ABB REL670 2.2 IEC - Setting of Zones for Parallel Line Application

Reverse zone
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The reverse zone that is normally used in the communication schemes for functions
like fault current reversal logic, weak-in-feed logic or issuing carrier send in
blocking scheme must detect all faults in the reverse direction which is detected in
the opposite IED by the overreaching zone 2. The maximum reach for the
protection in the opposite IED can be achieved with the series capacitor in
operation.
The reactive reach can be set according to the following formula: X1=1.3·
(X1
2Rem
-0.5(X1
L
-X
C
))
Settings of the resistive reaches are according to the minimum load impedance:
Optional higher distance protection zones
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When some additional distance protection zones (zone 4, for example) are used
they must be set according to the influence of the series capacitor.
8.13.4.6 Setting of zones for parallel line application
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Parallel line in service – Setting of zone 1
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With reference to section
"Parallel line applications", the zone reach can be set to
85% of the protected line.
However, influence of mutual impedance has to be taken into account.
Parallel line in service – setting of zone 2
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Overreaching zones (in general, zones 2 and 3) must overreach the protected circuit
in all cases. The greatest reduction of a reach occurs in cases when both parallel
circuits are in service with a single phase-to-earth fault located at the end of a
protected line. The equivalent zero sequence impedance circuit for this case is
equal to the one in figure
189.
The components of the zero sequence impedance for the overreaching zones must
be equal to at least:
R
0E
R
0
R
m0
+=
EQUATION553 V1 EN-US
(Equation 382)
X
0E
X
0
X
m0
+=
EQUATION554 V1 EN-US (Equation 383)
Check the reduction of a reach for the overreaching zones due to the effect of the
zero sequence mutual coupling. The reach is reduced for a factor:
1MRK 506 369-UEN B Section 8
Impedance protection
Line distance protection REL670 2.2 IEC 399
Application manual