电力电子技术专业翻译.doc

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1、本科毕业设计（论文）中英文翻译院（系部）电气工程与自动化学院专业名称电气工程及其自动化年级班级　学生姓名　学号指导老师2012年6月8日1PowerElectronicConceptsPowerelectronicsisarapidlydevelopingtechnology.Componentsarettinghighercurrentandvoltageratings,thepowerlossesdecreaseandthedevicesbecomemorereliable.Thedevices

2、arealsoveryeasytocontrolwithamegascalepoweramplification.Thepricesarestillgoingdownpr.kVAandpowerconvertersarebecomingattractiveasameantoimprovetheperformanceofawindturbine.Thischapterwilldiscussthestandardpowerconvertertopologiesfromthesimplestconvert

3、ersforstartinguptheturbinetoadvancedpowerconvertertopologies,wherethewholepowerisflowingthroughtheconverter.Further,differentparksolutionsusingpowerelectronicsarealsodiscussed.1.1CriteriaforconceptevaluationThemostcommontopologiesareselectedanddiscusse

4、dinrespecttoadvantagesanddrawbacks.Veryadvancedpowerconverters,wheremanyextradevicesarenecessaryinordertogetaproperoperation,areomitted.1.2PowerconvertersManydifferentpowerconverterscanbeusedinwindturbineapplications.Inthecaseofusinganinductiongenerato

5、r,thepowerconverterhastoconvertfromafixedvoltageandfrequencytoavariablevoltageandfrequency.Thismaybeimplementedinmanydifferentways,asitwillbeseeninthenextsection.Othergeneratortypescandemandothercomplexprotection.However,themostusedtopologysofarisasoft

6、-starter,whichisusedduringstartupinordertolimitthein-rushcurrentandtherebyreducethedisturbancestothegrid.1.2.1SoftstarterThesoftstarterisapowerconverter,whichhasbeenintroducedtofixedspeedwindturbinestoreducethetransientcurrentduringconnectionordisconne

7、ctionofthegeneratortothegrid.Whenthegeneratorspeedexceedsthesynchronousspeed,thesoft-starterisconnected.Usingfiringanglecontrolofthethyristorsinthesoftstarterthegeneratorissmoothlyconnectedtothegridoverapredefinednumberofgridperiods.Anexampleofconnecti

8、ondiagramforthesoftstarterwithageneratorispresentedinFigure1.Figure1.Connectiondiagramofsoftstarterwithgenerators.Thecommutatingdevicesaretwothyristorsforeachphase.Theseareconnectedinanti-parallel.Therelationshipbetweenthefiringangle(﹤)