BFP Basics

Topic:

Technology and Solutions Protection and Substation Automation

BREAKER FAILURE PROTECTION APPLICATION

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BASICS

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Topic Objectives Objectives r Fault condition in a power grid r Protection zones r System behavior in case of breaker failure situation r BFP solutions

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r BFP application

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Line

Busbar Transformer

Generator Transformer

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Busbar

Fault Condition in a Power Grid Protection zones

G BB

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Busbar

Fault Condition in a Power Grid Busbar Fault

G

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Fault Condition in a Power Grid

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Busbar Fault - cleared

G

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Fault Condition in a Power Grid Busbar Fault - Breaker Failure - solution

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a tripping command via the intertripping system

⇒ trip command to all surrounding CBs by a remote tripping command

G

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Line

Fault Condition in a Power Grid Line Fault

G

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Fault Condition in a Power Grid

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Line Fault - cleared

G

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Fault Condition in a Power Grid Line Fault - Breaker Failure - solution

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a tripping command via the intertripping system

⇒ trip command to all surrounding CBs by a remote tripping command

G

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Fault Condition in a Power Grid

Transformer

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Transformer or Generator - Transformer Fault

G

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Fault Condition in a Power Grid

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Transformer or Generator - Transformer Fault - cleared

G

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Fault Condition in a Power Grid Transformer or Generator - Transformer Fault - Breaker Failure - solution

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a tripping command via the intertripping system

⇒ trip command to all surrounding CBs by

G a remote tripping command

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Breaker Failure Protection Solutions

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How is it possible to detect a non operating circuit breaker (= Circuit Breaker Failure) ??? 

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Breaker Failure Protection Solutions 1.

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

2.

supervision of the CB auxiliary contacts after a tripping command OR

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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Breaker Failure Protection Solutions solution 1:

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

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

trip to CB from protection device

!!!

CB opening coil

BFP

&

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feeder current

I>

t1

t2

~120 ms

~120 ms

re-trip to

trip to the surrounding CBs by

faulty CB

• intertripping &

(coil 1 & 2)

• remote tripping

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Breaker Failure Protection Solutions t ~ higher than the highest possible CB opening time + arc extinguish time

solution 2:

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

trip to CB from protection device

!!!

CB opening coil

BFP

& CB closed

t1

t2

~120 ms

~120 ms

faulty CB BFP_basics / 2003-04-01 / RW

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re-trip to

(coil 1 & 2)

trip to the surrounding CBs by • intertripping & • remote tripping

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Breaker Failure Protection Solutions solution 3: trip to CB from protection device x

trip to CB from protection device y

CB opening coil

t2

~120 ms

~120 ms

BBP ∆I = 0 BFP logic

CB x

t1

&

CB y

∆I = IF

feeder current BFP_basics / 2003-04-01 / RW

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IF BFP logic re-trip to faulty CB (coil 1 & 2) &

BFP

inter-

remote trip

CB x

tripping

BFP CB y

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Breaker Failure Protection Solutions

Which solution must be used for which application BFP_basics / 2003-04-01 / RW

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

???

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Breaker Failure Protection Solutions Application & features of solution 1: ⇒ 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)

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⇒ 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

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Breaker Failure Protection Solutions solution 1: Start R S T Start R IR

Start S IS

Start T

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IT

≥1 &

t1

I> ≥1 &

t1 ≥1

I>

t2

≥1 & I>

t1

remote tripping re-trip to faulty CB

Trip Redirection

set t1 & t2 to 10ms

(coil 1 & 2)

trip to the surrounding CBs by intertripping

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Breaker Failure Protection Solutions phase segregated timers for the detection of evolving faults

solution 1:

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phase segregated starting inputs for single and double pole auto reclosure

Start R S T Start R IR

Start S IS

Start T IT

≥1 &

t1

remote tripping settable after t1 or t2

I> ≥1 &

t1 ≥1

I>

t2

≥1 &

t1

I>

remote tripping re-trip to faulty CB

Trip Redirection

set t1 & t2 to 10ms

advanced trip redirection functionality

(coil 1 & 2)

trip to the surrounding CBs by intertripping

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Breaker Failure Protection Solutions Application & features of solution 2: ⇒ 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

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⇒ 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 Solutions solution 2 in addition to solution 1: Start R S T Start R IR

Start S IS

Start T

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IT

≥1 &

t1

I> ≥1 &

t1 ≥1

I>

t2

≥1 &

t1

I>

External Start BFP

t1

remote tripping re-trip to faulty CB (coil 1 & 2)

Trip Redirection

set t1 & t2 to 10ms

trip to the surrounding CBs by intertripping

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Breaker Failure Protection Solutions solution 2 in addition to solution 1: current independent starting input

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Start R S T Start R IR

Start S IS

Start T IT

≥1 &

t1

I> ≥1 &

t1 ≥1

I>

t2

≥1 &

t1

I>

External Start BFP

t1

remote tripping re-trip to faulty CB (coil 1 & 2)

Trip Redirection

set t1 & t2 to 10ms

trip to the surrounding CBs by intertripping

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Breaker Failure Protection Solutions Application & features of solution 3: ⇒ 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

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⇒ 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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Breaker Failure Protection Solutions Coupler function: Zone 2

Zone 1 Input Current signal

∆I = 0

trip BBP Zone 1 CB open

≥1 CB reclaim time ~120 ms

coupler function ∆I = IF

Zone 2

BBP

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intertripping Zone 2

CB opening coil

CT bypass

t ≥1

IF

&

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Breaker Failure Protection Application Transformer, Transformer- Generator, Reactor feeder and coupler: Start R S T

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3 Phase trip

≥1

Start R

&

IR

t1

I> ≥1

Start S Reverse Power (32)

∆ I T & ∆ I G (87T & 87G)

CBx

IS

&

≥1

I> ≥1

Start T IT

&

t1

I>

External

G

t1

t1

“CB closed” Start BFP aux. contacts G/T Prot.

Trip Redirection

set t1 & t2 to 10ms

BFP CBx

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Breaker Failure Protection Application Line feeder with single phase auto reclosure: 3 Phase trip

CBx

Start R S T

≥1

single Phase trip Z< & DEF (21 & 67N)

OC (51)

Start R IR

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t1

I> ≥1

Start S IS

&

t1 ≥1

I> ≥1

Start T IT

AR

&

&

t1

I>

External

t1

Start BFP Syn

Line Prot.

Trip Redirection

set t1 & t2 to 10ms

BFP CBx

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Breaker Failure Protection Application Trip Redirection in case of CB SF6 Underpressure : 3 Phase trip

CBx

≥1

single Phase trip Z< & DEF (21 & 67N)

OC (51)

Start R

AR

&

IR

t1

I> ≥1

Start S IS

&

t1 ≥1

I> ≥1

Start T IT

arc is to low

pressure to extinguish the

CB is blocked since SF6 gas

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Start R S T

&

t1

I>

External

t1

Start BFP Syn

Line Prot.

Trip Redirection

set t1 & t2 to 10ms

BFP CBx

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