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ACTIVE ELECTRICAL DISTRIBUTION NETWORK ACTIVE ELECTRICAL DISTRIBUTION NETWORK Issues,Solution Techniques,and Applications Editedby
SANJEEVIKUMARPADMANABAN
DepartmentofElectricalandElectronicsEngineering,KPR InstituteofEngineeringandTechnology,Tamilnadu,India
BASEEMKHAN
DepartmentofElectricalandComputerEngineering, FacultyofElectricalEngineering,InstituteofTechnology, HawassaUniversity,Ethiopia
OMPRAKASHMAHELA
PowerSystemPlanningDivision,RajasthanRajyaVidyut PrasaranNigamLimited,Jaipur,India
HASSANHAESALHELOU
TishreenUniversity,Lattakia,Syria
S.RAJKUMAR
DepartmentofMechanicalEngineering,Facultyof Manufacturing,InstituteofTechnology,HawassaUniversity, Ethiopia
AcademicPressisanimprintofElsevier 125LondonWall,LondonEC2Y5AS,UnitedKingdom 525BStreet,Suite1650,SanDiego,CA92101,UnitedStates 50HampshireStreet,5thFloor,Cambridge,MA02139,UnitedStates TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UnitedKingdom
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Contributors
DessalegnBitewAeggegn
SchoolofElectricalandComputerEngineering,DebreMarkosUniversity,DebreMarkos, Ethiopia
TakeleFeredeAgajie
DepartmentofElectricalandElectronicsEngineering,UniversityofBuea,Buea,Cameroon; DebreMarkosUniversity,DebreMarkos;HawassaUniversity,Hawassa,Ethiopia
ZiadM.Ali
CollegeofEngineeringatWadiAddawasir,PrinceSattamBinAbdulazizUniversity, WadiAddawasir,SaudiArabia
YayehyiradAyalewAwoke
SchoolofElectricalandComputerEngineering,DebreMarkosUniversity,DebreMarkos, Ethiopia;DepartmentofElectricalandElectronicsEngineering,UniversityofBuea,Buea, Cameroon
MulusewAyalew
DepartmentofElectricalandComputerEngineering,HawassaUniversity,Hawassa, Ethiopia
I.Baranilingesan
RenewableEnergyLab,DepartmentofElectricalandElectronicsEngineering,KPR InstituteofEngineeringandTechnology,Coimbatore,TamilNadu,India
R.Bharathwaaj
DepartmentofMechanicalEngineering,KPRInstituteofEngineeringandTechnology, Coimbatore,TamilNadu,India
GajendraSinghChawda
DepartmentofElectricalEngineering,IITJodhpur,Jodhpur,India
V.KumarChinnaiyan
RenewableEnergyLab,DepartmentofElectricalandElectronicsEngineering,KPR InstituteofEngineeringandTechnology,Coimbatore,TamilNadu,India
EmenikeC.Ejiogu
LaboratoryofIndustrialElectronics,PowerDevicesandNewEnergySystems;AfricaCentre ofExcellenceforSustainablePowerandEnergyDevelopment,UniversityofNigeria, Nsukka,Nigeria
MkpamdiEke
DepartmentofMechanicalEngineering,UniversityofNigeria,Nsukka,Nigeria
RagabA.El-Sehiemy
KafrelsheikhUniversity,Kafrelsheikh,Egypt
AhmadEsmaeili
PowerSystemsOperationandPlanningResearchDepartment,NirooResearchInstitute, Tehran,Iran
MesfinFanuel
DebreMarkosUniversity,DebreMarkos;HawassaUniversity,Hawassa,Ethiopia
DamotGebregziabher
DepartmentofElectricalandComputerEngineering,HawassaUniversity,Hawassa, Ethiopia
JosepM.Guerrero
TheVillumCenterforResearchonMicrogrids(AAUCROM),AalborgUniversity, Aalborg,Denmark
IssaiasGideyHagos
DepartmentofElectricalandComputerEngineering;InstituteofTechnology,Hawassa University,Hawassa,Ethiopia
AmoussouIsaac
DepartmentofElectricalandElectronicsEngineering,UniversityofBuea,Buea,Cameroon
SalahKamel
DepartmentofElectricalEngineering,AswanUniversity,Aswan,Egypt
J.Karpagam
RenewableEnergyLab,DepartmentofElectricalandElectronicsEngineering,KPR InstituteofEngineeringandTechnology,Coimbatore,TamilNadu,India
AlagarKarthick
RenewableEnergyLab,DepartmentofElectricalandElectronicsEngineering,KPR InstituteofEngineeringandTechnology,Coimbatore,TamilNadu,India
OlaKhaddam
ElectricalPowerEngineering,TishreenUniversity,Latakia,Syria
BaseemKhan
DepartmentofElectricalandComputerEngineering;InstituteofTechnology,Hawassa University,Hawassa,Ethiopia
AshishKumar
DepartmentofElectricalEngineering,NITHamirpur,Hamirpur,India
PankajKumar
DepartmentofElectricalEngineering,RTUKota,Kota,India
RavitaLamba
DepartmentofElectricalEngineering,MalaviyaNationalInstituteofTechnologyJaipur, Jaipur,India
ChikaMaduabuchi
DepartmentofMechanicalEngineering,UniversityofNigeria,Nsukka,Nigeria
OmPrakashMahela
PowerSystemPlanningDivision,RajasthanRajyaVidyutPrasaranNigamLtd.,Jaipur, Rajasthan,India
RamNiwashMahia
DepartmentofElectricalEngineering,NITHamirpur,Hamirpur,India
AbbasMarini
PowerSystemsOperationandPlanningResearchDepartment,NirooResearchInstitute, Tehran,Iran
V.Mohanavel
CentreforMaterialsEngineeringandRegenerativeMedicine,BharathInstituteofHigher EducationandResearch,Chennai,TamilNadu,India
HowardO.Njoku
AppliedRenewableandSustainableEnergyResearchGroup,Departmentof MechanicalEngineering,UniversityofNigeria,Nsukka,Nigeria;Department ofMechanicalEngineeringScience,UniversityofJohannesburg,Johannesburg,South Africa
ChigboguOzoegwu
DepartmentofMechanicalEngineering,UniversityofNigeria,Nsukka,Nigeria
S.Rajkumar
DepartmentofMechanicalEngineering,FacultyofManufacturing,Instituteof Technology,HawassaUniversity,Hawassa,Ethiopia
AbdelhadyRamadan
DepartmentofElectricalEngineering,AswanUniversity,Aswan,Egypt
ManickamRavichandran
DepartmentofMechanicalEngineering,K.RamakrishnanCollegeofEngineering, Trichy,TamilNadu,India
T.Sakthi
DepartmentofMechanicalEngineering,NationalEngineeringCollege,Kovilpatti, TamilNadu,India
MortezaShabanzadeh
PowerSystemsOperationandPlanningResearchDepartment,NirooResearchInstitute, Tehran,Iran
AvdheshSharma
DepartmentofElectricalEngineering,FacultyofEngineeringandArchitecture,Jai NarainVyasUniversity,Jodhpur,Rajasthan,India
SurendraSingh
DepartmentofElectricalEngineering,FacultyofEngineeringandArchitecture,Jai NarainVyasUniversity,Jodhpur,Rajasthan,India
VishwajeetKumarSinha
DepartmentofElectricalEngineering,NITHamirpur,Hamirpur,India
EndeshawSolomon DepartmentofElectricalandComputerEngineering;InstituteofTechnology,Hawassa University,Hawassa,Ethiopia
S.Vasanthaseelan DepartmentofMechanicalEngineering,KPRInstituteofEngineeringandTechnology, Coimbatore,TamilNadu,India
Electricaldistributionnetwork: Anintroduction 1Introduction
Distributioncarriesenergyfromthetransmissionpointandsuppliesitto users.Itisthelaststepinthesupplyofelectricity.Low-voltagesubstations (distributionsubstations)linktothetransmissionlinesthroughtransformers andlowerthevoltageofthetransmissiontoamediumlevel,whichranges from2to35kV. Fig.1 showsacircuitdiagramoftheelectricalpowersystem [1,2].
Theprimarygoalofdistributionistosupplyenergytocustomersafter obtaininglargeamountsofpowerthroughatransmissionsubstation.Primaryandsecondary(customer)substationsarethetwomaintypesof
distributionsubstations.Thecustomersubstationcommunicateswiththe low-voltage(LV)network,whereasthemajorsubstationservesasaload center.Acustomersubstationisadistributionroomthatisoftenprovided bytheclient.Thetransformerandanumberofhigh-voltageswitchgear panelscanbeaccommodatedinthedistributionroomtopermitLVconnectiontothecustomer’sincomingswitchboard [3]
Transmissionanddistributionmeetatapowersubstation,whichhas manyfunctions.Thetransmissiongridcanbedisconnectedfromthesubstation,anddistributionlinescanbeterminatedwithcircuitbreakersand switches.Transformersconverthigh-voltagetransmissionlines(35kVor more)tolow-voltagemaindistributionlines.Thisisamedium-voltageline withavoltagerangeof600–35,000V.Thetransformerdeliverselectricityto thebus-bar,whichcandividethepowerfordistributioninmanyways.The bustransportsenergytodistributionlines,whichsubsequentlydeliveritto customers [4]
Thedistributionnetworkmighttaketheshapeofoverheadwiresor undergroundcables,dependingonthegeographicalarea.Inmetropolitan areas,cablesareoftenemployed,butinruralregions,overheadlinesare used.Inordertomeettherequiredsupplyreliability,variousnetwork designsareconceivable.Toensurethatthedistributionnetworkruns smoothly,protection,control,andmonitoringequipmentisinstalled.
2History Whenelectricitybegantobecreatedatpowerstationsinthe1880s,electric powerdistributionbecamenecessary.Previously,powerwastypicallygeneratedonsite.ThefirstpowerdistributionsystemsbuiltinEuropeanand Americantownswerewitharclighting(approximately3000V)alternating current(AC)ordirectcurrent(DC)andincandescentlighting(100V)DC.
Fig.1 Electricalpowersystem.
Forstreetlighting,arclightingisusedwhilegasisreplacedbyincandescent lightingforhouseholdandcommercialillumination [3].
Ashighvoltageisutilizedinarclighting,asinglegeneratingstationmay powercircuitsthatareupto11-kmlong [4].Fortransportingfourtimesthe power,thevoltageisdoubledwiththesamesizeconductorandpower losses.In1882,theEdisonPearlStreetStationwasbuilt,butithadtrouble reachingconsumersmorethanamiledistant.Thiswasbecauseoftheuseof a110VLVsystem.Thissystemrequiredconductorlines(thickcopper)and generatingfacilitieswithin2.4kmofthefurthestconsumertopreventcables thatweretoolargeandcostly.
3Structureofpowerdistributionnetwork Apowersystemdevelopednearorwithinacityorindustrialzoneisknown asadistributionsystem.Itreceiveselectricitythroughtransmissionlines. Astep-downtransformerisusedtoreducethehightransmissionvoltage tolowdistributionvoltage [5–8].Generally,electricitydistributionisperformedat11kV.Itcanvaryfrom2.4to33kV,dependinguponthedemand andtypeofcustomer.Thestructureoftheelectricitydistributionnetworkis depictedin Fig.2
3.1Distributionsystemcomponents Generally,anelectricdistributionsystemconsistsof [9]:
•Low-voltagesubstation
•Feederlines
•Transformers(distribution)
•Distributors
•Servicemains
Switches,protectiondevices,measuringdevices,andothercomponentsare includedinadistributionsystem.
A.Feederlines
Thevoltage,whichissteppeddown,iscarriedviafeedercablesafter thesubstationthroughthedistributiontransformers.Notappingsare takenfromthefeedersinthemajorityofsituations,ensuringthatthe currentremainsconstant.Thecurrent-carryingcapacityisthemost essentialaspecttoconsiderwhileconstructingafeeder(Fig.3).
B.Transformer(distributionlevel) Atransformeratthedistributionlevel,sometimesknownasaservice transformer,isthelasttransformerinthepowernetwork.Generally,itis athree-phasestep-downtransformer.Itstepsdowntheinputsupplyto 400Y/230V.Thephasevoltage(thevoltagebetweenanyphaseandthe neutral)is230Vwhilethelinevoltageis400V.
C.Distributors
Thetransformer’soutputispassedthroughthedistributor.The distributor’stappingsareusedtodistributeelectricitytousers.Ina distributor,theflowofcurrentisnotcontinuousbecausetappingsare performedatdifferentlocationsalongitsdistance.Asaresult,thedrop involtageoverthedistanceofadistributoristhemostessentialelement toconsider.
D.Servicemain
Thisisatinycablethatrunsfromthenearestpole’sdistributorconductortothecustomer’spremises.
Circuit Breakers
Sub station Bus
Circuit Breakers
Radial Feeders
Fig.3 Feeders.
4Classificationofdistributionnetwork Distributionsystemscanbeclassifiedasfollows [10]
4.1Typeofnatureofcurrent Basedonthetypeofthecurrent,distributionsystemsmaybedividedinto thefollowingcategories:
•Directcurrent(DC)
•Alternativecurrent(AC)
4.1.1DCdistributionsystem DCtechnologywasusedtobuildthefirstelectricaldistributionnetworks, whichwerebuiltbyEdisonneartheendofthe19thcentury.ACsystems, ontheotherhand,provedtobeconsiderablybetterthanDCsystemsatthe time,andACsystemswerewidelyemployedforpowerproduction,transmission,anddistribution.Thefactthatelectricityisnearlyentirelyproduced,transferred,andsuppliedasACisgeneralinformation.Some industrialsystems,however,necessitatetheuseofDCpower.Electrical machinessuchasDCmachinesandindustrialprocessessuchaselectrochemicalprocessesdemandDCpower.
TheDCsupplyfromthesubstationmighthavethefollowingforms:
•Two-wire
•Three-wire
A.Two-wire
Thisdistributionsystemismadeupoftwowires(+and ),asthe namesuggests.Thepositive(+)wireistheoutgoingconductorwhile thenegativeconductorprovidesthereturnpath.Betweenthesetwo wires,loadsareinterconnected.Thetwo-wiresystemisshownin Fig.4
B.Three-wire
Asshownin Fig.5,thisismadeupoftwooutsidewiresandaneutral conductorinthemiddle,whichisearthedatthesubstation.Thedifferenceinvoltagebetweentheouterandneutralconductorsistwotimes thevoltagedifferencebetweentheouterandneutralwires.
High-voltageloads(suchasmotors)arelinkedinparalleltotheoutside conductorswhilelow-voltageloadsarelinkedamongtheouterandthe neutral.
4.1.2ACdistributionsystem Electricityisbasicallygenerated,transmitted,anddistributedinACform. Adistributionsystemnormallystartsatasubstationfromwhicha
transmissionnetworkdeliverspower.Thedistributionsystemmaystartat thegeneratingstationinsomecases,suchasloadsavailablenearthegeneratingsystem.Thetermsprimaryandsecondarydistributionareusedforlarge areasandindustriallocations.Thedetaileddescriptionofthesetwotypesof distributionsystemsisasfollows:
•Primary
•Secondary A.Primary
Thisoperatesatslightlyhighervoltagesthannormalandcanhandle largeramountsofelectricitythanaregularlow-voltageconsumer. Becauseoftheexpense,primarydistributionisdonewithathree-phase, three-conductornetwork.
Theenergyfromthegeneratorissenttoasubstationatahighpotential.Afterward,thepotentialisloweredto11kVusingastep-downtransformer. Fig.1 showsthebasicprincipleofamaindistributionsystem.
DC/AC Inverter
DC/DC Converter
AC Transmission
Load 1
Load 2
AC/DC Sub station
Fig.4 Two-wiresystemfordistribution.
DC/AC Inverter
DC/DC Converter
AC Transmission
Load 1
Load 2
AC/DC Sub station
Fig.5 Three-wiresystemfordistribution.
B.Secondary TheratingofsecondaryACdistributionis400/230V.Itisathreephase,four-conductornetwork.Electricityisdistributedtoanumber ofdistributionsubstationsviathema jordistributioncircuit.Asillustratedin Fig.1 ,thelinepotentialis400Vwhilethephasepotential is230V.Domesticloadsthatarenormallyone-phasearelinkedto theneutralviaanyonephase.Ontheotherhand,commercialloads, whicharegenerallythree-phase,arelinkeddirectlytothethree-phase lines.TheACmethodiscurrentlyextensivelyutilizedfordistributing electricityduetoitssimplicityandcosteffectivenesscomparedtothe DCsystem.
4.2Basedonthetypesofconnection Basedontheschemeofconnection,distributionnetworkscanbecategorizedintothefollowingcategories:
•Radial
•Ringmain
•Interconnected
A.Radial
Thissystemutilizesdistinctfeederlinesextendingfromasubstation andservethedistributorconductorsfromjustoneend.Aradialdistributionsystemisdepictedasasinglelinediagramin Fig.6.Thistypeof distributionisusefulwhenthesupplyvoltageislowandthesubstationis withinthecity.Theadvantagesofthissystemareitssimplicityandlow initialcost.
Itdoes,however,containtheshortcomingslistedbelow.
(1) Thedistributor’sendnearthesupplypointwillbeseverelyloaded.
(2) Allthecustomersareservedbyalonedistributorandfeeder.
(3) Asaresult,outagesinanyfeederordistributorlinescutpowerto customersonthefault’sside.
(4) Considerablevoltagedeviationsarefacedbytheconsumersatthefar endduetofluctuationsintheloadonthedistributor.
Becauseofthesedrawbacks,thistechniqueisonlyemployedover smalllengths.Forfurtherexpansionoftheradialnetwork,morelaterals andsublateralsarerequired.
B.Ringmain Asthenameindicates,inthissystemthedistributiontransformer’s primarywindingcreatesaring.Itisinitiatedfromthebus-barsofthe substation,loopsovertheservicearea,andthenreturnstothesubstation. Fig.7 showstheringmainsystem.
Someoftheadvantagesoftheringmainsysteminclude:
(1) Thedistributionqualityisgoodastherearefewervoltagedeviations attheconsumerend.
(2) Thereliabilityofthesystemisincreasedcomparedtotheradialsystemaseachdistributorissuppliedbytwofeederlines.Therefore, withanoutageinanypartofthefeeder,thesupplywillbecontinuouslyavailable.
Fig.7 Ringmainsystem.
Fig.8 Interconnectedsystems.
C.Interconnectednetwork Theringofthefeederofaninterconnectedsystemiselectrifiedby twoormoresources. Fig.8 depictsasinglelinerepresentationofan interconnectedsystem.
Thefollowingaresomeofthebenefitsofaninterconnectedsystem: (1) Itimprovesservicedependability.
(2) Anyregionservedbyoneproducingstationcanbefedbyothergeneratingstationsduringpeakdemandhours.Thisdiminishesthesystem’sbackuppowercapacitywhileincreasingitsefficiency.
5Featuresofidealdistributionsystem Itrequiresalotofefforttokeepenergydistributionthatfulfillsthedemands ofnumerouscategoriesofcustomers.Foradequatedistributionofelectricity,differentcriteriainclude:
•Propervoltage
•Energyavailabilityondemand
•Reliablesystem Source 1
5.1Propervoltage Voltagedeviationattheuser’sendmustbeaslowaspossible.Itisacritical criterion.Loadvariationonthesystemtypicallycausesvariationsinvoltage. Lowvoltageresultsinrevenueloss,inadequatelighting,andtheriskof motorburnout.Highvoltagecanpermanentlyburnoutbulbsandcause otherequipmenttofail.
5.2Energyavailabilityondemand Consumersmustbeabletoobtainpowerinanyamounttheydemandatany time.Withoutnotifyingtheelectricutility,motorsandlightscanbestarted orstopped,andlightscanbeswitchedonoroff.Thedistributionsystem mustbeabletosatisfycustomerloadneedsbecauseelectricalenergycannot bestored.Thisrequiresthatoperationstaffresearchloadtrendsonaregular basistoanticipatebigloadfluctuationsthatfollowestablishedschedules.
5.3Reliablesupply Theoperationofmodernindustryisnearlyentirelyreliantonelectric power.Electricpowerisusedtolight,heat,chill,andventilatehomes andofficebuildings.Thisnecessitatesdependableservice.Electricpower, likeeverythingelsecreatedbyhumans,canneverbecompletelytrustworthy.However,thereareanumberofthingsthatmaybedonetoimprove reliability:
•Systeminterconnection.
•Automaticcontrolsystem.
•Reservefacilityincorporation.
6Designrequirements Adistributionnetwork’svoltagecontrolismostlikelythemostsignificant aspectinprovidinggoodservicetocustomers.Feederanddistributordesign mustbecarefullyconsideredforthisreason.
6.1Feeders Thecurrentcarryingcapacityofafeederisthemostessentialfeaturebecause thevoltagedropisverynegligibleinit.Thisisthecasebecausevoltageregulatingtechnologyatthesubstationcancompensateforvoltagedrops inafeeder.
6.2Distributors Whenconstructingadistributor,thevoltagedropistakenintoaccount.This isbecauseconsumersareservicedbyadistributor,andpotentialfluctuations attheconsumer’sterminalsarerestrictedbylaw(6%ofratedvalue).
6.3Earthing Itiscriticalthatdistributionsystemsareproperlyearthedsothathighvoltagesdonotoccuronindividualcustomerconnections.
Thepointsconnectedtotheeartharethetransformersecondaryoutput, theloadpointwithalocalmeterandprotectionfuse,theneutralconductor ofthefour-wiresystem,andthestarpointofthelowvoltagewindingonthe step-downtransformer. Fig.9 showstheprotectivemultipleearthsystem.
Theprotectivemultipleearth(PME)systemprotectsthemetalliccoveringsandequipmentfromthesupply.Thissystempreventsdangerously highvoltagesthatcouldjeopardizepeople’slives.
7Conclusion Abriefoverviewoftheelectricaldistributionsystemispresentedinthis chapter.Thechapterdiscussesthebackgroundandhistoryofthedistributionsystem.Thestructureofthenetworkanditstypesarealsodiscussedin detail.Moreover,thefeaturesanddesignrequirementsoftheelectricaldistributionnetworkarealsodiscussed.
References [1] T.A.Short,Chapter1—Fundamentalsofdistributionsystemsgivesanintroductionon distributionnetworkanditscomponents;Chapter8—Shortcircuitprotectionoutlines thebasicprincipleandcalculationofdistributionprotection,in:ElectricPowerDistributionHandbook,CRCPress,BocaRaton,FL,2004.
[2] J.J.Grainger,W.D.StevensonJr.,Chapter10—Symmetricalfaultgiveslogicaldiscussionandnumericalexampleson3-phasesymmetricalfault,in:PowerSystemAnalysis, McGraw-Hill,NewYork,1994.
[3] N.Hadjsaı¨d,J.-C.Sabonnadi’re,ElectricalDistributionNetworks,Wiley,2013.
[4] E.Lakervi,E.J.Holmes,ElectricityDistributionNetworkDesign,seconded.,IET, 2003.
[5] A.Arefi,F.Shahnia,G.Ledwich,ElectricDistributionNetworkManagementand Control,SpringerSingapore,2018.
[6] T.F.Agajie,B.Khan,J.M.Guerrero,O.P.Mahela,Reliabilityenhancementandvoltageprofileimprovementofdistributionnetworkusingoptimalcapacityallocationand placementofdistributedenergyresources,Comput.Electr.Eng.93(2021)107295.
[7] T.F.Agajie,B.Khan,H.H.Alhelou,O.P.Mahela,Optimalexpansionplanningofdistributionsystemusinggrid-basedmulti-objectiveharmonysearchalgorithm,Comput. Electr.Eng.87(2020)106823.
[8] B.Khan,H.H.Alhelou,F.Mebrahtu,Aholisticanalysisofdistributionsystemreliabilityassessmentmethodswithconventionalandrenewableenergysources,AIMSEnergy 7(4)(2019)413–442.
[9] https://www.electricaleasy.com/2018/01/electric-power-distribution-system.html (Accessed16June2021).
[10] https://electrical-engineering-portal.com/electrical-distribution-systems (Accessed 18June2021).
CHAPTER2 Electricaldistributionnetwork: BaseemKhana andJosepM.Guerrerob
aDepartmentofElectricalandComputerEngineering,HawassaUniversity,Hawassa,Ethiopia bTheVillumCenterforResearchonMicrogrids(AAUCROM),AalborgUniversity,Aalborg,Denmark
2.2
2.3
2.4
2.5
2.7
1Introduction
Powerisgeneratedatthegeneratingplantandtransmittedatahighervoltage throughtransmissionlines.Distributionsubstationtransformersscaledown thetransmissionsystemvoltagetolowerlevels.Thepartofthepowernetworkbetweenthedistributionsubstationandtheusagetransformersis knownastheprimarydistributionsystem.Theprimarydistributionsystem ismadeupofcircuitsknownasprimaryordistributionfeedersthatbeginat thedistributionsubstation’ssecondarybus.Inbigindustrialorcommercial applications,thedistributionsubstationisgenerallythepointofelectric powersupply [1].
Distributionnetworksprovideacriticalandoftenchallengingrolein ensuringthatwe,thecustomers,receivedependableandsafepower.Comparedtotheirtransmissioncounterparts,theyoftenhavelowerbudgetsand considerablybroaderserviceregions.Asaresult,networkmanagementisa majorendeavor.Obviously,eachnetworkregionandthedifficultiesitfaces aredistinct.However,itisthoughtthatthereareanumberofcommon pointsthatimpactthemajorityofoperators [2].
Customersmustcalltoreportanissuebecausethenetwork,particularly atlowerpowerlevels,haslittleornoreal-timemonitoring.Althoughsome automaticcontrolactionsareavailable,remotecontrolisonlyavailabletoa limitedextent.Atlowervoltagelevels,an“automated”reactionmayconsist ofmerelyremovingaload,generator,ornetworksegmentuntilanengineer arrives.
2Problemsassociatedwithdistributionsystem Thetraditionaldistributionnetworkfacesvariousproblems [2].Someof theseissuesarepresentedin Fig.1.
2.1Inadequacyoftheexistinggrid Thetraditionalsustainabilityofthelarge-scalepowergrid(generationand transmission)hasalreadybeendeterioratingformorethanadecadeandis anticipatedtocontinuetodosoatanincreasingrate [2]
Fig.1 Inadequacyissuesintheexistinggrid.
A.Thetraditionalpowersystemisexperiencingstressandstrain Thelarge-scalepowergridisjustfailing.Thecostofdepreciation surpassesthecostoffreshinvestment.Becauseofthefollowingreasons, economicexpansionisnotcatchingupwithnetworkdegradation [3]:
(1) Therateofcontinuousexponentialriseinpowerconsumption hasslowed.
(2) Environmentalandsustainability-relatedlegislativeandregulatory hurdlesobstruct,ifnotoutrightimpede,thesiting,building,and operationofnewgridinfrastructure.
(3) Inamorecompetitiveeconomy,thecostsofnewgenerating,transmission,anddistributionplantsisrising,andanymajornewconstructionmeansincreasedratesforcustomers.
(4) Utilitiesstandasubstantialdangerofnotrecoupingalltheir expenses,muchalonereceivingasufficientreturnonnewinfrastructureinvestments.
Asaconsequence,thetraditionallargeenergygridisstartingtoshow itsage,anditisprogressivelybeingmaintainedin“runtofail”mode.As aresult,significantdisruptionshavealmostquadrupledeach5yearsover thelast20years.
B.Powersystemadequacyisfurtherdeterioratedbyclimatechange Climatechangeputsgridadequacyatjeopardy.Apartfromthecontentiousrelationshipbetweenclimatechangeandtheuseofcarbon-based fuelsinutilities,thefrequency,length,andintensityofweatherevents havebeenprogressivelyincreasing.Eventhoughtheultimatecauses aredebatable,thenegativeimpactongriddependabilityisobvious [2] Inthemeantime,whenitcomestoclimatechange,societyis increasingopposedtotheuseofcarbon-basedfuels,believingthatthey arepartlyresponsibleforclimatechange.Moreover,theuseof“dirty” orhazardousfuelspollutesourair,land,andwatermoreandmore. “Perceptionisreality,”astheoldad agegoes.Ifusersstartbelieving thisoracceptingit,youareimpact edbyit.Itnotonlyrestrictsthe deploymentofnewpowergeneration,butalsotheoperationofcurrentgeneration [4]
C.Thereliabilityofthedistributionsystemseemstobeinsufficient Distributionnetworkbreakdownsgeneratemorecustomersupport disruptionsthanlargeelectricgridbreakdowns.Althoughtheelectric grid’scapabilityisdeteriorating,flawlesslargeelectricutilitydependabilitydoesnotimplyperfectdistributiongridreliability.However, asinthedigitalworld,itwillbecomeextremelyrelevant.
2.2Physicalandcybersecurityissuesoftheconventionalgrid Thepowernetworkarchitectureisvulnerable,asifthereweren’talready sufficientriskstosystemsufficiencyanddependability.Althoughdataprotectionhasreceivedalotofattentioninthebusiness,itisnotthesoleoreven themostsignificantissue.Informationsecuritymayultimatelyposeasawesomeadangertopowersystemreliabilityasitdoestoutilitycompanyand consumerdataprotection,asthepowersystemisbecomingmorevirtualand automated.Butevenmorealarming,thegridisincrediblyvulnerablein termsofphysicalsecurity [2,5].
Thereisn’tavitalcomponentinthenetwork(e.g.,production,transmitting,ordistributing)thatcan’tbeaccessedbyalmostanyone,generallywithoutevenbeingobservedorscreenedbythecompanyoranyotheragency. Eveniftheydon’treachorcutthroughthebarrier,theymaycertainlyget closeenoughtodeliverapunchandsurelycloseenoughtofirearifleor rocket-propelledgrenade.Directassaultsonthenetwork,includingthe mainelectricgridandenergydistributionsystems,arenowontheincrease. Identifyingandreactingtodirectassaultsaswellaspredictingandavoiding themwillbecomeespeciallycritical.
Oneofthemostseriouscybersecurityconcernsofthedaymaybethe grid’sphysicalvulnerability.Evenso,thewebisreliantonconsistentenergy. Therecanbenowebwithoutpower.Theonlywaytoassureadependable webinthepresentstateofthings,withtheelectricgrid’sdeterioratingreliabilityandworryingphysicalinsecurity,istodiscoversolutionstotraditional networkconnectivity.
2.3Traditionalvsfuturegrid Customersarelookingforoptionstotraditionalgridserviceascostsgoup, dependabilityfalls,andsustainabilityhasbecomemoreessential.Theycome upwithagrowingnumberofmethodstospendlessmoneywiththeirdominantcost-plusmonopolisticutilities.Companiesoftenseeksustainability andenergyeconomy,whicharethemoststraightforwardandreliable options [2,6].
Withdemandresponseandcrucialpeakpricingefforts,utilitieshave helpedcustomersbecomemoreawareoftheirenergyconsumptionand alternatives.Thosewerealldesignedtoalterconsumerhabitstokeepthe traditionalsystemalive.Consumers,ontheotherhand,arenotdrivento modifytheirhabitstohelptheirelectriccompanystayafloat.However, peoplearemuchmoreconcernedwithmorepracticalandcost-effective
methodstoget,control,andconsumeelectricitywiththeirownlifequality, companyproductivity,andinvestmentgoals.
Consumersarepreparedtogiveuponlysomuchintermsofcomfortto reduceconsumption,evenduringperiodswhentheyneedelectricitythe most.Theygenerallyseektorestrictconsumerusageatpeakhourswhen providersarelookingtobuyelectricity.Consumersarediscoveringnew optionsontheirsideofthesystem,includingdistributedgeneration(DG) unitssuchastraditionalemergencypower,solarrooftoppanels,combined heatandpower(CHP)plants,orevenmicrogrids.Withtheintroductionof electricvehicles,batterybanks,smarthomesandbuildings,andothertechnologies,eventhewaycustomersuseandmanagetheirelectricenergyis changingdramatically.
2.4Integrationofdistributedgeneration,energystoragewith managementsystems Thetraditionalpowersystemissuppliedbycompany-ownedgenerating facilities.Thesearedeployedfromacentralizedspottotransferelectricity throughpowerlinesthattransportittoloadcenters,whereitisdistributed tousersviautilitymeters.Distributedgeneration,storage,andadministrationareturningthiscentralized,one-wayapproachonitshead.Atthegrid’s distributionedges,therearecurrentlyhundredsofthousandsofenergygenerationunitsontheconsumersidesofthemeters [2,7]
Self-generationisseeninabouthalfofallmajorenterprises.Between nowand2030,itisanticipatedthatnearlyallnewgenerationcapacityin theelectricgridwillbecustomer-ownedandoperated,accountingfor 30%oftotalcapacity.
Theuseofdistributedenergyisincreasingatanexponentialrate.ConsidertherapidlyexpandingmarketfordistributedsolarPVproduction. Every3–4min,anewrooftopsolararrayisinstalled.
2.5Incorporationofnoveldisruptiveenablingtechniques Thisisasortofinnovationthatfundamentallyaltersthewayconsumers, businesses,andorganizationsoperate.Disruptivetechnologywashesaway theinstitutionsorpracticesitsubstitutesbecauseithasplainlysuperior features.
Afastexpandingvarietyofnewpower,electrical,information,andtelecommunicationstechnologies,gadgets,andapplicationsunderpinsthe advancesmentionedabove.ForthesamereasonsthatMoore’sLawholds
