Post on 03-Jun-2018
8/12/2019 Fundamentals of Bus Protection Handouts
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FUNDAMENTALSOFBUS
PROTECTION
KevinWright
SeniorProtectionEngineer
SacramentoMunicipalUtilityDistrict
WHAT
IS
A
BUS?
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WHATISABUS?
Allconnectionsareatthesamevoltage.
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WHATISABUS?
Allconnectionsareatthesamevoltage.
Madeofbusbarsuchasinswitchgearor,
overheadtransmissionlineconductorortube
suchas
in
open
air
substations.
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WHAT
IS
A
BUS? Allconnectionsareatthesamevoltage.
Madeofbusbarsuchasinswitchgearor,
overheadtransmissionlineconductorortube
suchasinopenairsubstations.
Node
8
WHAT
IS
A
BUS? Allconnectionsareatthesamevoltage.
Madeofbusbarsuchasinswitchgearor,
overheadtransmissionlineconductorortube
suchasinopenairsubstations.
Node
ZeroImpedance
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BUSCONFIGURATIONS
SingleBus/SingleBreaker
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BUS
CONFIGURATIONS
SingleBus/SingleBreaker
BreakerandAHalf
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BUSCONFIGURATIONS
SingleBus/SingleBreaker
BreakerandAHalf
DoubleBus/DoubleBreaker
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BUS
CONFIGURATIONS
SingleBus/SingleBreaker
BreakerandAHalf
DoubleBus/DoubleBreaker
MainandTransfer
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BUSCONFIGURATIONS
SingleBus/SingleBreaker
BreakerandAHalf
DoubleBus/DoubleBreaker
MainandTransfer
Ring
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BUS
PROTECTION
CHALLENGES Varietyofconfigurations
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BUSPROTECTIONCHALLENGES
Varietyofconfigurations
Lar e number of connections
22
BUSPROTECTIONCHALLENGES Varietyofconfigurations
Largenumberofconnections oranexterna au t,oneseto currenttrans ormers
(CTs)willseetotalcurrent
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BUS
PROTECTION
CHALLENGES Varietyofconfigurations
Largenumberofconnections ,
willseetotalcurrent
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BUS
PROTECTION
CHALLENGES Varietyofconfigurations
LargenumberofconnectionsForanexterna au t,oneseto currenttrans ormers
(CTs)willseetotalcurrent
HighavailablefaultcurrentCTsaturation
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[1]26
CURRENTTRANSFORMEREQUIVALENTCIRCUIT
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CURRENTTRANSFORMEREQUIVALENTCIRCUIT
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TYPESOFBUSPROTECTION
Overcurrent
r p oc ng c emes
CommunicationBasedSchemes
HighImpedance
Current
Differential
LowImpedanceCurrentDifferential
LinearCoupler
ArcFlashDetection
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DIFFERENTIALPROTECTION
Currentdifferentialprotectionverifiesthatall
currentt at ows ntoap eceo equ pment
alsoflowsout.
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DIFFERENTIAL
PROTECTION Currentdifferentialprotectionverifiesthatall
currentt at ows ntoap eceo equ pment
alsoflowsout.
HighImpedancebusdifferentialprotectioncan
accommodateanynumberofterminals.
Minimizessaturationeffect.
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[2]
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DIFFERENTIAL
PROTECTION Currentdifferentialprotectionverifiesthatall
currentt at ows ntoap eceo equ pment
alsoflowsout.
Lowimpedancebusdifferentialprotectioncan
accommodateavarietyofcurrenttransformer
ratios,buthasalimitednumberofcurrentinputs.
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LINEARCOUPLER
VoltageDifferential
AirCoreMutualReactors
Couplersareconnectedinseries
Nosaturation
due
to
air
core
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PROS
AND
CONSTYPE PROS CONSOvercurrent Simple
Inexpensive
Slow
Nothighlyselective
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PROSANDCONSTYPE PROS CONS
Overcurrent Simple
Inexpensive
Slow
Nothighlyselective
TripBlockingSchemes Highspeed
Selective
Additional wiring
Dependence onotherrelays
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PROSANDCONSTYPE PROS CONS
Overcurrent Simple
Inexpensive
Slow
Nothighlyselective
TripBlockingSchemes Highspeed
Selective
Additional wiring
Dependence onotherrelays
CommunicationBased
Schemes
Highspeed
Selective
Microprocessorbasedrelays
required
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PROSANDCONSTYPE PROS CONS
Overcurrent Simple
Inexpensive
Slow
Nothighlyselective
TripBlockingSchemes Highspeed
Selective
Additional wiring
Dependence onotherrelays
CommunicationBased
Schemes
Highspeed
Selective
Microprocessorbasedrelays
required
HighImpedanceDifferential Highspeed Selective
Easy toset
Easilyexpandable
DedicatedmatchedCTs
required
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PROSANDCONSTYPE PROS CONS
Overcurrent Simple
Inexpensive
Slow
Nothighlyselective
TripBlockingSchemes Highspeed
Selective
Additional wiring
Dependence onotherrelays
CommunicationBased
Schemes
Highspeed
Selective
Microprocessorbasedrelays
required
HighImpedanceDifferential Highspeed Selective
Easy toset
Easilyexpandable
DedicatedmatchedCTs
required
LowImpe ance
D erent a H g
spee
Se ect ve
Canuseshared
unmatched CTs
Flexible
L m te num ero
c rcu ts
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PROSANDCONSTYPE PROS CONS
Overcurrent Simple
Inexpensive
Slow
Nothighlyselective
TripBlockingSchemes Highspeed
Selective
Additional wiring
Dependence onotherrelays
CommunicationBased
Schemes
Highspeed
Selective
Microprocessorbasedrelays
required
HighImpedanceDifferential Highspeed Selective
Easy toset
Easilyexpandable
DedicatedmatchedCTs
required
owmpe ance eren a g spee e ec ve
Canuseshared
unmatched CTs
Flexible
m e num e ro c rcu s
LinearCoupler Highspeed Selective
Reliable
Expensive
Dedicatedcouplers
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PROSANDCONSTYPE PROS CONS
Overcurrent Simple
Inexpensive
Slow
Nothighlyselective
TripBlockingSchemes Highspeed
Selective
Additional wiring
Dependence onotherrelays
CommunicationBased
Schemes
Highspeed
Selective
Microprocessorbasedrelays
required
HighImpedanceDifferential Highspeed Selective
Easy toset
Easilyexpandable
DedicatedmatchedCTs
required
owmpe ance eren a g spee e ec ve
Canuseshared
unmatched CTs
Flexible
m e num e ro c rcu s
LinearCoupler Highspeed Selective
Reliable
Expensive
Dedicatedcouplers
ArcFlashDetection Highspeed Limitedapplication51
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References[1] A. R. Leoni and J. E. Bowen, Improving Safety and Reliabil ity Via Cost-Effective Upgrades of
Existing Systems,IEEE Trans. Ind. Appl.,vol. 43, no. 1, pp. 130-138, Jan./Feb. 2007
[2] H. J. Li of Westinghouse, Applied Protective Relaying, 1979
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