Setting Of Zones For Parallel Line Application - ABB RELION 670 SERIES Applications Manual

Section 8
Impedance protection
8.1.3.6
210
The safety factor of 1.5 appears due to speed requirements and possible under reaching
caused by the sub harmonic oscillations.
The increased reach related to the one used in non compensated system is recommended
for all protections in the vicinity of series capacitors to compensate for delay in the
operation caused by the sub harmonic swinging.
Settings of the resistive reaches are limited according to the minimum load impedance.
Reverse zone
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
· (X1 - X ))
L C
Settings of the resistive reaches are according to the minimum load impedance:
Optional higher distance protection zones
When some additional distance protection zones (zone 4, for example) are used they must
be set according to the influence of the series capacitor.

Setting of zones for parallel line application

Parallel line in service – Setting of zone1
With reference to section
can be set to 85% of protected line.
Parallel line in service – setting of zone2
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-ground 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
section "Parallel line in service".
The components of the zero-sequence impedance for the overreaching zones must be
equal to at least:
R = R + R
0E 0 m0
EQUATION553 V1 EN
"Parallel line application with mutual
1MRK 506 369-UUS -
coupling", the zone reach
(Equation 79)
Line distance protection REL670 2.2 ANSI
Application manual
- 0.5
2Rem
62 in