近年来，全国各地发生多起复合绝缘子酥朽断裂、异常发热事故，严重威胁到电力系统的安全可靠运行。目前，对于复合绝缘子酥朽断裂问题的研究聚焦于芯棒的酥朽，对于芯棒在酥朽老化过程中的断裂机理尚不清晰。由于芯棒上的机械载荷主要由玻璃纤维来承担，芯棒的断裂与否也取决于内部的玻璃纤维是否发生断裂。因此，研究酥朽老化过程中存在的老化因素对芯棒酥朽、玻璃纤维断裂的影响对于阐释芯棒酥朽断裂机理及酥朽断裂问题的防治具有重要意义。首先，在调研了近十年国家电网公司经营范围内发生的复合绝缘子酥朽断裂事故的详细信息的基础上，分析了事故所处自然环境和运行状况与酥朽事故的关联性，通过仿真计算模拟了110kV、220kV和500kV电压等级复合绝缘子芯棒-护套界面处的电场分布，讨论了不同串型对500kV电压等级复合绝缘子界面电场分布的影响。通过对现场出现发热故障复合绝缘子的型式试验和材料分析，得到了初步明确了局部放电、外界湿气侵入和高压侧的异常发热可能是导致芯棒酥朽后异常断裂的重要因素。其次，在电导率分别为0.5mS/cm和1.5mS/cm酸雾环境下模拟了局部放电对芯棒材料的破坏过程，通过扫描电子显微镜观察了芯棒表面放电区域的微观结构，验证了环氧树脂在局部放电下的分解。在水雾环境下研究了玻璃纤维在局部放电条件下的蚀损特性，测试局部放电后玻璃纤维的力学性能，讨论了玻璃纤维表面有水珠附着时电场分布情况，通过扫描电子显微镜、傅里叶红外光谱等方法研究了玻璃纤维在局部放电条件下的断裂机理。最后，对芯棒材料进行了200℃~600℃温度范围的热老化实验，研究了芯棒在不同温度下的热分解特性，借助电磁加热方式实现了复合绝缘子芯棒-护套界面发热，测试了玻璃纤维在受热后的力学性能，通过现代材料学分析方法研究了玻璃纤维在高温环境中力学性能下降的机理。考虑到实际运行过程中有外界潮气侵入复合绝缘子的可能，本文通过水煮的方式研究了芯棒、玻璃纤维在湿热环境下的劣化特性，测试了玻璃纤维水煮后的力学性能，借助元素能谱分析、傅里叶红外光谱研究了水煮过程中玻璃纤维力学性能的劣化机制。
In recent years, there have been found many Decay-like fractured and heating composite insulators online all over the country, which seriously threatens the safe and reliable operation of the power system. At present, the research on the accidents focuses on the decay of the glass fiber reinforced plastics, but the fracture mechanism of the mandrel in the aging process is still unclear. Since the mechanical load on the glass fiber reinforced plastics is mainly borne by the glass fibers, the fracture of the glass fiber reinforced plastics also depends on whether the internal glass fibers are fractured or not. Therefore, it is of great significance to study the effects of aging factors existing in the aging process on glass fiber reinforced plastics and glass fibers for explaining the mechanism of the composite insulators Decay-like fracture and preventing the problem.Firstly, on the basis of investigating the detailed information of the accidents of composite insulators Decay-like fracture in the business scope of State Grid Corporation of China in the past ten years, the correlation between the natural environment and operating conditions and the accidents was analyzed. The electric field distribution at the core rod-sheath interface of composite insulators with voltage levels of 110kV, 220kV and 500kV is simulated, and the influence of different string types on the electric field distribution at the interface of composite insulators with voltage levels of 500kV is discussed. Through the type tests and material analysis of composite insulators with heating faults, it is preliminarily clarified that partial discharge, external moisture intrusion and abnormal heating on the high-voltage side may be the important factors leading to the abnormal fracture of composite insulators.Secondly, the damage process of partial discharge on the glass fiber reinforced plastics was studied in the acid mist with electrical conductivity of 0.5mS/cm and 1.5mS/cm, respectively. The microstructure of the discharge area on the surface of the glass fiber reinforced plastics was observed by scanning electron microscope, and the decomposition of oxygen resin under partial discharge was validated. In the water mist environment, the degradation characteristics of glass fibers under partial discharge conditions were studied, the mechanical properties of glass fibers after partial discharge were tested, and the electric field distributions when water droplets were attached to the surface of glass fibers were discussed. The fracture mechanism of glass fibers under partial discharge conditions was studied by scanning electron microscope and Fourier transform infrared spectrum.Finally, the aging experiment was carried out on the glass fiber reinforced plastics in the temperature range of 200℃~600℃, and the decomposition characteristics of the glass fiber reinforced plastics at different temperatures were studied. The composite insulator core rod-sheath interface heating is realized by means of electromagnetic heating. The mechanical properties of glass fibers after being heated were obtained, and the mechanism of the decline of mechanical properties of glass fibers in high temperature environment was studied by modern materials analysis methods. Considering the possibility of external moisture intruding into the composite insulator during the actual operation, the deterioration characteristics of the glass fiber reinforced plastics and glass fibers were studied in a humid and hot environment by boiling in the paper, and the mechanical properties of the glass fiber after boiling were obtained. The deterioration mechanism of the mechanical properties of the glass fiber during the boiling process was studied by means of element energy spectrum analysis and Fourier transform infrared analysis.
