牵引供电系统的高次谐波的仿真与分析-毕设论文.doc

兰州交通大学毕业设计（论文）--牵引供电系统的高次谐波的仿真与分析摘要电气化铁道作为公用电网的非线性负载，已成为引起电力系统谐波污染的主要谐波源之一。这主要是因为在电气化铁道上行驶的电力机车是单相的整流型负荷。由于功率大，分布广，而且三相不对称，在其运行过程中必然会产生大量的高次谐波，并将在接触网上激发起沿线分布的高次电压和电流谐波，它们对电气化铁道沿线的通信系统会造成严重的干扰。随着交直交动车组在电气化铁道中的大量采用，使得牵引供电系统中的谐波特性发生变化，除了含有低频带的3、5、7次等谐波外，在高频带还出现了大量的高次谐波。尽管这些高频带谐波含有率不高，但其却大大增加了系统发生谐波谐振的可能性。当系统发生谐波谐振时，会形成较大的过电压和过电流，危害牵引变电所和电力机车等的绝缘设备，影响系统安全运行。本文对电力系统的谐波特性做了详细的理论研究和分析，重点阐述了牵引供电系统谐波的形成、谐波参数并对一些设备的谐波进行了分析，以便可以更加深刻的理解牵引供电系统的谐波分布，谐波形成和控制，维持牵引供电系统的稳定性和可靠性。最后，本文对牵引供电系统的高次谐波进行了仿真、分析，更加直观的展示了牵引供电系统的谐波特点及其分布，进一步加深理解。关键词：高次谐波；牵引供电；谐波电流放大；MATLAB/SimulinkAbstractElectrifiedrailway,asthenonlinearloadofpublicelectricnet,hasbecomeoneofmainharmonicsourcescausingharmonicpollutioninthepowersystem,whichismainlybecausethatelectriclocomotiverunningontheelectrifiedrailwayissingle-phaserectifierload.Onaccountofitsgreatpower,widedistributionandthree—phaseasymmetric,itwillproduceagreatdealofhigh—orderharmonicsandonthecontactnetwillexcitehigh—ordervoltageandcurrentharmonicsdistributingalongtheline,whichwillinterfereseriously,withthecommunicationsystemalongtheelectrifiedrailway．WiththewideapplicationofAC—DC—ACmultipleunitsinelectricrailway,harmoniccharacteristicinthetractionPowersupplysystemhasbeenchanged.Notonlythelow—orderharmonies,forexample,third—order,fifth—orderandseventh—orderharmonicwereincludedinthissystem,butalsoalotofhigh—orderharmonicwerecontained.Althoughthecontentrateofthesehigh—orderharmonicsverylow,thepossibilityofharmonicresonanceinthesystemwillgreatlyincrease.Whenharmonicresonanceoccurredinthesystem,overvoltageandovercurrentwillproduce,whichcanendangerequipmentinsulationoftractionsubstationandtrainandinfluencethesystemsafetyoperation.Inthispapertheharmoniccharacteristicofpowersystemtodoadetailedtheoreticalresearchandanalysis,expoundsthetractionpowersupplysystemharmonicformation,andsomeequipmentharmonicparametersareanalyzed,sothattheycanmoreprofoundunderstandingofharmonicdistributionofthetractionpowersupplysystem,harmonicformationandcontrol,maintaintraction