多巴胺接枝的纳米氮化硼改性环氧树脂绝缘表面电荷高频消散特性  

Study on the Surface Charge Dissipation Characteristics of Epoxy Resin Modified by Dopamine Grafted Nano Boron Nitride under High Frequency Electric Stress

作　　者：李志辉 解曾祺 李庆民 董紫薇 王忠东 Li Zhihui;Xie Zengqi;Li Qingmin;Dong Ziwei;Wang Zhongdong(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University,Beijing 102206 China;Beijing Key Lab of HV and EMC North China Electric Power University,Beijing 102206 China;College of Engineering Mathematics and Physical Sciences University of Exeter Exeter,EX44QJ United Kingdom)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京102206 [2]北京市高电压与电磁兼容重点实验室(华北电力大学),北京102206 [3]埃克塞特大学数学与物理工程学院,埃克塞特EX44QJ

出　　处：《电工技术学报》2023年第5期1116-1128,共13页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(51929701,51737005,52127812)。

摘　　要：环氧树脂(EP)常用作高频变压器的主绝缘材料,因长期受高频重复电应力作用,导致表面积累的电荷密度增加,容易诱发绝缘失效。纳米改性是提升复合绝缘界面电荷消散特性的重要手段。该文采用多巴胺接枝的纳米氮化硼(h-BN)改性制备了环氧树脂复合材料,重点考察绝缘表面电荷的高频消散特性。受耗散时间、高频致热效应及深陷阱能级的影响,高频下的绝缘表面电荷不易消散,而引入多巴胺接枝的BN可有效提升环氧树脂复合绝缘的电荷消散速率。具体结果表明,掺杂质量分数为10%时,电荷消散速率达到最大值62.15%,相较于纯EP提高了19.41%,与此同时高频沿面闪络电压比纯EP提高了14.73%。其提升机理主要缘于两个方面:一是BN表面接枝的氨基增强了填料与基体的相容性,形成的三维交联网络拓宽了电荷消散路径;二是材料表层浅陷阱密度的提高,使得载流子易通过隧穿效应参与到电导过程,提高了载流子迁移率;此二者协同作用有效提高了表面电荷的高频消散速率。上述研究结果为高频变压器主绝缘系统优化设计提供了基础依据。Epoxy resin(EP)has excellent electrical and mechanical properties,commonly used as the main insulation material of high frequency power transformer.However,due to long-term work in a short rise time,high frequency voltage operation,the surface charge accumulation and dissipation process of the main insulation is affected under high frequency voltage.Surface charge is difficult to dissipate makes the degree of accumulation increased,resulting in increased surface charge density,easy to induce insulation failure.Nano modification is an effective means as to improve charge dissipation along composite insulation surface.In this proposed research,EP composites were prepared with dopamine modified nano boron nitride(h-BN).In this paper,a surface potential test system was first built to characterize the surface charge distribution of EP composites after high-frequency corona discharge,and then the isothermal current decay method was used to calculate the trap energy level distribution of EP composite insulating materials.The results show that the increase of the voltage frequency will lead to the increase of the initial potential and the accumulated charge density on the EP surface,and the potential decay rate first decreases and then increases,and reaches a minimum value at 10kHz.In addition,the high-frequency dissipation characteristics of the modified EP composites were also studied,and it was found that the dopamine grafting modification could effectively improve the high-frequency dissipation rate of the EP surface charge.When the doping mass fraction was 10%,the charge dissipation rate It reaches the maximum value of 62.15%,which is 19.41%higher than that of pure EP.The high frequency surface flashover characteristics of the two composite materials were further tested by the uniform boost method.The experimental results show that doping a certain concentration of BN nanofillers and BN fillers grafted with polydopamine can improve the creeping insulation performance of EP composites under high frequency stress,but

关 键 词：高频变压器 纳米氮化硼 环氧树脂 表面电荷 浅陷阱 

分 类 号：TM216[一般工业技术—材料科学与工程]