
--------------- - -------------------------- -
K = +
è
3 ×
I Z Z + Z
A L 1 A DD
EQUATION106 V1 EN
and:
• Z = Z + Z for parallel lines.
ADD A B
• I , I and V are given in the above table.
A FA A
• K is calculated automatically according to equation 187.
N
• Z , Z , Z , Z and Z
A B L 0L
For a single line, Z = 0 and Z
0M
parallel lines.
Equation 188 can be divided into real and imaginary parts:
2
× ( ) ( ) R
p – p Re K + Re K –
1 2
EQUATION107 V1 EN
× × ( ) × ( ) R
– p Im K + Im K –
1 2
EQUATION108 V1 EN
If the imaginary part of K
then inserted to equation 192. According to equation 192, the relative distance to the
fault is solved as the root of a quadratic equation.
Equation 192 gives two different values for the relative distance to the fault as a
solution. A simplified load compensated algorithm, which gives an unequivocal figure
for the relative distance to the fault, is used to establish the value that should be selected.
+
1
ö
+
1
÷
ø
ö
1
ø
are setting parameters.
0M
= 0. Thus, equation
ADD
× ( )
Re K = 0
F 3
× × ( )
Im K = 0
F 3
is not zero, R can be solved according to equation 193, and
3 F
1MRK505222-UUS C
(Equation 189)
(Equation 190)
(Equation 191)
188 applies to both single and
(Equation 192)
(Equation 193)
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