The Structure of Electric Power Systems (Generation ...

From a general perspective, an electric power system is usually understood as a very large network that links power plants (large or small) ... Searchfor:PremiumMembershipStudyspecializedtechnicalarticles,papers&coursesinlow/highvoltagefields.Save50%onallcoursesattheEEPAcademywiththeEnterprisePlan.MoreInformation»EnergyandPower/TransmissionandDistributionTheStructureofElectricPowerSystems(Generation,DistributionandTransmissionOfEnergy)ByEdvard|October,9th2017|16comments|Translate|SavetoPDF♛Subscribe|Share!Home/TechnicalArticles/TheStructureofElectricPowerSystems(Generation,DistributionandTransmissionOfEnergy)Whatisthe electricpowersystem?Fromageneralperspective,anelectricpowersystemisusuallyunderstoodasaverylargenetworkthatlinkspowerplants(largeorsmall)toloads,bymeansofanelectricgridthatmayspanawholecontinent,suchasEuropeorNorthAmerica.TheStructureofElectricPowerSystemsYouMUSTFullyUnderstand(photocredit:CarlaWosniakviaFlickr)Apowersystemthustypicallyextendsfromapowerplantrightuptothesocketsinsidecustomers’premises.Thesearesometimesreferredtoasfullpowersystemsastheyareautonomous.Smallerpowersystemscouldbemadeofpartorsectionsofalarger,fullsystem.Figure1showsseveralelementsthatoperatetogetherandareconnectedtoapowersupplyingnetwork.ThesubsystemrepresentedinFigure1(a)couldbeoneofafinaluseroftheelectricenergyofafullpowersystem.ThesubsystemrepresentedinFigure1(b)couldbeoneofasmallpowerplantworkingasdistributedgeneration(DG).Mostofthesepowersystemsoperateonlywhenconnectedtoafullpowersystem.Powersystemsthataresuppliedbyanexternalelectricitysourceorthatproduce(byconversionfromothersources)electricityandconveyittoalargergridarecalledpartialpowersystems.Figure1(a,b)–SpecificpurposepowersubsystemsThepowersystemsthatareofinterestforourpurposesarethelargescale,fullpowersystemsthatspanlargedistancesandhavebeendeployedoverdecadesbypowercompanies.Generationistheproductionofelectricityatpowerstationsorgeneratingunitswhereaformofprimaryenergyisconvertedintoelectricity.Transmissionisthenetworkthatmovespowerfromonepartofacountryoraregiontoanother.Itisusuallyawell-interconnectedinfrastructureinwhichmultiplepowerlineslinkdifferentsubstations,whichchangevoltagelevels,offeringenhancedredundancy.Distributionfinallydeliversthepower(wecouldsaylocallywhencomparedtothetransmissionsystem)tothefinalloads(amajorityofwhicharesuppliedatlowvoltage)viaintermediatestepsatwhichthevoltageisconverteddown(transformed)tolowerlevels.Thedistributionsystemendsupattheenergyconsumptionpointsorloadswherepowerisusedforitsfinalpurpose.Therearepartsoftheworldinwhichthederegulationandprivatizationoftheindustryhasalreadycompletelychangedtheindustrylandscape,whileinotherstheimpactisstilltobeseen.PowerGenerationPowerplantsconverttheenergystoredinthefuel(mainlycoal,oil,naturalgas,enricheduranium)orrenewableenergies(water,wind,solar)intoelectricenergy.Conventionalmoderngeneratorsproduceelectricityatafrequencythatisamultipleoftherotationspeedofthemachine.Voltageisusuallynomorethan6to40kV.Thepoweroutputisdeterminedbytheamountofsteamdrivingtheturbine,whichdependsmainlyontheboiler.Thevoltageofthatpowerisdeterminedbythecurrentintherotatingwinding(i.e.,therotor)ofthesynchronousgenerator.Theoutputistakenfromthefixedwinding(i.e.,thestator).Thevoltageissteppedupbyatransformer,normallytoamuchhighervoltage.Atthathighvoltage,thegeneratorconnectstothegridinasubstation.Figure2–472-megawattsteamturbineandgenerator(STG)fortheAllenCombinedCyclePowerPlant(photocredit:businesswire.com)Traditionalpowerplantsgenerateacpowerfromsynchronousgeneratorsthatprovidethree-phaseelectricpower,suchthatthevoltagesourceisactuallyacombinationofthreeacvoltagesourcesderivedfromthegeneratorwiththeirrespectivevoltagephasorsseparatedbyphaseanglesof120°.Windturbinesandminihydrounitsnormallyemployasynchronousgenerators,inwhichthewaveformofthegeneratedvoltageisnotnecessarilysynchronizedwiththerotationofthegenerator.DGreferstogenerationthatconnectsintothedistributionsystem,asopposedtoconventionalcentralizedpowergenerationsystems.TheElectricPowerResearchInstitute(EPRI)hasdefineddistributedgenerationasthe“utilizationofsmall(0to5MW),modularpowergenerationtechnologiesdispersedthroughoutautility’sdistributionsysteminordertoreduceT&DloadingorloadgrowthandtherebydefertheupgradeofT&Dfacilities,reducesystemlosses,improvepowerquality,andreliability.”Smallgeneratorsareconstantlyimprovingintermsofcostandefficiency,becomingclosertotheperformanceoflargepowerplants.HowdoesaThermalpowerplantwork?TransmissionSystemsPowerfromgenerationplantsiscarriedfirstthroughtransmissionsystems,whichconsistoftransmissionlinesthatcarryelectricpoweratvariousvoltagelevels.Atransmissionsystemcorrespondstoanetworked,meshedtopologyinfrastructure,connectinggenerationandsubstationstogetherintoagridthatusuallyisdefinedat100kVormore.Figure3–ElectricpowersystemTheelectricityflowsoverhigh-voltage(HV)transmissionlinestoaseriesofsubstationswherethevoltageissteppeddownbytransformerstolevelsappropriatefordistributionsystems.ACrmsvoltagelevelsPreferredACrmsvoltagelevelsareinternationallystandardizedinIEC60038:2009as:362kVor420kV;420kVor550kV;800kV;1,100kVor1,200kVhighestvoltagesforthree-phasesystemshavingahighestvoltageforequipmentexceeding245kV.66(alternatively,69)kV;110(alternatively,115)kVor132(alternatively,138)kV;220(alternatively,230)kVnominalvoltagesforthree-phasesystemshavinganominalvoltageabove35kVandnotexceeding230kV.11(alternatively,10)kV;22(alternatively,20)kV;33(alternatively,30)kVor35kVnominalvoltagesforthree-phasesystemshavinganominalvoltageabove1kVandnotexceeding35kV.ThereisaseparatesetofvaluesspecificforNorthAmericanpractice.Inthecaseofsystemshavinganominalvoltagebetween100Vand1,000Vinclusive,230/400Visstandardforthree-phase,four-wiresystems(50Hzor60Hz)andalso120/208Vfor60Hz.Forthree-wiresystems,230Vbetweenphasesisstandardfor50Hzand240Vfor60Hz.Forsingle-phasethree-wiresystemsat60Hz,120/240Visstandard.Mediumvoltage(MV)asaconceptisnotusedinsomecountries(e.g.,UnitedKingdomandAustralia),itis“anysetofvoltagelevelslyingbetweenlowandhighvoltage”andtheproblemtodefineitisthattheactualboundarybetweenMVandHVlevelsdependsonlocalpractices.InEurope,overheadtransmissionlinesareusedinopenareassuchasinterconnectionsbetweencitiesoralongwideroadswithinthecity.Incongestedareaswithincities,undergroundcablesareusedforelectricenergytransmission.Theundergroundtransmissionsystemisenvironmentallypreferablebuthasasignificantlyhighercost.Transmissionlinesaredeployedwiththreewiresalongwithagroundwire.Virtuallyallactransmissionsystemsarethree-phasetransmissionsystems.DistributionSystemsDistributionsegmentiswidelyrecognizedasthemostchallengingpartofthesmartgridduetoitsubiquity.Voltagelevelsof132(110insomeplaces)or66kVareusualHVlevelsthatcanbefoundin(European)distributionnetworks.Voltagesbelowthat(e.g.,30,20,10kV)arecommonlyfoundinMVdistributionnetworks.Distributionlevelsbelow1kVarewithinwhatisknownasLVorLowVoltage.MVgridtopologiescanbeclassifiedinthreegroups:RadialtopologyRadiallinesareusedtoconnectprimarysubstations(PSs)withsecondarysubstations(SSs),andtheSSsamongthem.TheseMVlinesor“feeders”canbeusedexclusivelyforoneSSorcanbeusedtoreachseveralofthem.RadialsystemskeepcentralcontrolofalltheSSs.Theseradialtopologiesshowatree-shapedconfigurationwhentheygrowincomplexity.Theyarealessexpensivetopologytodevelop,operate,andmaintain,buttheyarealsolessreliable.Figure4 – RadialfeedersystemRingtopologyThisisafault-toleranttopologytoovercometheweaknessofradialtopologywhenthereisadisconnectionofoneelementoftheMVlinethatinterruptselectricityservice(outage)intherestoftheconnectedsubstations.Aringtopologyisanimprovedevolutionoftheradialtopology,connectingsubstationstootherMVlinestocreateredundancy.Independentlyofthephysicalconfiguration,thegridisoperatedradially,butontheeventofafailureinafeeder,otherelementsaremaneuveredtoreconfigurethegridinsuchawaythatoutagesareavoided.Figure5–RingBusArrangementNetworkedtopologyNetworkedtopologyconsistsofprimaryandsecondarysubstationsconnectedthroughmultipleMVlinestoprovideavarietyofdistributionalternatives.Thus,thereconfigurationoptionstoovercomefaultsaremultiple,andintheeventoffailure,alternativesolutionsmaybefoundtorerouteelectricity.LVdistributionsystemscanbesingle-phaseorthree-phase.InEurope,forexample,theyareusuallythree-phase,230V/400Vsystems(i.e.,eachphasehasanrmsvoltageof230Vandthermsvoltagebetweentwophasesis400V).LVgridspresentmorecomplexandheterogeneoustopologiesthanMVgrids.TheexacttopologyofLVsystemsdependsontheextensionandspecificfeaturesoftheservicearea,thetype,numberanddensityofpointsofsupply(loads),country-specificandutility-specificoperatingprocedures,andrangeofoptionsininternationalstandards.Figure6–NetworkDistributionSystemAnSStypicallysupplieselectricitytooneorseveralLVlines,withoneormultipleMV-to-LVtransformersatthesamesite.LVtopologyistypicallyradial,havingmultiplebranchesthatconnecttoextendedfeeders,buttherearealsocasesofnetworkedgridsandevenringordual-fedconfigurationsinLVnetworks.LVlinesaretypicallyshorterthanMVlines,andtheircharacteristicsaredifferentdependingontheservicearea.Reference//TelecommunicationNetworksfortheSmartGridbyAlbertoSendin(PurchasehardcoverfromAmazon)Relatedelectricalguides&articlesParametersofgenerators,transformers,linesandcablesforvars,voltageandloadscontrolHowtomodernizeapowersystemwhilecarryingthecost(examplesofexistingplant)FourabnormaloperatingconditionsofageneratorthatcouldshutdownthepowerplantTheartofloadsheddingandonlineapplicationsinapowersystemunderanemergencystateProtectioncoordinationpracticesindistributionsystemswithdistributedgenerationTheimpactofinterconnectiontransformerontheprotectionoftheutilitysystemwithDGPremiumMembershipGetaccesstopremiumHV/MV/LVtechnicalarticles,electricalengineeringguides,researchstudiesandmuchmore!Ithelpsyoutoshapeupyourtechnicalskillsinyoureverydaylifeasanelectricalengineer.MoreInformationEdvardCsanyiElectricalengineer,programmerandfounderofEEP.HighlyspecializedfordesignofLV/MVswitchgearsandLVhighpowerbusbartrunking(<6300A)inpowersubstations,commercialbuildingsandindustryfacilities.ProfessionalinAutoCADprogramming.16CommentsEdwardRaziMar13,2022Veryenlightening.ReplyLOBEJAMESFeb14,2022Veryricharticle,reallyknowledgeenriching.ReplySaghiralamMay02,2021GoodelectricaltopicsReplyZaharNov26,2020HelloEdward,IamastudentoftheRussianUniversity,afuturepowerengineer,wewereaskedtoreadandtranslateyourarticleintoRussian.Nowyoucanconsiderthatyourarticlehasinternationalrecognition.ReplyZaharNov26,2020HelloEduard,IamastudentoftheRussianUniversity,afuturepowerengineer,wewereaskedtoreadandtranslateyourarticleintoRussian.Nowyoucanconsiderthatyourarticlehasinternationalrecognition.ReplyVicenteAssantiApr10,2020Ilookingforexams,howtocalculate&layoutssafetyclearancetoelectricsupplystationelectricequipmentandimpenetrablefencesReplyL.BangarRajuJul25,2019DearEvard,Excellentarticle,veryusefulforpowerengineers.Keepdoinggoodthings.Godblessyou.Withwarmregards,L.BangarRaju.,ReplyNamaDec01,2018Thisissuchanicewriteup,Edvard!Keepupthegoodwork.Cheers,TeamNamaReplyPeterNov04,2018I’mElectricalPowerEngineer.ThanksEdvardforyourveryeducativearticlesinthefieldsofPowerEngineering.Yourarticlesarereallysohelpfulforus.Keepuploadingmorearticles.wearesogratefulforyourgreatwork.GodblessyouReplyAnandaSep20,2018Thankyouforeverythingyoucreateforfuturegeneration.LikeuptodatedinformationforGISIcanhaveachancetoknow.ReplyLiridonBilalliOct18,2017HiEdvard,IamElectricalPowerSystemsEngineerandthiswebsiteisamazingsokeedupworkingso.Iamlearningnewthingshereandiamthankfulforthat.Iwouldliketocooperateinthefuturewithcosihaveinnovativeideasalso.Bestregards!ReplyidrisSiddiquiOct13,2017thankyouforthisinformativpresentation.YouaregreattodothisReallyappreciated!ReplyEmilyOct12,2017Veryinformative.Iloveyourarticles.ReplyAbhasPandyaOct10,2017hibroitsnicearticlekeepuptogoodworkarticleReplyProfDIBJalelOct10,2017thankyouforalldocuments,thereareveryimportantinelectricalpowerfieldpleasecompletethembycalculationandsimulationtechniquesthankyouReplyEdvardOct10,2017You’rewelcome!ReplyLeaveaCommentCancelReplyTelluswhatyou'rethinking.Wecareaboutyouropinion!Pleasekeepinmindthatcommentsaremoderatedandrel="nofollow"isinuse.So,pleasedonotuseaspammykeywordoradomainasyourname,oritwillbedeleted.Let'shaveaprofessionalandmeaningfulconversationinstead.Thanksfordroppingby!Yourrealname*Emailaddress*ProvethatyouarenotR2-D2.Solvesomemath:seven  ×    =  56ΔLearnHowtoDesignPowerSystemsLearntodesignLV/MV/HVpowersystemsthroughprofessionalvideocourses.Lifetimeaccess.Enjoylearning!VideoCoursesSubscribetoWeeklyNewsletterSubscribetoourWeeklyDigestnewsletterandreceivefreeupdatesonnewtechnicalarticles,videocoursesandguides(PDF).Subscribe©2022EEP-ElectricalEngineeringPortal.AllRightsReserved|PrivacyPolicy|TermsandConditionsThecontentiscopyrightedtoEEPandmaynotbereproducedonotherwebsites.TechnicalArticlesTechnicalArticlesCategories(42)ElectricalGuidesElectricalEngineeringPowerSubstationsControl&ProtectionGenerationT&DABBProtectionBooksSiemensEEBasicsSchneiderElectricCTsIndustrialAutomationDataCenterGuidesABBDrivesGuidesAlternativeEnergyElectricalDesignDocsElectricalToolsExcelSpreadsheetsSoftwareReviewsVideoTrainingsElectricalEngineeringPLCProgrammingTesting&Commiss.EEResourcesHomeSitemapEEPAcademyCoursesContact/AdvertisementContactAdvertisementFreeNewsletterEEWeeklyDigestFacebookLinkedinLinkedinTwitterPremiumMembership♛PlansandPricingLogIn