powersystemsppt.docx

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powersystemsppt

PAPERPRESENTATIONON“POWERSYSTEMS”

ABSTRACT

Thispapernowconsistsoverallviewofpowersystems.Thispapercontainsintroductionaboutpowersystem,superiorityofelectricalenergy,Generatingofelectricalpowerusingbydifferentnaturalsourcesi.e（Hydroelectricalplant,thermalpowerplant,nuclearpowerplants）;Transfertheelectricalpowerbyusingtransmissionanddistributionlanes.Andwhatarethemainpartsintransmissionlines.i.e（conductors,insulators,poles）etc.,definegridinputandgridoutput.Andalsoitconsistofhistoryabouttransmissionlinesdistributionlines,transmissionlinesanddistributionlinefigures,arewhatarethemainprotectiveequipmentsinpowersystem.

POWERSYSTEMS

Introduction-SuperiorityofElectricalEnergy-GenerationofElectricalEnergy-AboutTransmissionandDistribution–Grid-Protection-Utilization.

INTRODUCTION

Poweristhebasicneedfortheeconomicdevelopmentofanycountry.Availabilityofelectricityhasbeenthemostpowerfulvehicleofintroducingeconomicdevelopmentandsocialchangethroughouttheworld.Theprocessofmodernization,increaseinproductivelyinindustryandagricultureandtheimprovementinthestandardoflivingofthepeoplebasicallydependupontheadequatesupplyofelectricalenergy.Electricalenergyhasbeenthehighestpriorityinthenationalplanningprocess.

InElectricalpowersystem“Generation”isthefirstprocessinthedeliveryofelectricitytoconsumers.Theotherprocessesareelectricalpower“Transmission”and“Distribution”.

Electricityhasbeengeneratedforthepurposeofpoweringhumantechnologiesforatleast120yearsfromvarioussourcesofpotentialenergy.Thefirstpowerplantswererunonwood,whiletodaywerelymainlyonpetroleum,naturalgas,coal,hydroelectricandnuclearpowerandasmallamountfromhydrogen,solarenergy,tidalharnesses,windgenerators,andgeothermalsources.

Generallyelectricalpowerisgeneratedatthegeneratingstationslocatedatfarawayfromloadcentres,inviewofeconomicconsiderationsthispowerhastobeconveyedtotheconsumersresidingatvariousplaces.Thereforethereisneedtotransmitpowerfromgeneratingstationstotheareastobeservedbyconductorsystemknownastransmmitionlinesanddistributionlines.

Inpowersystemconsistingofgenerators,trsnsformers,transmissionanddistributioncircuits,itisinvetablethatsoonorlatersomefailurewilloccursomewhereinsystem,itmustbequicklydetectedanddisconnectedfromthesystembyusingprotectingequipments.

SUPERIORITYOFELECTRICALENERGY

Electricalenergyisconsideredsuperiortoallotherforms（chemical,heat,light,sound,ormechanical）ofenergyduetothefollowingreasons:

-

i.cheapness:

itismuchcheaperthanthatinotherformsandtherefore,itiseconomicaltouseenergyinthisformfordomestic,commercial,industrialandagriculturalpurposes.

ii.ConvenientandefficientTransmission:

theelectricalenergycanbetransmittedconvenientlyandefficientlyfromthegeneratingstations,usuallylocatedquiteawayfromthecentresofusage,throughconsuctorsofsuitablesize.

iii.Easycontrol:

electricallyopratedmachineshavesimpleandconvenientstarting,controlandoperation.

iv.Cleanliness:

useofelectricity（electricdriveorelectricheating）doesnotproducesmoke,fumes,dustorpoisonousgasesandtherefore,itsuseensurecleanlinessandpolutionfreeconditions.

v.GreaterFlexibility:

Electricalenergyoffersgreaterflexibilityasitcanbetakentoanycornerfothehouse,factory,street,hospital,farm,mineetc.throughsolid,strandedorflexibleconductors.

vi.VersatileForm:

Electricalenergyisaveryconvenientformofenergyanditcanbeeasilyconvertedintootherformsofenergy-heat,light,mechanical,soundorchemical.

Thoughatpresentaboutthree-fourthofthetotalenergyisstillusedinnon-electricalform（transport,residentialheatingandindustrialheatinguseenergymostlyinnon-electricalform）butbecauseofnumerousadvantages,mentionedabove,electricitywillaccontforagreaterandgreaterportionoftotalenergyconsumptioninthecomingyears.Itisexpectedthattheelectricitydemandwillcontinuetogoupformanymoreyearstocome,evenindevelopedcountries.

Powersystem=GenerationTransmissionDistributionUtilization

GENERATION

Electricitygenerationisthefirstprocessinthedeliveryofelectricitytoconsumers.Electricalenergyisgeneratedbyconversionofenergyavailableindifferentformsformdifferentnaturalsourcessuchaskineticenergyofblowingwinds,pressureheadofwater,chemicalenergyoffuelsandnuclearenergyofradioactivesubstancesintoelectricalenergy.Theelectricalpowergeneratedbysomemajoravailableenergysources.Theseare

HydroelectricPowerPlant:

Hydroelectricityisarenewableenergysource.Hydroelectricpoweristhepowerobtainedfromtheenergyoffallingwaterwhereashydroelectricpowerplantisthepowerplantutilisingthepotentialenergyofwateratahighlevelforthegenerationofelectricalenergy.

Inhydroelectricpowerstation,waterheadiscreatedbyconstructingadamacrossareiverorlake.Thepressureheadofwaterorkineticenergyofwaterisutilizedtodrivethewaterturbinescoupledtoalternatorsand,therefore,generationofelectricalpower.

Hydroelectricpowrstationsareusuallylocatedinhighhillyareas,wherethedamcanbebuilteasilyandlarge

reservoirscanbeobtained.

Hydroelectricpowersupplies20%ofworldelectricity.Norwayproducesvirtuallyallofitselectricityfromhydro,whileIcelandproduces83%ofitsrequirements（2004）,Austriaproduces67%ofallelectricitygeneratedinthecountryfromhydro（over70%ofitsrequirements）.Canadaistheworld'slargestproducerofhydropowerandproducesover70%ofitselectricityfromhydroelectricsources.

Thermalpowerstation:

Itisalsocalledassteampowerplant.Coalisthefuel.Thefactthatthermalenergyisthemajorsourceofpowrgenerationitselfshowstheimportanceofthermalpowergenerationinindiamorethan60%ofelectricpowerisproducedbysteamplantsinindia.

Fig:

Vijayawadathermalpowerstation

Ageneratingstation,whichconvertsheatenergyofcoalcombutionintoelectricalenergy,isknownasasteam（thermal）powerstation.

Insteampowerstationcoalisburntinaboiler,whichconvertswaterintosteam.Thesteamisexpandedinaturbine,whichproducesmechanicalpowerdrivingthealternatorcoupledtotheturbine.Inalternatorthemechanicalpowerconvertintoelectricalpower.Thesteamafterexpansioninprimemoverisusuallycondensedinacondensertobefedintotheboileragain.Inpractice,however,alargenumberofmodificationsandimprovementshavebeenmadesoastoaffecteconomyandimprovethethermalefficiencyofthepalnt.

Nuclearpowerplant:

thefuelsmainlyusedinNuclearpowerplantsarenaturalUranium,thorium.

AgeneratingstationinwhichnuclearenergyisconvertedintoelectricalenergyisknownasaNuclearStation.Thenuclearpowerstationmainlyconsistsofthefollowing:

1.Nucelarreactor

2.Heatexchangerorsteamgenerator

3.Steamorgasturbine

4.A.Cgeneratorandexciter

5.Condenser.

Thereactorofanuclearpowerplantissimilertothefurnaceinasteampowerplant.Theheatliberatedinthereactorduetothenuclearfissionofthefuelistakenupbythecoolantcirculatinginthereactor.Hotcoolantleavesthereactorattopandthenflowsthroughthetubesofheatexchangerandtranasferitsheattothefeedwateronitsway.Thesteamproducedintheheatexchangerispassedthroughtheturbineandaftertheworkhasdonebytheexpansionofsteamintheturbine,steamleavestheturbineandflowstothecondenser.Themechanicalenergydevelopedbythetrubineistransferredtothegeneratorwhichinturngeneratestheelectricalenergyandsuppliestothebusthroughastep-uptransformer,circuitbreakerandisolator.

TRANSMISSIONANDDISTRIBUTION

Electricpowertransmissionisoneprocessinthetransmittingofelectricitytoconsumers.Thetermreferstothebulktransferofelectricalpowerfromplacetoplace.Typically,powertransmissionisbetweenthepowerplantandasubstationnearapopulatedarea.Thisisdistinctfromelectricitydistribution,whichisconcernedwiththedeliveryfromthesubstationtotheconsumers.Duetothelargeamountofpowerinvolved,transmissionnormallytakesplaceathighvoltage（110kVorabove）.Electricityisusuallytransmittedoverlongdistancethroughoverheadpowertransmissionlines.

Undergroundpowertransmissionisusedonlyindenselypopulatedareas（suchaslargecities）becauseofthehighcostofinstallationandmaintenance.

Engineersdesigntransmissionnetworkstotransporttheenergyasefficientlyasfeasible,whileatthesametimetakingintoaccounteconomicfactors,networksafetyandredundancy.Thesenetworksusecomponentssuchaspowerlines,cables,circuitbreakers,switchesandtransformers.

*Efficiencyisimprovedbyincreasingthetransmissionvoltageusingastep-uptransformer,whichhastheeffectofreducingthecurrentintheconductors,whilstkeepingthepowertransmittednearlyequaltothepowerinput.Thereducedcurrentflowingthroughtheconductorreducesthelossesintheconductorandsince,accordingtoOhmsLaw,thelossesareproportionaltothesquareofthecurrent,havingthecurrentresultsinafour-folddecreaseintransmissionlosses.

ElectricalpowerGeneratingStation（upto11kV）TransmissionlinesSubstation

andincreasevoltage（upto220kv）orGrid.

Atransmissiongridisa