ABB Relion 670 series - Consideration of Zero Sequence Mutual Coupling for Parallel Circuits; Load Impedance Limitation, Without Load Encroachment Function274

With this method of setting the zero sequence compensation factor K
N
can for zone 1 and
zone 2 be even better adapted for the real system conditions.
The table describes ground fault compensation settings to be adopted for different groups.
Table 23: Different groups of settings
Group
Operation mode Zone 1 and Zone 2 Zone 3 and Reverse Zone
Group1 Case 1: Parallel
line switched off
and grounded at
both ends
0 1 0
1
1 0
3
m
N Nm
K
Z Z Z
K
Z Z
=
-
-
0 1
1
3
N
Z Z
K
Z
=
-
×
Group2
Case 2: Parallel
line switched off
and not
grounded or
grounded at only
one end
0 1
1
3
N
Z Z
K
Z
=
-
×
0 1
1
3
N
Z Z
K
Z
=
-
×
Group3
Both lines in
service
0 1
1
3
N Nm
K
Z Z
K
Z
=
-
-
0
3
L L
N
L
K
Z Z
Z
=
-
For a discussion on other options of settings, refer to CIGRE SC34 report, WG-04
November 1991 “Application guide on protection of complex transmission network
configuration”.
8.4.3.6 Consideration of zero sequence mutual coupling for parallel circuits
For both zone 2 and zone 3 elements, the underreaching effect of zero sequence mutual
coupling for remote ground faults must also be considered in relation to the primary reach
setting criterion.
8.4.3.7 Load impedance limitation, without load encroachment function
The following instruction is valid when the load encroachment function or blinder
function is not activated (BlinderMode=Disabled).The load encroachment function will
not be activated if RLdFw and RLdRv is set to a value higher than expected minimal load
impedance. If the load encroachment or blinder function is to be used for all or some of the
measuring zones, the load limitation for those zones according to this chapter can be
omitted. Check the maximum permissible resistive reach for any zone to ensure that there
is a sufficient setting margin between the relay boundary and the minimum load
impedance. The minimum load impedance (Ω/phase) is calculated as:
Section 8 1MRK 506 369-UUS -
Impedance protection
274 Line distance protection REL670 2.2 ANSI
Application manual