一种电缆本体恢复技术及应用研究

在配网设备故障中,电缆中间接头故障率占50％以上,降低其故障率是提高配网供电可靠性的关键.采用电缆本体恢复技术实现电缆中间接头连接,具有以下优点:等径和异径恢复;连接牢固,电导率高;径向电场均匀分布,电能损耗小、载流量高;接头处弯曲半径小,可拖动;寿命长,与电缆同寿命.该电缆本体恢复技术具有可靠性高、故障率低等优点,可有效降低因电缆接头故障而造成的经济损失.     

110kV XLPE电缆GIS内锥插拔式快速中间接头的设计EI北大核心CSCD

故障快速修复目前高压交联聚乙烯电力电缆迫切需要解决和完善的问题。为缩短电缆故障时的抢修时间以及节约硬件成本,将电缆终端气体绝缘开关(GIS)技术创新化地运用到电缆中间接头上,开发出了一种用于110KV交联聚乙烯电缆或电缆接头在发生主绝缘故障后临时连接用的GIS内锥插拔式快速接头。利用有限元分析对接头的应力锥、高压屏蔽电极、附件材料电性参数的配合进行了优化设计,得出了最优配合,完成了接头样机的研制并进行了现场试验验证。结果表明:应力锥的轴向长度及端部半径最优值分别为135 mm和25 mm;应力锥与半导体屏蔽层的介电系数比值以及应力锥与主绝缘的电导率比值越小越好;高压屏蔽电极的倒角半径及电极长度最优值分别为10 mm及40 mm。使用设计的接头,可在4 h内完成电缆附件的安装。该接头可以实现异径电缆对接,通用性强,主体部分可以重复使用,满足系统的运行要求。     

110kV电缆中间接头局部放电高频电磁检测与优化

电缆中间接头局部放电是导致交联聚乙烯(XLPE)电力电缆事故的主要原因,因此必须进行电缆中间接头局部放电的研究。电缆接头屏蔽层对高频电磁波信号有屏蔽作用,高频电磁波信号在空间传播过程中还会产生较大衰减,针对用于三相交叉互联的电缆中间接头屏蔽层是断开的这一特征,进行了电缆接头局部放电的建模、仿真和现场检测。首先,利用高频结构仿真器(High Frequency Structure Simulator,简称HFSS)建立了电缆接头的三维仿真模型,分析了在电缆接头内部发生局部放电时,高频电磁波信号通过屏蔽层断开处辐射出来的强度及其分布特点,验证了采用外置式微带传感器进行电缆接头局部放电检测的可行性。然后设置了电磁场探测线,生成了此线上不同位置处的电磁场变化曲线,分析了不同曲线的幅值情况,得到了信号最强的传感器最佳安装位置。最后,根据微带贴片天线理论,制作了外置式微带传感器,在某电缆线路投运前的交流耐压试验中进行了电磁波检测,验证了仿真结果。     

110kV XLPE电缆GIS内锥插拔式快速中间接头的设计

故障快速修复目前高压交联聚乙烯电力电缆迫切需要解决和完善的问题。为缩短电缆故障时的抢修时间以及节约硬件成本,将电缆终端气体绝缘开关(GIS)技术创新化地运用到电缆中间接头上,开发出了一种用于110KV交联聚乙烯电缆或电缆接头在发生主绝缘故障后临时连接用的GIS内锥插拔式快速接头。利用有限元分析对接头的应力锥、高压屏蔽电极、附件材料电性参数的配合进行了优化设计,得出了最优配合,完成了接头样机的研制并进行了现场试验验证。结果表明:应力锥的轴向长度及端部半径最优值分别为135 mm和25 mm;应力锥与半导体屏蔽层的介电系数比值以及应力锥与主绝缘的电导率比值越小越好;高压屏蔽电极的倒角半径及电极长度最优值分别为10 mm及40 mm。使用设计的接头,可在4 h内完成电缆附件的安装。该接头可以实现异径电缆对接,通用性强,主体部分可以重复使用,满足系统的运行要求。     

电缆中间接头温度场特性研究

电缆中间接头是线路运行中的薄弱环节,研究电缆中间接头的温度场分布特性,对电缆安全可靠运行具有重要意义。以10 kV三芯电缆中间接头为研究对象,分析了电缆中间接头径向和轴向的温度场分布特性,并研究了环境温度和负荷电流对电缆中间接头导体最高温度、中间接头表面温度和本体表面温度的影响规律,最后结合安全工况分析给出基于电缆接头表面温度判断其是否处于安全运行状态的依据。该分析结果可为电缆中间接头的运行状态监测及预警提供参考依据。     

交联电缆热缩中间接头现场安装中的制作改进

0引言 根据国际行业标准,电缆中间接头应与电缆本体具有相同的工作特性,但由于施工员对中间接头制作安装的操作细节不够重视及现场安装工艺条件较差等原因,导致中间接头的制作尤其是维修安装中存在较多电缆实验无法测试.本文将对交联电缆中间接头的制作缺陷进行分析.`     

电缆中间接头在桥梁上的结构疲劳特性分析

以舟岱大桥沿桥敷设220 kV高压电缆预制式中间接头为研究对象,建立了实体电缆振动-热老化平台,采用振动台对220 kV电缆中间接头进行加速振动老化试验,并采用振动加速度传感器和界面压力传感器监测振动加速度及界面压力的变化情况,分析了随桥敷设电缆中间接头在机械振动作用下的结构层疲劳特性,发现当电缆接头受外施振动作用影响时,外界环境的振动传递至电缆与中间接头支架,电缆振动频率为外施振动频率,振幅远超电缆负荷引起的振幅。对电缆接头开展720 h的加速振动老化试验,发现机械振动对接头界面结构层应力影响较小;在电缆载流条件下机械振动引起的电缆接头界面疲劳寿命大于电缆设计使用寿命;振幅较大时应采取增加防振垫等措施来降低振幅,避免局部受力而对电缆中间接头产生破坏。     

基于有限元法对±320 kV直流XLPE电缆中间接头电场与空间电荷的仿真计算

电场、温度场及空间电荷分布是高压直流(HVDC)交联聚乙烯(XLPE)电缆中间接头设计优化的重要参数。为此,利用COMSOL仿真软件计算了组合预制式、整体预制式2种电缆中间接头的电场分布、温度场分布、以及空间电荷分布,并分析了不同类型电缆中间接头各自的特点,提出了选型建议;针对2种类型的电缆中间接头,研究了材料参数、结构尺寸等因素对其性能的影响。结果表明:相较于整体预制式电缆中间接头,组合预制式电缆中间接头拥有更好的应用前景;通过对材料参数以及尺寸的研究发现,当使用硅橡胶(SR)作为电缆附件主要绝缘材料且硅橡胶电导率与电缆本体绝缘XLPE电导率的比值k约为10时,绝缘界面上的电场、温度场和空间电荷分布最优;优化应力锥曲线曲率半径、压接管厚度、内屏蔽层厚度等尺寸均能改善电场分布,且尺寸变化所达到的优化效果不如材料改性的优化效果显著,但却更具针对性。因此高压直流电缆中间接头的设计应以材料研制为主,以尺寸修正为辅。     

配电电缆中受潮接头的阻抗特性及其检测方法研究

电缆接头是电力电缆中最脆弱的部位,接头受潮是中压交联电缆的常见缺陷,如果未能及时得到修复,将导致电缆过早失效。文章围绕中间接头受潮后的阻抗特性及其检测方法开展研究,阐述了波在电缆中传播的折反射现象,以时域反射法的理论知识为基础,在CST (Computer Simulation Technology) Studio Suite中建立了10kV冷缩式中间接头的三维单芯模型,对中间接头不同程度进水情况下的阻抗特性和反射波形进行研究;在实验室10kV交联聚乙烯电缆中间部位的电缆接头上制作进水缺陷,分别进行电缆接头S参数测量和时域脉冲反射实验;最后,分析和比较了电缆受潮接头的阻抗特性仿真和实验结果,证明了使用时域脉冲反射技术对受潮电缆中间接头进行受潮诊断的可行性和有效性。     

XLPE电缆及其中间接头中局部放电电磁波传播特性的数值分析

局部放电(PD)检测和定位对电力电缆绝缘状态监测具有十分重要的意义,有必要建立一个精确的电缆模型对局部放电电磁脉冲的传播特性进行分析。考虑到电缆结构的复杂性,难以得到高精度的等效电路模型,因此采用数值电磁方法,通过构建良好的电缆模型,在时域中分析电缆及其中间接头的局部放电电磁波的传播特性,并对其传播特性进行仿真,计算局部放电源沿不同方向传播产生的电场,将计算得到的电缆中的PD信号波形与接头模型中的信号波形进行对比。结果表明,局部放电产生的电磁波在电缆和电缆中间接头中的传播规律存在很大差异,因此,在电缆局部放电检测与定位时要考虑电缆中间接头的影响。     

动态缆整体水动力响应对浮筒布局的敏感性分析

海洋柔性动态缆广泛地应用于远海风电设备以及深海油气开发中,安装其上的浮筒对柔性动态缆的力学行为有着明显的影响。分布式浮筒作为保持动态缆线型的装备,目前从整体分析和线型设计的角度对浮筒段浮力模块之间分布间距等应用研究较少。引入柔性动态缆整体线型的顺应性能指标,并采用OrcaFlex软件建立了陡波线型的数值模型。通过改变不同浮筒段浮力模块之间的距离等主要布置参数,研究了各参数对柔性动态缆顺应性能的影响,对柔性动态缆线型整体布置设计具有一定的参考价值。     

典型敷设环境下超高压交流XLPE海底电缆载流量分析

超高压海底电缆线路跨度大,运行环境复杂多变,不同敷设环境下海底电缆的输送容量也不尽相同,有必要对典型敷设环境下超高压海缆输送载流量进行具体分析。文中基于IEC 60287建立考虑外界敷设环境影响下的500 kV交流交联聚乙烯(XLPE)超高压海底电缆稳态热路模型,分析不同敷设段、不同敷设方式、不同环境温度以及不同埋设深度对海缆载流量的影响规律进行分析,并建立超高压海底电缆磁-热-流多物理场耦合有限元仿真模型对稳态热路模型计算结果进行验证。结果表明：海缆登陆段为整条线路的载流量瓶颈段,当登陆段海缆采用管道敷设时,其载流量要比采用土壤直埋敷设时的载流量降低约150 A,海缆载流量随着外界温度的升高以及土壤埋设深度的增加而逐渐降低。有限元仿真结果验证了文中所建立的热路模型计算结果的准确性。     

Improved calculations for no-load transformer switching surges

This paper deals with a modeling of components and calculation of transient overvoltages that build up on the transformer primary terminals after the transformer has been switched off by a vacuum circuit breaker (VCB). The transformer is connected to the circuit breaker by a cable. The transient overvoltages are calculated for different cable lengths, and the cumulative probability of different arc angles is investigated. In this study two cases are considered: transient overvoltages due to steady-state magnetizing current switching, and transient overvoltages due to inrush current switching. It is shown that the case of inrush current switching is worse, as virtual current chopping is possible. The cable is modeled by pi sections, whereas the transformer model is based on a terminal impedance. The VCB re-ignitions are modeled by means of withstand voltage characteristics and high-frequency quenching capability. Due to shortage of field tests, this work uses only literature references to compare the results with actual measurements     

现代架空线输电系统中的高压电缆段

Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have proven their operational reliability and functional assurance.In the past,cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables.New developments of high voltage XLPE cables make it possible to use this technology for EHV level applications in transmission networks.Within this paper,mixed network configurations,consisting of overhead lines and high voltage cables,are investigated.An exemplary EHV transmission line with a total length of about 100 km,which is quite typical for Central Europe,has been studied.Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice.The length of the cable sections are ranging from several kilometers up to lengths of 100 km.In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts.A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system.Numerical programs like ATP/EMTP have been used for these simulations.Peak values and wave shapes of the transient voltage stress have been evaluated,based on different systems and within possible combinations.In respect of the insulation coordination and transient stress at network nodes,the voltage-time trends are also analyzed.The combination of high voltage overhead and cable transmission systems,especially such with lengths of more than about 50 km,are making tightened and extended demands to the network design,to the operational management and of course to the network protection also.As an output of this investigations,the results might influence the strategy in running this new type of combined transmission systems.     

陷阱参数及其与交联聚乙烯电缆绝缘状态（英文）

Space charge issues have raised many attentions in recent years,especially in high voltage direct current(HVDC)application.Space charge accumulation in insulation system will give rise to acceleration of ageing and even cause premature failure of the material.However,from another angle,space charge might be also considered as a diagnostic tool of ageing for insulation materials.In this paper,a trapping-detrapping model has been developed to estimate trapping parameters of cross-linked polyethylene(XLPE)cable sections,which were taken from different HVAC operation conditions of 12 years and 8 years.The results reveal that,for both cable sections,samples from the inner location have the greatest trap density and the deepest trap depth.Additionally,breakdown strength tests and FTIR(Fourier-transform infrared)measurements on those samples have been carried out.From FTIR measurement results,the degree of oxidation among three layers could be found by the carbonyl index values.The oxidation degree of aged cable at the outer layer is higher than that at the other two layers probably because of the most sufficient contact with oxygen.Also,it has been noticed that the results from these measurements show some correlations with the estimated trapping parameters,especially for breakdown strength.     

Tackling sheath problems: Latest research developments in solving operational sheath problems in underground power transmission cables

In a power transmission cable system, the uniformly configuration of the cables between sections is sometimes difficult to achieve because of the geometrical limitation. This will cause the increase of sheath circulating current which results in the increase of sheath loss and the decrease of permissible current of the power transmission system. While the cable is on operation, because of cable aging and other unexpected reasons, sheath fault always occurs which leads to the further damage of the insulation layer and the life of the cable. These two problems were particularly addressed in this paper. Over last few years, two research groups in South Korea and the United Kingston have worked together extensively to solve these problems and made some great achievements. For tackling the problem of the increase of sheath circulating current, one special device was designed to measure this kind of current; an effective measure was proposed to reduce the current and the new measure was well protected from any further threats like cable fault and lightning. Regarding the problem with sheath fault, one data acquisition system was designed to monitor the sheath fault on field; a new fault phenomenon was discovered for the cable buried in sand; based on the new discovery, the fault was characterised, modelled and simulated; furthermore advanced signal processing techniques were introduced to extract the fault signals from the sheath, detect and locate the fault. These new solutions have either been successfully applied in practical operation of the power cable system or used in further research to propose more advanced solutions. The paper reviewed the latest developments of these new solutions.     

电缆线路改造引起的护层感应电压变化及其补偿

电力电缆线路改造时交叉互联后容易造成换位的三段电缆不等长,从而引起护层感应电压不平衡。本文通过对电缆护层感应电压的理论分析,提出了在末端电缆护层上连接电感元件进行电压补偿的方法,可有效地减小由于护层感应电压不平衡所造成的影响。     

Traveling wave fault locator for mixed,overhead, and underground teed transmission feeders

Society is increasingly concerned about the environmental impact of energy systems, and prefers to locate power lines underground. This is especially true in regions of outstanding natural beauty or if they affect environmental/political/planning constrained areas. However, the use of underground sections within a predominantly overhead feeder introduces significant problems for the auto‐reclosure of circuit breakers. Auto‐reclosure is important on an overhead feeder, since most faults are transient and, once the feeder has been de‐energized, the insulation strength of the air at the fault recovers and the line can be restored to service. Faults on an underground cable are different because, once the insulation is damaged, the fault is normally permanent. In addition, if the breaker is allowed to reclose onto a cable fault, the area of damage increases and health and safety concerns exist for humans in the vicinity of the faulted cable section. The main purpose of the traveling‐wave‐based measurement scheme described in this paper is to locate a fault on a teed transmission feeder with mixed overhead and underground sections. Simulation results demonstrate that the fault locator can accurately locate all realistic faults, including ones that are high resistance or occur at nonideal points on wave. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

某500 kV线缆混合线路的故障定位方案

针对某500 kV线缆混合输电线路,通过现场实测其内部各段工频参数和波阻抗,分析其分布特性及行波在输电线的传播特性,发现各段工频参数极不均匀,且各段的零序补偿系数之间、波阻抗之间也相差较大;内部固有行波反射点较多,在线缆连接处反射系数较大.根据以上特点,提出分两步的两端阻抗法和分段两端行波法对该输电线路进行故障定位,并基于当前设备条件进行技术经济比较,对线缆混合输电线路推荐采用分段两端电流行波法,可以有效地提高了线缆混合线路故障测距精度.     

架空线路用货运索道承载索数值模拟分析

架空输电线路施工专用货运索道多用于高山大岭、地形起伏较大的地区,因此索道架设时承载索的断面参数和张力复杂多变。计算索道承载索荷载后断面参数及张力的变化,该结果对提高货运索道的安全性和经济性具有重要意义。当承载索的跨距足够大时,将连续索道的承载索简化为多跨的悬链线方程组,并假定各索道支架处承载索支点摩阻系数为0,利用Excel的规划求解工具,将各跨水平张力和荷载点高程设置为可变单元格,以各跨支点处张力平衡、空载和荷载时线长平衡及荷载点处荷重与承载索张力的垂直分量平衡为约束条件,快速求解各未知量,从而得出索道承载索断面参数及张力的变化。该模型的计算结果与实测记录相吻合,适用于施工现场的实际应用。