Breaker Failure Protection - Hrs 2012 - Brent Carper -- Presentation Slides

29th Annual

HANDS-ON RELAY SCHOOL March 12 - 16, 2012

BREAKER FAILURE PROTECTION

Brent Carper, PE P r o te c t i o n & I n te g r a t i o n E n g i n e e r b r e n t . c @ r e l aya p p l i c a t i o n . c o m

OUTLINE       

Protection System Failures and Breaker Failures BF Protection versus BF Relaying BF Relay Schemes and Logic Special BF Situations BF Setting Calculation Exercise Impacts from Changing Technology Testing and Maintenance of BF Schemes

P r i m a r y Re f e r e n c e : C 37. 1 1 9 - 2 0 0 5 I E E E G u i d e f o r B r e a ke r Fa i l u r e P r o te c t i o n o f Pow e r C i r c u i t B r e a ke r s

PROTECTION FAILURE Protection System Failures      

Relay failure Settings failure Control system failure CT/PT failure Batter y system failure Catastrophic control house failure (fire)

Breaker Failures        

Fails to trip Trips too slow Fails to interrupt fault current Fails to interrupt load current Flashover when open Fails to close Auxiliar y contact problems Catastrophic failure

Breaker Failure Protection versus Breaker Failure Relaying

BREAKER FAILURE PROTECTION BY COORDINATION

T

A

B

BREAKER FAILURE PROTECTION BY COORDINATION

T

A

B

BREAKER FAILURE PROTECTION BY COORDINATION

T

A

B

BREAKER FAILURE PROTECTION BY COORDINATION

T

A

B

BREAKER FAILURE PROTECTION BY COORDINATION

T

A

B

Advantages:

Disadvantages:

 S i m p l e – N o ex t r a e q u i p m e n t  Simple – No risk of misoperation  U l t i m a te p r o te c t i o n . C ov e r s A L L f a i l u r e s , n o t j u s t B r e a ke r Fa i l u r e ( f a i l u r e o f b r e a ke r, r e l ay, s e t t i n g s , c o n t r o l s a n d w i r i n g , b a t te r y, e t c . )

 S l ow  M ay n o t b e p o s s i b l e f o r t h e b a c ku p r e l ay i n g a t [ A ] to s e e a l l f a u l t s

Conclusions:   

C o m m o n p r a c t i c e f o r D i s t r i b u t i o n , b u t t y p i c a l l y n o t s u f f i c i e n t f o r Tr a n s m i s s i o n . T h e r e i s “ B r e a ke r Fa i l P r o te c t i o n ” eve n t h o u g h t h e r e i s n o t “ B r e a ke r Fa i l Re l ay i n g ” . B r e a ke r f a i l u r e p r o te c t i o n i s b u i l t - i n to g o o d p r o te c t i o n p r a c t i c e s .

BREAKER FAILURE PROTECTION BY COORDINATION A

T

1 2 T

M

3 4 5

B

BREAKER FAILURE PROTECTION BY COORDINATION A

T

B

1 2 T

M

3 4 5

[ A ] c a n p r o b a b l y b a c k u p [ B ] a n d s e e a m i n i m u m f a u l t a l l t h e way a t t h e e n d o f t h e l i n e . [ M ] m ay n o t b e a b l e to f u l l y b a c k u p t h e f e e d e r b r e a ke r s f o r a n e n d o f l i n e f a u l t . Example:

Assume 200A load per feeder section, and 800A minimum fault current at the end of line. [A] has 400A max load and needs to pickup on an 800A fault. [M] has 1000A max load, so it cannot be set to pickup on an 800A fault.

IEEE EXAMPLE B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE PROPER CLEARING B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE PROPER CLEARING B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE BREAKER FAILURE B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE BREAKER FAILURE B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE REMOTE BACKUP B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE REMOTE BACKUP B

C

A

A

1

2

3

4

5

6

Load

C

Load 7

8 Load

Advantages:

Disadvantages:

 C o m p l e te l y i n d e p e n d e n t o f Substation B.

   

S l ow – s y s te m i n s t a b i l i t y S l ow – vo l t a g e d i p s Wide area outage M ay n o t b e p o s s i b l e f o r t h e b a c ku p r e l ay to s e e a l l f a u l t s

IEEE EXAMPLE B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE BREAKER FAILURE RELAYING B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE BREAKER FAILURE RELAYING B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

C

IEEE EXAMPLE BREAKER FAILURE RELAYING B A

A

1

2

C 3

4

5

6

Load

Load 7

8 Load

BFR on breaker [3] detects breaker failure condition  B F R t r i p s a L o c ko u t r e l ay  L o c ko u t r e l ay ( 8 6 ) t r i p s b r e a ke r s [ 2 ] , [ 5 ] , a n d [ 7 ]  L o c ko u t r e l ay b l o c k s c l o s e o f [ 2 ] , [ 5 ] , a n d [ 7 ] What else?  Tr a n s f e r Tr i p to b r e a ke r [ 4 ]  Cancel reclose of [4]

C

BREAKER FAILURE RELAYING

01 21 Z1

87B 21 Z2

21 Z2 67 G

86B

67 G 50 62

BFI

86BF

trip all adjacent bkrs

trip all bkrs on bus

DTT/RC to remote bkrs

BREAKER FAILURE RELAYING

21 B

87B

BFI

21 P

BFI

50 62

86BF

BFI

86B

BREAKER FAILURE RELAYING

1

3

2

87B

87B

BF 1

BF 2 21 B

21 P BF 3 21 B

21 P

BREAKER FAILURE LOGIC 1. 2. 3. 4. 5. 6. 7. 8. 9.

Basic Breaker Failure Scheme 50BF Torque Control Breaker Re-Trip Logic BFI Control Timer BFI Seal-In Minimal Current Scheme Timer Bypass Scheme Dual Timer Scheme Special Schemes

BASIC BREAKER FAILURE SCHEME

 Four Par ts to a Breaker Failure Scheme:    

Fault Detector (50) or other Failure Detectors Initiator Circuit (BFI) Logic and Timers (62) Output Circuit (BFT)

50BF TORQUE CONTROL

BREAKER RE-TRIP LOGIC

BFI CONTROL TIMER

BFI SEAL-IN

MINIMAL CURRENT SCHEME

TIMER BYPASS SCHEME

Note: This logic is for illustrative purposes only. Not intended as a complete scheme. The timer bypass scheme should be supervised by a fault detector, which may not be compatible with torque controlled 50BF.

EXAMPLE BE1-50BF LOGIC

DUAL TIMER SCHEMES  Use fast BF timer for multi-phase faults (L-L, L-L-G, 3P)  Use slower BF timer for single-phase faults (SLG)  Multi-phase faults have larger impact on system stability, and may require fast breaker failure times.  Single-phase faults are more common.  Dual timer allows fast BFT for the multi-phase fault, but keeps the security of a slower BFT for the most common fault scenario.

SPECIAL SCHEMES     

Voltage dif ferential Frame leakage detection Breaker dif ferential IPO breakers Redundant breakers

BF SETTINGS    

Logic Fault or Load Current Detector Pickup Other Breaker Failure Detectors Set Timers

NORMAL CLEARING TIME PROTECTIVE RELAY OPERATE TIME

BREAKER OPERATE TIME

BFI INPUT P/U

50FD RESET

MARGIN

BF TIMER SETTING

50FD P/U

CONTROL TIMER SETTING

86BF BFR OUTPUT OPERATE TIME RELAY TIME

LOCAL BACKUP BREAKER OPERATE TIME TT CHANNEL TIME

REMOTE END BACKUP BREAKER OPERATE TIME

MAX CRITICAL CLEARING TIME BY COMPANY POLICY

FAULT

PROPER OPERATION FAULT CLEARED

CRITICAL CLEARING TIME CALCULATED BY STUDY

CALCULATING BF SCHEME TIMERS

NORMAL CLEARING TIME PROTECTIVE RELAY OPERATE TIME

BREAKER OPERATE TIME

BFI INPUT P/U

50FD RESET

MARGIN

BF TIMER SETTING

50FD P/U

CONTROL TIMER SETTING

86BF BFR OUTPUT OPERATE TIME RELAY TIME

LOCAL BACKUP BREAKER OPERATE TIME TT CHANNEL TIME

REMOTE END BACKUP BREAKER OPERATE TIME

MAX CRITICAL CLEARING TIME BY COMPANY POLICY

FAULT

PROPER OPERATION FAULT CLEARED

CRITICAL CLEARING TIME CALCULATED BY STUDY

CALCULATING BF SCHEME TIMERS

EXERCISE

IMPACT OF CHANGING TECHNOLOGY  Digital Relay BF Protection: Faster, Better, Cheaper, More    

Solved transient stability problems previously unsolvable Better protection against wide-area and cascading outages Protect against all breaker failure modes, not just one or two Can be more secure if designed well

 Most utilities moving away from Stand- Alone BF Relays  Some utilities (not many) are reversing the trend and going back to stand alone Breaker Failure Relays  Reduce misoperations “unscheduled maintenance tests”  Use longer maintenance cycles for BF protection systems

IMPACT OF CHANGING TECHNOLOGY

21 B

87B

BFI

21 P

BFI

50 62

86BF

BFI

86B

IMPACT OF CHANGING TECHNOLOGY

21 B

87B

BFI

21 P

BFI

BF

86BF

BFI

86B

IMPACT OF CHANGING TECHNOLOGY

BF

21 B

87B

BFI

BFI

21 P

BF

86BF

BFI

86B

IMPACT OF CHANGING TECHNOLOGY

21 B

87B

BF

I

21 P

BF

BF

86BF

BFI

86B

IMPACT OF CHANGING TECHNOLOGY

BF

21 B

BF

BFI

87B

BFI

BFI

21 P

BF

86BF

86B

IMPACT OF CHANGING TECHNOLOGY

1

3

2

87B

87B

BF 1

BF 2 21 B

21 P BF 3 21 B

21 P

IMPACT OF CHANGING TECHNOLOGY

1

BF 1

3

2

87B

87B

BF 1

21 B

BF 2

BF 1

21 P

BF 2

BF 2

21 B

BF 3

BF 2

21 P

BF 3

BF 3

IMPACT OF CHANGING TECHNOLOGY  Digital Relay Timing and Logic  Precise timing eliminates relay misoperations due to calibration drift  Precise timing and logic allows reducing “design margins”

 Digital Relay I/O  Sensitive BFI inputs (transients, DC grounds)  Solid state relay outputs (sneak circuits)

 Digital Relay Protective Elements  Used to be limited to a 50FD  Now we can use 50L and other sensitive detectors that may pick up a lot  Solution: Consider using other elements to help add Security, not just Sensitivity (negative sequence, voltage elements, synch check and frequency elements, etc.)

IMPACT OF CHANGING TECHNOLOGY  Challenges from Complexity      

Elaborate/exotic BF logic Wide variety of BF schemes, even in the same model of relay at the same utility May have more than one BF scheme in a single relay May have more than one BF scheme for single breaker Solution: Engineering Standardization Solution: Documentation (written setting descriptions, logic diagrams, and test plans)

 Challenges with Integrated BF    

May not be able to disable all BFI’s May not be able to disable all BFT’s Trend is to completely eliminate all hardwired BFT and lockout relays (IEC 61850) Solution: Design with test switch to relay input that disables the BFI and/or BFT. Especially important for BFTT or 61850.

TESTING AND MAINTENANCE OF BREAKER FAILURE PROTECTION Challenges with BF Protection  D i f f i c u l t to te s t i n te n t i o n a l l y  E a s y to te s t u n i n te n t i o n a l l y

TESTING AND MAINTENANCE OF BREAKER FAILURE PROTECTION There is a dif ference between testing the BF Relay and testing the BF Relaying System  M a ny u t i l i t i e s p e r f o r m m a i n te n a n c e te s t i n g o f t h e B F Re l ay, b u t a r e n o t te s t i n g t h e e n t i r e B r e a ke r Fa i l u r e P r o te c t i o n S y s te m .  G o o d m a i n te n a n c e p r a c t i c e s ( a n d N E R C c o m p l i a n c e r e q u i r e m e n t s ) a r e to te s t t h e P r o te c t i o n S y s te m :  Maintenance program for the BF Relay  Maintenance program for CT’s/PT’s  Maintenance program for the Battery and DC system  Maintenance of the BFR Protection System must include:  Rolling lockout relays and tripping breakers  Best practice: simultaneous functional test (clear the bus)