ABB REL650 - Weak-End Infeed Logic

The unwanted operations that might occur can be explained by looking into Figure 195
and Figure 196. Initially the protection A2 at A side will detect a fault in forward direction
and send a communication signal to the protection B2 at remote end, which is measuring
a fault in reverse direction.
en99000043_ansi.vsd
Strong
source
LINE 1
LINE 2
A:1
A:2
B:1
B:2
A B
Weak
source
FAULT
CLOSED
CLOSED
CLOSED
CLOSED
ANSI99000043 V1 EN
Figure 195: Current distribution for a fault close to B side when all breakers are closed
When the breaker B1 opens for clearing the fault, the fault current through B2 bay will
invert. If the communication signal has not reset at the same time as the distance protection
function used in the teleprotection scheme has switched on to forward direction, we will
have an unwanted operation of breaker B2 at B side.
en99000044_ansi.vsd
Strong
source
LINE 1
LINE 2
A:1
A:2
B:1
B:2
A B
Weak
source
CLOSED
CLOSED
OPEN
CLOSED
FAULT
ANSI99000044 V1 EN
Figure 196: Current distribution for a fault close to B side when breaker B1 has
opened
To handle this the send signal CS from B2 is held back until the reverse zone IRVL has
reset and the tDelayRev time has elapsed. To achieve this the reverse zone on the distance
protection shall be connected to input IRV and the output IRVL shall be connected to input
BLKCS on the communication function block ZCPSCH.
The function can be blocked by activating the input IRVBLK or the general BLOCK
input.
12.2.2.2 Weak-end infeed logic
Permissive communication schemes can basically operate only when the protection in the
remote IED can detect the fault. The detection requires a sufficient minimum fault current,
normally >20% of In. The fault current can be too low due to an open breaker or low short-
Section 12 1MRK 506 334-UUS A
Scheme communication
400
Application manual