交联聚乙烯电缆中空间电荷的研究现状

在电力系统中,交联聚乙烯绝缘因其优良的介电和耐热性能已被广泛应用于高压和超高压塑料绝缘电力电缆中。但在直流电场作用下,绝缘中容易形成空间电荷,空间电荷会使电场分布发生畸变,加速了绝缘老化,降低电缆使用寿命。总结了空间电荷在聚合物特别是聚乙烯电缆绝缘材料老化中的研究现状,概述了近20 a国内外在聚乙烯材料中抑制同极性和异极性空间电荷产生的方法,最后从工程实际应用出发,简要介绍了从空间电荷角度诊断交联聚乙烯电缆中电介质老化的方法及现状。     

牵引电动机绝缘检修现状与改进的探讨

提出从绝缘材料、工艺方法和检测手段3个方面改善牵引电动机绝缘结构的机械性能和介电强度,提高牵引电动机运用可靠性.     

混合绝缘系统油浸式配电变压器过载能力分析及结构优化

随着电网安全可靠性要求的不断提高,油浸式配电变压器过载性能亟待提升。在对混合绝缘系统和常规绝缘系统油浸式配电变压器的耐热等级和温升限值进行分析的基础上,采用热点温度模型评估不同绝缘系统油浸式配变的过载能力,给出了混合绝缘系统油浸式配变的结构调整建议,并进行了成本对比。结果表明,采用耐高温的DPE绝缘纸取代普通纤维素纸,可将油浸式配电变压器过载能力由1.34倍提升至1.53倍,相应成本只增加1.1倍,具有很强的实用性和经济性。     

基于电机轴承绝缘的轴电流抑制策略研究

随着水电行业的快速发展,水轮发电机工况愈加复杂,电机轴承的正常运行至关重要。本文针对轴承绝缘对电机轴电流的抑制作用展开研究,首先分析轴电流的产生机理,然后建立轴承绝缘等效模型,分析绝缘电容和轴承油膜电容与轴承分压比的关系;进而提出一种将陶瓷绝缘材料喷涂在电机轴对应位置上的轴绝缘方案,以有效抑制轴电流,为水轮电机轴承维护提供工程应用参考。     

电机绝缘技术发展历程与方向

简要介绍了电机绝缘技术的几个基本概念及主要研究内容,回顾了电机技术选用的绝缘材料由天然材料到合成聚合物的发展及回归环保的历程,以及高压交流电机主绝缘历年发展情况和现代高压交流电机绝缘技术的发展方向.     

干式变压器的应用

随着#8机炉的建成、投产、安全运行，我厂实现了对干式变压器安全有效、地使用。21世纪的配电变压器将属于性能优越、低噪声、节能、维护工作量小的树脂绝缘干式变压器。因此说，我厂积极推广使用干式变压器是顺应了配电装置的发展方向。     

环氧复合绝缘材料表面电荷积聚与消散特性研究

为明确环氧复合绝缘材料表面电荷积聚与消散特性,搭建了一套空气中绝缘材料表面电位二维自动测量装置,采用有源静电探头法测量了直流充电后环氧复合绝缘表面电位分布。结果表明,绝缘表面主要积聚与外施电压极性相同的电荷,提高直流电压幅值会显著增加表面电荷密度。随直流电压施加时间的增加,表面电荷密度先快速增加,而后趋于饱和。当加压至闪络后,绝缘材料表面存在清晰的放电通道,绝缘表面仍然积聚大量的电荷,并关于闪络通道对称分布。表面电位消散分为表面电荷自发电场主导的消散阶段和电荷扩散主导的消散阶段。外施电压幅值越高,表面初始电荷密度越高,起始消散速度越快,消散到一定值需耗费更长的时间。     

太赫兹波在电网绝缘材料厚度检测中的应用研究

传统的无损检测方法存在衰减大、精度低、辐射等问题,难以实现多层涂层厚度检测。为此提出了采用太赫兹波技术来测量绝缘材料的厚度,通过对变压器绝缘纸板和绝缘子室温硫化硅橡胶（RTV）涂层厚度的检测试验,验证了太赫兹波检测绝缘材料厚度的可行性。试验结果表明,太赫兹波在变压器绝缘纸板和绝缘子RTV涂层厚度测量中具有较高的精度,可推广至其他绝缘材料厚度检测场合。该研究为绝缘材料厚度检测提供了一种新方法,同时也为绝缘材料在线监测和状态评价提供了一种新技术手段。     

基于SF_6气体分解成分检测的设备内部潜伏性故障分析

依据SF6绝缘气体及各种固体绝缘材料在放电或过热等异常情况下的分解机理及分解产物的形成过程,通过对众多运行设备进行分解产物的种类及体积分数含量普查过程中发现设备内部可能存在异常并且这种质疑正好与设备解体验证相符。在实践的基础上,验证了通过SF6分解产物体积分数的检测来预判SF6气体绝缘设备是否存在潜在缺陷的实际可行性和有效性,为今后SF6气体绝缘设备的运行维护和开展设备的状态检修提供参考依据和技术支撑。     

750 kV变压器长时感应耐压试验标准探讨

750 kV官亭—兰州东示范工程投运5年来,西北750 kV电网建设突飞猛进,但作为主设备的变压器频繁出现绝缘事故,对于多年前制定的750 kV变压器技术规范、标准有必要进行反思。长时感应耐压试验标准是750 kV变压器绝缘设计和考核的重要依据,通过750 kV变压器技术规范、试验标准与1 000 kV变压器技术规范、试验标准进行比对,结合现场变压器绝缘击穿案例,通过计算和分析,提出了750 kV变压器长时感应耐压试验标准的改进方案。     

环氧树脂浇注电流互感器的工艺缺陷及改进

由环氧树脂浇注的电流互感器（TA）,具有体积小、质量轻、绝缘好和可靠性高等特点,在超高压电网中广泛应用.然而,随着TA服役时间的增长,该类型TA会出现内部开裂等缺陷,直接影响电网安全和可靠运行.从环氧树脂浇注TA的制造工艺及原材料入手,认为外绝缘表面开裂的主要原因是浇注固化时的收缩力和热应力,而且原材料对环氧树脂TA也有一定影响.从监造TA质量、完善TA制造工艺、加强对TA检测与寿命评估,提出了相应的消缺措施.     

Comprehensive evaluation of the transformer oil-paper insulation state based on RF-combination weighting and an improved TOPSIS method

The accurate identification of the oil-paper insulation state of a transformer is crucial for most maintenance strategies. This paper presents a multi-feature comprehensive evaluation model based on combination weighting and an improved technique for order of preference by similarity to ideal solution(TOPSIS) method to perform an objective and scientific evaluation of the transformer oil-paper insulation state. Firstly, multiple aging features are extracted from the recovery voltage polarization...     

水分对天然酯变压器油热老化特性的影响

水分被认为是除温度外影响变压器油纸绝缘寿命最主要的因素,为研究水分对天然酯变压器油热老化特性的影响,通过设计不同初始水分含量油纸绝缘试品在130℃下进行加速热老化试验,测试分析天然酯变压器油在不同老化时间下的介电性能和油色谱特性。结果表明,初始水分含量越高,天然酯变压器油热老化过程中相对介电常数增加的速率越快、介质损耗因数越高,除对CH4的生成速率表现为抑制作用,对其他气体的生成速率均表现为促进作用;天然酯变压器油纸绝缘热老化特征气体为CO2和C2H6。     

Well-being analysis of GSU transformer insulation incorporating the impact on power generation using fuzzy logic

With the prevailing power scenario, every watt-second of electrical energy has its own merit in satisfying the consumer demand. At the state of such a stringent energy demanding era, failure of a power generation equipment compounds the energy constraints which will not only result in a huge loss of generation but also have an impact on capital revenue. The unexpected failure of generator step-up (GSU) transformer is especially a major disturbance in the power system operation and leads to unscheduled outages with power delivery problems. The time lag in bringing back the equipment in service after rectification or replacement may increase the criticality as the process involves mobilization of spares and maintenance professionals. Hot atmosphere existing in the vicinity of thermal power stations running round-the-clock with more than 100% plant load factor (PLF) increases the thermal stress of the electrical insulation which leads to premature failure of windings, bushings, core laminations, etc. The healthy state of the GSU transformer has to be ensured to minimize the loss of power generation. As the predication related to failure of a GSU transformer is associated with some uncertainties, a fuzzy approach is employed in this paper along with actual field data and case studies for the well-being analysis of GSU transformer.     

A probabilistic model for evaluating the remaining life ofevaluating the remaining life of electrical insulation in rotatingmachines

A Markov model is introduced for estimating the remaining life of electrical insulation in large motors and generators. The model incorporates various levels of insulation deterioration and periodic (minor) maintenance. The model permits computation of the average time before insulation failure occurs. A mathematical formulation of the expected transition time from any deterioration state to the failure state (expected remaining life) is given. Data requirements are discussed, and numerical examples are presented. This model would also allow assessment through sensitivity studies of the relative effects of various other parameters in the process which are controllable, e.g. maintenance policy and stress level. Even though it is theoretically possible to apply the Markov models to any particular insulation deterioration mechanism, this approach is best applied to an overall insulation determination problem which combines the effects of all individual processes. The models are fairly flexible. They allow, for example, representation of changing stresses acting on the machine insulation as the utility operating environment changes     

用录波分析软件分析主变差动动作原因

针对110 kV万茜变电站35 kV侧线路遭受雷击,线路保护电流一段动作现象,使用录波分析软件分析故障前的电流相位、差动动作值和C相动作轨迹.在分析主变差动保护动作原因的基础上,得出了在单相接地故障状况下,主变高压侧出现三相电流幅值基本相同以及相位基本一致的结果.证实了此次故障是一起典型的B相区外故障,差动B相可靠不动;C相区内故障,差动C相正确动作.C相区内故障,主要是一体化电流互感器遭受高电压,绝缘被击穿,导致区内C相接地.通过分析主变差动动作原因和总结经验,提出改进措施,旨在更好地完善变压器保护的运行和维护.     

基于鸡群算法参数优化的改进GM(1,1)模型的变压器绝缘水平预测

针对GM(1,1)模型背景值及初始值设置方面存在的缺陷,为减少绝缘事故的发生,提出一种基于鸡群算法参数优化的改进GM(1,1)模型,以南方电网某变电站SSP9-H-120000/220型220kV主变压器为例,选取绝缘电阻和油介质损耗因数两种指标作为反映变压器整体绝缘水平的状态量,采用所提模型对其进行预测。实例应用结果表明,改进模型在提高变压器绝缘水平预测精度方面效果显著,更符合实际工程需要。     

Power systems of the future. 2

For pt.1 see ibid., vo.20, no.1 (2000). The assets and working philosophy of individual utilities will in large measure be reflected by the modernization of their power systems in the next 20 years. The power system of the future should enable utilities to: be more competitive with their overall strategies; provide better service; better manage their assets; extend equipment life; improve diagnostics; and develop reliability-centered maintenance. This paper features FACTS (operating systems, custom power, and improved capacitors), electrical insulation, distribution cables (extruded dielectrics, polymeric insulation, underground vault explosions, fault location, smart cables, neutral and ground corrosion and protection), and transformers (compact transformers, ferroresonance, and solid state transformers)     

330 kV变压器故障原因分析

通常变压器发生内部故障会使变压器油或固体绝缘材料分解,产生气体并大部分溶于油中,其气体成分与变压器的内部故障性质有很大关系。针对具体故障实例,采用对变压器油中气体含量进行分析并结合电气试验判断,能比较准确判断出故障原因和定位出故障位置。