ABB Relion 670 series - Page 133

en05000294_ansi.vsd
Calculation
of
instantaneous
differential
currents
(3x)
Calculation of
fundamental
frequency
differential
currents (3x)
& bias current
Magnitudes of
differential
currents
Bias current
[magnitude]
[samples]
Instantaneous
differential
currents
(samples)
Differential
and bias currents
applied to
operate / bias-,
and unrestrained
characteristics
Harmonic
analysis
( 2
nd
and 5
th
)
Trip by unrestrained differential protection
Calculation
of
negative-
sequence
differential
current
(1x)
Two to six
contributions
to neg. seq.
differential
current as
phasors
High sensitive
internal/external fault
discriminator
Internal fault
External fault
Output logic:
- 2
nd
harmonic block
- 5
th
harmonic block
-
Cross block logic
-
Enhanced trip for
internal faults
-
Decreased
sensitivity for
external faults
-
Conditional trip for
simultaneous external
and internal faults
-
Conditional extra time
delay for trip signals
Start L1
Start L2
Start L3
2
nd
h. block
5th h. block
CH1IL1SM
CH1IL2SM
CH1IL3SM
CH2IL1SM
Curr. samples
from all ends
CH1IL1RE
CH1IL1IM
CH1IL2RE
CH1IL2IM
Currents from
all ends as
phasors
CH1INSRE
CH1INSIM
CH1INSRE
CH1INSIM
Neg. seq.
currents from
all ends
as phasors
T
r
i
p
c
o
m
m
a
n
d
s
TRIP
³1
TRIPRES
TRIPUNRE
TRIPENHA
START
STL1
STL2
STL3
BLK2H
BLK2HL1
BLK2HL2
BLK2HL3
BLK5H
BLK5HL1
BLK5HL2
BLK5HL3
INTFAULT
EXTFAULT
I
n
f
o
r
m
a
t
i
o
n
TRL1
TRL2
TRL3
-,
-
-
-
-
Line Diffferential Function
Local end RED670
Remote end RED670
St L1 low sens
St L3 low sens
St L2 low sens
Local end
Remote end
LDCM
Current
samples from
remote end
Current
samples from
local end
A/D
Converter
LDCM
Pre-processing
Block
Analog Input
Module
ANSI05000294 V1 EN
Figure 51: The principle for the line differential protection
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
1MRK505222-UUS C Section 5
Differential protection
127
Technical reference manual