等传输容量铜、铝导体海缆技术经济性比较

针对铜资源日益紧张造成电线电缆行业原材料成本压力的问题,分析铜、铝材料性能差异,完成等传输容量下铜、铝导体截面换算,依据现有生产工艺,采用解析法,完成铜、铝导体海缆参数计算,对比分析铜、铝导体海缆的技术经济性,进一步研究铝导体连接性能。结果表明：等传输容量条件下,铜、铝导体海缆单位质量近似相等,两者损耗及短路电流特性相近,铜导体海缆材料成本为铝导体海缆的110%~180%,采用交流氩弧焊可使铝导体接头具备良好电气与机械性能,铝导体海缆经济性更优。     

Insulation coordination of MV power cables

In medium voltage power cables, the concept of cost/reliability has been current since the end of the 1980s when the Brazilian Standards introduced ethylene-propylene-rubber (EPR) insulated cables, with different thicknesses of insulation for conventional cables and for those with blocked conductors or with water tightness constructions. However, despite the benefits obtainable by use of such cables, they have had limited use by electrical power utilities; perhaps because the concept has not become widely recognized. This paper intends to clarify and submit a new approach for design of the dielectric system of medium voltage cables, for use in underground and insulated overhead distribution feeders. Theoretical aspects of sizing the dielectric system, by means of coordinating the insulation, and also using reliability parameters, is dealt with in the paper. Results of practical applications are also presented and discussed     

排管内部强制水冷对地下电缆载流温度场的影响

为了提高地下电缆输电载流量,提出在排管内通入冷却空气或铺设冷却水管2种强制冷却方法,以提高地下电力电缆载流量。建立了在3×3阵列的排管内部直接通入冷却空气和铺设水管（铜管或PPR管）条件下的计算模型,根据IEC 60287标准计算了铜芯绞线损耗、铝护套损耗和绝缘介损,采用有限元方法计算了不同冷却条件下冷却空气和冷却水的雷诺数、努塞尔参数及对流换热系数,模拟了排管内部强制气冷和强制水冷条件下的电缆温度场和最大载流量。计算表明,采用排管内强制冷却可以显著提高电缆载流量,且随着管内空气速度或冷却水流速增大,冷却效果更明显。通过排管内强制冷却,可使电缆最大载流量由1 560 A提高至2 000 A,输电效率提升28%。     

Comparative Corrosion and Current Burst Testing of Copper and Aluminum Electrical Power Connectors

Crimped and mechanically bolted aluminum and copper connectors are commonly used for terminating industrial electrical power cables with ratings up to 600 V. Aluminum connectors are available for use with aluminum and copper conductors, and copper connectors are available for use with copper conductor only. The performance of copper and aluminum connectors was compared by conducting accelerated aging under corrosive environmental conditions. The testing consisted of 2000 h of cyclic salt fog environmental exposure, in conjunction with periodic electrical current burst testing. The connectors were evaluated by comparing the change in resistance of the test samples as the test progressed     

硅烷交联聚乙烯电缆绝缘线芯火花检验击穿原因的分析及工艺改进

本文主要阐述了硅烷交联聚乙烯电缆在制造过程中 ,绝缘线芯容易出现由各种原因引起的火检 (火花检验 )击穿 ,通过对击穿原因深入分析和研究 ,提出一些可有效地避免火检击穿发生的改进工艺及预防措施     

地下通信电缆外套金属管道与附近铺设屏蔽线屏蔽效果的比较

提出了一种同时考虑感性耦合和阻性耦合时的地下导体电磁屏蔽的计算模型,利用该模型进行了地下金属管道对其内通信电缆和屏蔽线对其附近通信电缆的电磁屏蔽计算。计算结果表明,不仅从感性耦合的屏蔽效果考虑,则金属管道和屏蔽线对地下通信电缆屏蔽保护效果基本相同;从阻性耦合影响和对防雷影响的屏蔽效果考虑,则套装金属管道的效果要优于敷设屏蔽线。     

Effect of ageing conditions on the type of water treeing [powercables]

A concept is presented that can serve as a tool in discussions of the improvement of materials and tests to prevent water treeing in underground power cables. It describes the ways in which ageing conditions, processes, and degradation characteristics are related. The concept is based on an extensive collection of experimental data, which show that water trees grown under different conditions have quite different compositions. Since the degradation products differ fundamentally, it is concluded that different water tree growth processes take place. Three principles for reliable testing are discussed in relation to the present concept of water treeing. The principles concern the correlation between test results and breakdown strength reduction in service, obtaining results in a reasonable amount of time, and obtaining sufficient accuracy     

地下管线对通信电缆的屏蔽效应计算方法

提出了一种同时考虑感性耦合和阻性耦合时的地下管线对通信电缆的电磁屏蔽模型,以管线节点电流代替管线单元电流进行插值,改进了传统电磁屏蔽效应计算方法,在此基础上,进行了地下管线对地下通信电缆的电磁屏蔽系数计算,探讨了屏蔽保护的规律,计算结果表明,管线粗细和端接阻抗将明显影响屏蔽保护效果。     

Nonlinear-coupled electric-thermal modeling of underground cable systems

An original nonlinear-coupled electric-thermal model of underground cables with the solid sheaths is proposed. The model deals with the numerical evaluation of losses, heating, and ampacity. The computation of the current dependent losses is undertaken by means of the filament method, where conductors and sheaths are represented by a number of smaller subconductors or filaments. Furthermore, heat-transfer phenomena through an "infinite" domain beneath the soil surface are modeled combining the finite and the mapped infinite elements, respectively. The corresponding finite-element meshes are generated by the advancing front method. The numerical results presented throughout this work suggest that the International Electrotechnical Commission relation concerning the external thermal resistance for touching cables, placed in flat formation, having appreciable sheath losses, should be re-examined.     

Investigation of water effects on degradation of crosslinkedpolyethylene (XLPE) insulation

This paper presents the results of the study of the influence of moisture on the electrical characteristics of XLPE power cable insulation under various service conditions. Tap water was put into the cable conductors and the ends were properly closed by terminal boxes in the first case, and opened in the second case. The samples of cables were subjected to electric stress and heating. Results from the accelerated aging tests of XLPE cables in these conditions are reported with reference to the changing of the XLPE's electrical characteristics. On the basis of the compared performances of XLPE cables given by this investigation, the lifetime of XLPE cables was estimated in the case of service under these conditions. Results of testing indicate that the combined effects of pressure of water or water vapour, electric field and temperature will greatly accelerate the deterioration of XLPE insulation     

Computer aided evaluation of pipeline current near toroidal HVDCground electrodes

The effect of the return current of an HVDC toroidal electrode on underground metallic installations such as pipelines and cables is evaluated. In order to quantify the effect of HVDC electrodes on the buried conductor, an equivalent model is first presented that takes into account the electrical properties of the pipeline and its surrounding. In particular, infinitely long pipelines with different coatings are considered. The pipelines are assumed to be continuously buried in homogeneous soil and are located in the vicinity of the HVDC electrode. It is found that the voltage gradient in the vicinity of the electrode results in return currents in grounded conductors, the effects of which can extend several kilometers. Protective coatings reduce stray current from local voltage disturbances but have limited effect against distant electrodes     

采用进端热处理技术悬链式CCV生产线生产220kV及以上超高压XLPE电缆

介绍了在悬链式CCV生产线上生产220 kV及以上超高压电缆绝缘线芯的一种最新技术,即在悬链式CCV生产线的硫化管进端采用特殊的热处理技术———进端热处理技术EHT,使绝缘层较厚的绝缘线芯(如220kV及以上超高压XLPE电缆绝缘线芯等),在进入硫化管硫化交联的过程中可以避免绝缘体的下垂,以提高绝缘线芯的圆整度和同心度,从而使在悬链式CCV生产线上生产超高压电缆绝缘线芯成为一种成熟稳定的技术,这样极大提升了普通悬链式CCV生产线的技术等级。     

A proposal for ground measurement techniques in substations fedexclusively by power cables

It was previously reported that when a fault to ground occurs in a substation fed exclusively by power cables, around 98% of the fault current can flow along the cable sheaths and auxiliary underground conductors, producing no local potential rise. This can modify greatly the results of ground measurements carried out in this type of substation, unless special care is taken and correction factors are suitably applied. The authors extend the experience gained during those measurement and determine a set of procedures that allow ground measurements to be made in substations fed solely by power cables. They set forth basic requirements for the measuring circuits and for handling the measured data. They then discuss power cable sheath characteristics in some step-down urban substations and ground measurement strategy for such substations     

基于改进模态分解的中压地埋电缆载波通信信道特性分析

对中压电力线信道特性的研究是构建中压载波通信系统的重要基础。针对目前中压地埋电缆的多模传输特性尚未明确,屏蔽层与钢铠接地对信道特性的影响尚未被详细考虑的情况,将多导体传输线模型与回路分析相结合,通过改进模态分解确定了中压地埋电缆的4类传输模态及其传输特性,并通过比较该方法与高频结构仿真(HFSS)的计算结果验证了所提方法的有效性。之后,基于模态分解的结果计算了载波信号的衰减与相移特性,并通过实验测量验证了其可信性。最后,结合多模态传输特性讨论了屏蔽层与钢铠接地对中压地埋电缆信道特性的影响。结果表明:当信号通过芯线与屏蔽耦合时,其信道特性几乎不受屏蔽层与钢铠接地的影响;当信号通过屏蔽与地耦合时,信道特性与接地阻抗密切相关。     

A model to predict current distributions in bundled cables forelectric glass melters

A model for predicting the current distribution in high-current cables that are constructed from bundles of parallel conductors (strands) is presented. These cables are typically used in electric glass melters to interconnect the power transformers and the melter secondary bus installations. Due to the phenomenon known as the skin effect, the magnetic field forces inside the bundled cable will tend to drive the current toward the outermost strands. The proposed model is developed by starting from the fundamentals of the skin effect phenomenon for solid conductors and then extending the concept for bundled cables. The model has also been coded in a simple FORTRAN computer program. Results obtained using the proposed model for a variety of cable bundling configurations are presented for demonstration purposes. These results show that currents in the outermost layers of bundled cables can exceed those of the innermost layers by a factor of four or more, depending on the total cable size     

基于温度概率预测的地下电力电缆可靠性模型研究

地下电力电缆周围气象温度具有不确定性。通过考虑气象温度对地下电力电缆可靠运行的实时影响,借助广义极值分布(Generalized extreme value distribution,GEV)对气象温度进行概率分布拟合,在此基础上分析了地下电力电缆的温度场和热阻等效电路,提出了基于温度概率预测的地下电力电缆可靠性模型,从而有效预测地下电力电缆的导体温度。数值仿真计算与实际测量结果的比较验证了该预测模型的有效性和准确性,为地下电力电缆可靠运行和温度在线监测提供了重要的技术支撑。     

Computation of Cable Impedances Based on Subdivision of Conductors

The frequency-dependent resistances and inductances of cables can either be found from analyt ical formulas, or with numerical methods based on finite elements or subdivision of conductors. While analytical formulas are limited to coaxial configurations, numerical methods can be used for non-concentric configurations as well. This paper discusses the method of subdivision into subconductors of circular, square or elemental shape, and compares the results for the case of a coaxial cable, where exact solutions are available from analytical formulas. The inclusion of ground return impedances is discussed next. The method is then applied to the calculation of impedances of pipe-type cables with magnetic pipe material, and of internal impedances of stranded conductors in the power line carrier frequency range.     

Polymer insulated high voltage cables

This article reviews the different components, conductors, semiconductive shields, insulation, sheaths, and jackets, that make up extruded, high-voltage cables. The different types of conductors are described as are the different insulation systems that are available for medium and HV cables. There is a comparison of the two main insulators used in extruded HV cables, EPR, and XLPE. Each material has some properties that are better than those of the other material.     

憎水涂层对铝单丝表面覆冰性能的影响

为研究憎水性涂层对铝单丝表面覆冰性能的影响,在低温过冷水条件下,利用实验室导线覆冰模拟系统试验研究了不同憎水性铝单丝表面覆冰的形成过程.研究发现:用普通憎水涂层涂覆铝单丝虽不能抑制表面覆冰的形成和增长,但可以延缓表面覆冰层的形成时间;硬脂酸涂覆制备的超憎水铝单丝表面可以有效抑制表面覆冰的形成和增长.分析表明:普通憎水性表面可以抑制表面附着水滴的湿润和扩散,但表面附着水滴与涂层间的作用力较大,水滴滑行角较大,水滴小易滑落表面:硬脂酸涂覆制备的超憎水铝单丝表面具有特殊的微纳米结构和较小的水滴滑行角,不利于水滴的粘附和冻结.     

Development of flexible joint for 500 kV Al-sheathed OF cable

The authors have developed a flexible dimensionally flush joint for 500 kV aluminum-sheathed oil-filled cables with handling characteristics similar to the cable itself so that it may be readily drawn into ducts in the same way as the cable without suffering damage. The process and characteristics are outlined. This joint is intended for use at intermediate points on long bridges or tunnels where local assembly and installation of conventional joints would be difficult. In developing the joint, various novel techniques have been used, including the flexible flush jointing of segmental conductors, the flexible jointing of paper insulation by a combination of wrapping-back and stepping methods, and on-site aluminum sheath corrugating and sealing methods