R
jX
ArgLd
(ZMRPSB)
ArgLd
(FDPSPDIS)
Z
S
1
jX
Z
S
A
1
Z
L1
Z
S
B
1
Impe
danc
e loc
us fo
r |E
A
| = |E
B
|
R
Z
C
O
IEC09000225-1-en.vsd
IEC09000225 V1 EN-US
Figure 241: Impedance diagrams with corresponding impedances under consideration
The outer boundary of oscillation detection characteristic in forward direction
RLdOutFw
should be set with certain safety margin K
L
compared to the minimum expected load
resistance R
Lmin
. When the exact value of the minimum load resistance is not known, the
following approximations may be considered for lines with rated voltage 400 kV:
•
K
L
= 0.9 for lines longer than 150 km
•
K
L
= 0.85 for lines between 80 and 150 km
•
K
L
= 0.8 for lines shorter than 80 km
Multiply the required resistance for the same safety factor K
L
with the ratio between actual
voltage and 400kV when the rated voltage of the line under consideration is higher than
Section 7
1MRK 505 343-UEN B
Impedance protection
368
Application manual
Summary of Contents for Relion 670 series
Page 1: ...RELION 670 SERIES Line differential protection RED670 Version 2 1 IEC Application manual...
Page 2: ......
Page 40: ...34...
Page 64: ...58...
Page 150: ...144...
Page 406: ...400...
Page 472: ...466...
Page 494: ...488...
Page 512: ...506...
Page 524: ...518...
Page 604: ...598...
Page 686: ...680...
Page 718: ...712...
Page 722: ...716...
Page 758: ...752...
Page 759: ...753...