ppt- of- ehv-ac-transmission-pdf (1).pdf

High voltage Electrical engineering

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2. Thetermhighvoltagecharacterizeselectricalcircuitsinwhichthevoltage
usedisthecauseofparticularsafetyconcernsandinsulationrequirements.
Highvoltageisusedinelectricalpowerdistribution,incathoderaytubes,to
generateX-raysandparticlebeams,todemonstratearcing,forignition,in
photomultipliertubes,andhighpoweramplifiervacuumtubesandother
industrialandscientificapplications
.
WHATISEHVTRANSMISSION ?
Twofactorsconsideredintheclassificationofa"highvoltage"arethepossibility
ofcausingasparkinair,andthedangerofelectricshockbycontactorproximity.
In
electricpowertransmissionengineering,highvoltageisusually
consideredanyvoltageoverapproximately35,000volts.
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3. In digital electronics, a high voltage is the one that represents a logic1; this may
be only several hundred millivoltsfor some logic families.
Inelectricpowertransmissionengineeringthisreferstoequipment
designedformorethan345,000voltsbetweenconductors.Inelectronics
systems,apowersupplythatprovidesgreaterthan275,000voltsisknownas
an"EHVPowerSupply".Itisoftenusedinexperimentsinphysics.
SAFETY:
Voltages of greater than 50V applied across dry unbroken human skin are
capable of producing heart fibrillation if they produce electric currents in
body tissues which happen to pass through the chest area.
The
electrocutiondanger is mostly determined by the low electrical
conductivityof dry human skin.

4. (International safety symbol "Caution, risk of electric shock" (ISO 3864), colloquially
known as high voltage symbol)
Accidentalcontactwithhighvoltagesupplyingsufficientenergywillusually
resultinsevereinjuryordeath.
low-energyexposuretohighvoltagemaybeharmless,suchasthespark
producedinadryclimatewhentouchingadoorknobafterwalkingacrossa
carpetedfloor.

5. Electricaltransmissionanddistributionlinesforelectricpoweralwaysuse
voltagessignificantlyhigherthan50volts,socontactwithorcloseapproachto
thelineconductorspresentsadangerofelectrocution.
(High tension power lines)
Forhighvoltageandextra-highvoltagetransmissionlines,speciallytrained
personneluseso-called"liveline"techniquestoallowhands-oncontactwith
energizedequipment.

6. Withtheincreaseintransmissionvoltage,forsameamountofpowerto
betransmittedcurrentinthelinedecreaseswhichreducesI
2
Rlosses.This
willleadtoincreaseintransmissionefficiency.
Withdecreaseintransmissioncurrent,sizeofconductorrequired
reduceswhichdecreasesthevolumeofconductor.
Thetransmissioncapacityisproportionaltosquareofoperatingvoltages.
Thusthetransmissioncapacityoflineincreaseswithincreaseinvoltage.
Withincreaseinleveloftransmissionvoltage,theinstallationcostofthe
transmissionlineperkmdecreases.
ItiseconomicalwithEHVtransmissiontointerconnectthepower
systemsonalargescale.
Theno.ofcircuitsandthelandrequirementfortransmissiondecreases
withtheuseofhighertransmissionvoltages.

7. Themajoradvantagesare:
Redutioninthecurrent.
Reductioninthelosses.
Reductioninvolumeofconductormaterialrequired.
Decreaseinvoltagedrop&improvementofvoltageregulation.
IncreaseinTransmissionEfficiency.
Increasedpowerhandlingcapacity.
Theno.ofcircuits&thelandrequirementreducesastransmissionvoltage
increases.
ThetotallinecostperMWperkmdecreasesconsiderablywiththeincrease
inlinevoltage.

8. Themajordisadvantagesare:
Coronaloss&radiointerference
Linesupports
Erectiondifficulties
Insulationneeds
Thecostoftransformers,switchgearequipments&protectiveequipments
increaseswithincreaseintransmissionlinevoltage.
TheEHVlinesgenerateselectrostaticeffectswhichareharmfultohuman
beings&animals.

9. FACTSconsistsofthreetechnologybranches:
seriescompensation
dynamicshuntcompensation
dynamicenergystorage
FACTStechnologieshaveasmallfootprintandminimalimpactonthe
environment.Projectimplementationtimesareconsiderablyfasterand
investmentcostssubstantiallylowerthanthealternativeofbuildingmore
transmissionlinesor new power generationfacilities.
(SC in Imperatiz , Brazil)
Series compensation:
Series compensation was invented by ABB in
1950. It made possible the world's first 400
kV transmission in the 1950s by resolving the
issue of how to transmit power over long
distances.

10. (SVC in Newark, US)
Thebenefitsofseriescompensation-improvedsystemstability,increased
transmissioncapacity,andreducedoverallpowerlosses.
Astransmissioncapacitiesrose,sodidtheneedforhigherseries
compensationvoltages.
Controllableseriescompensation(TCSC)wasinstalledbyABBin
thelate1990sandisalsopartoftheFACTSfamily.

11. (SVC Light)
SVC Light®:
In1998,ABBlaunchedanewgenerationof
dynamicshuntcompensationtechnologyfor
transmission,steelandrailapplications-SVC
Light(oftenreferredtointheUnitedStates
bythegenericnameSTATCOM).
SVC Light with Energy Storage:
Theintegrationofdynamicenergystorageintotransmissionanddistribution
systemshasthepotential.
ThenewtechnologyisbasedonSVCLight,combinedwithLi-ionbattery
storage.

12. [Conceptual Map of Interstate Grid for Wind Integration (Source: NREL)]

13. SupportisgrowingforanationalEHVinterstatetransmissiongrid.Above
figureillustratesoneoftenreferencedconceptforsuchaninterstatesystem,
superimposedonamapoftheexistingEHVtransmissionsystemandwind
resourcesintheUS.
Theabovefigureindicatesanoverlayofpredominantly765kVlines.Other
voltagescanbechosenandapplied.
ForUHV,fewerlineswouldbeneeded,andforvoltagesbelow765kV
morelineswouldbeneeded.
Itisunderstood,however,thatthecompletionofthisgridrequires
collaborationamongstakeholders,especiallytransmissionownersand
operators
.

14. Highvoltageisused:
inelectricalpowerdistribution,
incathoderaytubes,togenerateX-raysandparticlebeams, todemonstrate
arcing,forignition,
inphotomultipliertubes,andhighpoweramplifiervacuumtubesandother
industrialandscientificapplications.

16. References
slideshare.net
Pdfslide.net
Vdocuments.mx