ABB Relion 670 Series Technical Reference Manual page 133

1MRK505222-UUS C
Local end
Analog Input
Module
CH1IL1RE
CH1IL1IM
Calculation of
fundamental
CH1IL2RE
frequency
CH1IL2IM
differential
currents (3x)
Currents from
& bias current
all ends as
phasors
CH1IL1SM
CH1IL2SM
Calculation
CH1IL3SM
of
instantaneous
CH2IL1SM
differential
currents
Curr. samples
(3x)
from all ends
CH1INSRE
Calculation
CH1INSIM
of
CH1INSRE
negative-
CH1INSIM
sequence
differential
Neg. seq. current
currents from
(1x)
all ends
as phasors
ANSI05000294 V1 EN
Figure 51: The principle for the line differential protection
Technical reference manual
Local end RED670
samples from
A/D
Converter
samples from
LDCM
Line Diffferential Function
[magnitude]
Differential
and bias currents
Magnitudes of applied to
differential
operate / bias -,
currents
and unrestrained
characteristics
Bias current
[samples]
Harmonic
analysis
Instantaneous
differential
nd th
( 2 and 5 )
currents
(samples)
High sensitive
-
Two to six
internal/external fault
contributions
discriminator
to neg. seq.
differential
current as
phasors
The remote currents are received to the IED as samples via a communication link.
When entering the IED, they are processed in the Line Differential Communication
Current
local end
Current
Pre-processing
Block
remote end
Trip by unrestrained differential protection
Start L1
Start L2
-,
Output logic:
Start L3
- 2 nd
harmonic block
St L1 low sens
- 5 th
harmonic block
St L2 low sens
St L3 low sens
- -
Cross block logic
2 nd h. block
- - Enhanced trip for
internal faults
- Decreased
5th h. block
sensitivity for
external faults
- -
Conditional trip for
simultaneous external
and internal faults
Internal fault
-
External fault
Conditional extra time
delay for trip signals
Section 5
Differential protection
Remote end
Remote end RED670
LDCM
³1 TRIP
TRL1
TRL2
TRL3
TRIPRES
TRIPUNRE
TRIPENHA
START
STL1
STL2
STL3
BLK2H
BLK2HL1
BLK2HL2
BLK2HL3
BLK5H
BLK5HL1
BLK5HL2
BLK5HL3
INTFAULT
EXTFAULT
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