【作者】 刘弘景；

【导师】 杜伯学；

【作者基本信息】 天津大学 ， 高电压与绝缘技术， 2010， 博士

【摘要】 聚合物电介质材料在电力系统中发挥着重要作用,一旦发生绝缘破坏,就极有可能会导致短路、停电甚至着火、爆炸等事故的发生,后果严重。聚合物电介质材料在宇宙及核聚变环境中受到大量放射线辐射后,其绝缘性能将发生很大变化,高能辐射严重影响了聚合物电介质材料的应用。因此,研究高能辐射对聚合物电介质绝缘特性的影响对于工程电介质的实际使用有着极为重要的意义。随着宇宙航天事业和核工业的发展,越来越多的电气电子设备将在各种辐射场环境下运行,聚合物电介质材料的使用环境也趋于多样化。很多聚合物电介质在受到高能辐射的同时,还会受到其它一些环境因素如真空、强磁场磁场等极端环境的影响。目前,多因素并存辐射环境下聚合物电介质绝缘性能方面的研究还比较少。所以研究多因素并存辐射环境下聚合物电介质的绝缘破坏具有较大的理论和现实意义。本文以广泛应用在变压器、电动机、继电器、电缆以及电容器等电力设备中的聚萘二甲酸丁二醇酯(PBN)、聚对苯二甲酸丁二醇酯(PBT)、聚对苯二甲酸乙二醇酯(PET)、环氧树脂(EX)、聚碳酸酯(PC)等常用聚合物电介质为试样,采用60Co伽马射线放射源以10 kGy/h辐射率对试样进行辐照处理,辐射量分别达到100 kGy和1000 kGy。基于针-板电痕破坏和IEC60112耐电痕实验法,着重考察了高能辐射及其与低气压、强磁场辐射复合环境下的电痕破坏现象。主要研究工作和取得的成果如下:1.针对太空和核聚变环境中聚合物电介质老化绝缘性能下降的现象,本文采用高压脉冲下针-板沿面放电绝缘破坏的方法,研究了高能辐射对PBN、PBT、PET、EX和PPO等常用工程电介质电痕破坏的影响。通过考察绝缘破坏时间和放电能量两个重要参数,得出了高能辐射对它们绝缘破坏特性的影响规律,并结合交联与降解理论从材料化学结构的角度深入探讨了高能辐射环境下聚合物电介质绝缘特性的变化机理。2.在研究高能辐射对聚合物电介质绝缘破坏特性影响的基础上,本文进一步考察了辐射改性(将辐射类型不同的电介质混合)对聚合物电介质耐电痕特性的影响。实验参照IEC60112国际标准法,考察了掺加3%聚乙烯的聚碳酸酯(改性PC)高能辐射后侵蚀深度和重量减轻的变化规律。另外还从放电电流的特征入手,运用递归图和递归定量分析的方法,对高能辐射条件下改性PC的耐电痕特性进行了评定,更加直观的揭示了放电电流的变化与聚合物电介质绝缘破坏特性之间的关系。结果表明,辐射改性能够改善高能辐射环境下电介质的耐电痕特性,递归技术可以为分析聚合物电介质的绝缘破坏特性提供很好的帮助。3.随着电力电子技术高速发展,越来越多的输电线路和电力设备工作在高原地带。高海拔环境具有低气压和强紫外辐射的特点,这些都对电力设备的绝缘造成了很大的影响。高海拔环境下很多低海拔的经验公式、机理都不再适用,但是这个方面的研究现在还比较少。基于这个背景本文研究了低气压和高能辐射复合条件下的电痕破坏现象,进一步探讨了低气压和高能辐射复合环境对聚合物电介质绝缘破坏特性影响的机理,为高海拔环境下电力设备绝缘破坏的研究打下了一定的基础。4.电和磁是密不可分的,由于大电流的作用,很多电力设备像变压器、电动机等当中都分布有强磁场,而GIS断路器开断时的电磁暂态环境中磁场强度也非常大,这些都对于电力电子设备的绝缘特性造成了很大的影响,设备运行的安全性和可靠性也受到了威胁。所以本文研究了强磁场和高能辐射复合条件下的电痕破坏现象,分析了出现各种差异的原因和机理,本研究对强磁场和高能辐射复合环境下电力设备的设计和制造有一定的指导意义。更多还原

【Abstract】 Polymer insulating materials play an important role in power and electronics systems. The insulation failure will cause short-circuit, fires even explosion in the in electrical appliances and devices. In space and nuclear power stations, polymer insulating materials are inevitably exposed to various kinds of rays. The rays can change the structures and electrical performance of the polymers. High-energy radiation will seriously affect the application of polymer insulation materials. Accordingly, it becomes necessary to investigate the effects of the radiation on insulation materials, which is very important for the application in project.With the development of aerospace and the nuclear technology, more and more electrical and electronic equipment are used in various irradiation environments. In practice, many environments factors are co-existing. Besides the High-energy radiation, the polymer insulating materials are affected by the factors of vacuum, magnetic field and so on. However, the knowledge about the effects of Multifactor irradiation on the electrical performance of the polymer insulating materials is limited. Therefore, it is very important to investigate the insulation failure of the polymer insulating materials under the combined irradiation environments.In this paper, polybutylene naphthalate (PBN), and polybutylene terephthalate (PBT), polyethylene terephthalate (PET), Epoxy resin (EX) and Polycarbonate (PC), which use in practical transformers, motors, relays, cables and capacitors and other equipment, were toke as the experimental samples. The samples were irradiated in air up to 100 kGy and then up to 1000 kGy with a dosage rate of 10 kGy/h by using a 60Co gamma-source. Based on point-plate tracking failure and IEC60112 method, the effects of high-energy radiation, low pressure and strong magnetic field on the tracking failure were investigated. The study and results are as follows:1. For the change of polymer dielectric insulating properties in radiation environment, this paper studied the effects of high-energy radiation on the tracking failure of PBN, PBT, PET, EX, PPO under high-voltage pulse. By investigating the two important parameters of time to tracking failure and discharge quantity, the regular pattern of the tracking failure was obtained. The experimental results suggest that the chemical structure of the polymers play a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction. 2. Based on the above study, the effect of radiation modification on tracking failure of the polymer insulating materials was studied. With IEC60112 international standard experiment, the variation of erosion depth and weight loss of Irradiated polycarbonate mixed with 3% polyethylene (modified PC) was investigated. A recurrence plot analysis of discharge current has been made to evaluate the tracking resistance more consistently. Obtained results showed that after Gamma-ray irradiation, the tracking resistance was improved. The irradiation effects on the tracking resistance can be visually identified by the recurrence plot.3. With the rapid development of power and electronics technology, more and more transmission lines and power equipment work in the highlands. High-altitude environment has the characteristics of low air pressure and strong ultraviolet radiation, which worsens the dielectric performance of the insulation in electrical equipment. The experience, mechanism and formula of low altitude are no longer applicable, but the research of insulation failure of the polymer is still few. Based on this background, the effects of low pressure and high-energy radiation on the tracking failure of polymers were investigated, and the mechanism of the two factors was analyzed .the results can lay a foundation for the insulation failure analysis for power equipment in high-altitude environment.4. Electricity and magnetism are inextricably linked. Because of high current there are high-intensity magnetic fields in the electrical equipment such as transformers, motors, etc. Meanwhile, the magnetic field strength in the GIS circuit breaker is also very large when the electromagnetic transient. The magnetic fields have great impact on insulating properties of power electronic devices and the equipment. Therefore, the effects of magnetic field and high-energy on the tracking failure of polymers were investigated, and the mechanism of differences was analyzed. The results have significance in the design and manufacture of electrical equipment applied in magnetic field and radiation conditions.更多还原