Underground 161 kV transmission project in Des Moines, Iowa

The design of a 161 kV XLPE-insulated underground cable installed in Iowa Power and Light Company's transmission line system and its accessories is described. The cables, cable terminators, and cable splices were designed specifically to provide an underground electric power transmission path through downtown Des Moines, Iowa. Electrical characteristics, thermomechanical design, and installation are covered     

基于zigbee的电力电缆接头远程温度监测系统研究

现有的电缆接头温度在线监测系统大多由于现场监测装置供电困难、布线复杂、难以维护等问题而无法大规模使用。针对以上问题,研制出一套新型的监测系统,该系统利用低功耗数字式温度传感器DS18B20实现地下电缆接头温度采集,通过内部集成C8051F系列单片机的新一代超低功耗的无线射频芯片CC2530实现近距离的通信,并利用全球移动通信系统(GPRS)网络来实现远程数据的传输,完成远方监测与管理。该系统实现了电缆接头温度数据的采集与处理、温度曲线显示、数据分析与保存、温度超限报警等多种功能,极大地延长了电缆接头的使用寿命。     

地下电缆表面温度监测系统的分析

作为一种重要的电能传输介质,地下电缆线路深埋地下,具有可靠性高,供电安全的优点,但同时也因其局部温度过高从而容易引发火灾事故,因此,实时监测地下电缆温度具有重要的意义。本文基于分布式光纤传感器的原理,改进了光纤温度传感系统温度信号的解调方法,提出了地下电缆表面温度监测系统的优化结构。     

110 kV交联聚乙烯绝缘电力电缆的施工与敷设

随着城市建设的发展,城区内的架空输配电线路正逐步改造为地下敷设的电缆线路,而旧城区的敷设路径错综复杂,给电缆工程的施工带来极大困难。本文介绍汕头市热-东线电缆线路工程的施工过程及经验总结。     

Conductor temperature monitoring system in underground powertransmission XLPE cable joints

A conductor temperature monitoring system using the current method was developed to estimate conductor temperatures at joints of extra-high-voltage (EHV) underground power transmission XLPE cables in real time. The validity of the software and hardware was confirmed by measurements on an extrusion molded joint (EMJ) of a 275 kV 1×2500 mm² aluminum-sheathed XLPE cable. The mean circumferential jacket surface temperature over the EMJ, where the cross section was larger than that at the cable portion, was measured by a line thermosensor using thermocouples or a distributed temperature sensor using an optical fiber. The conductor temperature in the cable joint was estimated by numerically solving simultaneous differential equations with 31 unknowns. A system which allows measurement of the cable conductor current at insulation joints of installed lines was also developed     

水下电缆的选择及施工技术

结合鄂州35 kV长梁线水下电缆的施工经验,重点对水下电缆的选择及对水下电缆敷设过程进行分析,为水下电缆的选择和施工提供参考和借鉴。     

Fault section detection system for 66 kV underground branchtransmission lines using optical magnetic field sensors

A fault section detection system that uses optical magnetic field sensors and instantly detects the section in which a ground fault occurred was developed for 66 kV underground multiterminal systems having Y-branch joint boxes. The optical magnetic field sensor, which is based on the Faraday effect in Bi-doped YIG ((BiYbGd)₃Fe₅O₁₂) having a large Verdet constant, detects cable conductor currents of 0 to 2000 A with high precision with the use of a laminated magnetic ring core of silicon steel plates. Sensors and a fault section detector/indicator of a system are connected with optical fibers capable of nonrepeated transmission of over 6 km     

高温超导电缆在城市地下输电系统应用的可行性研究

大城市有可能最先采用商业化运行高温超导电缆 ,用于城市地下交流输电系统。其主要应用目标是用于地下电缆工程改造 ,利用现有排管以高温超导电缆取代现有的常导电缆 ,增加地下电缆传输容量以及采用高温超导电缆将巨大电能 (1GVA以上 )输入到城市负荷中心。采用常导电力电缆传输 1GVA以上的电能进入中心城区 ,输电电压一般要求为 5 0 0 k V。在城市中心区不可能建设 5 0 0 k V变电站。 5 0 0 k V电缆线路所需的 5 0 0 k V大长度电缆和相应附件 ,目前尚未研制开发。采用高温超导电缆将有可能降低输电电压等级 ,可以采用 2 2 0 k V高温超导电缆将 1GVA以上的电能输入到城市负荷中心 ,满足特大型城市负荷中心供电需求。采用 110 k V高温超导电缆 ,亦有可能传输 1GVA左右电能。本文通过对交流高温超导电缆系列设计计算对额定电压 35 k V、110 k V、2 2 0 k V的高温超导电缆 ,按不同传输电流 (或传输容量 ) ,以高温超导电缆的传输效率 (损耗与传输容量比 )、高温超导电缆外径限值和超导导体绕制结构限制条件 ,确定高温超导电缆适用性界定条件 ,提出城市地下输电、配电系统用高温超导电缆可行方案。     

地下电缆群稳态温度场和载流量计算新方法

根据地表对流和深层土壤温度不变的原则,将地下电缆群开域温度场等效为闭域温度场,应用有限元分析了给定电缆负荷电流的地下电缆群闭域温度场分布.采用热路法将电缆金属套损耗归算到电缆导体,应用调和平均法对电缆导体外的薄层进行处理,最终将电缆等效为导体和外护两层结构,减少了剖分节点数,提高了计算精度和收敛速度.采用弦截法计算了地下电缆群载流量.试验和计算结果表明,利用有限元计算地下电缆群温度场和载流量满足工程实际需求.     

Operation control of internally conductor cooled cable system

The development of 275 kV internally-conductor-cooled cable systems is under way for application to long-distance large-capacity (1500 MVA/cct) underground transmission systems. From the viewpoint of the reliability and the energy economy of these systems, the operational control system for the cooling facilities is especially important, because the facilities require large cooling capacity due to the large heat loss of the cable conductor. The cooling device characteristics are described, and the effects of operation control on energy savings are examined. A long-term field test has shown that the computer-controlled operation system is very useful. Simulation results for the operational control system confirm that calculated values are in good agreement with measurement results     

Technical trends of high voltage and large capacity underground power cables

A 275 kV cross‐linked polyethylene (XLPE) cable with a large size conductor is mainly used for large‐capacity underground transmission lines in Japan. Furthermore, 275 kV gas insulated transmission line (GIL), which has a larger transmission capacity than 275 kV XLPE cable, has been developed and is in operation. The achievements regarding high voltage, large capacity underground transmission lines applied by the Chubu Electric Power Company will be introduced. In addition to these technologies, recent technical trends such as Rubber Blocked Joints (RBJ) will be presented. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

浮标水下传感器非接触供电及通讯系统设计

为实现浮标系统全天候、全天时的海洋数据采集,设计并实现了一套适用于浮标系统的水下传感器供电及通讯系统,预期技术指标为传输功率达到20 W,效率50%以上,数据传输正确率99%以上。系统采用浮标的系泊线缆作为传导介质,通过两级电磁耦合进行水上及水下的能量及数据的传输,采用合理的水上水下电路设计保证了模块的稳定工作及低功耗运行,利用可靠的通讯协议设计保证了数据的有效传输。只需在该平台的水下系统上挂接不同的传感器即可实现对各种水文数据的实时测量。对系统的测试表明该系统能够实现设计功能,运行稳定,效率较高。     

电缆铺设对气象设备的防雷效果对比分析

安装在野外的气象设备一般需要输电线路提供电源,出于工程施工方便输电电缆往往采用架空方式铺设,由于架空电缆容易感应雷电脉冲,造成后端连接的设备受到冲击而损坏.为了分析研究输电线路不同铺设方式是否有不同的防雷效果,通过建立等效模型对输电电缆自身分布电容电感特性进行分析,以及对电缆不同铺设方式引起分布参数变化的分析,利用电缆分布参数能够对雷电脉冲产生的衰减作用,得出了电缆埋地铺设对系统设备具有较好的防雷效果.工程实例表明,供电电缆半埋方式效果一般,直埋入土壤防雷效果最佳,而且埋地长度越长防雷效果越好.     

Steady-state operating conditions of very long EHVAC cable lines

In the present paper the authors investigate steady-state capabilities of very long EHVAC underground cable lines, without intermediate compensating stations, installed in meshed networks. Analytical formulas of cable length-loading relationship are presented to this purpose. The study shows that, in optimal operating conditions, most of the ampacity of such long underground cable lines can be exploited for active power transmission. Non-optimal operating envelopes are studied, showing the effect of terminal voltages and line losses on cable utilization and evidencing limited derating under realistic hypotheses. A parametric analysis of loading limits and possible voltage violations along the cable is shown; a simple criterion for optimal utilization of lossy cable lines is also proposed. Line-end shunt compensation requirements for integration of long EHVAC cable lines in transmission networks are then specified. Studies performed for both ideal and real cables and shunt reactors show that active power transmission of 100 km long, 400 kV-50 Hz underground cable lines can attain 90% of their thermal limit, without intermediate compensating stations. Excess reactive power and temporary overvoltages are effectively controlled by line-end compensation around 90%.     

Transformation of mechanized locomotives into semi-autonomousmachines

Computerized communications (radio) command, control, and monitoring (C⁴M) technology has been developed to replace mechanical controllers on 35 ton locomotives (loci). The C⁴M technology uses medium frequency (MF) underground radio technology developed in prior US Bureau of Mines research to achieve high-quality voice and data transmission in the mining complex. Robust electrical conductors such as rail, air/hydro pipe, and cable provide a signal transmission medium with an attenuation rate of 4 dB/304 m (1000 ft). The signal-to-noise ratio (SNR) exceeds 30 dB in the transmission system. A surface supervisory computer communicates with the C⁴ M controller via MF radio to create a semiautonomous locomotive. Diagnostic algorithms monitor locomotive sensors and locate failures in the propulsion system. The C⁴M controller has reduced propulsion system diagnostic time from an average of 40 to less than 10 min. The increased machine availability time contributes 17000 tons of additional ore to the trains' haul age potential each year     

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     

构建地下能源综合通道的设想

珠三角地区及其他大城市周围输电线路错综分布、密度高,一方面严重影响环境景观,另一方面压缩了人类的生存空间。面对电力与环境的突出矛盾,如何实现电力与环境的和谐发展是未来电网发展需要解决的关键问题之一。提出了构建地下能源综合通道的设想,采用大容量的电缆输电和管道输电技术,将地面输电线路全部转移到地下,实现土地资源的立体利用,解决电力与自然环境这一突出矛盾。在经济发达地区地下管网建设过程中应综合优化布局,综合考虑能源输送通道、信息输送通道、轨道交通通道等建设,实现地下走廊的广泛共享。另外,分析了面向大容量输电的直流电缆和交直流输电管道等技术的发展现状。     

Availability analysis in a cable transmission system with repairrestrictions

Single-system generating capacity adequacy analysis normally does not include recognition of transmission constraints or availabilities. These considerations are usually included in multiarea adequacy studies and in single system studies involving remote generating facilities connected to the system through either high-voltage AC or DC transmission. The availability of the transmission link can be critical to the overall system adequacy and to the benefit associated with the remote generation facility. The authors present a technique for modelling a transmission facility with repair restrictions. The example chosen is an underwater direct-current cable installation. The system is analyzed using a Markov model, and results are presented on time-dependent and steady-state unavailability, as well as on the common mode failure of trenches     

电力电缆接头温度监控系统研究

现有的电力电缆接头温度在线监测报警系统存在测量数据传输距离受限制、检测装置供电困难、需进行大量现场施工建设成本过高等问题。文章结合城市地下电缆沟内电力电缆实际运行情况,经过分析论证,首次提出了以低功耗单片机为采集终端,以电力电缆为感应导体,用感应通信传输前端测量结果,再用GPRS通信模块将测量数据远距离传输到控制中心的新方案。该方案特别适用于地下电力电缆分布范围广、供电距离长的大中城市。     

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