ABB Relion 670 series - Impact of Series Compensation on Protective IED of Adjacent Lines

• Series capacitor becomes nearly completely bridged by MOV when the line current
becomes higher than 10-times the protective current level (I £ 10· k
p
· I
NC
).
8.1.2.10 Impact of series compensation on protective IED of adjacent lines
Voltage inversion is not characteristic for the buses and IED points closest to the series
compensated line only. It can spread also deeper into the network and this way influences
the selection of protection devices (mostly distance IEDs) on remote ends of lines adjacent
to the series compensated circuit, and sometimes even deeper in the network.
en06000616_ansi.vsd
~
~
Z
L F
Z
LA
Z
LB
E
A
E
B
V
A
V
B
V
D
I
B
I
A
I
F
-jX
C
F
A
B
D
Z
SA
Z
SB
ANSI06000616 V1 EN
Figure 92: Voltage inversion in series compensated network due to fault current
infeed
Voltage at the B bus (as shown in figure 92) is calculated for the loss-less system
according to the equation below.
( ) ( )
= + × = + × - + ×
B D B LB A B LF C B LB
V V I jX I I j X X I jX
EQUATION1998-ANSI V1 EN (Equation 63)
Further development of equation 63 gives the following expressions:
( )
1= × + + × -
é ù
æ ö
ê ç ÷ ú
è ø
ë û
A
B B LB LF C
B
I
V jI X X X
I
EQUATION1999-ANSI V1 EN (Equation 64)
( )
0
1
= = +
+
LB
C B LF
A
B
X
X V X
I
I
EQUATION2000-ANSI V1 EN (Equation 65)
Equation 64 indicates the fact that the infeed current I
A
increases the apparent value of
capacitive reactance in system: bigger the infeed of fault current, bigger the apparent
series capacitor in a complete series compensated network. It is possible to say that
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 193
Application manual