ABB Relion 670 series, Applications Manual

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Table 30: Definition of long and very long lines
Line category Un Un
110 kV 500 kV
Long lines 77 km - 99 km 350 km - 450 km
Very long lines > 99 km > 450 km
The IED's ability to set resistive and reactive reach independent for positive and zero sequence
fault loops and individual fault resistance settings for phase-to-phase and phase-to-earth fault
together with load encroachment algorithm improves the possibility to detect high resistive
faults at the same time as the security is improved (risk for unwanted trip due to load
encroachment is eliminated), see figure 203 .
en05000220.vsd
R
Zm
ARGLd
ARGLd
ARGLd
ARGLd
RLdFw RLdRv
ZL
IEC05000220 V1 EN-US
Figure 203: Characteristic for zone measurement for a long line
[6]
7.13.2.6 Parallel line application with mutual coupling
GUID-1F856628-0CEE-4679-BB71-40177187390D v1
General
GUID-1D633249-8BF6-4992-A06E-E8BD23B2C315 v2
Introduction of parallel lines in the network is increasing due to difficulties to get necessary
area for new lines.
Parallel lines introduce an error in the zero sequence measurement due to the mutual coupling
between the parallel lines. The lines need not be of the same voltage in order to have mutual
coupling, and some coupling exists even for lines that are separated by 100 meters or more.
The mutual coupling does not normally cause voltage inversion.
It can be shown from analytical calculations of line impedances that the mutual impedances
for positive and negative sequence are very small (< 1-2%) of the self impedance and it is a
practice to neglect them.
From an application point of view there exists three types of network configurations (classes)
that must be considered when making the settings for the protection function.
[6] RLdRv=RLdRvFactor*RLdFw.
1MRK 505 343-UEN B Section 7
Impedance protection
329
Application manual