ABB REL670 2.2 IEC, Руководство по применению

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8.13.2.2 Fault infeed from remote end
GUID-DDFE8B5C-A064-4956-B8BB-49DEAC38558E v3
All transmission and most sub-transmission networks are operated meshed. Typical
for this type of network is that fault infeed from remote end will happen when fault
occurs on the protected line. The fault current infeed will enlarge the fault
impedance seen by the distance protection. This effect is very important to keep in
mind when both planning the protection system and making the settings.
The equation for the bus voltage U
A
at A side is:
U I p Z I I Rf
A A L A B
= ⋅ ⋅ + +
( )
⋅
EQUATION1273-IEC-650 V2 EN-US
(Equation 338)
If we divide U
A
by I
A
we get Z present to the IED at A side:
I
A
+ I
B
U
A
I
A
I
A
Z
A
= = p ·Z
L
+ ·R
f
EQUATION1274-IEC-650 V1 EN-US
(Equation 339)
The infeed factor (I
A
+I
B
)/I
A
can be very high, 10-20 depending on the differences
in source impedances at local and remote end.
Z <
ZL
Z <
E
SA
U
A
U
B
A B
E
SB
I
A
I
B
R
f
p*ZL
(1-p)*ZL
Z
SA
Z
SB
IEC09000247-1-en.vsd
IEC09000247 V1 EN-US
Figure 185: Influence of fault current infeed from remote line end
The effect of fault current infeed from remote line end is one of the most driving
factors to justify complementary protection to distance protection.
When the line is heavily loaded, the distance protection at the exporting end will
have a tendency to overreach. To handle this phenomenon, the IED has an adaptive
built-in algorithm, which compensates the overreach tendency of zone 1 at the
exporting end and reduces the underreach at the importing end. No settings are
required for this function.
Section 8
1MRK 506 369-UEN B
Impedance protection
362 Line distance protection REL670 2.2 IEC
Application manual