A competitive evaluation of urban energy systems from viewpoints of energy conservation and mitigating environmental impact

Although various energy system alternatives for business, commercial, and residential customers have recently been developed in order to reduce energy consumption and CO₂ emission, it is important to evaluate competitive characteristics among such new energy system alternatives quantitatively, in consideration of tradeoff relations among economic cost, energy consumption, and CO₂ emission. In this paper, using multiobjective optimization model for urban energy system planning, two competitive evaluations are performed. One is the break‐even cost analysis for introducing more efficient, but more expensive energy equipment, such as photovoltaic system and fuel cell system. The other is that we evaluate the competitiveness of a certain energy system from the viewpoint of a whole urban area because there are multiple alternatives for attaining the same target of reducing CO₂ emission of energy consumption. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 71–79, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20421     

交联聚乙烯绝缘电缆的新应用

本文就ABB公司XLPE绝缘电缆的一系列新应用进行简单介绍,它的特点是采用电缆作为绕组,并就电缆做绕组产生的一系列与传统电磁装置的许多不同特性进行分析比较。通过比较,可以认为XLPE绝缘电缆绕组的新型电力设备将是21世纪电力的主流产品。     

The OSHA Hazard Communication Standards impact on cables

Since regulators have begun to consider acetophenone as toxic or hazardous, manufacturers and users of products containing this chemical must review its impact on their compliance programs, particularly the Hazard Communication Standard. Electrical wire and cable containing acetophenone can no longer be considered an “Article” exempt from the Hazard Communication Standard. Therefore, manufacturers of electrical wire and cable must now issue material safety data sheets (MSDSs) for any wire and cable product containing acetophenone in order to comply which federal regulations. Electrical distributors, who are subject to OSHA requirements, must add the MSDSs for these products into their existing Hazard Communication Program or institute such a program. The electrical distributors must also provide copies of the Manufacturer's MSDSs to the end user as required under the law. Industrial and commercial users of these wire and cable produces must add the MSDSs for these products into their Hazard Communication Programs at each facility. They must also provide the MSDSs with scrap or obsolete wire and cable sent to metal reclaimers     

汽车用线缆的新发展

本文介绍随着汽车工业的现代化而对汽车内所用的电线电缆的改进。这些改进主要是用双金属线(铜包钢和铜包铝)来替代传统的铜导线;用新型的可交联聚酯弹性体来替代传统的绝缘材料。其主要目的在于减小线缆的尺寸和重量,增加了线缆的柔软性、耐热水性和耐热性等机械物理性能。文章描述了这些新产品的开发、性能试验和应用。     

United Nations advances global environmental awareness

The need to address global environmental concerns on an international basis is discussed. Programs underway are noted. The role of the United Nations (UN) in the International Space Year is examined. Activities planned by the UN are described, and their purpose and funding are discussed     

New protection method for HVDC lines including cables

For the third project of the Hokkaido-Honshu HVDC Link in Japan, called the HVDC Link III project (rated at 250 kVDC-1200 A-300 MW), we developed an HVDC transmission line protection method based on a new working principle that allows high-speed and highly sensitive detection of faults, enhancing reliability in the supply of electric power. In general, increasing the sensitivity of relays will lead to an increased likelihood of undesired operation whereas lowering the sensitivity will impair the responsiveness of the relays. Our proposed method meets these apparently incompatible requirements very well. Basically classified as a differential scheme, the HVDC transmission line protection method compensates for a charging and discharging current that flows through the line-to-ground capacitance at times of voltage variations caused by a line fault or by the operation of DC power systems. The developed protection method is also characterized in that it uses current changes induced by voltage variations to restrain the operation of a relay. This configuration has made the proposed method far superior in responsiveness and sensitivity to the conventional protection method. A simulation using an EMTP (Electro-Magnetic Transients Program) was conducted on this method. Developed relay equipment embodying the new protection method was subjected to various verification tests, where this equipment was connected to a power system simulator, before being delivered to the HVDC Link III facility     

A finite-element method solution of the zero-sequence impedance ofunderground pipe-type cable

In order to provide adequate circuit protection for underground pipe-type cable systems from ground fault currents, it is important to be able to determine the zero-sequence impedance of pipe-type cables. For better knowledge of the impedance, a more accurate method needs to be developed. In this paper, we present a numerical method for computing the zero-sequence impedance of a pipe-type cable. This method is developed based on a finite-element analysis. Special attention is paid to the nonlinear B-H characteristic of the steel pipe, and an iterative procedure is employed for determining the permeability varying in the steel pipe. To validate the numerical method presented, measurements are made for the zero-sequence impedance at different current levels. A good agreement is observed between the numerical results and the measurement data     

管式皮带运输机在珠海电厂除灰系统的应用

珠海电厂从日本三菱引进了管式皮带运输机作为除灰的主要设备,其与气力除灰相结合把灰渣运送到贮灰场。经运行实践证明,其运行稳定,检修、维护量少,对机组的安全运行和节水节能、改善环境起到了较大的作用。     

Detection and location of dielectric fluid leaks on pipe-type cablesystems

The feasibility of using a hydrocarbon sensing wire to detect and accurately locate dielectric fluid leaks in power cables is shown. The construction of sensor cables developed for this purpose is described. The tests carried out on the cable are also described, and field trial results are reported. Because retrofitting old and operational feeders requires costly excavations, the system is suitable for installation on new feeders. However, use of boring techniques, which eliminate the disruption and expense of surface excavation by producing a small diameter tunnel beneath the surface, is an alternative option that is presently under investigation     

Disposal of cables at the "end of life"; some of the environmental considerations

Underground cables form an efficient and environmentally attractive means by which to supply electrical power and transmit information. Cables for both energy and data transmission are designed and manufactured for many years of problem-free operation, normally in the range of 10 to 30 years. However, it is clear that, for a variety of reasons, these cables will reach a point at which they can no longer operate, the so-called end of life (EOL). At this point, actions need to be taken on the fate of these cables. Often the decision may be either leave in situ or remove. This paper focuses on some of the many issues that need to be faced when the remove option is selected. The paper does not explicitly address the issues associated with disposal of paper cables, which have the added complexities of mixed materials: paper and polymer, oil, and lead. However, it should be noted that some of the considerations (separation of metals, the importance of separation, reuse of materials that are no longer approved, and disposal of insulation materials) are likely.     

Retrofitting-new high voltage XLPE cables substitutingpaper-insulated power cables in steel pipes

Many utilities still have paper-insulated pipe type cables in service. In the near future they may have to replace some of these systems due to local increases in electric power demand or aged cable insulation. In many cases the steel pipes are well protected against corrosion and thus suitable for further use. For retrofitting in such installations, XLPE-insulated cables offer several advantages. Felten & Guilleaume Energietechnik AG has developed a new three-core XLPE-insulated 64/110 kV cable with reduced insulation thickness (10 mm), that can be pulled into a pipe. In co-operation with VEW ENERGIE AG, the cable performance is being investigated in a field test, that started in October 1996. This long-term loading cycle test will last for three years. The test voltage, applied between conductor and earth, amounts to 127 kV. The temperature is measured with the help of an optical-fiber measurement system. This device is computer controlled and works as a remote monitoring system     

Investigation of the magnetic field produced by unbalanced phase current in an underground three-phase pipe-type cable

This paper presents a numerical technique for investigating the magnetic field produced by an underground three-phase pipe-type cable, which may carry unbalanced phase current. The numerical technique is based on finite element method and the equivalence principle. To validate the numerical technique, numerical results of the magnetic field generated by a pipe-type cable carrying balanced phase current are compared with the existing measurement data first. Then, the numerical results of the magnetic field generated by unbalanced phase current in a pipe-type cable are presented and analyzed. Through the analysis of the data, we observe that the zero-sequence current returning in the pipe, resulting from the unbalanced phase current, may significantly alter the magnetic field above the pipe.     

Ampacity of wrapped cables

Analytical equations that permit quick computation of the ampacity of power cables wrapped with refractory silica are presented. Ampacity test results are given for several wrapping methods and cable configurations. These test results show that the analytical method is reasonably accurate in determining the ampacity of wrapped cable     

New pole tip shapes mitigating torque ripple in short pitched and fully pitched switched reluctance motors

High torque ripple is one of the major disadvantages of switched reluctance motor (SRM). Although there are several publications in the literature addressing the full or partial solution to the problem for conventional SRM, no publication exists for the torque ripple reduction of recently emerging fully pitched SRM. This paper deals with finding best dimension set for a particular stator and rotor pole tip shape aiming to reduce torque ripple in both short pitched and fully pitched SRMs. Five new stator and rotor pole tip structures have been investigated and compared with conventional pole tip. Analyses have been performed with the finite element (FE) models of 6/43-phase short pitched and fully pitched SRM with unipolar excitation. With the proposed pole tips, torque ripple is reduced by 24.1% in short pitched SRM for 10 A phase current and by 22.6% in fully pitched SRM for 5.59 A phase current.     

通信电缆及光缆用填充膏的现状和发展

:对通信电缆和光缆用的填充膏的现状和发展进行了论述 ,对国内外众多厂家生产的填充膏的各种性能进行了详细的比较 ,提出了明确的分析意见 ,并对其应用和发展进行了预测和分析     

Electric fields in HVDC paper-insulated cables

HVDC cables start playing a more and more important role in interconnecting national grids. This paper deals with the calculation of electric fields in HVDC cables. The calculation of fields in an HVDC cable is far more complex than the equivalent case in HV ac cables. This is due to the fact that the conductivity of the cable insulation is temperature and field dependent and due to the fact that the electric fields under dc voltage may be time-dependent. The field distribution in an HVDC cable may be of a capacitive, intermediate (and time-dependent) or resistive nature. The kind of field depends on the stage the cable finds itself in: for instance, whether the voltage has just been applied, whether a polarity reversal has occurred or whether the field distribution has become stable. For each stage, the method of calculating, together with the computed results on a real HVDC cable are discussed. Usually, the effect of heating of the insulation by the leakage current may be disregarded. However, in certain cases, i.e. the cable temperature and applied voltage are high enough, the field distribution is influenced by these insulation losses. They even may lead to an instability that causes breakdown of the cable. A cable in service may be subjected to impulses superimposed on the dc voltage. The most severe case is that of an impulse superimposed on a dc voltage of opposite polarity. The calculation of the field distribution in this situation also is carried out     

On-line partial discharge detection in cables

This paper describes an on-line PD (partial discharge) detection technique applicable to power cables. The method can be applied to both wire screen and solid shielded cables. In wire screen shielded cables, PD components with frequencies <100 MHz can be detected at distances over 150 m from the source, PD activity with levels as low as 20 pC can be detected within 100 m. However, in the case of solid shielded cables, PD levels of ⩾50 pC can be measured within 60 m in the frequency range <50 MHz. This method also can be utilized to check cable accessories such as splices and terminations. PD pulses with frequencies to ~300 MHz can be measured near the joints and terminations. The suitability and the sensitivity of the VHF technique were checked against two other alternative PD detecting techniques (pulse phase analyzer and high speed digital oscilloscope) by performing PD measurements in standard air gap and defects induced in EPR-insulated cable under laboratory-controlled conditions. The suitability and sensitivity of the VHF method were as good as the two alternative PD detection techniques     

Ampacity of cables in single covered trays

A mathematical thermal model is developed to predict the operating temperatures of cables in a single covered tray when there is load diversity in the power cable bundle. The model accommodates two different loading scenarios: one in which the heat is distributed evenly across the cable tray cross section; and one which concentrates the heavily loaded cables along the centerline, while surrounding them with more lightly loaded cables. The temperature predictions provided by the model are compared to data found in other IEEE papers, data collected in laboratory measurements, and new data from a four-year study of cable trays in an operating nuclear plant. Reasons for differences between the field data and the computer results are discussed. The model is used to evaluate the conservatism in the available Codes and Standards. A derating factor is introduced that is defined in terms of the ampacity of power cables in open-top trays. The derating factor accounts for the added thermal resistance present when a cover is placed over the cables, trapping a layer of stagnant air on top of the cable mass. The computer model is then used to predict values for the derating factor as a function of cable depth. The derating factor is shown to be independent of the composition of cables in the tray. The presence of a cover is shown to reduce the ampacity based on an uncovered tray by up to 25 percent depending on the depth of the cables in the tray