文档名：不同热老化温度下高压电缆绝缘特性及失效机理
摘要：高压电缆的运行温度是影响其绝缘性能的关键因素.该文通过对交联聚乙烯(XLPE)开展不同温度下的加速热老化实验,对比了XLPE微观理化性能和宏观电学性能的变化规律.同时,在微观层面模拟了XLPE分子在不同温度下自由体积与均方位移的变化规律,在宏观层面结合XLPE的介电性能分析了高压电缆内部温度场的变化规律,进而揭示了高温下高压电缆的绝缘失效机理.研究结果表明,随着老化温度的升高,XLPE分子的劣化程度加快,羰基、碳碳双键等官能团含量增大;介质损耗因数与介电常数逐渐增加,甚至出现了突增的现象;结晶区结构的被破坏加快了击穿场强的下降;分子运动加剧,自由体积率从12.53%增大至14.07%.老化后介电性能的下降会导致电缆内部温度升高,从而对电缆的热老化起到了正反馈作用.
Abstract：Cross-linkedpolyethylene(XLPE)high-voltagecablesareaffectedbyenvironmentalfactorssuchastemperature,voltageandhumidityduringoperation,resultinginthedegradationoftheinsulationpropertiesofhigh-voltagecablesandtheoccurrenceofagingproblems.Temperatureisthemainfactorcausingcableaging.Whenashortcircuitoccursinthecable,thetemperatureofthecablecanreachupto250℃,whichseriouslyaffectstheinsulationcharacteristicsofthecable.Atpresent,theagingproblemofhigh-voltagecablesismainlystudiedfortheinsulationstateatindividualtemperatures,andthereisalackofcorrespondingresearchreportsonthelong-termoperatingcharacteristicsofhigh-voltagecablesatdifferenttemperatures.Inthispaper,thephysicochemicalandelectricalpropertiesofhigh-voltagecableinsulationatdifferentthermalagingtemperatureswerestudied,andthechangesofmoleculardynamicsandinternaltemperaturefieldofXLPEhigh-voltagecableswereanalyzedbycombiningexperimentalresultswithmolecularsimulationandfiniteelementsimulationanalysis.Firstly,commercialhigh-voltagecableinsulationmaterialwasusedtomakeXLPEinsulationlayerbymeltpreparation.TheXLPEwasplacedinovenswithdifferentthermalagingtemperatures,andtheagingtemperaturesweresetto140℃,160℃and180℃,respectively.Thechangepatternsoffunctionalgroups,dielectricconstant,dielectriclossandbreakdownstrengthofXLPEweretestedunderdifferentagingtimes,respectively.Secondly,thethermal-oxidativeagingmechanismofhigh-voltagecableswasanalyzedaccordingtothechangepatternofphysicochemicalandelectricalpropertiesofXLPEunderdifferentthermalagingtemperatures.TheresultsshowthedeteriorationofXLPEmolecularchainsacceleratesthegenerationofpolarfunctionalgroups,mainlyincludingcarbonylandcarbon-carbondoublebonds,withtheincreaseofagingtemperature.Theinsulationperformancereachesacriticalvaluewhentheagingtimeofthehigh-voltagecableinsulationlayerexceedsthefailurepointofthelife,thecontentofpolargroupsincreasesrapidly.Thechangeofmicroscopicmolecularstructureleadstotherapiddeclineofmacroscopicelectricalproperties.Thehigherthetemperature,thefasterthedecreaseofbreakdownfieldstrength,andthebreakdownfieldstrengthdecreasedto53.73kV/mmafteragingat180℃for24h.Finally,themoleculardynamicscharacteristicsofthehigh-voltagecableareanalyzedincombinationwithmolecularsimulationandfiniteelementsimulationwithrespecttothevariationoftheinternaltemperaturefield.ThefreevolumerateofXLPEis12.53%,13.40%,and14.07%whenthetemperatureis140℃,160℃,and180℃,respectively.Thehighertheagingtemperature,thehigherthefreevolumeofXLPEmolecules.TheincreaseinthefreevolumeofXLPEmoleculesleadstoanincreaseinthespaceavailableforthefreemovementofelectrons,adecreaseintheresistancetoelectronmovementandanincreaseinthekineticenergyoftheelectrons,whichexacerbatesthedegreeofdamagetothemolecularchain.Forexample,in2000ps,themeansquaredisplacementsare22.43?2,26.57?2,and44.77?2attemperaturesof140℃,160℃,and180℃,respectively.Accordingtothevariationrulesofdielectricconstantanddielectriclossatdifferentagingtemperatures,theinternaltemperatureofhigh-voltagecablesincreaseswiththeincreaseofdielectricconstantanddielectricloss,whichplaysapositivefeedbackroleinthethermalagingofhigh-voltagecables.
作者：段玉兵 韩明明 王兆琛 兰锐 李国倡 Author：DuanYubing HanMingming WangZhaochen LanRui LiGuochang
作者单位：国网山东省电力公司电力科学研究院济南250002山东省高压绝缘系统与先进电工材料工程研究中心(青岛科技大学先进电工材料研究院)青岛266042
刊名：电工技术学报
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(1)
分类号：TM852
关键词：高压电缆 热老化 交联聚乙烯 仿真分析
Keywords：High-voltagecable thermalaging cross-linkedpolyethylene simulationanalysis
机标分类号：TS176+.3TK421TM247
在线出版日期：2024年1月18日
基金项目：国网山东省电力公司科技项目不同热老化温度下高压电缆绝缘特性及失效机理[
期刊论文] 电工技术学报--2024, 39(1)段玉兵 韩明明 王兆琛 兰锐 李国倡高压电缆的运行温度是影响其绝缘性能的关键因素.该文通过对交联聚乙烯(XLPE)开展不同温度下的加速热老化实验,对比了XLPE微观理化性能和宏观电学性能的变化规律.同时,在微观层面模拟了XLPE分子在不同温度下自由体积与均...参考文献和引证文献
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不同热老化温度下高压电缆绝缘特性及失效机理 Insulation Characteristics and Failure Mechanism of High-Voltage Cables under Different Thermal Aging Temperatures
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