bfp basics

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Technology and SolutionsProtection and Substation Automation

Topic:

BREAKER FAILUREPROTECTIONAPPLICATION

BASICS BASICS

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WTopic Objectives

r Fault condition in a power grid

r Protection zones

r System behavior in case of breaker failure situation

r BFP solutions

r BFP application

Objectives

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Bus

bar

Busbar

Line

Tran

sfor

mer

Gen

erat

or -

Tran

sfor

mer

BB

Fault Condition in a Power Grid

Protection zones

G

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Bus

bar


Busbar Fault

G

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WFault Condition in a Power Grid

Busbar Fault

G

- cleared

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Busbar Fault

G

- Breaker Failure - solution

⇒ trip command to all surrounding CBs by

a remote tripping command

a tripping command via the intertripping system

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Line


Line Fault

G

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Line Fault

G

- cleared

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Line Fault

G





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ansf

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Transformer or Generator - Transformer Fault

G

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G

Transformer or Generator - Transformer Fault - cleared

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Transformer or Generator - Transformer FaultFault Condition in a Power Grid

G





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How is it possible to detect a non operating

circuit breaker (= Circuit Breaker Failure)

???

Breaker Failure Protection Solutions

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1. supervision of the feeder current (with an overcurrent criteria) after a tripping command

OR2. supervision of the CB auxiliary contacts

after a tripping commandOR

3. supervision of the feeder current (with the BBP measurement algorithm) after a tripping command (only applicable if the BFP is installed in the BBP system) - BBP unbalancing


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feeder current

t ~ higher than the highest possible CB opening time + arc extinguish time

Breaker Failure Protection Solutionssolution 1:

t2

~120 ms

re-trip to

faulty CB

(coil 1 & 2)

trip to the surrounding

CBs by

• intertripping &

• remote tripping

CB opening coil

trip to CB from protection device

BFP

t1

~120 ms

&

I >

the trip from the protection device is called „Starting BFP“

!!!

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CB closed

t ~ higher than the highest possible CB opening time + arc extinguish time


t2

~120 ms

re-trip to

faulty CB

(coil 1 & 2)


CBs by

• intertripping &

• remote tripping

CB opening coil

trip to CB from protection device

t1

~120 ms

&

BFP

the trip from the protection device is called „Starting BFP“

!!!

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re-trip to faulty CB

(coil 1 & 2) &

remote trip

inter-

tripping

CB opening coil

trip to CB from protection device x

BFP

CB x

t1

~120 ms

t2

~120 ms

BBP

BFP

CB y

CB x CB y

trip to CB from protection device y

&

BFP

logi

c

feeder current

BFP logic

∆I = 0

IF

∆I =

IF

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An advanced BFP (& BBP) system offers all 3 solutions

!!!

Which solution must be used for which application

???


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⇒ standard BFP application (most common used)⇒ for line, transformer, generator, generator- transformer, reactors and

coupler CBs⇒ for all voltage levels and switchgear configurations ⇒ overcurrent settable independently for all feeders (depending on the

minimum feeder short current)⇒ operation independent on the CB auxiliary contacts (aux. contacts are

a week part of the protection chain)⇒ for single, double and three phase auto- reclosure (tripping), (phase

segregated starting inputs)⇒ for detection of evolving faults (phase segregated timers for t1)⇒ remote tripping signal settable after timer 1 or timer 2⇒ advanced trip- redirection functionality in case of CB SF6

underpressure condition⇒ not applicable for very low fault currents (e.g. generator

reverse power function) -> solution 2

Application & features of solution 1:

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re-trip to

faulty CB

(coil 1 & 2)


CBs by intertripping

IR

Start R&

I >

≥ 1t1

IS

Start S&

I >

≥ 1t1

IT

Start T&

I >

≥ 1t1

Start R S T

≥ 1 t2

remote tripping

Trip Redirection

set t1 & t2 to 10ms

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advanced trip redirection functionality

remote tripping settable after t1

or t2

phase segregated timers for the detection of evolving faults

phas

e se

greg

ated

sta

rtin

g in

puts

for s

ingl

e an

d do

uble

po

le a

uto

recl

osur

e


re-trip to

faulty CB

(coil 1 & 2)



IR

Start R&

I >

≥ 1t1

IS

Start S&

I >

≥ 1t1

IT

Start T&

I >

≥ 1t1

Start R S T

≥ 1 t2

remote tripping

Trip Redirection

set t1 & t2 to 10ms

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⇒ applicable for very low fault currents (e.g. generator reverse power function)

⇒ remote tripping signal settable after timer 1 or timer 2⇒ advanced trip- redirection functionality in case of CB SF6

underpressure condition⇒ very good addition to solution 1⇒ no overcurrent (fault current) supervision ⇒ the starting signal must be switch off by the CB “OFF” aux. contact to

prevent an unwanted trip⇒ operation dependent on the CB auxiliary contacts (aux. contacts are a

week part of the protection chain)⇒ not applicable for single and double phase auto- reclosure (tripping)⇒ not applicable for detection of evolving faults


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Breaker Failure Protection Solutionssolution 2 in addition to solution 1:

re-trip to

faulty CB

(coil 1 & 2)



IR

Start R&

I >

≥ 1t1

IS

Start S&

I >

≥ 1t1

IT

Start T&

I >

≥ 1t1

External Start BFP

t1

Start R S T

≥ 1 t2

remote tripping

Trip Redirection

set t1 & t2 to 10ms

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Breaker Failure Protection Solutionssolution 2 in addition to solution 1:

re-trip to

faulty CB

(coil 1 & 2)



IR

Start R&

I >

≥ 1t1

IS

Start S&

I >

≥ 1t1

IT

Start T&

I >

≥ 1t1

External Start BFP

t1

Start R S T

≥ 1 t2

remote tripping

Trip Redirection

set t1 & t2 to 10ms

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⇒ applicable as basic BBP coupler functionality for the detection of faults between coupler CB and CT (coupler function - CB reclaim time)

⇒ not applicable for line, transformer, generator, generator- transformer, reactors feeders in HV systems

⇒ overcurrent (fault current) supervision depending on the BBP differential current setting (high short current required)

⇒ functionality depending on the BBP⇒ not applicable for single and double phase auto- reclosure (tripping)⇒ not applicable for detection of evolving faults⇒ the starting signal must be switch off by the CB “OFF” aux. contact to

prevent an unwanted trip to the CB after timer 1⇒ operation dependent on the CB auxiliary contacts (aux. contacts are a

week part of the protection chain)⇒ no trip- redirection functionality in case of CB SF6 underpressure

condition⇒ remote tripping signal fixed to timer 1


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coup

ler f

unct

ion

Breaker Failure Protection SolutionsCoupler function:

CB opening coil

Input Current signal

CB open

≥ 1

t

≥ 1

CT bypass

CB

recl

aim

tim

e ~1

20 m

s

IF

trip BBP Zone 1inter-

tripping Zone 2

BB

P

Zone

2

∆I = 0

∆I =

IF

Zone 2Zone 1

&

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Breaker Failure Protection ApplicationTransformer, Transformer- Generator, Reactor feeder and coupler:

G

IRStart R

&I >

≥ 1t1

ISStart S

&I >

≥ 1t1

IT

Start T&

I >

≥ 1t1

External

Start BFPt1

≥ 1

Trip Redirection

set t1 & t2 to 10ms BFP

CBx

CBx

G/T Prot.

∆I T

& ∆

I G (8

7T &

87G

)

Rev

erse

Pow

er (3

2)

Start R S T

3 Phase trip

“CB closed” aux. contacts

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Start R S T3 Phase trip

Start R

Start S

Start T

single Phase trip

Breaker Failure Protection ApplicationLine feeder with single phase auto reclosure:

IR &I >

≥ 1t1

IS&

I >

≥ 1t1

IT&

I >

≥ 1t1

External

Start BFPt1

≥ 1

Trip Redirection

set t1 & t2 to 10ms BFP

CBx

CBx

LineProt.

OC

(51)

Z< &

DEF

(21

& 6

7N)

AR

Syn

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CB

is b

lock

ed s

ince

SF6

gas

pres

sure

to e

xtin

guis

h th

e

arc

is to

low

Start R S T3 Phase trip

Start R

Start S

Start T

single Phase trip

Breaker Failure Protection ApplicationTrip Redirection in case of CB SF6 Underpressure :

IR &I >

≥ 1t1

IS&

I >

≥ 1t1

IT&

I >

≥ 1t1

External

Start BFPt1

≥ 1

Trip Redirection set t1 & t2

to 10ms BFP CBx

CBx

LineProt.

OC

(51)

Z< &

DEF

(21

& 6

7N)

AR

Syn

bfp basics

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