光伏发电逆变器及控制策略的研究

分类号学号201104710032学校代码10488密级硕士学位论文光伏发电逆变器及控制策略的研究学位申请人：张轶婷学科专业：控制理论与控制工程指导教师：王斌答辩日期：2014年5月20日ADissertationSubmittedinPartialFulfillmentoftheRequirementsfortheDegreeofMasterinEngineeringResearchofphotovoltaicinverterandcontrolstrategyPh.D.Candidate：ZhangYitingMajor：ControlTheoryandControlEngineeringSupervisor：Prof.WangBinWuhanUniversityofScienceandTechnologyWuhan,Hubei430081,P.R.ChinaMay20th,2014I摘要在能源消费日益增长和可持续发展要求越来越高的今天，太阳能光伏发电作为清洁可再生的能源，已经逐步成为新能源开发中的主要形式。逆变器是太阳能光伏发电系统的核心部分，本文以光伏发电逆变系统为研究对象，以逆变器及其控制策略为重点，在PSCAD4.5Schematic环境中设计了由光伏电池，双向Buck-Boost逆变器组成的双级光伏逆变系统，仿真结果表明系统能够达到设计要求。针对光伏发电系统的特点，逆变器要有较大的直流输入电压范围。本文选择了一种新型的双向Buck-BoostDC/AC电压源逆变电路，由两组双向Buck-Boost斩波电路输入并联、输出反向串联组成，该拓扑能够实现单级升-降压逆变。本文采用的是PWM控制技术对脉冲的宽度进行调制，进而控制开关管的占空比。为了改善多环PI控制方法中存在的纹波干扰较大的问题，本文展开了对电感电流、负载电压、负载电流的归一化控制方法的研究，将电流内环控制与电压外环控制统一起来，在一定程度上改善了输出电压的纹波问题，提高了系统的稳定速度。为了验证该逆变系统对光伏发电的适用性，本文对光伏电池及基于Boost电路的MPPT控制进行了仿真建模，通过对比各种MPPT控制算法后，选择了适合本系统的电导增量法，能够较好地跟踪到光伏电池的最大功率点。最后将光伏电池模块与逆变器组成光伏发电逆变系统进行了仿真联调，分析了光照，温度以及MPPT控制等各种影响因素，并对系统的输出特性进行了详细的仿真测试与研究，结果表明光伏电池能工作在最大功率点，逆变器的输出达到了设计指标。关键词：光伏发电；最大功率跟踪；升-降压逆变；归一化控制IIAbstractWiththegrowingenergyconsumptionandincreasingrequirementforsustainabledevelopment,solarphotovoltaicpowergeneration,asacleanandrenewableenergy,hasgraduallybecomethemainformofnewenergydevelopment.Theinverteristhecorepartofthesolarphotovoltaicpowergenerationsystem.Thispaperstudiesthephotovoltaicinvertersystem，focusoninverteranditscontrolstrategy.Atwo-levelphotovoltaicinvertersystemisdesignedinSchematicenvironmentofPSCAD4.5,whichiscomposedbythephotovoltaiccellsandbidirectionalBuck-Boostinverter.Simulationresultsshowthatthesystemcanmeetthedesignrequirements.Accordingtothecharacteristicsofphotovoltaicpowergenerationsystem,theinverterrequiresalargeDCinputvoltagerange.Inthispaper,anovelDC/ACvoltageinvertercircuitisselected.ThiscircuitconsistsoftwobidirectionalBuck-Boostchoppercircuitinputparalleloutputreverseinseries,whichenablessingle-stageBuck-BoostDCtoACconversion.Thispaperusespulsewidthmodulationtechnologytocontroltheswitchdutycycle.Inordertoimprovetherippleinterferenceproblemofmulti-loopPIcontrolmethod,thisarticlelaunchedastudyonthenormalizationmethodforcontrollingtheinductorcurrent,loadvoltage,loadcurrent,unifiedthecurrentloopcontrolandoutervoltagecontrol,andimprovedtheproblemoftheoutputvoltagerippleandimprovethestabilityofthesystemspeed.Inordertoverifytheapplicabilityoftheinverterforphotovoltaicpowergenerationsystem,modelingandsimulationsforphotovoltaiccellsandBoostbasedMPPTcontrolcircuithavebeenmadeinthispaper.BycomparingthevariousMPPTcontrolalgorithm，GNCmethodisselectedtoadaptthesystem.GNCmethodcantrackthemaximumpowerpointofthephotovoltaiccelleffectively.Finally,asimulationsystemcomposedofthePVmodulesandthePVinverterisframed.Withvariouseffectivefactorsofradiationintensity,temperature,andMPPTcontrolhavebeentakenintoaccount,theoutputcharacteristicsofthesimulationsystemaretestedandresearchedindetail.Theresultsshowthatphotovoltaiccellscanworkatthemaximumpowerandtheoutputparametersoftheinverterconformthedesignspecifications.Keywords:Photovoltaicpowergeneration;Maximumpowerpointtracking;Buck-Boostinverter;NormalizationcontrolIII目录摘要...............................................................................................................................IAbstract.............................................................................................................................II第1章绪论......................................................................................................................11.1课题背景及意义..................................................................................................11.2光伏发电逆变系统的发展现状...........................................................................21.3本文采用的系统方案...........................................................................................41.4本文的研究内容..................................................................................................5第2章光伏电池的特性研究...........................................................................................72.1光伏电池的仿真建模...........................................................................................72.1.1光伏电池的工作原理................................................................................72.1.2光伏电池的输出特性仿真........................................................................82.2MPPT控制的仿真与设计.................................................................................102.2.1MPPT控制原理...................................................................................102.2.2各种MPPT控制方法的比较.................................................................112.2.3基于Boost电路的MPPT仿真设计......................................................142.2.4仿真结果分析.........................................................................................162.3本章小结...........................................................................................................18第3章逆变器及其控制策略的研究............................................................