水利水电工程毕业设计外文翻译.doc

水利水电工程毕业设计外文翻译.doc

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外文翻译

Thechangingroleofhydropower:

fromcheaplocalenergysupplytostrategicregionalresource

Abstract:

Theroleofhydropowerhasevolvedfrombeingalocal,low-costenergysourcetobeingaflexibleresourceofferingavarietyofancillaryservicesincludingregionalfrequencycontrolandenergystorageforlargeinterconnectedpowersystems.ThispaperexploresthisdevelopmentasitrelatestoaNorthAmericanmidcontinentelectricalpowerregion.Itreviewstraditionalbenefitsfromhydropowerinathermal-power-dominatedregionandtraditionaleffortstoquantitythosebenefits.Withthechallengesofintegratingincreasingquantitiesofvariablegenerationsuchaswindandsolarpower,newbenefitsfromhydropowerhavebeenidentifiedandnewmethodstoquantifythosebenefitshavebeendeveloped.Recentresultsofamajorstudyofthesub-hourlybehaviourofahydropowersysteminaMidwesternUnitedStateselectricalmarketarereviewed.

Keywords:

conventionalhydropower,renewableintegration,accommodatingvariablegeneration,hydroplantoptimization,benefitsofhydropower

Inthepast,therehavebeenmanydriversforintegratingCanadianhydropowersystemswiththermalsystemsintheUnitedStates.Theyincludedthesaleofsurplushydraulicenergy,leveragingtheloaddiversitybetweenwarmerandcoolerclimates,short-termenergyarbitrage,systemreliabilityimprovements,andfueldiversificationandemissionreduction.

Morerecently,increasedpenetrationlevelsofvariablerenewablegeneration,suchaswindandsolarpower,areincreasingtheuncertaintyandvariabilityintheelectricload–supplybalance.Thisposeschallengestotheoperationofregionalelectricalsystems.Theflexibilityandenergy-storagecharacteristicsofhydropowercanassistelectricalutilitiesandsystemoperatorsinmanagingthevariabilitythroughloadbalancingandshiftingenergyproductiontomoreopportunetimes.Manyhydrofacilitiesalreadyprovidesimilarbalancingservicesforload,whileothersmaynotbeabletobecauseofoperationalrestrictions.

Traditionalbenefitanalysesmaynotadequatelycapturealltheeconomicbenefitsattributabletoflexiblehydrogeneration,thusleavingsomethingonthetablewhenjustifyingnewdevelopments.Withthegrowthinvariablerenewableresources,thereisanincreasedneedformorecomprehensivebenefitcalculations.SeveralmajorstudiesintheUShaveattemptedtofullyquantifythebenefitshydropowerbringstotheelectricalsystemusinghourlymarketsimulations（GEEnergy,20109.GEEnergy.（2010）.WesternWindandSolarIntegrationStudy.Akeyconclusionofthesestudiesisthattofullycapturethebenefitsarisingfromthesynergyofhydropowerandvariablerenewablegeneration,sub-hourlymodellingandanalysisarerequired.

TheManitobaHydroWindSynergyStudy（MHWSS）,completedbytheMidcontinentIndependentSystemOperator（MISO）andManitobaHydro（MH）,isoneofthefirstpower-marketmodellingstudiesaimedatquantifyingthebenefitsofhydropoweratsub-hourlytimeframes.Thestudyexplicitlymodelsthevariabilityinwindpowerandtheenergy-storagecapabilitiesofmajorhydropowerfacilitiesinManitoba,inadditiontothetypicalcharacteristicsofday-aheadandreal-timeenergyandancillary-servicesmarkets.Thebenefitsarequantifiedintermsofsystemoperating-costreductions.Otherbenefits,includingreductionsinwindcurtailments,andadescriptionofthesynergybetweenwindandhydroarepresented.

Thisarticleisbrokenintoseveralsections.ThefirstsectionpresentsthehistoryofelectricpowergrowthinManitobaandthetraditionalbenefitsassociatedwithhydro–thermalintegration.Thesecondsectiondescribestheroleofhydropowerintheintegrationofvariablegenerationtechnologiesandthepreviouseffortstoquantifythebenefitsfromhydropower.ThefinalsectionpresentsarecentstudyintheUSMidwestandconclusionsfromthatwork.

Hydropowerresourcesarenotdistributeduniformlyaroundtheglobe.Someregionsarehydro-rich;othershavefewexistingorpotentialhydro-generationsites.Regionsrichinhydropowerresourceshavetraditionallydevelopedhydro-dominatedgenerationfleetsandbenefitedfromlow-costenergy,whileinregionswithfewerhydropowerresources,hydropower,whereavailable,hasplayedarelativelyminorrole.

ThreecommonelectricalpowersourcesinNorthAmericaaresteam-thermal（e.g.coalandnuclear）,combustionturbine（gas）andhydropower.Steam-thermalstationsarerelativelydifficulttostartandstopandtorampupordown.Asaresult,theyaretypicallyusedforcontinuous,base-loadedoperations.Combustionturbinesandhydropoweraremuchmoreflexibleandaretypicallyusedtorespondtopeakenergydemand.

Hydrostationshavemuchloweroperatingcoststhansteam-thermalorcombustionturbines,primarilythankstozerofuelcosts.However,hydrodoeshaveitsownsetofdrawbacks.Hydropowerdependsonstreamflowvolumes,anditsenergyoutputisoftenlimitedbycurrenthydro-climaticconditions.Additionally,thewaterresourceistypicallysharedwithotherusersandhydropoweroperationcanberestrictedinconsiderationoftheseotheruses.

InCanada,hydropowerplaysamajorrole:

formorethanacentury,hydropowerhasrepresentedmorethan60%ofCanada'selectricalgeneration.Threeofitsprovinces（Quebecintheeast,BritishColumbiainthewestandManitobaintheheartofthecountry）getmorethan90%oftheirelectricityfromwater（Rosano,201325.Rosano,M.（2013,June）.ThispaperiswrittenfromtheperspectiveofManitobaHydro.

CommercialuseofelectricitybeganinManitobain1882,withthefirstyear-roundhydropowerplantbeingdevelopedin1906.Thatfirstplant,Pinawa,producedelectricitythatfueledthedramaticgrowthoftheprovincefor45years,untilitwasshutdowntoallowanotherplant,SevenSisters,tousethewatermoreefficiently.TheSevenSistersgeneratingstationcontinuesinoperationover80yearspastitsfirstproduction–anoutstandingexampleoflow-cost,reliable,renewableenergy.

AsManitobawasdevelopingitsalmostexclusivelyhydropowergeneratingfleet,neighbouringprovincesandstatesweregenerallydevelopingthermal-poweredgenerationoramixtureofcoal-,nuclear-,gas-andhydro-fueledgeneration,asappropriate.

Manitobabuiltitsfirstextra-provincialinterconnection,a115kVconnectionfromSevenSisterstonorth-westernOntario,in1956.A138kVinterconnectiontoSaskatchewanwasbuiltin1960.Thecompletionofseveralhydroelectricstationsintheearly1960sandintothelate1970sprovidedManitobawithasurplusofgeneratingcapacityandenergy,leadingtotheconstructionofnineadditionalinterconnectionsbetween1970and1980.Seasonaldiversityexchanges–agreementsthatleveragetheloaddiversitybetweencolderandwarmerclimates–werethekeyeconomicdriverforthelargestoftheseinterconnections,a500kVlinebetweenManitobaandMinnesota.The12thandmostrecentinterconnectionwasbuiltin2002,a230kVlineconnectingwesternManitobatoNorthDakota.

Inthe1990s,theUSderegulatedenergymarketstoincreasecompetitionandthustoreduceresidentialandcommercialpowerratesandencourageinnovation.Today,accesstothetransmissionsystemisopentoall.Thishasledtothedevelopmentofelectrical-energymarketswithincreasedtransparencyandreducedmarketdominancefromutilities,providingcustomerswitheconomicbenefitsthroughreducedelectrical-energycosts.

ManitobaHydro'shydropowersystemlieswithintheChurchill–Nelsonriverbasin,whichhasadrainageareaofapproximately1.2millionkm2.ManitobaHydrocurrentlyhas17generatingstations（15hydropowerand2thermal）,withatotalratedcapacityof5700°MW（Figure2）.Over70%ofManitobaHydro'sinstalledcapacityisfromthreehydrostationslocateddownstreamoftheStephensLakeReservoirinnorthernManitoba:

Kettle,LongSpruceandLimestone.ThisallowsalargeportionofManitobaHydro'spowergenerationtoutilizetheshort-termstorageavailableinStephensLake.AnotherkeystationforManitobaHydroistheGrandRapidshydroelectricgeneratingstationlocatedattheoutletofCedarLake.GrandRapidshasacapacityof480°MWandisusedforbothlong-andshort-termstorageoperations.

ThemajorityofManitobaHydro'senergyexchangeiswiththemarketoperatedbyMISOandcounterpartieswithintheMISOmarket.MISOisthesecond-largestenergymarketintheUSbycapacity.theremaining14%comesfromhydro,windandothersources.

Traditionalintegrationbenefits

TheinterconnectionsbetweenManitoba'shydro-dominatedsystemandthermal-dominatedsystemsintheUSweredevelopedbasedonmutuallybeneficialeconomicsarisingfromintegratingthecharacteristicsofthetwosystems.Theseincludehydraulicsurplus,seasonaldiversity,short-termarbitrage,fueldiversificationandemissionreduction,andelectricalsystemreliabilitysupport.

Hydraulicsurplusisaresultingcharacteristicofhydropowersystemsasstreamflowinriversvariesfromyeartoyearbasedonhydroclimaticconditions.Streamflowvariabilityisamajorconcernforhydroelectricutilitiesbecauseitcausessignificantchangesinannualgeneration.Forexample,infiscalyear2003–2004（alower-streamflowyear）,ManitobaHydrogenerated19.3°TWh.Infiscalyear2004–2005（ahigher-streamflowyear）,ManitobaHydrogenerated31.5°TWh（ManitobaHydro,200515.ManitobaHydro.（2005）.ManitobaHydro-ElectricBoard54thAnnualReport.Winnipeg,Manitoba:

ManitobaHydro.

Thisrepresentsachangeingenerationof62%betweentwoconsecutivefiscalyears.Hydro-dominantutilitiestypicallyplantohaveenoughenergysupplytoservetheirloadrequirementsduringperiodsoflo