Busbar Protection by GE

8/17/2019 Busbar Protection by GE

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Fundamentals of Fundamentals of

Bus BarBus BarProtectionProtection

GE Multilin


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2

GE Consumer & IndustrialMultilin

May 3, 2016

Outline

• Bus arrangements• Bus components• Bus protection techniques• CT Saturation• Application Considerations: igh impedance !us di"erentialrela#ing $o% impedance !us di"erential

rela#ing Special topics


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3


May 3, 2016

1 2 3 n-1 n

ZONE 1

- - - -

• &istri!ution and lo%er transmission

'oltage le'els• (o operating )e*i!ilit#

• Fault on the !us trips all circuit !rea+ers

Single !us , single !rea+er


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4


May 3, 2016

ZONE 1ZONE 2

•&istri!ution and lo%er transmission

'oltage le'els

•$imited operating )e*i!ilit#

Multiple !us sections , single!rea+er %ith !us tie


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May 3, 2016

ZONE 1

ZONE 2

•Transmission and distri!ution 'oltage le'els•Brea+er maintenance %ithout circuit remo'al

•Fault on a !us disconnects onl# the circuits

!eing connected to that !us

&ou!le !us , single !rea+er %ith!us tie


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May 3, 2016

ZONE 1

MAIN BUS

TRANFER BUS

• -ncreased operating )e*i!ilit#•A !us fault requires tripping all

!rea+ers

•Transfer !us for !rea+er maintenance

Main and transfer !uses


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May 3, 2016

ZONE 1

ZONE 2

•.er# high operating )e*i!ilit#•Transfer !us for !rea+er

maintenance

&ou!le !us / single !rea+er %0 tra


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May 3, 2016

ZONE 1

ZONE 2

•igh operating )e*i!ilit#•$ine protection co'ers !us section !et%een

t%o CTs

•Fault on a !us does not distur! the po%er to

circuits

&ou!le !us , dou!le !rea+er


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May 3, 2016

ZONE 1

ZONE 2

•1sed on higher 'oltage le'els

•More operating )e*i!ilit#

•2equires more !rea+ers

•Middle !us sections co'ered !# line or

other equipment protection

Brea+er,and,a,half !us


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May 3, 2016

•igher 'oltage le'els•igh operating )e*i!ilit# %ith minimum

!rea+ers

•Separate !us protection not required at

B1 B2

TB1

L1 L2

L3 L4

TB1

2ing !us


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May 3, 2016

Bus components !rea+ers

SF34 E. 5 . ,S nchro u"

$o% .oltage circuit!rea+ers

BUS 2

CB 1

BUS 1

ISO 1 ISO 2

ISO 3

BYPASS


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May 3, 2016

-

+

F1aF1c

Contact Input F1a OnContact Input F1c On

F1b

I S O L A T O R 1

ISOLATOR 1 OPEN

7B 7A

BUS 1

-

+

F1aF1c

Contact Input F1a OnContact Input F1c On

F1b

I S O L A T

O R 1

ISOLATOR 1 CLOSED

7B 7A

BUS 1

&isconnect s%itches 5 au*iliar#contacts

BUS 2

CB 1

BUS 1

ISO 1 ISO 2

ISO 3

BYPASS


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May 3, 2016

BUS 2

CB 1

BUS 1

ISO 1 ISO 2

ISO 3

BYPASS

Current Transformers

Oil insulated currenttransformer 678+. up to

9+.;

Gas 6SF3; insulatedcurrent transformer

Bushing t#pe

6medium 'oltages%itchgear;


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May 3, 2016

Protection 2equirements

igh !us fault currents due to large num!er ofcircuits connected:• CT saturation often !ecomes a pro!lem as CTs ma# not !e

su


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May 3, 2016

Bus Protection Techniques

• -nterloc+ing schemes• O'ercurrent 6>unrestrained? or

>un!iased?; di"erential

• O'ercurrent percent 6>restrained? or>!iased?; di"erential

• $inear couplers

• igh,impedance !us di"erential schemes

• $o%,impedance !us di"erential schemes


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17GE Consumer & Industrial

Multilin

May 3, 2016

O'ercurrent 6unrestrained;&i"erential

• &i"erential signal formed!# summation of allcurrents feeding the !us

• CT ratio matching ma# !erequired

• On e*ternal faults4saturated CTs #ieldspurious di"erentialcurrent

• Time dela# used to cope%ith CT saturation

• -nstantaneous di"erentialOC function useful onintegrated microprocessor,!ased rela#s

51


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Multilin

May 3, 2016

59

$inear Couplers

ZC = 2 – 20 - typi!" #i" i$p%&!'%

()* p%+ 1000A$p, = 0.00) / 0

-f @9 A

0 ! 10 ! 10 ! 0 ! 20 !

2000 A

0 !

E*ternalFault


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Multilin

May 3, 2016

59

$inearCouplersEsec@ -primDm , secondar# 'oltage on rela# terminals-2@ -primDm 062 C; / minimum operating current

%here4-prim / primar# current in each circuit

Dm / liner coupler mutual reactance 68. per Amps @H I8 J

3K ;2 / rela# tap impedance

C / sum of all linear coupler self impedances-f @9 A

0 ! 10 ! 10 ! 0 ! 20 !

0 !

-nternal BusFault


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Multilin

May 3, 2016

• Fast4 secure and pro'en

• 2equire dedicated air gap CTs4 %hich ma# not!e used for an# other protection

• Cannot !e easil# applied to reconLgura!le!uses

• The scheme uses a simple 'oltage detector /it does not pro'ide !eneLts of amicroprocessor,!ased rela# 6eIgIoscillograph#4 !rea+er failure protection4other functions;

$inearCouplers


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Multilin

May 3, 2016

igh -mpedance &i"erential• Operating signal created !#

connecting all CT secondaries in

parallelo CTs must all ha'e the same ratio

o Must ha'e dedicated CTs

• O'er'oltage element operateson 'oltage de'eloped acrossresistor connected in secondar#

circuito 2equires 'aristors or AC

shorting rela#s to limit energ#during faults

• Accurac# dependent onsecondar# circuit resistance

o 1suall# requires larger CTca!les to reduce errors ⇒ highercost

Cannot easily be alied to re!on"#urablebuses and o$ers no ad%an!ed un!tionality

)4


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Multilin

May 3, 2016

Percent &i"erential

• Percent characteristicused to cope %ith CTsaturation and othererrors

• 2estraining signal can

!e formed in a num!erof %a#s

• (o dedicated CTsneeded

• 1sed for protection ofre,conLgura!le !usespossi!le

51"7

n DIF I I I I +++= ...21

n RES I I I I +++= ...21 ( )n RES I I I I ...,,,max 21=


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Multilin

May 3, 2016

$o% -mpedance Percent&i"erential• -ndi'idual currents sampled !# protection and summateddigitall#

o CT ratio matching done internall# 6no au*iliar# CTs;

o &edicated CTs not necessar#

• Additional algorithms impro'e securit# of percent di"erentialcharacteristic during CT saturation

• namic !us replica allo%s application to reconLgura!le !useso &one digitall# %ith logic to add0remo'e current inputs from

di"erential computation

o S%itching of CT secondar# circuits not required

• $o% secondar# !urdens

• Additional functionalit# a'aila!le

o &igital oscillograph# and monitoring of each circuit connected to!us Kone

o Time,stamped e'ent recording

o Brea+er failure protection


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Multilin

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&igital &i"erential AlgorithmGoals• -mpro'e the main di"erential algorithm operationo Better Lltering

o Faster response

o Better restraint techniques

o S%itching transient !loc+ing

• Pro'ide d#namic !us replica for reconLgura!le !us !ars• &ependa!l# detect CT saturation in a fast and relia!le

manner4 especiall# for e*ternal faults

• -mplement additional securit# to the main di"erentialalgorithm to pre'ent incorrect operation

oE*ternal faults %ith CT saturationo CT secondar# circuit trou!le 6eIgI short circuits;


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Multilin

May 3, 2016

$o% -mpedance &i"erential6&istri!uted;

• &ata Acquisition 1nits

6&A1s; installed in !a#s• Central Processing 1nit

6CP1; processes all datafrom &A1s

• Communications !et%een

&A1s and CP1 o'er L!erusing proprietar# protocol

• Sampling s#nchronisation!et%een &A1s is required

• Percei'ed less relia!le

6more hard%are needed;• &i


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Multilin

May 3, 2016

$o% -mpedance &i"erential6CentraliKed;

• All currents applied to asingle central processor

• (o communications4e*ternal samplings#nchronisation necessar#

• Percei'ed more relia!le6less hard%are needed;

• =ell suited to !oth ne%and retroLt applicationsI

52 52 52

CU

copp$%


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Multilin

May 3, 2016

CT Saturation


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Multilin

May 3, 2016

CT Saturation Concepts

• CT saturation depends on a num!er of factorso Ph#sical CT characteristics 6siKe4 rating4 %inding

resistance4 saturation 'oltage;

o Connected CT secondar# !urden 6%ires rela#s;

o Primar# current magnitude4 &C o"set 6s#stem D02;

o 2esidual )u* in CT core• Actual CT secondar# currents ma# not !eha'e in the same

manner as the ratio 6scaled primar#; current during faults

• End result is spurious di"erential current appearing in thesummation of the secondar# currents %hich ma# cause

di"erential elements to operate if additional securit# isnot applied


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Multilin

May 3, 2016

CT Saturation

(at'o Cu%%$nt C) Cu%%$nt

(at'o Cu% %$nt C) Cu% %$nt

(o &C O"set

• =a'eform remainsfairl# s#mmetrical

=ith &C O"set

• =a'eform starts o"!eing as#mmetrical4then s#mmetrical instead# state


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Multilin

May 3, 2016

E*ternal Fault 5 -deal CTs

• Fault starts at t

• Stead#,state fault conditions occur at t

t0

t1

-deal CTs ha'e no saturation or mismatcherrors thus produce no di"erential current


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Multilin

May 3, 2016

E*ternal Fault 5 Actual CTs

• Fault starts at t

• Stead#,state fault conditions occur at t

t0

t1

Actual CTs do introduce errors4 producing somedi"erential current 6%ithout CT saturation;


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MultilinMay 3, 2016

E*ternal Fault %ith CTSaturation

• Fault starts at t4 CT !egins to saturate at t

• CT full# saturated at t

t0

t1

t2

CT saturation causes increasing di"erentialcurrent that ma# enter the di"erential

element operate regionI


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MultilinMay 3, 2016

Some Methods of Securing Bus&i"erential• Bloc+ the !us di"erential for a period of time 6intentional dela#;

o -ncreases securit# as !us Kone %ill not trip %hen CT saturation ispresent

o Pre'ents high,speed clearance for internal faults %ith CT saturationor e'ol'ing faults

• Change settings of the percent di"erential characteristic

6usuall# Slope ;o -mpro'es securit# of di"erential element !# increasing the amount

of spurious di"erential current needed to incorrectl# trip

o &i


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MultilinMay 3, 2016

igh,

-mpedance

Bus&i"erential


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MultilinMay 3, 2016

igh -mpedance .oltage,operated 2ela#

E*ternal Fault• 59 element set abo%e ma' ossible %olta#ede%eloed a!ross relay durin# e'ternal ault !ausin#(orst !ase C) saturation• *or internal aults+ e'tremely ,i#, %olta#es -(ell

abo%e 59 element i!.u/ (ill de%elo a!ross relay


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MultilinMay 3, 2016

igh -mpedance .oltageOperated 2ela# 2atio matching %ith

Multi,ratio CTs• li!ation o ,i#, imedan!e di$erential relays(it, C)s o di$erent ratios but ratio mat!,in# tas isossible+ but !ould lead to %olta#e ma#ni"!ation

• olta#e de%eloed a!ross ull (indin# o taed C)does not e'!eed C) ratin#+ terminal blo!.s+ et!


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MultilinMay 3, 2016

igh -mpedance .oltageOperated 2ela# 2atio matching %ith

Multi,ratio CTs• se o au'iliary C)s to obtain !orre!t ratio mat!,in#is also ossible+ but t,ese C)s must be able to deli%erenou#, %olta#e ne!essary to rodu!e relay oerationor internal aults


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MultilinMay 3, 2016

Electromechanical igh-mpedance Bus &i"erential

2ela#s• Single phase rela#s• igh,speed

• igh impedance 'oltage sensing

• igh seismic -OC unit

P ! d i h - d B


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MultilinMay 3, 2016

Op$%at'n* t'+$, 20 30+. / I 15K

µP ,!ased igh,-mpedance Bus&i"erential Protection 2ela#s


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MultilinMay 3, 2016

2ST @ , sta!iliKing resistor to limit thecurrent through the rela#4 and force it tothe lo%er impedance CT %indingsIMO. / Metal O*ide .aristor to limit the'oltage to .olts93 / latching contact pre'enting theresistors from o'erheating after the fault is

detected

igh -mpedance Module for&igital 2ela#s

i h - d M d l


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MultilinMay 3, 2016

igh,-mpedance Module

O'ercurrent 2ela#


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MultilinMay 3, 2016

• Fast4 secure and pro'en

• 2equires dedicated CTs4 prefera!l# %ith the sameCT ratio and using full tap

• Can !e applied to small !uses

• &epending on !us internal and e*ternal faultcurrents4 high impedance !us di" ma# not pro'ideadequate settings for !oth sensiti'it# and securit#

• Cannot !e easil# applied to reconLgura!le !uses

• 2equire 'oltage limiting 'aristor capa!le ofa!sor!ing signiLcant energ#

• Ma# require au*iliar# CTs• &o not pro'ide full !eneLts of microprocessor,

!ased rela# s#stem 6eIgI metering4 monitoring4oscillograph#4 etcI;

igh -mpedance Bus Protection ,Summar#


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MultilinMay 3, 2016

$o%,

-mpedance

Bus&i"erential


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MultilinMay 3, 2016

µP,!ased $o%,-mpedance 2ela#s

• (o need for dedicated CTs

• -nternal CT ratio mismatch compensation

• Ad'anced algorithms supplement percent diferential

protection function ma+ing the rela# 'er# secure

• namic !us replica 6!us image; principle is used in

protection of reconLgura!le !us !ars4 eliminating the

need for s%itching ph#sicall# secondar# current

circuits

• -ntegrated Brea+er Failure 6BF; function can pro'ide

optimal tripping strateg# depending on the actualconLguration of a !us !ar


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MultilinMay 3, 2016

• 1p to Current -nputs• ones

• one @ Phase A• one @ Phase B• one 7 @ Phase C• one @ (ot used

• &i"erent CT 2atioCapa!ilit# for EachCircuit

• $argest CT Primar# isBase in 2ela#

,9 CircuitApplications

Small Bus Applications


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MultilinMay 3, 2016

• 2ela# , Current -nputs

• ones• one @ Phase A 6 currents;• one @ Phase B 6 currents;• one 7 @ (ot used• one @ (ot used

C12

C11

• &i"erent CT 2atio Capa!ilit# for Each Circuit• $argest CT Primar# is Base in 2ela#

• 2ela# , Current -nputs

• ones• one @ (ot used• one @ (ot used• one 7 @ Phase C 6 currents;• one @ (ot used

, CircuitApplications

Medium to $arge BusApplications


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MultilinMay 3, 2016

$arge Bus Applications

56B p7!,% A

56B p7!,% B

56B p7!,% C

L#8i +%"!y

(,9it7 ,t!t:,;

#pti#'!" BF

$ B A li ti


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MultilinMay 3, 2016

$arge Bus Applications*or buses (it, u to 24 !ir!uits


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MultilinMay 3, 2016

&eLnitions of 2estraint Signals

+a'+u+ o&6

*$o+$t%'ca7 a8$%a*$6

.ca7$ .u+ o&6

.u+ o&6n R iiiii ++++= ...321

( )n R iiiin

i ++++= ...1

321

( )n R

iiii Maxi ,...,,, 321=

nn R

iiiii ⋅⋅⋅⋅= ...321


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MultilinMay 3, 2016

>Sum Of? 'sI >Ma* Of? 2estraintMethods

>Sum Of? Approach• ore restraint on e'ternal

aults less sensiti%e or internalaults

• :;!aled aroa!,ta.es into a!!ount number o!onne!ted !ir!uits and mayin!rease sensiti%ity

• rea.oint settin#s or t,eer!ent di$erential!,ara!teristi! more di?!ult toset

>Ma* Of? Approach• @ess restraint on e'ternal aults

more sensiti%e or internal aults

• rea.oint settin#s or t,eer!ent di$erential!,ara!teristi! easier to set

• etter ,andles situation (,ereone C) may saturate !omletely-99A sloe settin#s ossible/


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MultilinMay 3, 2016

Bus &i"erential Adapti'eApproach

9 ' & & $ % $ n

t ' a 7

%$.t%a'n'n*

R%8i#' 1

:7o; 9'&&$%$nt'a7

cu%%$nt.<

R%8i#' 2

:='*= 9'&& $%$nt'a7

cu%%$nt.<


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MultilinMay 3, 2016

Bus &i"erential Adapti'e $ogic&iagram

DIFL

DIR

SAT

DIF

OR

AND

O

R56B BIASED OP

AND


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MultilinMay 3, 2016

Phase Comparison Principle• -nternal Faults: ll ault -:lar#e>/ !urrents are

aro'imately in ,ase

• E*ternal Faults: =ne ault -:lar#e>/ !urrent (ill be outo ,ase

• (o .oltages are required or needed

S$cona%> Cu%%$nt o&Fau7t$ C'%cu't

:S$8$%$ C) Satu%at'on<


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MultilinMay 3, 2016

Phase Comparison PrincipleContinuedQ

BLOC=

OPERATE

BLOC=

− p D

p

I I

I real

− p D

p

I I

I imag

I p

I D

- I p

E>t%+'!" F!:"t C#'&iti#',

OPERATE

BLOC=

BLOC=

− p D p

I I

I real

− p D

p

I I

I imag

I p

I D

- I p

I't%+'!" F!:"t C#'&iti#',

OPERATE

OPERATE


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MultilinMay 3, 2016

CT Saturation

• *ault starts at t0+ C) be#ins to saturate at t1

• C) ully saturated at t2

t0

t1

t2

i


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MultilinMay 3, 2016

CT Saturation &etector StateMachine NORMAL

SAT := 0

EXTERNAL

FAULT

SAT := 1

EXTERNAL

FAULT & CTSATURATION

SAT := 1

The differential

characteritic

entered

The differential!

retrainin" tra#ect$r%

$t $f the differential

characteritic f$r

certain 'eri$d $f ti(e

atrati$n

c$nditi$n

The differential

crrent )el$* the

firt l$'e f$r

certain 'eri$d $f

ti(e

C S i


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MultilinMay 3, 2016

CT Saturation &etectorOperating Principles

• The 9B SAT )ag WILL NOT !e set duringinternal faults4 regardless of %hether or notan# of the CTs saturateI

• The 9B SAT )ag WILL !e set duringe*ternal faults4 regardless of %hether or notan# of the CTs saturateI

• B# design4 the 9B SAT )ag WILL force the

rela# to use the additional 9B &-2 phasecomparison for 2egion The Saturation &etector =-$$ (OT Bloc+ theOperation of the &i"erential Element / it %illonl# Force ,out,of, Operation

CT S i &


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MultilinMay 3, 2016

CT Saturation &etector ,E*amples• The oscillograph# records on the ne*t t%o slides %ere

captured from a B7 rela# under test on a real,time digital

po%er s#stem simulator• First slide sho%s an e*ternal fault %ith deep CT saturation

6RI8 msec of good CT performance;

o SAT saturation detector )ag asserts prior to B-ASE& PP!us di"erential pic+up

o &-2 directional )ag does not assert 6one current )o%sout of Kone;4 so e'en though !us di"erential pic+s up4 notrip results

• Second slide sho%s an internal fault %ith mild CT saturation

o B-ASE& PP and B-ASE& OP !oth assert !efore &-2

assertso CT saturation does not !loc+ !us di"erential

• More e*amples a'aila!le 6COMT2A&E Lles; upon request

CT S t ti E l


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MultilinMay 3, 2016

)=$ bu. 9'&&$%$nt'a

p%ot$ct'on $$+$ntp'c?. up 9u$ to =$a8>

C) .atu%at'on

)=$ C) .atu%at'on &a*

'. .$t .a&$> b$&o%$ t=$p'c?up &a*

)=$9'%$ct'ona &a*

'. not .$t

)=$ $$+$nt9o$. not

+aop$%at$

#$.p't$ =$a8> C).atu%at'on t=$$t$%na7 &au7t cu%%$nt'. .$$n 'n t=$oppo.'t$ '%$ct'on

CT Saturation E*ample /E*ternal Fault

0.06 0.07 0.08 0.09 0.1 0.11 0.12-200

-150

-100

-50

0

50

100

150

200

time, sec

c u r r e n t , A

@1 +.

CT S t ti - t l F lt


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MultilinMay 3, 2016

)=$ bu. 9'&&$%$nt'ap%ot$ct'on $$+$ntp'c?. up

)=$ .atu%at'on&a* '. not .$t - no

9'%$ct'ona

9$c'.'on %$u'%$9

)=$ $$+$ntop$%at$. 'n

10+.

)=$9'%$ct'ona

&a* '. .$t

A t=$ &aut cu%%$nt.a%$ .$$n 'n on$

9'%$ct'on

CT Saturation / -nternal FaultE*ample

A l i $ - d


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MultilinMay 3, 2016

Appl#ing $o%,-mpedance&i"erential 2ela#s for Bus!ar

ProtectionBasic Topics• ConLgure ph#sical CT -nputs

• ConLgure Bus one and namic Bus

2eplica• Calculating Bus &i"erential Element settings

Ad'anced Topics

• -solator s%itch monitoring for

reconLgura!le !uses• &i"erential one CT Trou!le

• -ntegrated Brea+er Failure protection

C L i CT - t


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MultilinMay 3, 2016

ConLguring CT -nputs

•For each connected CT circuit enter Primar#rating and select Secondar# ratingI

• Each 7,phase !an+ of CT inputs must !eassigned to a Signal Source that is used todeLne the Bus one and namic Bus 2eplica

;ome relays de"ne 1 u as t,ema'imum rimary !urrent o all o t,eC)s !onne!ted in t,e #i%en us Bone

P 1 it C t & L iti


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MultilinMay 3, 2016

Per,1nit Current &eLnition ,E*ample

CurrentChannel

Primar#

Secondar#

one

CT,

F 3200 A

CT,

F A 8 A

CT,7

F7 A A

CT,

F 7 A A

CT,8

F8 A 8 A

CT,F3 5000 8 A

• For one 4 pIuI @ 7 AP

• For one 4 pIuI @ 8 AP


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C L i th B &i" ti l


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MultilinMay 3, 2016

ConLguring the Bus &i"erentialone

I ConLgure the ph#sical CT -nputso CT Primar# and Secondar# 'alues

o Both 8 A and A inputs are supported !# the 12 hard%are

o 2atio compensation done automaticall# for CT ratiodi"erences up to 7:

I ConLgure AC Signal Sources

7I ConLgure Bus one %ith namic Bus 2eplica

Bus one settings deLnes the !oundaries of

the &i"erential Protection and CT Trou!leMonitoringI

& l P t &i" ti l


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MultilinMay 3, 2016

&ual Percent &i"erentialCharacteristic

i87B+%!?p#i't

L#9

B+%!?p#i't

L#9 S"#p%

i87 S"#p%

i87 S%t

(U'+%,t+!i'%&

Mi' Pi?:p


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Calculating Bus &i"erential


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MultilinMay 3, 2016

Calculating Bus &i"erentialSettings / Minimum Pic+up

• &eLnes the minimum di"erential current requiredfor operation of the Bus one &i"erential element

• Must !e set a!o'e ma*imum lea+age current not

Koned o" in the !us di"erential Kone• Ma# also !e set a!o'e ma*imum load conditions

for added securit# in case of CT trou!le4 !ut!etter alternati'es e*ist


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MultilinMay 3, 2016

Calculating Bus &i"erentialSettings / $o% Brea+point

• &eLnes the upper limit to restraint currents that %ill!e !iased according to the $o% Slope setting

• Should !e set to !e a!o'e the ma*imum load !utnot more than the ma*imum current %here the CTs

still operate linearl# 6including residual )u*;• Assumption is that the CTs %ill !e operating linearl#

6no signiLcant saturation e"ects up to 9 residual)u*; up to the $o% Brea+point setting



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MultilinMay 3, 2016

Calculating Bus &i"erentialSettings / igh Brea+point

• &eLnes the minimum restraint currents that %ill !e!iased according to the igh Slope setting

• Should !e set to !e !elo% the minimum current

%here the %ea+est CT %ill saturate %ith noresidual )u*

• Assumption is that the CTs %ill !e operatinglinearl# 6no signiLcant saturation e"ects up to 9residual )u*; up to the $o% Brea+point setting



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Calculating Bus &i"erentialSettings / igh Slope

• &eLnes the percent !ias for the restraint currents-2EST≥igh Brea+point

• Setting determines the sta!ilit# of the di"erentialelement for high current e*ternal faults

• Traditionall#4 should !e set high enough toaccommodate the spurious di"erential currentresulting from saturation of the CTs during hea'#e*ternal faults

• Setting can !e rela*ed in fa'our of sensiti'it# andspeed as the rela# detects CT saturation and applies

the directional principle to pre'ent maloperation• 2ange: 8 to in I increments


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2econLgura!le Buses


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NO() BUS

SOU) BUS

C)-7

C)-"

B-7

B-5

B-

C)-5

C)-

S-5

S-

B-C)-

S-3

S-

B-3C)-3

S-1

S-2

B-2C)-2C)-1

B-1

C-1 C-2 C-

C-3 C-5

%ot$ct'n* %$-con&'*u%ab7$ bu.$.

2econLgura!le Buses

2econLgura!le Buses


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NO() BUS

SOU) BUS

C)-7

C)-"

B-7

B-5

B-

C)-5

C)-

S-5

S-

B-C)-

S-3

S-

B-3C)-3

S-1

S-2

B-2C)-2C)-1

B-1

C-1 C-2 C-

C-3 C-5


2econLgura!le Buses

2econLgura!le Buses


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NO() BUS

SOU) BUS

C)-"

B-5

B-

C)-5

C)-

S-5

S-

B-C)-

S-3

S-

B-3C)-3

S-1

S-2

B-2C)-2

C)-1

B-1

C-1 C-2 C-

C-3 C-5

C)-7

B-7


2econLgura!le Buses


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-solator / T#pical Open0Closed


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-solator / T#pical Open0ClosedConnections

S%itch Status $ogic and


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-solatorOpenAu*iliar#Contact

-solatorClosedAu*iliar#Contact

-solatorPosition

Alarm Bloc+S%itching

O" On C$OSE& (o (o

O" O" $AST .A$-& After timedela#untilac+no%ledged

1ntil -solator

Position is'alid

On On C$OSE&

On O" OPE( (o (o

(OTE: -solator monitoring function ma# !e a !uilt,in featureor user,programma!le in lo% impedance !us di"erentialdigital rela#s

S c S a us og c a danamic Bus 2eplica

&i"erential one CT Trou!le


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• Each Bus &i"erential one ma# a dedicated CTTrou!le Monitor

• &eLnite time dela# o'ercurrent element operatingon the Kone di"erential current4 !ased on theconLgured namic Bus 2eplica

• Three strategies to deal %ith CT pro!lems:

I Trip the !us Kone as the pro!lem %ith a CT %illli+el# e'ol'e into a !us fault an#%a#

I &o not trip the !us4 raise an alarm and tr# tocorrect the pro!lem manuall#

7I S%itch to setting group %ith 9B minimumpic+up setting a!o'e the ma*imum loadcurrentI



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• Strategies and 7 can !eaccomplished !#: 1sing under'oltage super'ision to ride through

the period from the !eginning of the pro!lem%ith a CT until declaring a CT trou!le condition

1sing an e*ternal chec+ Kone to super'ise the9B function

1sing CT Trou!le to pre'ent the Bus &i"erentialtripping 6;

1sing setting groups to increase the pic+up

'alue for the 9B function 67;


&i"erential one CT Trou!le /


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&i"erential one CT Trou!le /Strateg# V E*ample

• CT Trou!le operand is used to rise an alarm

• The 9B trip is inhi!ited after CT Trou!le elementoperates

• The rela# ma# misoperate if an e*ternal fault

occurs after CT trou!le !ut !efore the CT trou!lecondition is declared 6dou!le,contingenc#;

56B #p%+!t%,

U'&%+@#"t!8% #'&iti#'

CT O

E*ample Architecture for $arge


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E*ample Architecture for $argeBus!ars

&ual 6redundant; L!er%ith 7msec deli'er#time !et%een

neigh!ouring -E&sI 1pto 9 rela#s in the ring

Phase A C si#nals andtri !onta!ts

Phase B C si#nals andtri !onta!ts

Phase C C si#nals andtri !onta!ts

&igital -nputs orisolator monitorin# and*

E*ample Architecture / namic


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Phase A C si#nals(ired ,ere+ bus reli!a!on"#ured ,ere

Phase B C si#nals(ired ,ere+ bus reli!a!on"#ured ,ere

Phase C C si#nals(ired ,ere+ bus reli!a

!on"#ured ,ere

Auu7'a%> .;'tc=$. ;'%$ =$%$D

I.o7ato% on'to%'n* &unct'on

con&'*u%$ =$%$

I s o l a t o r

7 o s i t i o

n

I s o l a t o r 7 o s i t i o n

I s o l a t o r 7 o s i t i o n

I s o l a t

o r 7 o s i t i o n

E*ample Architecture namicBus 2eplica and -solator

Position

E*ample Architecture / BF


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Phase A C si#nals(ired ,ere+ !urrentstatus monitored ,ere

Phase B C si#nals(ired ,ere+ !urrentstatus monitored ,ere

Phase C C si#nals(ired ,ere+ !urrent

status monitored ,ere

rea.er *ailureelements!on"#ured ,ere

5 * I n i t i a

t e &

C u r r e n t

; u %1

5 * I n i t i a t e & C u r r e n t ; u % 1

5 * I n i t i a t e & C u r r e n t ; u % 1

5 * I n i t i a

t e & C u r r e

n t ; u

%1

E*ample Architecture BF-nitiation 5 Current Super'ision

E*ample Architecture / Brea+er


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Phase A C si#nals(ired ,ere+ !urrentstatus monitored ,ere

Phase B C si#nals(ired ,ere+ !urrentstatus monitored ,ere

Phase C C si#nals(ired ,ere+ !urrent

status monitored ,ere

rea.er *ail = !ommand#enerated ,ere and send totri aroriate brea.ers

5 r e a . e r

* a i l =

5 r e a . e r * a i l =

5 r e

a . e r * a i l =

5 r e a . e

r * a i l =

)ri

)ri )ri

E*ample Architecture Brea+erFailure Tripping )ri

-EEE 7I7


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-EEE 7I7

• >Guide for Protecti'e 2ela# Applicationsto Po%er S#stem Buses? is currentl#!eing re'ised !# the =or+ing Groupof the -EEE Po%er S#stem 2ela#ing

CommitteeI


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Busbar Protection by GE

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