Sel 411L - Figure 3.35 Disturbance Detection Logic Responding to Local Current and Voltage Signals

P.3.62
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
87L Differential Elements
remote data. By using values independent of the alignment mechanism, the
local disturbance detection logic guards against issues that temporary
misalignment of data might cause because of problems with communications
channels or time sources, if in use.
Figure 3.35 Disturbance Detection Logic Responding to Local Current and Voltage Signals
As Figure 3.36 shows, the remote disturbance detection logic monitors the
negative-sequence (87IQpAFR), ground (87IGpAFR), and positive-sequence
(87I1pAFR) current phasors in all required channels of the 87L function
(channels with the 87CHpRQ Relay Word bits asserted).
If any one of the positive-sequence, negative-sequence, or zero-sequence
remote current phasors shows a sign of disturbance (a magnitude change,
angle change, or a combination), in any of the required remote terminal
currents, the remote disturbance detection asserts.
To account for a potential situation when all remote terminals have weak
infeed conditions or have their breakers opened, the logic checks the level of
the positive-sequence current magnitude in the remote currents. If all
necessary currents have positive-sequence magnitudes of less than 0.1 pu of
IA1WF
I0WF
87CTWL
IA1XF
0
10 cyc
87DDL
I0XF
87CTXL
VA1YF
VA2YF
V0YF
87LINEV = Y
VA1ZF
VA2ZF
V0ZF
87LINEV = Z
DD Algorithm
DD Algorithm
DD Algorithm
DD Algorithm
DD Algorithm
DD Algorithm
DD Algorithm
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DD Algorithm
DD Algorithm
Relay
Word
Bits
LOP
ALTV
IWDD
Relay
Word
Bit
IXDD
Relay
Word
Bit
VYDD
Relay
Word
Bit
VZDD
Relay
Word
Bit
Relay
Word
Bit
87DDIL
Relay
Word
Bit
87DDVL
Relay
Word
Bit
2 cyc
0
IA1WFM
0.1 • CTnom
87CTWL
IA1XFM
0.1 • CTnom
87CTXL