Definition of long lines with respect to the performance of distance protection can generally
, long lines have SIR’s less than 0.5.
Table 17: Definition of 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 possibility in IED 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), as shown in figure
en05000220.vsd
R
Zm
ARGLd
ARGLd
ARGLd
ARGLd
RLdFw
RLdRv
ZL
IEC05000220 V1 EN-US
Figure 73: Characteristic for zone measurement for long line with load encroachment
activated
7.1.2.6
Parallel line application with mutual coupling
SEMOD168232-149 v2
General
SEMOD168232-151 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 measurement due to the mutual coupling between the
parallel lines. The lines need not be of the same voltage to experience mutual coupling, and
some coupling exists even for lines that are separated by 100 meters or more. The reason to
the introduced error in measuring due to mutual coupling is the zero sequence voltage
inversion that occurs.
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
practice to neglect them.
1MRK 505 343-UEN B
Section 7
Impedance protection
149
Application manual
Содержание Relion 670 series
Страница 1: ...RELION 670 SERIES Line differential protection RED670 Version 2 1 IEC Application manual...
Страница 2: ......
Страница 40: ...34...
Страница 64: ...58...
Страница 150: ...144...
Страница 406: ...400...
Страница 472: ...466...
Страница 494: ...488...
Страница 512: ...506...
Страница 524: ...518...
Страница 604: ...598...
Страница 686: ...680...
Страница 718: ...712...
Страница 722: ...716...
Страница 758: ...752...
Страница 759: ...753...