专业外文文献翻译--分布式发电Word格式文档下载.doc

专业外文文献翻译--分布式发电Word格式文档下载.doc

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KEYWORDS:

distributedenergyresources；

distributedgeneration；

powersystemdesignandoperation

0Introduction

Distributedgeneration（DG）ordecentralizedgenerationisnotanewindustryconcept.In1882,ThomasEdisonbuilthisfirstcommercialelectricplant—“PearlStreet”.Thispowerstationprovided110VDCelectricityto59customersinlowerManhattan.In1887,therewere121EdisonpowerstationsintheUnitedStatesdeliveringDCelectricitytocustomers.Thesefirstpowerplantswererunonwaterorcoal.Centralizedpowergenerationbecamepossiblewhenitwasrecognizedthatalternatingcurrentpowercouldbetransportedatrelativelylowcostsandreducepowerlossesacrossgreatdistancesbytakingadvantageoftheabilitytoraisethevoltageatthegenerationstationandlowerthevoltagenearcustomerloads.Inaddition,theconceptsofimprovedsystemperformance（systemstability）andmoreeffectivegenerationassetutilizationprovidedaplatformforwide-area/globalgridintegration.Inrecentyears,therehasbeenarapidlygrowinginterestinwidedeploymentofDG.CommerciallyavailabletechnologiesforDGarebasedoncombustionengines,micro-andmini-gasturbines,windturbines,fuel-cells,variousphotovoltaic（PV）solutions,low-headhydrounitsandgeothermalsystems.

Deregulationoftheelectricutilityindustry（insomecountries）,environmentalconcernsassociatedwithtraditionalfossilfuelgenerationpowerplants,volatilityofelectricenergycosts,FederalandStateregulatorysupportof“green”energyandrapidtechnologicaldevelopmentsallsupporttheproliferationofDGunitsinelectricutilitysystems.ThegrowingrateofDGdeploymentsuggeststhatalternativeenergy-basedsolutionsplayanincreasinglyimportantroleinthesmartgridandmodernutility.

Large-scaleimplementationofDGcanleadtosituationsinwhichthedistribution/mediumvoltagenetworkevolvesfroma“passive”（local/limitedautomation,monitoringandcontrol）systemtoonethatactively（global/integrated,self-monitoring,semi-automated）respondstothevariousdynamicsoftheelectricgrid.Thisposesachallengefordesign,operationandmanagementofthepowergridasthenetworknolongerbehavesasitoncedid.Consequently,theplanningandoperationofnewsystemsmustbeapproachedsomewhatdifferentlywithagreateramountofattentionpaidtoglobalsystemchallenges.

Theprincipalgoalofthispaperistoaddressthetopicofhighpenetrationofdistributedgenerationanditsimpactongriddesignandoperations.Thefollowingsectionsdescribeavisionforthemodernutility,DGtechnologylandscape,andDGdesign/engineeringchallengesandhighlightssomeoftheutilityDGdemonstrationprojects.

1Visionformodernutilities

1.1Centralizedvs.distributed

Thebulkofelectricpowerusedworldwideisproducedatcentralpowerplants,mostofwhichutilizelargefossilfuelcombustion,hydroornuclearreactors.Amajorityofthesecentralstationshaveanoutputbetween30MW（industrialplant）and1.7GW.ThismakesthemrelativelylargeintermsofbothphysicalsizeandfacilityrequirementsascomparedwithDGalternatives.Incontrast,DGis:

1）Installedatvariouslocations（closertotheload）throughoutthepowersystemandmostlyoperatedbyindependentpowerproducersorconsumers.

2）Notcentrallydispatched（althoughthedevelopmentof“virtual”powerplants,wheremanydecentralizedDGunitsoperateasonesingleunit,maybeanexceptiontothisdefinition）.

3）DefinedbypowerratinginawiderangefromafewkWtotensofMW（insomecountriesMWlimitationisdefinedbystandards,e.g.US,IEEE1547definesDGupto10MW–eitherasasingleunitoraggregatecapacity）.

4）Connectedtothedistribution/mediumvoltagenetwork-whichgenerallyreferstothepartofthenetworkthathasanoperatingvoltageof600Vupto110kV（dependsontheutility/country）.

Themainreasonswhycentral,ratherthandistributed,generationstilldominatescurrentelectricityproductionincludeeconomyofscale,fuelcostandavailability,andlifetime.IncreasingthesizeofaproductionunitdecreasesthecostperMW;

however,theadvantageofeconomyofscaleisdecreasing—technologicaladvancesinfuelconversionhaveimprovedtheeconomyofsmallunits.Fuelcostandavailabilityisstillanotherreasontokeepbuildinglargepowerplants.Additionally,withalifetimeof25~50years,largepowerplantswillcontinuetoremaintheprimesourceofelectricityformanyyearstocome.

Thebenefitsofdistributedgenerationinclude:

higherefficiency;

improvedsecurityofsupply;

improveddemand-responsecapabilities;

avoidanceofovercapacity;

betterpeakloadmanagement;

reductionofgridlosses;

networkinfrastructurecostdeferral;

powerqualitysupport;

reliabilityimprovement;

andenvironmentalandaestheticconcerns（offersawiderangeofalternativestotraditionalpowersystemdesign）.DGoffersextraordinaryvaluebecauseitprovidesaflexiblerangeofcombinationsbetweencostandreliability.Inaddition,DGmayeventuallybecomeamoredesirablegenerationassetbecauseitis“closer”tothecustomerandismoreeconomicalthancentralstationgenerationanditsassociatedtransmissioninfrastructure.ThedisadvantagesofDGareownershipandoperation,fueldelivery（machine-basedDG,remotelocations）,costofconnection,dispatchabilityandcontrollability（windandsolar）.

1.2Developmentof“smartgrid”

Inrecentyears,therehasbeenarapidlygrowinginterestinwhatiscalled“SmartGrid–DigitizedGrid–GridoftheFuture”.Themaindriversbehindthismarkettrendaregridperformance,technologyenhancementandstakeholders’attention.Themainvisionbehindthismarkettrendistheuseofenhancedpowerequipment/technologies,monitoringdevices（sensors）,digitalandfullyintegratedcommunications,andembeddeddigitalprocessingtomakethepowergridobservable（abletomeasurethestatesofcriticalgridelements）,controllable（abletoaffectthestateofanycriticalgridelement）,automated（abletoadaptandself-heal）,anduser-friendly（bi-directionalutility–customerinteraction）.TheSmartGridconceptshouldbeviewedthroughthemodernutilityperspectiveofremainingprofitable（goodvaluetoshareholders）,continuingtogrowrevenuestreams,providingsuperiorcustomerservice,investingintechnologies,makingproductofferingscosteffectiveandpainfreeforcustomerstoparticipateandpartneringwithnewplayersintheindustrytoprovidemorevaluetosociety.ItisimportanttorecognizethatthereismeritintheSmartGridconceptandshouldbeviewedinlightofitbringingevolutionaryratherthanrevolutionarychangesintheindustry.

Ingeneral,thismarkettrendrequiresanewapproachtosystemdesign,re-designandnetworkintegrationandimplementationneeds.Inaddition,utilitieswillhavetodevelopwell-definedengineeringandconstructionstandardsandoperationandmaintenancepracticesaddressinghighpenetrationlevelsofDG.

2DGtechnologylandscape

DGsystemscanutilizeeitherwell-establishedconventionalpowergenerationtechnologiessuchaslow/hightemperaturefuelcells,diesel,combustionturbines,combinedcycleturbines,low-headhydroorotherrotatingmachines,renewableenergytechnologiesincludingPV,concentratedPV（CPV）,solarconcentrators,thin-film,solarthermalandwind/mini-windturbinesortechnologiesthatareemergingonthemarket（e.g.tidal/wave,etc.）.EachoftheDGtechnologieshasitsownadvantagesanddisadvantageswhichneedtobetakenintoconsiderationduringtheselectionprocess.

3DRinterconnectionrequirements

DRinterconnectiondesignandengineeringdetailsdependonthespecificinstallationsize（kWvs.MW）;

however,theoverallcomponentsoftheinstallationshouldincludethefollowing:

1）DGprimemover（orprimeenergysource）anditspowerconverter.

2）Interface/step-uptransformer.

3）Grounding（whenneeded—groundingtypedependsonutilityspecificsystemequirements）．

4）Microprocessorprotectiverelaysfor:

①Three-,single-phasefaultdetectionandDGoverload.

②Islandingandabnormalsystemconditionsdetection.

③Voltageandcurrentunbalancesdetection.

④Undesirablereversepowerdetection.

⑤Machine-basedDGsynchronization.

5）Disconnectswitchesand/orswitchgear（s）.

6）Metering,controlanddataloggingequipment.

7）Communicationlink（s）fortransfertripanddispatchcontrolfunctions（whenneeded）.

4ImpactofDRintegrationand“penetration”level

IntegrationofDGmayhaveanimpactonsystemperformance.Thisimpactcanbeassessedbasedon:

1）SizeandtypeofDGdesign:

powerconvertertype,unitrating,unitimpedance,protectiverelayfunctions,interfacetransformer,grounding,etc.

2）TypeofDGprimemover:

wind,PV,ICE,CT,etc.

3）IntendedDGoperatingmode（s）:

loadshavi