Line Differential Protection IED RED670

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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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Contents

Application

Main features

User Friendly Packages

Functions

Benefits

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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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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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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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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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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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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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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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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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Simple line differential protection application

Application as REL 551 and REL 561

RED670

RED670

Protected zone

Comm. Channel

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Three ended line application

Fault current can be fed from all line ends

RED670

RED670

RED670

Protected zone

Communication

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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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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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1 ½ breaker switchyard application

No external current summation

RED670

RED670

RED670

Protected zone

Communication

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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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RED670

RED670

Protected zone

Communication

Often required application

Application with power transformer in the protected zone

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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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Differential protection function

Main biased differential current function

Complementary functions Negative sequence fault discriminator

2nd harmonic restrain

5th harmonic restrain

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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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Biased Differential Protection Characteristic

Ibias

Idiff

Section 1

Section 2

Section 3

Operation

Restrain

Idmin

EndSection1 EndSection2

SlopeSection2

SlopeSection3

Unrestrain

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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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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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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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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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Transformer Overexcitation

If Transformer in the zone: Overexcitation: Differential Current

Detection: 5th Harmonic

As in normal transformer differential protection

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Current Transformer Saturation

Primary Current

Secondary Current

High Degree of Harmonics (2nd and 5th)

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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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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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Simplified block diagram

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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


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



INTFAULT EXTFAULT

Info

rma

tion

TRL1TRL2TRL3

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Charging Current

RED670

RED670

Communication

Ic1Ic2Idiff,false = Ic1 + Ic2

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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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Time synchronization

90deg

msms

oo

1820

360Time coordination error ≤ 1 ms

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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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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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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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Communication principle

RED670

RED670

Protected zone

Comm. Channels

RED670

RED670

RED670

5-terminal line with master-master system

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Communication principle

RED670

RED670

Protected zone

Comm. Channels

RED670

RED670

RED670

5-terminal line with master-slave system

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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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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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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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Communication hardware solutions

LDCM

LDCM

LDCM

LDCM

Max 3 km with LDCM

LDCM with direct fiber (multi mode)

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*) 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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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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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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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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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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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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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

Line Differential Protection IED RED670

Documents

Transcript of Line Differential Protection IED RED670