基于IRC和逐级耐压法的110kV XLPE电缆剩余寿命评估

在运行20多年的电缆上截取长、短试样,分别进行等温松弛电流法试验,再利用电热老化前后的长样进行等温松弛电流法试验.结果显示长样由于带有电缆接头而体现出老化因子大的特点,表明电缆接头是电缆的薄弱环节,接头更容易受到电热作用而发生老化;经电热老化后的长样因内部缺陷增加而使老化因子增大,说明电热处理会加重电缆老化程度;通过逐级耐压法对电缆试样进行试验,结果表明试样的剩余寿命在10~20年的范围内,和设计时的预期寿命一致.基于等温松弛电流法的试验结果对XLPE电缆进行老化状况评估,通过耐压法试验结果给出其具体的剩余寿命,两者相辅助结合可以进行比较全面的判断.     

基于超声波的XLPE电力电缆局部放电测量与分析

为准确判断电缆附件内部的绝缘状态,避免电缆发生绝缘击穿,对交联聚乙烯(crosslinking polyethylene,XLPE)电力电缆局部放电进行研究。在实验室环境下对尖端放电、气隙放电和沿面放电3种XLPE电力电缆放电类型进行模拟,采用超声检测系统研究了XLPE电力电缆三种缺陷局部放电特性,分析不同缺陷放电超声信号的时域特征和相位谱图特征,研究了不同电压与最大放电幅值、平均放电幅值及放电次数之间的关系,得到典型放电谱图。结果表明:同一缺陷类型在相同条件下放电稳定,重复性好;不同缺陷类型的放电发展过程有所差别,所呈现出来的局部放电谱图、单个脉冲波形、PRPD谱图区别明显。     

XLPE电缆老化状况对绝缘层微观结构的影响

对两条退役110 kV XLPE电缆和一条备用电缆进行试验,利用电声脉冲法(PEA)和X射线衍射技术(XRD)研究了老化状况对XLPE电缆绝缘层微观结构的影响.结果表明:电缆的老化会造成绝缘晶体尺寸减小,结晶度降低,因此其捕获空间电荷的能力增强;老化过程始于电缆最外层,而长时间的老化作用对绝缘中间层的影响更大,中间层可能是击穿的薄弱环节;XLPE电缆绝缘老化使绝缘微观结构从"中间高两端低"转变为"均匀化".     

基于HDS的交联聚乙烯电缆健康诊断研究

随着国内外电缆技术的迅速发展,电气性能良好的交联聚乙烯电缆取代了原有的电缆;为了对电缆的劣化值和使用寿命进行评估:首先对电缆产生高次谐波的原因进行了分析,对电缆的劣化值进行了量化百分比的处理;其次,对于劣化值在70%以上的电缆利用韦布尔系数推算其剩余寿命;最后通过对13条10kV高压电缆的老化情况和剩余寿命的测量与现有技术得到结果的对比显示出可以利用电缆的劣化情况,能较合理地估计电缆剩余寿命,指导电缆的维修和更换工作,为交联聚乙烯电缆的老化评估和寿命估计提供较为有效的方法。     

10 kV XLPE电力电缆稳态温度场和额定载流量的计算

目的电力电缆的载流量的确定受几种因素的影响,其中包括电缆结构、敷设条件和周围环境,电力电缆温度场和载流量计算对于在保证电缆线路运行可靠性和使用寿命的条件下,充分发挥电缆的输送能力、提高其经济性具有重要的意义。方法针对排管敷设方式的10 kV三芯交联聚乙烯(XLPE)电力电缆,以IEC60287标准算法为依据,采用热路解析法对其在稳态运行条件下的温度场和载流量进行了计算研究。结果电缆载流量随着电缆敷设根数的增加而明显下降,受周围环境影响较大。结论计算结果有助于运行中电缆载流量的评估和新敷设电缆线路的设计。     

基于有限元分析的XLPE电力电缆仿真实验

交联聚乙烯(XLPE)电力电缆的电树枝老化威胁其安全运行,为了研究针尖缺陷对电缆绝缘电树枝产生的影响,文中运用ANSYS软件对电缆内部针尖缺陷进行模拟仿真和理论分析,并与现场所测得中压XLPE电缆的耐压强度进行对比,对试验结果进行了验证,并指出了局部电场畸变是引发贯穿性放电通道的主要因素.     

XLPE电缆绝缘残余寿命评估的初步研究

开展电缆残余寿命评估的研究具有巨大的意义,本文在简单回顾国外XLEP电缆残余寿命评估技术的基础上,初步研究了XLPE交联电缆的寿命评估问题。文中提出根据已有的电缆敷设状态和电缆绝缘参数进行数学分析和实验室综合试验相结合的XLPE电缆残余寿命评估技术方案,并搭建了评估软件框架,为研究XLPE绝缘寿命预测技术提供参考。     

核磁共振原理的交联聚乙烯电缆热老化行为分析

在实际运行过程中,交联聚乙烯电缆(XLPE)在高温的长期作用下,会发生不可逆的破坏,使用寿命缩短。研究从材料学的角度,利用核磁共振分析仪研究XLPE的热老化行为,发现了能表征XLPE热老化规律的特征量—纵向弛豫时间和波峰面积。实验结果表明,波峰面积随老化温度和老化时间增大而减小,且波峰面积与老化时间呈近似线性规律;纵向弛豫时间也随热老化程度增大而下降。此方法为准确监测电缆老化情况提供了重要的应用价值。     

电缆热老化寿命的预测研究

利用热分析技术,对电缆绝缘材料的热老化寿命进行了研究,得到了电缆绝缘材料的热老化寿命的计算公式。在不同载流量下,对电缆绝缘材料热老化寿命进行了比较,给出了电缆热老化寿命与载流量的函数关系,为电流致热型电缆火灾的防治提供了基础数据。     

检测电缆附件局部放电内置传感器的特性分析

针对高压交联聚乙烯(cross-linked polyethylen,XLPE)电缆的结构及其附件内部易出现绝缘缺陷而导致放电的特点,基于电容耦合原理研制出用于电缆附件局部放电(partialdischarge,PD)信号检测的宽频带电容型内置传感器,通过建立传感器特性分析的电路模型,全面分析了影响传感器性能的各个因素,对其响应的频率特性进行了实测,并在实验室110 kV XLPE电缆PD试验平台上对电缆接头内部沿固体复合介质表面产生的放电进行试验研究。测试结果表明:研制的内置电容型传感器频率响应特性优异,能传感纳秒级暂态脉冲信号,其有效频带达500 MHz,可以用于XLPE电缆及附件PD超高频(Ultra-high frequency,UHF)信号的检测。     

Partial Discharge Characteristics in the Course of Aging within XLPE Insulation

This paper deals with the experimental study on the correlation between partial discharge （PD） characteristic parameters and corresponding aging degree of insulation in the course of the aging within eros,s-linked polyethylene （XLPE） insulation. The aging tests were performed on a section of 10 kV transmission cable by means of water needle method. The PD macroscopic characteristic parameters were found to be significantly dependent on the corresponding aging degree of insulation in the course of aging of XLPE, and different kind of aging stage has different characteristics. Beside, there are similar regularity but different PD amplitude in the course of aging of XI.PE insulation in different electrolyte, and their insulation life is different. Therefore, according to the chan ging regularity of the PD macroscopic characteristic parame ters within XLPE insulation judging the aging degree of XLPE insulation will be an effective method.     

DC Insulation Parameter Characteristics of XLPE in the Course of Its Aging

This paper deals with the experimental study on the correlation between insulation resistance (R) and direct current (DC) component (idc) and corresponding aging degree of insulation in the course of the aging within cross linked polyethylene (XLPE) insulation. The aging tests were performed on a section of 10 kV transmission XLPE cable by means of water needle method, and R was measured by dc voltage superimposed method. R and idc were found to be significantly dependent on the corresponding aging degree of insulation in the course of aging of XLPE, and different kind of aging stage has different characteristics. Beside, there are generally similar regularity but different amplitude in the course of aging of XLPE insulation in different electrolyte, and the various electrochemical tree were found on the surface of aging XLPE cable immersed in CuSO, solution. Therefore. according to the changing regularity of the DC characteristic parameters i.e. R and idc within XLPE insulation judging the aging degree of XLPE insulation will be an effective method.     

Correlation between geometrical parameters of electrical tree and corresponding partial discharge parameters in XLPE

This paper deals with the experimental study on the correlation between the geometrical parameters of electrical tree and corresponding partial discharge (PD) characteristic parameters in the course of electrical tree aging within cross linked polyethylene (XLPE) insulation. The electrical tree aging tests were performed on specimens removed from a section of 220 kV transmission cable. The PD macroscopic characteristic parameters were found to be significantly dependent on the corresponding geometrical parameters of electrical tree channels in the course of aging of XLPE, and different kind of electrical tree has different characteristics, and there is obvious correlation between the type of electrical tree and the pre-applied power-frequency stress. Beside, using regression analysis, the expression of the relation between them were obtained, and from which it can be seen that there is significant nonlinear correlation between geometrical parameters of electrical tree and corresponding PD characteristic parameters in the course of aging of XLPE. Therefore, the aging degree of XLPE can be effectively evaluated by recognizing the changing regularity of the PD rnacroscopic characteristic parameters.     

Gradient Changing Morphology Research of Cross-linked Polyethylene Thick Insulation of 110 kV Power Cable

The thick insulation layer of 110 kV XLPE power cables will result in the gradient changing morphology with the radius due to crosslinking process and cooling of the XLPE insulation. In this paper, the morphology of cross-linked polyethylene （XLPE） insulation of 110 kV cable and the uniforming effect of the heating process on it are researched by the differential scanning calorimetry （DSC） and X-ray diffraction （WAXD）. The middle layer morphology structures of insulation produced by normal technology are of better uniform, while the crystallinity of the inner and outer layer of the insulation is lower than that of the middle one. The melting enthalpy AHm of materials displays the difference of the crystal morphologies sensitively. The difference of crystallizing morphology in different layers of the high-voltage power cable insulation can be improved by heating process. But the uniforming of morphology of the insulation by heating process requires sufficient ttanperature and time. The effect of the on-line stress-relaxation equipment used widely by cable works now should be doubted. The test results of WAXD reveal that thermal stress changes the interplanar distances in the crystal region. So the radical stress in the insulation is tensile mainly.     

交联聚乙烯电缆树枝发展过程及其防止

通过一些实验结论阐述了交联聚乙烯电缆绝缘电树枝老化的发展过程,探讨了预防交联聚乙烯电缆绝缘电树枝化的可能方法     

高压交联聚乙烯电缆绝缘结构的可靠性设计方法

采用可靠性理论中的应力-强度干涉模型来设计交联聚乙烯（XLPE）电缆绝缘厚度，通过考虑绝缘强度的概率分布与所承受电压分布之间的相互干涉来计算绝缘可靠度。采用的可靠性设计方法可以使所设计的国产220kV XLPE电缆绝缘厚度从27mm减薄到23mm。计算结果表明，在制造过程中，减小绝缘厚度分布的标准差可以提高电缆的可靠度。     

高压电缆中间接头局部放电统计特性分析

设计制作了高压电缆中间接头内部4种典型绝缘缺陷物理模型,并构建了相应的局部放电(Partial Discharge,PD)试验研究平台,利用内置宽频带圆环型传感器获取了不同绝缘缺陷模型下的大量PD数据。通过放电统计特征分析表明,4种放电形式在相位分布和偏斜度、峭度、不对称度等统计特性上有显著的区别,可作为反映不同绝缘缺陷的有效特征。此外,沿面滑闪和导电微粒两种放电对电缆接头绝缘性能的破坏较为严重,建议现场运行应给予高度重视。     

高压电力电缆温度场和载流量数值计算软件的研究

利用VB6.0开发基于有限元的高压交联聚乙烯电力电缆在直埋、排管、隧道和沟槽等敷设方式下的温度场和载流量计算软件.该软件集成了图形化技术和数据库技术,建立了各种电力电缆参数的数据库,可以动态修改电缆参数,方便地选择和设置电缆型号、敷设方式、接地方式、排列方式和环境参数.测试表明,该软件可以满足大多数工程需求.