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1、ControlandProtectionofMulti-DERMicrogridsbyAmirHosseinEtemadiAdissertationsubmittedinconformitywiththerequirementsforthedegreeofDoctorofPhilosophyGraduateDepartmentofElectricalandComputerEngineeringUniversityofTorontoCopyrightc2012byAmirHosseinEtemadiAbstractCont
2、rolandProtectionofMulti-DERMicrogridsAmirHosseinEtemadiDoctorofPhilosophyGraduateDepartmentofElectricalandComputerEngineeringUniversityofToronto2012Thisdissertationproposesapowermanagementandcontrolstrategyforislandedmicrogrids,whichconsistofmultipleelectronicall
3、y-interfaceddistributedenergyresource(DER)units,toachieveaprescribedloadsharingscheme.Thisstrategyprovidesi)apowermanagementsystemtospecifyvoltagesetpointsbasedonaclassicalpowerflowanalysis;2)DERlocalcontrollers,designedbasedonarobust,decentralized,servomechanisma
4、pproach,totrackthesetpoints;and3)afrequencycontrolandsynchronizationscheme.Thisstrategyisthengeneralizedtoincorporatebothpower-controlledandvoltage-controlledDERunits.Sincethevoltage-controlledDERunitsdonotuseinnercurrentcontrolloops,theyarevulnerabletoovercurren
5、t/overloadtransientssubsequenttosystemseveredisturbances,e.g.,faultsandoverloadingconditions.TopreventDERunittrip-outordamageundertheseconditions,anovercurrent/overloadprotectionschemeisproposedthatdetectsmicrogridabnormalconditions,modifiestheterminalvoltageofthe
6、correspondingVSCtolimitDERunitoutputcurrent/powerwithinthepermissiblerange,andrestoresvoltagecontrollerssubsequently.Undercertaincircumstances,e.g.,microgridislandingandcommunicationfailure,thereisaneedtoswitchfromanactivetoalatentmicrogridcontroller.Tominimizeth
7、eresultanttransients,controltransitionshouldbeperformedsmoothly.Fortheaforementionedtwocircumstances,twosmoothcontroltransitiontechniques,basedon1)anobserverand2)anauxiliarytrackingcontroller,areproposedtoachieveasmoothcontroltransition.Atypicalmicrogridsystemtha
8、tadoptstheproposedstrategyisinvestigated.Themicrogriddynamicsareinvestigatedbasedoneigenvaluesensitivityandrobustanalysisstudiestoevaluatetheperformanceofthecl
