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2006-03-30 Substation Automation Products Training 1
Substation Automation Products
Training
REL 670 Line Distance Protection IED
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2006-03-30 Substation Automation Products Training 2
Contents
Application
Main features
User Friendly Packages
Functions
Benefits
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2006-03-30 Substation Automation Products Training 3
Line Differential Protection: RED670
Application Areas Multi-terminal lines with
communication to 4 remote line ends
Multi-terminal lines with transformers in the protected zone
Tapped lines Tapped lines with
transformers Short lines Long lines with charging
current compensation
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2006-03-30 Substation Automation Products Training 4
Features: RED670
Line differential terminal for: All voltage levels OH-lines Cables Double circuit lines Series compensated lines Single and two pole tripping Optional protection functions Digital communication between
line ends Route switched communication
networks Easy upgrading from 2 terminal to
tapped line protection
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2006-03-30 Substation Automation Products Training 5
RED670 User Friendly Package
IED with a pre-selected set of functions: configured
First Alternative: Single-Breaker application Functionality for all over-head and cable lines: The user can
order this version and apply it directly
Three-pole or single/three pole trip
Second Alternative: Multi-Breaker application Functionality for all over-head and cable lines: The user can
order this version and apply it directly
Breaker related functions for each breaker
Three-pole or single/three pole trip
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2006-03-30 Substation Automation Products Training 6
RED670 User Friendly Package: Single breaker
Line differential function Main function of the IED
clearing all shunt faults
Phase overcurrent protection Simple back-up short circuit
protection
Residual overcurrent protection Simple back-up earth fault
protection
Breaker failure protection Essential in a local redundant
fault clearance system
Over-/Undervoltage protection Often required equipment
protection
Residual overvoltage protection Simple and sensitive earth
fault protection
Pole Discordance protection Limitation of consequences of
unsymmetric breaker function
Distance Protection (option) Best redundancy at
communication failure
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2006-03-30 Substation Automation Products Training 7
RED670 User Friendly Package: Single breaker
Fuse Failure detection Necessary to avoid protection
malfunction (voltage related)
Trip logic Enables choice of trip
possibilities, 1 or 3 pole trip at single phase faults
Autoreclosing Standard functionality to
increase network availability
Synchrocheck To avoid dangerous breaker
closing
Power Swing Blocking (option)
Disturbance recording Essential for analysis of
disturbances
Primary fault classification
Check of fault clearance Fault clearance time
Selectivity
Over/Under function
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2006-03-30 Substation Automation Products Training 8
RED670 User Friendly Package: Multi-breaker
Same as single breaker with addition:
STUB Protection Fault clearance of faulted 1 ½
breaker diagonal, when line out
Breaker Failure protection for two breakers Necessary for power system
security
Auotoreclosing for two breakers Sequential
Synchrocheck for two breakers
Pole discordance for two breakers
Trip logic for two breakers
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2006-03-30 Substation Automation Products Training 9
Line Protection: Distance/Differential prot.
Distance Protection Local measurements of
voltage and current
Enables remote back-up protection
Communication not primarily needed
Great Flexibility
Independent of IED at the other line end
Differential Protection Instantaneous fault clearance
Absolute selectivity
Best for Multi-terminal lines
High sensitivity
Not sensitive for power swing
Suitable for series compensated systems
Suitable for protection of short lines
Easy to set
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2006-03-30 Substation Automation Products Training 10
RED670: Differential and Distance protection
Differential Protection: Dependent of communication
Distance protection in RED670: Selective back-up protection if the communication is unavailable
The distance protection will also serve as protection (main protection or back-up protection) for the adjacent busbar.
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2006-03-30 Substation Automation Products Training 11
Simple line differential protection application
Application as REL 551 and REL 561
RED670
RED670
Protected zone
Comm. Channel
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2006-03-30 Substation Automation Products Training 12
Three ended line application
Fault current can be fed from all line ends
RED670
RED670
RED670
Protected zone
Communication
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2006-03-30 Substation Automation Products Training 13
Five end line application
Fault current can be fed from all line ends
RED670
RED670
Protected zone
RED670
RED670
RED670
Communication
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2006-03-30 Substation Automation Products Training 14
CT connection to the protection
Internal summation: Improved stability of the differential protection
Enables the integration of some breaker related functions
RED670 has internal summation
Prot.IED
External currentsummation
Prot.IED
Internal currentsummation
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2006-03-30 Substation Automation Products Training 15
1 ½ breaker switchyard application
No external current summation
RED670
RED670
RED670
Protected zone
Communication
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2006-03-30 Substation Automation Products Training 16
Application with power transformer in the protected zone
RED670
RED670
RED670
Protected zone
Communication
Considered phenomena: Phase shift of the current through the transformer at different vector groups The inability of many transformers to transform zero sequence currents The inrush current, appearing at the energization of a transformer, will be
detected as a differential current it the transformer is within the protected zone Deviation of tap changer position will cause false differential current to the
protection, if not compensated for
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2006-03-30 Substation Automation Products Training 17
RED670
RED670
Protected zone
Communication
Often required application
Application with power transformer in the protected zone
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2006-03-30 Substation Automation Products Training 18
Application with one delayed function
RED670
RED670
Protected zone instantaneous function
Protected zone delayed function
Comm. Channel
Enables selectivity to other protection IEDs
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2006-03-30 Substation Automation Products Training 19
Differential protection function
Main biased differential current function
Complementary functions Negative sequence fault discriminator
2nd harmonic restrain
5th harmonic restrain
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2006-03-30 Substation Automation Products Training 20
Fundamental frequency current phasors
RED670
RED670
RED670
I1 I2
I3
1 1 1 2 1 3 1DiffL L L LI I I I
Differential and bias currents in phase L1:
),,,,,,,,max( 332313322212312111 LLLLLLLLLBias IIIIIIIIII
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2006-03-30 Substation Automation Products Training 21
Biased Differential Protection Characteristic
Ibias
Idiff
Section 1
Section 2
Section 3
Operation
Restrain
Idmin
EndSection1 EndSection2
SlopeSection2
SlopeSection3
Unrestrain
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2006-03-30 Substation Automation Products Training 22
Negative sequence current
Negative sequence currents will occur during all types of faults, also for a transient period during three phase short circuits
The fault point will serve as a source for negative sequence current
Negative sequence current can be seen as normal phase currents but with reverse phase rotation
In normal operation, under balance conditions, the negative sequence current components are zero
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2006-03-30 Substation Automation Products Training 23
Negative Sequence Source at Fault Point
RED670
RED670
Protected zone
Communication
RED670
RED670
Protected zone
Communication
I-
Fault Point
I-
Fault Point
External Fault
Internal Fault
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2006-03-30 Substation Automation Products Training 24
Negative Sequence Current Fault Discriminator
If the two currents flow in the same direction, the fault is internal.
If the two currents flow in opposite directions, the fault is external.
RED670
RED670
RED670
I- LocalI- Remote 1
I- Remote 2
StudiedTerminal
I- Remote = I- Remote 1 + I- Remote 2
30
60
90
120
150
180
210
240
270
300
330
Local I- : Reference
Internal Fault ZoneExternal Fault Zone
ROA
Minimum Operation I-
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2006-03-30 Substation Automation Products Training 25
Transformer Inrush Currentcurrentin pu
time in ms
iL1
iL2
iL3
10.0
0 20 40 60 80 100
5.0
0.0
-5.0
phase L3 current
phase L1 current
CBcloses
currentin pu
time in ms
iL1
iL2
iL3
10.0
0 20 40 60 80 100
5.0
0.0
-5.0
phase L3 current
phase L1 current
CBcloses
Detection: 2nd Harmonic and 5th Harmonic
If Transformer in the zone: Inrush Current: Differential Current
As in normal transformer differential protection
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2006-03-30 Substation Automation Products Training 26
Transformer Overexcitation
If Transformer in the zone: Overexcitation: Differential Current
Detection: 5th Harmonic
As in normal transformer differential protection
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2006-03-30 Substation Automation Products Training 27
Current Transformer Saturation
Primary Current
Secondary Current
High Degree of Harmonics (2nd and 5th)
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2006-03-30 Substation Automation Products Training 28
Functional Logic
Negative Sequence Fault Discriminator: Internal Fault 2nd and 5threstrain function are overridden The biased differential function operates without delay (start) Exception: Inrush current of transformer in the protected zone: Special
logic will detect this
Negative Sequence Fault Discriminator: External Fault 2nd and 5th harmonic restrain is active, with cross blocking function. This
means that harmonics also in non-faulted phase will block the function. Temporarily (as long as external fault is declared plus 100 ms) the limit
of differential current for operation will be increased to the value of “IdminHigh”.
Negative Sequence Fault Discriminator: No Operation Normal differential protection function with 2nd and 5th harmonic restrain
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2006-03-30 Substation Automation Products Training 29
Temporary characteristic at external fault detection
Ibias
Idiff
Section 1
Section 2
Section 3
Operation
Restrain
Idmin
EndSection1 EndSection2
SlopeSection2
SlopeSection3
Unrestrain
IdminHigh
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2006-03-30 Substation Automation Products Training 30
Simplified block diagram
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2006-03-30 Substation Automation Products Training 31
Simplified block diagram
Calculationof
instantaneousdifferential currents
(3x)
Calculation offundamental
frequencydifferential
currents (3x)& bias current
Magnitudes of differential currents
Bias current
[magnitude]
[samples]
Instantaneous differential currents
(samples)
Differentialand bias currents
applied tooperate / bias-,
and unrestrainedcharacteristics
Harmonicanalysis(the 2nd,
and the 5th),
Trip request by unrestrained differential protection
Calculationof
negative-sequencedifferential
current(1x)
Two to sixcontributionsto neg. seq.differentialcurrent as phasors
[real, imag]Disturbance detected withhigh sensitivity
andcharacterized
as internal or external
Internal fault
External fault
Output logic:
- 2nd harmonic block,- 5th harmonic block,
-Cross-block logic
- Enhanced trip for internal faults,
- Blocked trip for external faults
- Trip allowed for external and simultaneous internal faults
- Conditional extra delay for trip signals
Start L1
Start L2
Start L2
2nd h. block
5th h. block
CH1IL1SM
CH1IL2SM
CH1IL3SM
CH2IL1SM
Curr. samples from all ends
CH1IL1RE
CH1IL1IM
CH1IL2RE
CH1IL2IM
Currents fromall ends asphasors
CH1INSRE
CH1INSIM
CH1INSRE
CH1INSIM
Neg. seq.currents from
all endsas phasors
Tri
p c
om
ma
nds
TRIP>= 1
TRIPRESTRIPUNRETRNSUNRETRNSSENS
STARTSTL1STL2STL3
BLK2HBLK2HL1BLK2HL2BLK2HL3
BLK5HBLK5HL1BLK5HL2BLK5HL3
INTFAULT EXTFAULT
Info
rma
tion
TRL1TRL2TRL3
Calculationof
instantaneousdifferential currents
(3x)
Calculation offundamental
frequencydifferential
currents (3x)& bias current
Magnitudes of differential currents
Bias current
[magnitude]
[samples]
Instantaneous differential currents
(samples)
Differentialand bias currents
applied tooperate / bias-,
and unrestrainedcharacteristics
Harmonicanalysis(the 2nd,
and the 5th),
Trip request by unrestrained differential protection
Calculationof
negative-sequencedifferential
current(1x)
Two to sixcontributionsto neg. seq.differentialcurrent as phasors
[real, imag]Disturbance detected withhigh sensitivity
andcharacterized
as internal or external
Internal fault
External fault
Output logic:
- 2nd harmonic block,- 5th harmonic block,
-Cross-block logic
- Enhanced trip for internal faults,
- Blocked trip for external faults
- Trip allowed for external and simultaneous internal faults
- Conditional extra delay for trip signals
Start L1
Start L2
Start L2
2nd h. block
5th h. block
CH1IL1SM
CH1IL2SM
CH1IL3SM
CH2IL1SM
Curr. samples from all ends
CH1IL1RE
CH1IL1IM
CH1IL2RE
CH1IL2IM
Currents fromall ends asphasors
CH1INSRE
CH1INSIM
CH1INSRE
CH1INSIM
Neg. seq.currents from
all endsas phasors
Tri
p c
om
ma
nds
TRIP>= 1
TRIPRESTRIPUNRETRNSUNRETRNSSENS
STARTSTL1STL2STL3
BLK2HBLK2HL1BLK2HL2BLK2HL3
BLK5HBLK5HL1BLK5HL2BLK5HL3
INTFAULT EXTFAULT
Info
rma
tion
TRL1TRL2TRL3
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2006-03-30 Substation Automation Products Training 32
Charging Current
RED670
RED670
Communication
Ic1Ic2Idiff,false = Ic1 + Ic2
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2006-03-30 Substation Automation Products Training 33
Charging Current Compensation
Continuous estimation of differential current at no-fault condition: Charging current
Pre-fault charging current estimation kept during faults
Subtraction of the false pre-fault differential currents At low resistance faults the fault current is large: dominating
over the charging current: Error in the charging current compensation has minor influence
At high resistive faults the voltage is maintained and the charging current is close to the non-faulted case
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2006-03-30 Substation Automation Products Training 34
Time synchronization
90deg
msms
oo
1820
360Time coordination error ≤ 1 ms
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2006-03-30 Substation Automation Products Training 35
Time synchronizing with the echo method
T1
T2 T3
T4
B
A
2
)()( 3412 TTTTTd
2
)()( 3241 TTTTt
Time delay:
Clock difference:
Provided that send and receive delay times are equal
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2006-03-30 Substation Automation Products Training 36
Route switched networks with delay symmetry The echo method allows for route switching with equal delay times for send and receive
Maximum transmission timeTd < 40 ms
A B
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2006-03-30 Substation Automation Products Training 37
Route switched network without delay symmetry GPS system required for set up GPS loss tolerated with:
Free-wheeling IED clocks Fall back to the echo method
Maximum transmission timeTd < 40 ms
GPSclock
D
BA C
GPSclock
GPSclock
GPSclock
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2006-03-30 Substation Automation Products Training 38
Communication principle
RED670
RED670
Protected zone
Comm. Channels
RED670
RED670
RED670
5-terminal line with master-master system
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2006-03-30 Substation Automation Products Training 39
Communication principle
RED670
RED670
Protected zone
Comm. Channels
RED670
RED670
RED670
5-terminal line with master-slave system
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2006-03-30 Substation Automation Products Training 40
Communication of current sampled values
0Time(ms)5 10 15 20 25 30 35
Current sampling moment
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
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2006-03-30 Substation Automation Products Training 41
Communication of current sampled values at fault
0Time(ms)5 10 15 20 25 30 35
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Currentsample
telegramsent
Current sampling moment Fault current measured
Faultoccurs
Current collectiontime
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2006-03-30 Substation Automation Products Training 42
Communication of binary signals
In each telegram there are eight binary signals freely configurable by the user in CAP configuration.
These signals can be used for any purpose.
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2006-03-30 Substation Automation Products Training 43
Communication hardware solutions
LDCM
LDCM
LDCM
LDCM
Max 3 km with LDCM
LDCM with direct fiber (multi mode)
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2006-03-30 Substation Automation Products Training 44
Communication hardware solutions
*) Converting optical to galvanic G.703 or V.35 alternatively
LDCM with an external optical to galvanic converter and a multiplexer
LDCM
LDCM
LDCM
LDCM
Telecom. Network
*) *)
Multiplexer Multiplexer
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2006-03-30 Substation Automation Products Training 45
Communication hardware solutions
LDCM with an external optical to optical converter for direct connection to a telecommunications network
G.703.E1
LDCM
LDCM
LDCM
LDCM
Telecom. NetworkG.703.E1
64kbit/s 64kbit/s
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2006-03-30 Substation Automation Products Training 46
Redundant communication channels2-terminal line with single breaker connected to route switched network via multiplexer, redundant channels
With redundant channels the primary channel normally is in operation.If the primary channel becomes faulty the operation is switched overto the redundant channel. If the primary is OK again it will take overthe operation after a time delay.
LDC
M
LDCM
Telecom. Network
Telecom. Network
Primary channel
Secondary redundant channel
LDC
M
LDCM
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2006-03-30 Substation Automation Products Training 47
RED Single-Breaker application
1/3phO->I
79
SC/VC
25/27
Z<21
ZPSB68
51/67NI
60FF
52PDPD
ContInterl
86/94I->O
3I>BF50BF
Trip Bus
DR
´REL670
´REL670
3U>3U<
27
UN59N 59
Start
f< f>81U 81O
3Id/I>87L
To Remote end
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2006-03-30 Substation Automation Products Training 48
RED 670 Double-Breaker application
1/3phO->I
79
SC/VC
25/27
Z<21
ZPSB68
60FF
52PDPD
ContInterl
86/94I->O
3I>BF50BF
DR
´REL670
´REL670
3U>3U<
27UN
59N 59
Start
f< f>81U 81O
3I>BF50BF
52PDPD
86/94I->O
SC/VC
25/27
1/3phO->I
79
Start
51N/67N
IN>444
L2
L2
3Id/I>
To Remote end
87L
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2006-03-30 Substation Automation Products Training 49
RED 670 Multi-Breaker application
1/3phO->I
79
SC/VC
25/27
Z<21
ZPSB68
51/67NI
60FF
52PDPD
ContInterl
86/94I->O
3I>BF50BF
Trip Bus
DR
´REL670
´REL670
3U>3U<
27UN
59N 59
Start
52PDPD
3I>BF50BF
3I>ST50ST
86/94I->O
1/3phO->I
79
SC/VC
25/27Start
MainB
MainB
f< f>81U 81O
3Id/I>87L
To Remote end
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2006-03-30 Substation Automation Products Training 50
RED 670 Multi-Breaker application w. Tee
1/3phO->I
79
SC/VC
25/27
Z<21
ZPSB68
51/67NI
60FF
52PDPD
ContInterl
86/94I->O
3I>BF50BF
Trip Bus
DR
3U>3U<27
UN59N 59
Start
52PDPD
3I>BF50BF
3I>ST50ST
86/94I->O
1/3phO->I
79
SC/VC
25/27Start
MainB
MainB
3Id>OCT
87Tee
MainB
´REL670
´REL670
f< f>81U 81O
3Id/I>
To Remote end
87L