ABB Relion 670 series, Руководство по применению, Страница: 336 / 760

The different network configuration classes are:
1. Parallel line with common positive and zero sequence network
2. Parallel circuits with common positive but separated zero sequence network
3. Parallel circuits with positive and zero sequence sources separated.
One example of class 3 networks could be the mutual coupling between a 400 kV line and rail
road overhead lines. This type of mutual coupling is not so common although it exists and is
not treated any further in this manual.
For each type of network class, there are three different topologies; the parallel line can be in
service, out of service, out of service and earthed in both ends.
The reach of the distance protection zone 1 will be different depending on the operation
condition of the parallel line. This can be handled by the use of different setting groups for
handling the cases when the parallel line is in operation and out of service and earthed at both
ends.
The distance protection within the IED can compensate for the influence of a zero sequence
mutual coupling on the measurement at single phase-to-earth faults in the following ways, by
using:
• The possibility of different setting values that influence the earth-return compensation
for different distance zones within the same group of setting parameters.
• Different groups of setting parameters for different operating conditions of a protected
multi circuit line.
Most multi circuit lines have two parallel operating circuits.
Parallel line applications
GUID-74355B21-61D3-47A9-A3AE-2D56B2EDDC3C v1
This type of networks is defined as those networks where the parallel transmission lines
terminate at common nodes at both ends.
The three most common operation modes are:
1. Parallel line in service.
2. Parallel line out of service and earthed.
3. Parallel line out of service and not earthed.
Parallel line in service
GUID-0C0B1323-C69D-4EFE-A3CF-C81D762ED146 v2
This type of application is very common and applies to all normal sub-transmission and
transmission networks.
Let us analyze what happens when a fault occurs on the parallel line see figure 204 .
From symmetrical components, we can derive the impedance Z at the relay point for normal
lines without mutual coupling according to equation 363 .
Z
U
I I
Z Z
Z
U
I I K
ph
ph
ph
ph N
=
+ ⋅
−
⋅
=
+ ⋅
3
3
3
0
0 1
1
0
IECEQUATION1275 V2 EN-US
(Equation 363)
Section 7 1MRK 505 343-UEN B
Impedance protection
330
Application manual