ABB RELION 670 SERIES Applications Manual page 188

Section 8
Impedance protection
182
drop DV
on series capacitor lags the fault current by 90 degrees. Note that line impedance
C
X could be divided into two parts: one between the IED point and the capacitor and one
L1
between the capacitor and the fault position. The resulting voltage V
way proportional to sum of voltage drops on partial impedances between the IED point
and the fault position F, as presented by
( )
= × -
V I j X X
M F L1 C
EQUATION1995-ANSI V1 EN
With bypassed
Source voltage
Source
X
S
~
I
F
ANSI06000605 V1 EN
Figure 81: Voltage inversion on series compensated line
With bypassed
capacitor
I
F
ANSI06000606 V1 EN
Figure 82: Phasor diagrams of currents and voltages for the bypassed and inserted
series capacitor during voltage inversion
It is obvious that voltage V
situation corresponds, from the directionality point of view, to fault conditions on line
With inserted
capacitor capacitor
V'
M
V
M
V
X
L1
X
F
X
C
21
en06000605_ansi.vsd
With inserted
capacitor
en06000606_ansi.vsd
will lead the fault current I
M
1MRK 506 369-UUS -
in IED point is this
M
Pre -fault voltage
Fault voltage
I
F
as long as X > X
F L1
Line distance protection REL670 2.2 ANSI
Application manual
(Equation 52)
. This
C