Line Differential Protection IED RED670

Substation  Automation Products Training

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

REL 670 Line Distance Protection IED

Contents 

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

 Application  Application



Main features



User Friendly Packages



Functions



Benefits

Line Differential Protection: RED670 

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

 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

Features: RED670 

Line differential terminal for: 

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

 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

RED670 User Friendly Package 

IED with a pre-selected set of functions: configured configured



First Alternative: Single-Breaker application



   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A



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

RED670 User Friendly Package: Single breaker  

Line differential function 





    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A





Essential in a local redundant fault clearance system

Simple and sensitive earth fault protection

Pole Discordance protection 



Often required equipment protection

Residual overvoltage protection 

Simple back-up earth fault protection

Breaker failure protection

Over-/Undervoltage protection 

Simple back-up short circuit protection

Residual overcurrent protection 



Main function of the IED clearing all shunt faults

Phase overcurrent protection 



Limitation of consequences of  unsymmetric breaker function

Distance Protection (option) 

Best redundancy at communication failure

RED670 User Friendly Package: Single breaker  

Fuse Failure detection 



Trip logic 



Standard functionality to increase network availability

Synchrocheck 

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Enables choice of trip possibilities, 1 or 3 pole trip at single phase faults

 Autoreclosing 



Necessary to avoid protection malfunction (voltage related)

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

RED670 User Friendly Package: Multi-breaker  

Same as single breaker with addition:



STUB Protection 



Breaker Failure protection for  two breakers 

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Fault clearance of faulted 1 ½ breaker diagonal, when line out

Necessary for power system security



 Auotoreclosing for two breakers 

Sequential



Synchrocheck for two breakers



Pole discordance for two breakers



Trip logic for two breakers

Line Protection: Distance/Differential prot. 

Distance Protection 

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

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

RED670: Differential and Distance protection

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A



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.

Simple line differential protection application Protected zone

RED 670

Comm. Channel

Application as REL 551 and REL 561

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

RED 670

Three ended line application

Protected zone

RED 670

RED 670

RED 670

Fault current can be fed from all line ends    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Communication

Five end line application Protected zone

RED 670

RED 670

Communication RED 670

RED 670

RED 670

Fault current can be fed from all line ends    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

CT connection to the protection External current summation

Internal current summation

Prot. IED



   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Prot. IED

Internal summation: 

Improved stability of the differential protection



Enables the integration of some breaker related functions



RED670 has internal summation

1 ½ breaker switchyard application Protected zone

RED 670

RED 670

RED 670

 No external current summation    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Communication

Application with power transformer in the protected zone Protected zone

RED 670

RED 670

RED 670



   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

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 

Application with power transformer in the protected zone

Protected zone

RED 670

RED 670

Communication

Often required application    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Application with one delayed function Protected zone instantaneous function

RED 670

Comm. Channel

Protected zone delayed function

Enables selectivity to other protection IEDs    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

RED 670

Differential protection function

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A



Main biased differential current function



Complementary functions 

Negative sequence fault discriminator 



2nd harmonic restrain



5th harmonic restrain

Fundamental frequency current phasors I1

I2

RED 670

RED 670

RED 670

I3

Differential and bias currents in phase L1:    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

 I DiffL1  I1L1  I2 L1  I 3L1  I  Bias



max( I 1 L1 ,  I 1 L 2 ,  I 1 L 3 ,  I 2 L1 ,  I 2 L 2 ,  I 2 L3 ,  I 3 L1 ,  I 3 L 2 , I 3 L3 )

Biased Differential Protection Characteristic Idiff  Unrestrain

SlopeSection3

Operation

SlopeSection2

Restrain

Idmin    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

EndSection1 Section 1

Ibias

EndSection2 Section 2 Section 3

Negative sequence current

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A



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

Negative Sequence Source at Fault Point Internal Fault Protected zone Fault Point RED 670

Communication

RED 670

I-

External Fault Protected zone Fault Point RED 670

Communication

RED 670

I   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Negative Sequence Current Fault Discriminator  I- Remote 1

I- Local

RED 670

RED 670

I- Remote = I- Remote 1 + I- Remote 2

Studied Terminal 90 120

RED 670

60

I- Remote 2 150





   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

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.

30

External Fault Zone

Internal Fault Zone ROA

180

Minimum Operation I-

Local I- : Reference 210

330

240

300 270

Transformer Inrush Current current  in pu

5.0 

iL1 iL2 

 phase L3 current 

10.0 

CB closes

0.0 

iL3 -5.0   phase L1 current 

0 

20 

40

60

80

100

 

time in ms

If Transformer in the zone: Inrush Current: Differential Current    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Detection: 2nd Harmonic and 5th Harmonic  As in normal transformer differential protection

Transformer Overexcitation

If Transformer in the zone: Overexcitation: Differential Current Detection: 5th Harmonic    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

 As in normal transformer differential protection

Current Transformer Saturation

Primary Current

Secondary Current

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

High Degree of Harmonics (2 nd and 5th)

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 



    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

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

Temporary characteristic at external fault detection Idiff  Unrestrain

SlopeSection3

Operation

IdminHigh SlopeSection2

Restrain

Idmin    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

EndSection1 Section 1

Ibias

EndSection2 Section 2 Section 3

Simplified block diagram

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Simplified block diagram [magnitude]

CH1IL1RE CH1IL1IM CH1IL2RE CH1IL2IM

Currents from all ends as phasors

Calculation of  fundamental Magnitudes of  frequency differential differential currents currents (3 x) & bias current Bias current

CH1IL1SM CH1IL2SM CH1IL3SM CH2IL1SM

Curr. samples from all ends

Trip request by unrestrained differential protection

Differential and bias currents applied to operate / bias-, and unrestrained characteristics

>= 1 Start L1 Start L2 Start L2

[samples]

Calculation of  instantaneous differential currents (3x)

Instantaneous differential currents (samples)

Harmonic analysis (the 2nd, and the 5th),

CH1INSIM CH1INSRE CH1INSIM    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Neg. seq. currents from all ends as phasors

[real, imag]

Calculation of  negativesequence differential current (1x)

Two to six contributions to neg. seq. differential current as phasors

Disturbance detected with high sensitivity and characterized as internal or external

Output logic: - 2nd harmonic block, - 5th harmonic block, -Cross-block logic

2nd h. block

5th h. block CH1INSRE

TRIP

Internal fault External fault

- Enhanced trip for  internal faults, - Blocked trip for  external faults - Trip allowed for  external and simultaneous internal faults - Conditional extra delay for trip signals

TRL1 TRL2 TRL3

  s    d   n   a   m   m   o   c   p    i   r    T

TRIPRES TRIPUNRE TRNSUNRE TRNSSENS START STL1 STL2 STL3 BLK2H BLK2HL1 BLK2HL2 BLK2HL3 BLK5H BLK5HL1 BLK5HL2 BLK5HL3 INTFAULT EXTFAULT

  n   o    i    t   a   m   r   o    f   n    I

Charging Current

Ic1

RED 670

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Idiff,false = Ic1 + Ic2

Communication

Ic2

RED 670

Charging Current Compensation

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A



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

Time synchronization

90deg

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Time coordination error ≤ 1 ms

360 o 20 ms

 18

o

ms

Time synchronizing with the echo method T2 A

T3

B T1

Time delay:

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Clock difference:

T d 

T4



t  

(T 2

 T 1 )  (T 4  T 3 )

2

(T 1

 T 4 )  (T 2  T 3 )

2

Provided that send and receive delay times are equal

Route switched networks with delay symmetry 

The echo method allows for route switching with equal delay times for send and receive

A

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

B

Maximum transmission time Td < 40 ms

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

D GPS clock

A

C

GPS clock GPS clock

B    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Maximum transmission time Td < 40 ms

GPS clock

Communication principle

5-terminal line with master-master system Protected zone

RED 670

RED 670

Comm. Channels

RED 670    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

RED 670

RED 670

Communication principle

5-terminal line with master-slave system Protected zone

RED 670

RED 670

Comm. Channels RED 670

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

RED 670

RED 670

Communication of current sampled values

Current sample telegram sent

0

5

Current sample telegram sent

10

Current sampling moment

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Current sample telegram sent

15

Current sample telegram sent

20

Current sample telegram sent

25

Current sample telegram sent

30

Current sample telegram sent

35

Current sample telegram sent

Time (ms)

Communication of current sampled values at fault Current sample telegram sent

0

Current sample telegram sent

5

10

Current sample telegram sent

15

Current sample telegram sent

20

Current collection time

Current sampling moment

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Fault occurs

Fault current measured

Current sample telegram sent

25

Current sample telegram sent

30

Current sample telegram sent

35

Current sample telegram sent

Time (ms)

Communication of binary signals

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A



In each telegram there are eight binary signals freely configurable by the user in CAP configuration.



These signals can be used for  any purpose.

Communication hardware solutions

LDCM with direct fiber (multi mode)

Max 3 km with LDCM

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Communication hardware solutions LDCM with an external optical to galvanic converter and a multiplexer  Multiplexer

Multiplexer  Telecom. Network

*)

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

*) Converting optical to galvanic G.703 or V.35 alternatively

*)

Communication hardware solutions LDCM with an external optical to optical converter for direct  connection to a telecommunications network 

G.703.E1

G.703.E1 Telecom. Network

64kbit/s

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

64kbit/s

Redundant communication channels 2-terminal line with single breaker connected to route switched network via multiplexer, redundant channels

Telecom. Network

Telecom. Network

Primary channel Secondary redundant channel    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

With redundant channels the primary channel normally is in operation. If the primary channel becomes faulty the operation is switched over  to the redundant channel. If the primary is OK again it will take over  the operation after a time delay.

RED Single-Breaker application Trip Bus

79 1/3ph Start O->I 86/94 I->O 50BF 3I>BF 21 Z<

´REL670

´REL670

68 ZPSB 51/67N

I 60 FF

DR    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

87L 3Id/I>

Cont Interl

59N UN

27 3U<

59 3U>

81U f<

81O f>

To Remote end

25/27 SC/VC

52PD PD

RED 670 Double-Breaker application L2 L2

79 1/3ph Start O->I 86/94 I->O

´REL670

25/27 SC/VC

25/27

79 1/3ph Start O->I

´REL670

SC/VC

86/94 I->O 21 Z<

68 ZPSB 51N/67N

IN> 4 4 4    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

60 FF

DR Cont Interl

59N UN

27 3U<

59 3U>

81U f<

81O f>

87L 3Id/I>

52PD PD

50BF 3I>BF S

50BF 3I>BF

52PD PD

RED 670 Multi-Breaker application Trip Bus

86/94 I->O 50ST 3I>ST 21 Z< ´REL670

68 ZPSB 51/67N

I

79 1/3ph Start O->I

25/27 SC/VC

52PD PD

50BF 3I>BF

S

MainB

Start

79 1/3ph O->I

25/27 SC/VC

´REL670

60 FF

DR

   5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

86/94 I->O 87L 3Id/I>

Cont Interl

59N UN

27 3U<

59 3U>

81U f<

81O f>

To Remote end

MainB 50BF 3I>BF

52PD PD

RED 670 Multi-Breaker application w. Tee Trip Bus

86/94 I->O 50ST 3I>ST 21 Z< ´REL670

68 ZPSB 51/67N

I

79 1/3ph Start O->I

25/27 SC/VC

52PD PD

50BF 3I>BF MainB

Start

79 1/3ph O->I

MainB

25/27 SC/VC

´REL670

60 FF

DR 86/94 I->O    5    0    0    2  ,    B    A   s   e    i   g   o    l   o   n    h   c   e    T   r   e   w   o    P    B    B    A

Cont Interl

59N UN

27 3U<

59 3U>

81U f<

81O f>

87Tee 3Id> OCT 87L 3Id/I>

To Remote end

MainB 50BF 3I>BF

52PD PD