The Non-Compensated Impedance Model - ABB REC650 ANSI Technical Manual

Section 12
Monitoring
12.14.7.3
514
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 67.
N
• Z , Z , Z , Z and Z
A B L 0L
For a single line, Z = 0 and Z
0M
parallel lines.
Equation 68 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
inserted to equation 72. According to equation 72, the relative distance to the fault is
solved as the root of a quadratic equation.
Equation 72 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.
If the load compensated algorithms according to the above do not give a reliable solution,
a less accurate, non-compensated impedance model is used to calculate the relative
distance to the fault.

The non-compensated impedance model

In the non-compensated impedance model, I
current:
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 73, and then
3 F
line current is used instead of I
A
1MRK 511 287-UUS A
(Equation 71)
68 applies to both single and
(Equation 72)
(Equation 73)
fault
FA
Technical manual