![background image](http://html1.mh-extra.com/html/abb/relion-670-series/relion-670-series_applications-manual_3052129313.webp)
Table 27: Definition of short and very short line
Line category
Un
Un
110 kV
500 kV
Very short line
1.1-5.5 km
5-25 km
Short line
5.5-11 km
25-50 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 without conflict with the load impedance.
For very short line applications, the underreaching zone 1 can not be used due to the fact that
the voltage drop distribution throughout the line will be too low causing risk for overreaching.
7.12.2.5
Long transmission line application
GUID-0C99A197-06CD-4668-A017-3CA9E5E01ED2 v3
For long transmission lines, the margin to the load impedance, that is, to avoid load
encroachment, will normally be a major concern. It is well known that it is difficult to achieve
high sensitivity for phase-to-earth fault at remote line end of long lines when the line is heavy
loaded.
What can be recognized as long lines with respect to the performance of distance protection
can generally be described as in
. Long lines have Source impedance ratio (SIR’s) less
than 0.5.
Table 28: 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
7.12.2.6
Parallel line application with mutual coupling
GUID-4720AB55-0E59-4531-AE14-6A6EEC72C924 v1
General
GUID-E2FFF4A4-7D81-4440-87CE-3DCEAE2E42BD v2
Introduction of parallel lines in the network is increasing due to difficulties to get necessary
land to build 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 level in order to experience mutual
coupling, and some coupling exists even for lines that are separated by 100 meters or more.
The mutual coupling does influence the zero sequence impedance to the fault point but it 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
common practice to neglect them.
1MRK 505 343-UEN B
Section 7
Impedance protection
307
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...