【作者】 吕程；

【导师】 廖瑞金；

【作者基本信息】 重庆大学 ， 电气工程， 2014， 博士

【摘要】 超特高压输电技术的发展对输变电设备的绝缘性能提出了更高的要求，特别是直流换流变压器，在交流、直流、脉动、直流极性反转等复杂运行条件下，要求其油纸绝缘不但具有高的交流耐受能力，在直流尤其是极性反转情况下的绝缘能力仍然很强，研究高性能的换流变油纸绝缘材料成为行业发展之必需。同时，从材料本质性能提高来改善油纸绝缘能力也面临着电气与材料领域交叉的理论和制备等难题。因此，论文选择研究纳米改性纤维素绝缘纸来提高油纸绝缘的性能，具有重要理论和实际价值。本论文的主要目的是制备出一种在交直流电场下均具有较高绝缘性能的新型绝缘纸。首先研究纳米TiO2改性绝缘纸的制备工艺，然后对新的改性绝缘纸的抗张强度、介电性能、工频下的击穿性能进行测试，得到最佳的配比。再对具有最优配比的新型绝缘纸交直流下的各种击穿性能、直流条件下空间电荷的积聚与消散特性进行研究，最后分析纳米TiO2影响纤维素绝缘纸绝缘性能的机理，本文的主要研究成果有：①研究得到了利用纳米TiO2改性绝缘纸的制备工艺和配比，在制备出纳米TiO2改性绝缘纸后，对纳米TiO2改性绝缘纸和未改性绝缘纸的抗张强度、介电性能、以及其在工频下的击穿特性进行对比分析，得到纳米TiO2的最佳添加量为3%，含3%纳米TiO2改性绝缘纸与未改性绝缘纸相比，抗张强度没有降低，工频下击穿场强、局部放电起始放电电压，直流下的击穿电压、局部放电起始放电电压都有大幅度提高；②含3%纳米TiO2改性绝缘纸与未改性绝缘纸相比，正极性直流下的击穿电压显著提高，预加正负极性电压后的正极性直流击穿电压均显著提高，能够在发生极性反转时保持更高的击穿电压，有利于降低击穿事故的发生。③首次研究成功了具有抑制空间电荷向绝缘纸中注入，降低绝缘纸内部电场畸变和加快空间电荷消散作用的纳米TiO2改性绝缘纸。PEA空间电荷测试表明不论较低、较高场强作用下，含3%纳米TiO2改性绝缘纸均具有抑制空间电荷向绝缘纸内部注入、降低内部场强畸变的作用。在去掉外加场强后，含3%纳米TiO2改性绝缘纸内部空间电荷消散速率大大提高。④首次分析得到了纳米TiO2提高纳米TiO2改性绝缘纸击穿性能和改善空间电荷积聚、消散性能的机理。纳米TiO2与纤维素间的强相互作用改变了纤维素与纳米TiO2接触面的结构，形成了类似多核模型的界面结构，有利于形成更多的陷阱；进一步通过TSC测试表明，纳米TiO2与纤维素的接触界面大大增加了绝缘纸中浅陷阱的数量，减少了深陷阱的数量。陷阱数量和能级的变化改变了绝缘纸的击穿性能和空间电荷性能。更多还原

【Abstract】 Because of the development of ultra-UHV power transmission insulation level ofpower transmission equipment is asked to rise. Especially for HVDC convertertransformers，oil-paper insulation not only has a high AC breakdown strength, but alsostrong DC breakdown strength when the voltage polarity is reversed in AC, DC, pulseand DC reverse polarity complex operating conditions. That converter transformeroil-paper insulation material is studied becomes necessary for the development of theindustry. Meanwhile, oil-paper insulation capability is improved from materialproperties of nature, difficult problem of electrical and field theory and the preparationof the material cross that is faced. Thus, nanoparticles are used to modified theperformance of oil-paper insulation has important theoretical and practical value.The main purpose of this paper is to prepare a new type of insulation paper whichhas high insulation propertiesin the AC and DC fields. First the preparation of insulationpapermodified by nano-TiO2is studied. Then the best match is given by studying thetensile strength, dielectric properties and power frequency breakdown strength. Then thevariety of ACbreakdown strength, DC breakdown strength are studied, the accumulationand dissipation characteristics of space charge under DC field strength are studied.Mechanism thatthe insulation properties of cellulose insulation paper are affected bynano-TiO2is analyzed at last. This paper achieves following results:①The preparation process and ratio of nano-TiO2were obtained. After theinsulation paper modified by nano-TiO2was prepared.Tensile strength, dielectricproperties, as well as breakdown strength of insulation paper modified by nano-TiO2were analyzed. The best ratio of nano-TiO2in insulation paper was3%, tensile strengthof insulation paper modified by nano-TiO2did not decrease, the breakdown fieldstrength of power frequency, the partial discharge inception voltage, the breakdownvoltage, the partial discharge inception discharge voltage underDC of insulation papermodified by nano-TiO2have increased significantlycompared with the unmodifiedinsulation paper;②Insulation paper modified by3%nano-TiO2compared to the unmodifiedinsulation paper, Dc breakdown voltage of positive polarity is significantly improvedafter Pre-pressurized positive and negative polarity voltage, high breakdown voltage ismaintained when the voltage polarity is reversed, that helps to reduce the occurrence accidents of breakdown.③For the first time the insulation paper that can suppress the space chargeinjected to insulation paper, reduce electric field distortion, accelerates the dissipation ofspace charge is prepared with nano-TiO2. PEA space charge tests show that insulationpaper modified by3%nano-TiO2can suppress the space charge injected to insulationpaper, reduce electric field distortion, accelerates the dissipation of space charge underlow and high field strength. Space charge dissipation rate of insulation paper modifiedby3%nano-TiO2is greatly improved.④For the first time mechanism that insulation paper breakdown performance andspace charge accumulation, dissipation performance are improved is studied. Thecontact surface structure between cellulose and nano-TiO2is changed because of thestrong interaction between the nano-TiO2nanoparticles and cellulose. Multi-core modelsimilar interface structure is formed, more traps are formed. TSC tests show that thenumber of shallow traps is greatly increased because of the nano-TiO2contact interfacewith cellulose, the number of deep traps is reduced. Breakdown strength performanceand space charge performance are improved because of changes in the number and levelof the trap.更多还原