高压XLPE电缆绝缘V t特性研究综述

交联聚乙烯（cross linked polyethylene,XLPE）绝缘电力电缆是输电线路的重要电 力设备。针对高压交流和直流电缆系统的运行现状,介绍了运用V t特性（击穿电压与击穿时间的关系）曲线描述XLPE电缆绝缘的电老化寿命模型,分析了国内外高压交、直流XLPE电缆绝缘V t特性的研究方法及相关结果。已有的研究结果表明,交流XLPE电缆绝缘的电老化寿命指数n值在9~25之间,直流XLPE电缆绝缘的电老化寿命指数n值在13~20之间。国内目前尚未见有关直流电缆绝缘V t特性研究的文献报道。     

水树老化XLPE电缆绝缘温度特性的研究

为了确保电力系统的安全可靠运行,运行中的XLPE绝缘电力电缆老化状态的评价和估计具有十分现实的意义。本文通过实验,研究了温度对水树老化XLPE电缆绝缘的tgδ、损耗电流谐波分量的影响,并探讨了采用电缆绝缘的交流不平衡分量来诊断电缆中水树状态的可行性。     

电力电缆技术的发展与研究动向

电力电缆广泛应用于城市电网中,经历了从充油电缆(OF电缆)、钢管电缆到交联聚乙烯电缆(XLPE电缆)的发展过程。XLPE电缆与其他电缆相比,有不需要供油、供气设备、防火性能好、安装维护简单等优良性能,被越来越多的国家所采用。电力电缆的安全运行关系到城市电网的安全可靠性,逐渐受到了各国的高度重视。提高高压电缆路径通道的管理水平、安全运行以及输送能力,其关键技术的研究非常重要。笔者叙述了电力电缆及其附件相关技术的研究状况和今后的发展趋势,得出提高城市电网的可靠性和安全性,降低运行成本是今后的发展趋势。     

Successful testing of 345-kV XLPE cables and premolded joints atIREQ

Extruded polymeric cables and accessories are an alternative to self-contained fluid filled (SCFF) cables for extra-high-voltage (EHV) systems. Crosslinked polyethylene (XLPE) insulated cables have many advantages over the traditional fluid-filled pressurized cable system with the elimination of the hydraulic system and the associated equipment and complications during the installation and operation/maintenance of such systems. Other advantages of the extruded cable system arise from the new accessory technologies and the use of splices and terminations that are prefabricated and pretested in the factory and require less time to install on site. Concerns over the long term reliability of high voltage cable systems, in particular the accessories and the lack of service experience above 300 kV led to the decision of Hydro-Quebec to carry out a prequalification (long-term) test program to assess the reliability of the cable materials and to verify the cable and accessory installation methods to be employed. The cables were installed in duct banks and manholes simulating actual installation conditions used in Hydro-Quebec underground cable network. This paper describes the program and results of the prequalification tests of 345-kV XLPE cables and accessories performed at Hydro-Quebec's Research Institute (IREQ) in partnership with three international cable manufacturers, Alcatel, Fujikura and Pirelli     

采用MATLAB仿真的变电站高压进线温度场和载流量数值计算

随着电力电缆在输配电线路中的广泛应用,准确确定电力电缆及其周围环境温度场的分布和电缆的载流量对于提高电力电缆的使用率、动态调整负荷具有重要的意义。为此,以地下排管敷设的交联聚乙烯电力电缆为研究对象,其实际模型为1个容量为250MVA、额定电压为230kV的变电站的高压进线。根据传热学和有限元法(finite element method,FEM)基本原理,建立了1种基于有限元法的水泥排管敷设电缆温度场计算模型,并对电缆及其周围环境的求解区域进行复合有限三角形单元剖分,即对电缆区域进行较密集的网格划分,而对电缆周围的土壤区域则进行较为稀疏的网格划分,以提高程序的运算精度和运行速度。结果表明:用MATLAB软件仿真,从而得到电缆及其周围环境的温度场分布,迭代计算了排管敷设交联聚乙烯电缆的载流量。证明使用有限元的方法分析地下电缆温度场,为电力工程中电缆载流量确定提供了一个比较可靠的计算方法。     

国产高压XLPE电缆绝缆中允许杂质尺寸的试验研究及方法

电树枝是影响XLPE电缆长期老化性能的重要因素,而确定高压XLPE电缆绝缘层中允许的最大杂质尺寸对于保证其长期老化性能是很重要的。本文利用针电极模拟杂质对从国产220kVXLPE电缆绝缘中所取得的试样进行了相关试验,得到电树枝起始电场强度约为270kV/mm,而杂质尖端最小曲率半径约为10μm。通过计算得到对于220kVXLPE电缆,杂质的最大允许尺寸约为130μm。这一结果与国家标准规定的允许杂质尺寸125μm基本符合,这一试验方法可以用于高压XLPE电缆中允许杂质尺寸的研究。     

挤包绝缘高压直流电缆应用现状与研究展望

挤包绝缘高压直流电缆已成为远距离、大容量输电线路建设的主要装备之一,现阶段广泛应用的挤包绝缘直流电缆以交联聚乙烯(XLPE)绝缘为主.针对XLPE绝缘高压直流电缆研发和应用中的绝缘空间电荷特性、副产物脱气等主要问题进行全面综述,指出在工业化生产方式下,超纯净体系XLPE绝缘材料是目前用来缓解空间电荷问题和实现电缆批量化...     

Development of prefabricated joint for 275-kV XLPE cable

Application of XLPE cables to extra-high-voltage (EHV) transmission lines is expanding due to their excellent electrical properties and ease of maintenance, and 275-kV long-distance underground transmission lines are reaching the stage of practical utility. Extrusion molded joints (EMJs) are widely used as the XLPE cable joint for EHV transmission lines. However, EMJs have presented problems because of their insulation. They are formed on site through extruding and molding of crosslinkable PE like the cable, and need a long time for installation on site and higher jointing technique. The prefabricated joints (PJs), which are already applied to 154-kV transmission line, are installed on site by using the parts manufactured and tested in the factory, they require a shorter installation environment. This report introduces the results obtained regarding the improvement of the electrical property, workability and the performance of PJs, designed for 275-kV XLPE cable. These joints are planned to be used for 275-kV transmission lines from 1995     

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.     

Comparative laboratory evaluation of TR-XLPE and XLPE cables with Super-smooth conductor shields

This paper provides data on four commercial tree retardant crosslinked polyethylene (TR-XLPE) and one cross-linked polyethylene (XLPE) insulated 15 kV cables supplied by three manufacturers. The cables have "super-smooth" conductor shields and "extra-clean" insulation and insulation shields. AC and impulse voltage breakdown and selected other characterization data are presented for cables that were aged immersed in room temperature water (15-30/spl deg/C) up to 24 months of a planned 48 months aging program. The five cables have high ac voltage breakdown strength, three of the TR-XLPE cables, actually increased in breakdown strength during aging. The one TR-XLPE cable that had the lowest ac voltage breakdown had vented trees at the insulation shield and high dissipation factor, which the other cables did not have. The impulse voltage breakdown strength of all cables decreased during aging; the cable with the lowest ac voltage breakdown also has the lowest impulse voltage breakdown. The dissimilar performance of the TR-XLPE cables and the excellent performance of the XLPE cable indicates evaluations at longer times are required to differentiate between modern TR-XLPE and XLPE insulated cables.     

我国发展直流海底电力电缆的前景

例举世界重要的海底电缆工程,表明其中大部分为直流海底电缆工程。叙述直流输电特点,着重以不同类型的直流和交流海缆载流量计算,证明直流海底电缆在输电容量、输电损耗和电缆线路长度限制方面显著优于交流海底电缆。肯定了我国发展直流海底电缆的必要性。有些运行条件下直流海底电缆会是优先的方案,甚至是唯一的选择。提出以发展直流交联聚乙烯(XLPE)海底电缆作为主要目标,并在比较不同类型海缆绝缘中的空间电荷对电场分布和电气绝缘性能影响和深入研究空间电荷积聚、抑制和移去机理基础上,积极研发抑制空间电荷积聚的XLPE绝缘料,作为关键技术突破,用于开发直流XLPE绝缘海底电缆,推进我国直流海底电力电缆的技术发展。     

交联聚乙烯电力电缆的电树枝化试验及其局部放电特征

电树枝化是影响交联聚乙烯（cross—linked polyethylene,XLPE）绝缘电力电缆长期安全运行的瓶颈,需要深入研究XLPE电缆绝缘的老化机制,尤其是电树枝化的规律,为XLPE电缆的设计制造和现场的运行管理,特别是在线诊断提供理论支撑。设计了交联聚乙烯电缆样品和相应的试验电极装置,并搭建基于实际XLPE电缆的电树枝化试验平台进行试验。结果表明该试验系统能满足XLPE电缆电树枝化试验研究的要求。以15kV的XLPE电缆作为试验样品,开展常温下工频12～21kV和50～90℃下的电树枝化试验,分析了电压和温度对电树枝形态的影响,得到电树枝局部放电的统计图谱,并将电树枝的生长发展分成4个阶段,分析了电树枝在不同生长阶段局部放电的最大放电量相位和平均放电量相位的分布,提取了其偏斜度等统计特征量,结果表明电压和温度对实际XLPE电缆中电树枝形态的影响与针一板电极得到的结果趋势相同,但是电树枝生长过程存在着一定的差异,同时最大放电量相位分布和平均放电量相位分布的3阶矩随着电树枝的生长发展而减小,可作为诊断电树枝生长发展阶段的参考量。     

Performance characteristics of XLPE versus EPR as insulation forhigh voltage cables

The physical and electrical properties of crosslinked polyethylene (XLPE) and ethylene propylene rubber (EPR) are compared in the context of their use in transmission class cables. Results indicate that the 138-kV XLPE cable has AC withstand/breakdown strength at least 25% higher than the 150-kV EPR cable. The XLPE cable exhibits about 70% higher impulse strength than the EPR cable. The loss factor of the XLPE cable is at least 20 times lower than that of EPR cable. Thus with XLPE cables, the yearly energy savings can be on the order of 15 MWh/cct. km for a 69-kV system, 52 MWh/cct. km for a 138-kV system and 127 MHh/cct. km for a 230-kV system     

XLPE电缆绝缘老化临界时间现象及其动力学仿真

为深入探究交联聚乙烯(cross-linked polyethylene,XLPE)电缆绝缘的老化特性,评判XLPE电缆绝缘的老化程度,文中对110kV XLPE电缆绝缘在135℃进行加速老化实验,采用拉伸试验表征XLPE断裂伸长率的变化规律,采用傅里叶变换红外光谱表征XLPE中羰基浓度与抗氧剂含量的变化规律。结果表明,XLPE电缆绝缘老化存在临界时间现象,即随着老化时间的增长,XLPE断裂伸长率由缓慢下降转变为快速下降,羰基浓度由缓慢增大转变为快速增大,临界时间均为2016h;而抗氧剂含量则随老化时间逐渐下降,不存在拐点。基于链式自由基理论,建立考虑抗氧剂反应过程的XLPE热老化动力学模型,进一步仿真计算XLPE电缆绝缘热老化过程中抗氧剂含量和羰基浓度的变化过程,仿真计算结果能够很好地吻合实验结果。研究结果表明抗氧剂含量可用于表征XLPE电缆绝缘的老化程度。     

Thermoluminescence in XLPE cable insulation

Crosslinked polyethylene (XLPE) has been employed in underground transmission and distribution cables because of its excellent electrical and mechanical properties, such as low permittivity and dielectric loss, high degree of toughness, and good flexibility. An underground power cable operates at temperatures above ambient and the polymeric insulation is usually crosslinked to provide mechanical strength to withstand the high temperatures. Chemical crosslinking is commonly employed; however, chemical crosslinking creates byproducts such as acetophenone, α-methylene styrene, and cumyl alcohol. The general practice is to decrease the concentration of the volatile crosslinking byproducts from the newly manufactured transmission class cables before they are commissioned into service. The concentration of the byproducts is decreased by treating the cables at a high temperature in a vacuum oven. At present, to determine the residual concentration of the byproducts, the treatment has to be stopped, a sample of the polymer has to be cut from the treated cable and the byproducts have to be extracted for several hours from the polymer before they can be analyzed. This paper describes a novel, non-destructive optical method for determining the concentration of the byproducts in XLPE prior to cable installation. The method involves in situ detection and measurement of thermoluminescence emitted by the crosslinking byproducts during the pretreatment of the cable, It is shown that the measurement of the intensity of thermoluminescence provides a direct indication of the concentration of the byproducts and that it is more sensitive than mass spectrometry     

Effect of Thermal Overload on the Voltage Breakdown Strength of Service-Aged URD Cables

Present industry specifications allow thermoset insulated polymeric cables to be subjected to emergency conductor temperatures of up to 130°C. The effect of the high temperatures on cable integrity has been questioned. This study shows that cyclic, long-term or fast-rise application of 130°C to service-aged, water treed underground residential distribution (URD), crosslinked polyethylene (XLPE) insulated cables, result in an increase in dielectric strength. Contrary to what happens in new cables, an increase in temperature from ambient to 130°C also results in an increase in voltage breakdown strength. It appears that at high temperature, moisture and some remnant by-products of the crosslinking reaction such as volatiles, diffuse from the insulation, contributing to the higher levels of dielectric strength. It is shown that thermoplastic insulation shields on XLPE service-aged cables are adversely affected by emergency temperatures.     

Application of dielectric response measurement on power cable systems

Water treeing is one of the factors leading to failure of medium voltage XLPE cables in long-term service. Increased moisture content inside oil-paper insulated cable is not desirable. To identify water tree degraded XLPE cables or oil-paper cables with high moisture content, diagnostic tests based on dielectric response (DR) measurement in time and frequency domain are used. Review of individual DR measurement techniques in the time and frequency domains indicates that measurement of one parameter in either domain may not be sufficient to reveal the status of the cable insulation. But a combination of several DR parameters can improve diagnostic results with respect to water trees present in XLPE cables or increased moisture content in oil-paper cables. DR measurement is a very useful tool that reveals average condition of cable systems. However, it is unlikely that DR measurement will detect few, but long water trees. In addition, DR cannot locate the defect or water tree site within the cable system. Combination of DR and partial discharge (PD) measurements can improve diagnostic results with respect to global and local defects. However, it is doubtful whether PD test can identify the presence of water trees inside a cable in a nondestructive manner. Further research is needed for more detailed conclusions regarding the status of a particular insulation and for predicting the remaining life of the insulation system.     

我国高压及超高压交联聚乙烯绝缘电力电缆的应用与发展

本文介绍我国 110 k V及 2 2 0 k V交联聚乙烯 (XL PE)绝缘电缆及其附件的发展。高压 XL PE电缆是我国城市电网建设与改造工程采用地下电缆输电系统的首选产品。本文叙述 XL PE电缆的绝缘设计原则、绝缘质量控制要求 ,特别是绝缘中杂质、微孔以及绝缘与半导电屏蔽界面的微孔与凸起、绝缘收缩与交联工艺的关系 ,及电缆附件的选型与预制附件橡胶应力锥的设计方法。介绍了我国特大城市 ,上海、北京与广州高压电缆系统的应用情况。最后对我国 110 k V及 2 2 0 k V XL PE电缆及附件进一步发展以及 5 0 0 k V XL PE电缆系统发展与应用前景作了预测     

Evaluation of service aged 35 kV TR-XLPE URD cables

This paper provides information on the aging of URD power cable insulated with a tree-retardant crosslinked polyethylene (TR-XLPE) compound, installed in a typical utility environment, Numerous evaluations were performed on samples of power cables aged up to 7 years in-service. AC and impulse voltage breakdown data are compared with data for similar 35 kV ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE) insulated cables removed from the same utility system. The data show that, to date, the rate of degradation of TR-XLPE cables is less than that of the EPR and XLPE insulated cables. Extrapolation of the data, assuming the same rate, indicates TR-XLPE cable will have the longest life     

Development of 500-kV XLPE cables and accessories for long distanceunderground transmission line-Part I: insulation design of cables

This paper discusses the results of a basic study for the development of 500 kV XLPE power cables. The authors have established that the factors that decide the performance of today's XLPE cables are impurities in the insulator and protrusions on the semiconductive layer, and that the insulation performance of XLPE power cables is determined by the size of these defects. In model tests of XLPE power cables, the minimum insulation breakdown stress of cables was determined, to set the design values for 500 kV XLPE cable. As a result, it was found that it is possible to design cables having an insulation thickness of 25 mm