基于指纹参量的环氧云母绝缘多因子老化的实验研究

局部放电的统计参量,即指纹参量是评定绝缘放电状态的重要参量,本文在实验室中进行了环氧云母绝缘电机线棒的多因子老化实验,在不同老化阶段测量了线棒的局部放电,并分析了放电参量各种分布的指纹参量,实验结果表明,相位分布的互相关系数及不对称度等指纹参量随老化时间呈现明显的变化规律,并且这些指纹参量与剩余击穿电压有较大相关性,所以,可以用局部放电指纹参量来评定环氧云母绝缘的老化状态。     

基于交流电流法评估大型电动机环氧云母绝缘老化特征的研究

对大型电动机环氧云母绝缘线棒进行了多因子加速老化试验,在不同老化阶段进行了交流电流、击穿电压测量。根据交流电流曲线的特点,提出了求取第二电流急增点电压的新方法－－逐点拟合法,并分析了第二电流急增点电压与剩余击穿电压的相关性。结果表明：逐点拟合法能准确地求取第二电流急增点电压,且用此电压值推算环氧云母主绝缘的剩余击穿电压是有效的。     

大电机环氧云母定子绝缘超声波速的研究

本文用A型脉冲回波法超声波检测系统，详细研究了大地机定子线棒不同的绝缘部位对检测超声波速的影响，以及波速随绝缘老化的变化规律。结果表明：大电机定子线棒的正面绝缘适合于超声检测；线棒表面半导体层的存在更有利于超声检测；超声波速能用来表征绝缘的老化状态。     

Infrared detection of transformer insulation degradation due toaccelerated thermal aging

Regular monitoring of the paper insulation of electrical windings is necessary to ensure safe and reliable operation of oil-paper insulated electrical transformers. The degradation of the paper insulation due to thermal aging yields furanic derivatives which are specific to the paper and cannot be produced by general oxidation of the oil. The concentration of such furan compounds in the oil gives an accurate indication of the condition of the paper insulation. Normally, off-line methods such as HPLC (high performance liquid chromatography) are applied to periodically assess the furan concentration within oil samples which have been extracted from the transformer. We report experimental findings on the production of the furan compound FFA (furfuraldehyde) in an oil-paper system subject to accelerated thermal aging. Our approach is based on IR spectroscopy. This technique could lay the basis for the construction of direct online monitoring equipment suitable for monitoring of transformer winding insulation     

油纸绝缘老化评估的Davidson-Cole模型参数提取方法

针对目前变压器油纸绝缘老化状态评估中的纸板聚合度测定破坏性取样、介电响应法测量没有定量判据等问题,提出一种基于Davidson-Cole模型的现场绝缘老化状态定量评估方法。首先仿真研究Davidson-Cole模型参数提取方法,借助现场测量的去极化电流数据,计算出油纸绝缘等值电路参数与频域复介电常数,并利用所得数据绘制Davidson-Cole图,采用多变量最小二乘拟合方法得出松弛时间、介电常数变化量等Davidson-Cole模型参量。实验研究了油纸绝缘不同老化程度的Davidson-Cole模型,采用非线性拟合方法对其老化状态进行Davidson-Cole模型参量提取并分析参数变化,研究结果表明,模型参数与老化程度有直接关系,仿真结果与实验结果一致,对变压器油纸绝缘老化状态评估有参考价值。     

Voltage life characteristics of epoxy micaceous insulation systems under flexural stress

Voltage endurance tests under flexural stress were carried out on high-voltage rotating machine insulations with various mica tapes. The following interesting observations were obtained from the test data. The relationship between flexural stress and voltage life is comparatively differentiated by the mica tape construction. In a region exceeding a certain level of flexural stress, voltage lives are shortened abruptly for the insulation with mica papers only. On the other hand, for the insulation with mica splittings only, voltage lives are shortened more slowly with an increase of flexural stress, compared with the case for the insulation with mica papers only. Generally, breakdown occurs on the tensile side for the insulation with mica papers only, but on the compressive side for the insulation with mica splittings only. In the case of insulation using a combination of mica papers and mica splittings, breakdown occurs mostly on the compressive side, some-times on the tensile side when voltage is rather low. As the displacement becomes larger, the breakdown path becomes longer for the insulation with mica papers only, and shorter for the insulation with mica splittings only. It becomes longer with the increase of voltage, when the displacement is constant. From an examination of the relationships between nondestructive insulation characteristics and voltage life, almost no correlation was found between conventionally known characteristics (tan δ₀, Δ tan δ and ΔC/C₀) and voltage life. However, comparatively clear correlation was found between the void formation coefficient K and voltage life.     

一种油浸式电力变压器纸绝缘老化评估新特征量

针对油中糠醛含量随变压器运行时间变化的分散性较大,难以准确评估油浸式变压器纸绝缘老化状态的不足,对甲醇、乙醇等低分子醇作为变压器纸绝缘老化评估新特征量进行了理论分析与实验研究。对绝缘纸的老化机理以及化学键断裂进行分析,从理论上探究甲醇、乙醇等低分子醇的产生原理及主要生成途径。采用气相色谱-质谱联用法对现场2台老旧变压器绝缘油样品中的甲醇、乙醇及糠醛含量进行了测定。实验结果表明,2组样品中均未检测到糠醛,但却检测到数量可观的乙醇。进一步地,对现场2台刚投运变压器的检测结果对比分析,分析结果揭示了乙醇可以作为一种有效表征变压器绝缘纸老化的新特征量,且比糠醛特征量相比更为有效。     

桐马环氧胶粘剂的改性研究

为缩短桐马环氧胶粘剂的固化温度和时间，对粉云母带用桐马环氧胶粘剂配方进行研究，探索了新型固化促进剂对胶粘剂固化速度及温度的影响。用该促进剂配制的环氧胶粘剂具有凝胶时间短、介质损耗小、固化温度低绝缘性能好等特点，明显降低了能耗。     

Surface degradation properties of ultraviolet treated epoxy/glassfiber

In order to analyze the degradation process of epoxy/glass fiber in outdoor conditions, FRP laminate was exposed to different wavelengths of ultraviolet (UV) rays and evaluated by comparing contact angle, surface resistivity, surface potential decay, and XPS. As irradiation energy increased, the surface properties deteriorated remarkably at the region of 300 nm. But the measured values within 400 to 440 nm showed a slightly abnormal increase compared with the untreated FRP laminate. Also, the results of XPS confirmed that a great deal of oxygen groups appeared on the spot which showed the maximum decrease of surface properties, particularly the existence of ether groups on the surface of the discoloured spot. It was concluded that the surface degradation of UV-treated epoxy composites is dominated by the abrupt increase of ester and carboxyl groups as hydrocarbon chains are oxidized. This degradation process occurs continuously through the reorientation of oxygen groups by thermodynamic reaction and the formation of an electric double layer by electrostatic force     

A computer experiment to determine the impregnability of mica tapebased insulation

A simulation method is developed to characterize the influence of the tape application method on the resin permeability of mica tape based insulations. The method is based on the finite element solution of the standard Darcy porous media flow equations. It is shown that the two-dimensional periodic cell can be used to describe the tape application method. From a simulated flow experiment, an effective permeability K* is derived which characterizes the case of impregnation. The dependence of K* on bandwidth, relative layer position and degree of lap is investigated     

不饱和聚酯亚胺/少胶粉云母带绝缘及VPI工艺在高压电机中的应用

论文介绍了不饱和聚酯亚胺／少胶粉云母带绝缘体系及真空压力浸渍（VPI）电机工艺技术，对模拟线棒进行了常规电气性能，电热老化试验，检测结果和模拟线圈的检测在电机上应用的结果表明绝缘完全可以满足电机的绝缘性能要求。     

Effect of water on aging of XLPE cable insulation

Cables as elements of power distribution system have great influence on its reliable service and overall planning requirements. During last years, crosslinked polyethylene (XLPE) cables have been more and more used in power systems. This paper presents the results of an investigation of changing of (XLPE) cables insulation breakdown stress (AC BDS) due to water absorption. The paper deals with AC BDS of the following kinds of XLPE cable insulations: steam and dry cured with water tree retardant crosslinked polyethylene (TR-XLPE) and non-tree retardant crosslinked polyethylene (XLPE). During tests, the tap water was injected into, (1) conductor with cable ends closed; (2) into cable conductor with ends opened; and (3) into metallic screen with cable ends opened. The presence of water in XLPE cables was subjected to electrical stress and heating. AC BDS tests were performed as a function of aging time and water content in the cable insulation at different aging temperatures. Also, in this investigation, tests with the changing of AC BDS in the radial direction of unaged and aged XLPE cable insulations were carried out.     

电缆绝缘层老化对接头界面压力的影响研究

为研究老化电缆绝缘层弹性模量变化对界面压力的影响,本文实测三根不同运行年限电缆绝缘的击穿场强与介质损耗角正切表征其电性能,以及在不同温度下的弹性模量表征力学性能。基于超弹性材料本构理论,计算电缆接头与本体装配后的界面压力,并建立电缆接头的二维轴向仿真模型,计算轴向上的界面压力。仿真与理论计算结果的对比表明,运用二维轴向仿真模型计算电缆接头与本体之间的界面压力的误差不超过3.2%,仿真模型计算的准确度可为研究接头轴向上的界面压力分布提供可靠的数据,虽然不同运行年限电缆绝缘层电性能不同,且弹性模量最大差异为29%,但界面压力仅变化0.275%。因此,全新接头与已运行一定年限的电缆装配后,仍能保证足够的界面压力。     

1000kV交直流环氧树脂胶浸纸绝缘穿墙套管现场安装工艺

本文结合国家电网输电线路防灾技术实验室的1000kV交直流环氧树脂胶浸纸绝缘穿墙套管的结构特点,提出现场吊装工艺,详细介绍现场配重、起吊、重心调整、就位后套管旋转对孔等主要过程,并分析吊装过程中存在的问题及解决方法。     

Thermal aging of silicone oil aromatic polyamide insulation systems

The thermal degradation behavior of silicone oil/aromatic polyamide insulation system was studied. It was found that the flash and fire points decreased due to the formation of low molecular weight by-products of such cyclic siloxane oligomers as D₃, D₄ and D₅. The gel permeation chromatography (GPC) and high performance liquid chromatography (HPLC) analysis clarified that the depolymerization of siloxane molecules happened during the thermal aging, resulting in the high- and low- molecular by-products formation. The thermal stability index (TGI) index obtained by the thermogravity (TG) measurements and cyclic oligomer detection could be used for the insulation diagnosis     

变频电机的匝间绝缘电老化机理

结合近年来国内外的文献资料,对变频电机匝间绝缘过早破坏机理进行了系统的阐述。变频电机的匝间电压特性与普通电机有着显著的不同,由此引起的局部放电是导致匝间绝缘快速老化的根本原因,而由局部放电产生的电子轰击、臭氧氧化等作用直接造成了匝绝缘的过早破坏。提高变频电机使用寿命的方法之一就是提高绝缘材料高温条件下的耐局部放电能力,即提高绝缘材料在较高温度下的耐臭氧侵蚀能力和耐空间电荷的破坏能力。     

电热联合老化对XLPE电缆绝缘特性的影响

为了探究达到设计寿命的高压交联电缆继续运行的可靠性,文中对一回实际运行32 a的110 kV高压交联聚乙烯(XLPE)电缆采用预鉴定试验方法,进行为期180 d的电热循环加速老化试验。通过综合分析比较试验过程中电缆绝缘内、中和外层的电场强度和温度场变化的差异,并将各绝缘层试验条件转化为导体芯表面得到相应的等效试验条件,发现电缆绝缘中层和外层的等效试验条件接近电缆的实际运行情况。通过相关理化实验分析比较试验前后电缆绝缘各层的微观和聚集态状况。结果发现:绝缘内层在严苛的试验条件下热氧化降解占主导;绝缘中层虽然发生一定的氧化降解,但晶体结构仍有所改善;绝缘外层的结晶形态在温度效应的热刺激下趋于完善。因此,可以评估该退役电缆的其余部分在实际运行条件下仍具有长期服役的潜能。     

高压电机少胶VPI绝缘的现状及发展方向

在11篇文献的基础上综述了国内外高压电机少胶VPI绝缘的发展状况，分别比较了国外几家公司的少胶VPI绝缘结构的性能，分析了国内VPI绝缘存在的问题以及解决这些问题的方法，指出了我国VPI绝缘的发展方向。