ABB Relion 650 Series Technical Manual page 119

1MRK 506 326-UUS B
Phase-to-ground fault
Mho
The measuring of ground faults uses ground-return compensation applied in a conventional way.
The compensation voltage is derived by considering the influence from the ground-return path.
For a ground fault in phase A, the compensation voltage Vcomp can be derived, as shown in figure
62.
Vcomp
EQUATION1793-ANSI V1 EN-US
where
V
pol
Z
loop
where
Z
1
KN
The angle β between the Vcomp and the polarize voltage Vpol for a A-to-ground fault is
é
b =
arg V
ë
EQUATION1592 V1 EN-US
where
V
A
I
A
IN
KN
EQUATION1593 V1 EN-US
V
pol
Line distance protection REL650
Technical manual
- ×
=
V I Z
A loop
pol
is the polarizing voltage (memorized VA for Phase A-to- ground fault)
is the loop impedance, which in general terms can be expressed as
(
= × +
Z +ZN Z 1 KN
1 1
EQUATION1799 V1 EN-US
is the positive sequence impedance of the line (Ohm/phase)
is the zero-sequence compensator factor
( )
ù
- + × ×
I IN KN ZPE
û
A A
is the phase voltage in faulty phase A
is the phase current in faulty phase A
is the zero-sequence current in faulty phase A (3I0)
Z0-Z1
×
3 Z1
EQUATION1594 V1 EN-US
the setting parameter for the zero-sequence compensation consisting of the magnitude
KNMag and the angle KNAng .
is the 100% of positive sequence memorized voltage V
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)
-
arg(Vpol)
Impedance protection
(Equation 15)
(Equation 16)
(Equation 17)
A
Section 5
SEMOD154224-283 v2
SEMOD154224-120 v4
113