空间电荷

哈尔滨理工大学工学硕士学位论文-I-摘要纳米聚合物复合材料作为一种新材料，已经引起了越来越多的关注。通过向聚合物中填加少量的纳米填料，原有的性能将会被改善。纳米氧化镁交联聚乙烯复合介质已经被成功应用于高压直流输电系统中，这种新材料可以提升直流电压下的击穿电压。在本论文中，将会对外国学者近年来对纳米聚合物复合材料电特性所做的研究和实验结果做总结。它们包括电导率，介电特性，局部放电，电树及空间电荷特性。还会对ToshikatsuTanaka所提出的用于解释纳米复合材料各种性能的多核模型做介绍。在实验部分，首先，用电声脉冲法对加入纳米MgO的复合介质做空间电荷测试。发现加入纳米粒子后，空间电荷降低。当填量大于0.5phr时，对空间电荷的抑制作用就会非常明显。然后，通过光刺激电流法测量了XLPE和MgO/XLPE的陷阱能级。结果发现MgO/XLPE拥有更深的陷阱。最后，对XLPE和MgO/XLPE的电致发光起始电压及发光光谱进行了测量。结果表明，复合介质提升了EL的起始电压并且降低了发光量。并且XLPE与MgO/XLPE的光谱存在很大的区别。关键词纳米复合材料，交联聚乙烯，空间电荷，陷阱哈尔滨理工大学工学硕士学位论文-II-AbstractPolymernanocompositematerialshavebeenattractingmuchattentionasanewmaterialbecausethepropertiesoftheoriginalmaterialcanbedrasticallyimprovedbyaddingafewpercentofnano-sizedfiller.Ithasbeenfoundthatnano-sizedMgO-filleraddedintoXLPE(crosslinkpolyethylene),whichhadbeendevelopedforHVDCcableinsulation,improvedthedcbreakdownpropertyofconventionalXLPEcable.Inthispaper,recenttopicsandtheirimportantresultswillbereviewedonelectricalpropertiesofpolymernanocompositematerials.Theyincludecharacteristicsassociatedwithelectricalconduction,dielectricproperties,partialdischarge,electricaltreeingandspacechargeformation.Amulti-coremodelproposedbyToshikatsuTanakaisdiscussedtounderstandvariouspropertiesandphenomenainnanocomposite.Atfirst,toinvestigatetheinfluenceofMgOnano-filleronspacechargeproperties,wemeasuredthespacechargedistributionsusingPEA(pulsedelectro-acousticmethod)systemunderDCelectricfield.InthecaseofLDPEwithnano-filler,thereislessspacechargeinjectionthanLDPE.Itisthoughtthatspacechargeinjectionisdrasticallypreventedbyaddingonlymorethan0.5phrofMgOtoLDPE.Also,wemeasuredthetrapdepthofconventionalXLPEandMgO/XLPEbyusingaphoto-stimulateddischargesystem.WefoundthatthetrapdepthinMgO/XLPEisdeeperthaninXLPE.Spacechargeisexpectedtobecloselyrelatedtothenatureofcarriertraps.Finally,electricfielddependence,timevariationsandthespectraofEL哈尔滨理工大学工学硕士学位论文-III-(electroluminescence)pulseswereexamined.Astheresultsoftheseexperiments,theadditionofMgOnanoparticlesinXLPEmatrixmakeselevatetheELinceptionlevelanddecreasethenumberofELpulses.TheELspectraisdifferentbetweenXLPEandMgO/XLPE.Keywords:nanocomposite,crosslinkpolyethylene,spacecharge,trap,electroluminescence哈尔滨理工大学工学硕士学位论文-IV-目录摘要...............................................................................................................................IAbstract.......................................................................................................................II第1章绪论............................................................................................................11.1课题研究的背景及意义...................................................................................11.2影响聚合物中空间电荷行为的主要因素.......................................................21.3本文的主要工作...............................................................................................3第2章国外对纳米MgO聚合物复合绝缘材料的研究现状.................................42.1纳米MgO聚合物复合材料电性能................................................................42.1.1电阻率........................................................................................................42.1.2介电常数与损耗........................................................................................42.1.3局部放电....................................................................................................52.1.4电树............................................................................................................52.1.5空间电荷....................................................................................................52.1.6基于纳米聚合物复合材料的多核模型....................................................5第3章纳米MgO复合介质的空间电荷行为.........................................................73.1MgO/PE复合介质的制备.................................................................................73.1.1MgO的制备...............................................................................................73.1.2MgO的表面改性.......................................................................................73.1.3MgO/LDPE的制备....................................................................................73.1.4平板试样的制备........................................................................................83.2空间电荷测量...................................................................................................83.2.1测量系统....................................................................................................83.2.2实验数据与结果分析................................................................................83.3本章小结...........................................................................................................9结论............................................................................................................................10参考文献....................................................................................................................11哈尔滨理工大学工学硕士学位论文-1-第1章绪论1.1课题研究的背景及意义自1882年开创用直流输电输送电能的历史以来，随着电力电子技术的突飞猛进，高压直流输电技术也得到飞速发展。由于高压直流输电在长距离输电、电网互联等方面具有独特的优点，