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1.
《Electric Power Systems Research》1999,48(3):177-192
Magnetic field management is concerned with the minimization of the effects of such fields on the public health, without sacrificing the effectiveness or reliability of the power system. The essential management techniques used for the underground transmission cables comprise geometry manipulation phase placement, and source shielding. In this paper, the simulation results of the standard recommended stack, triangular and flat configurations are presented. The simulations have been carried out for single and three phase cables. The resulting fields for different depths have been evaluated and compared. The results led to the conclusion that judicious placement of phases is a very powerful management technique to reduce the magnetic field as cost has not been changed. The appropriate phase placements corresponding to minimal field values are obtained. 相似文献
2.
《Electric Power Systems Research》1998,45(2):141-148
This paper addresses one of the most important sources of magnetic fields: underground power cables. New design configurations for one, two, three and four cables per phase are presented from a magnetic field perspective. Different management techniques are studied in detail. Judicious placement of cable phases in multiconductor lines to reduce the field effect is implemented by computer modeling and simulations. The state-of-the-art magnetic field simulation package PCFIELD developed by EPRI is used to quantify and present the tool used to manage the field values. The new design configuration cases are very useful from a magnetic field point of view and have low cost schemes that can be easily implemented. 相似文献
3.
In this paper a solution to reduce magnetic field emission levels generated by MV/LV substation power cables is proposed. The reduction is obtained by the arrangement of the phases in a proper way and by shielding the cables with magnetic or conductive materials. The effects introduced by these two options have been analyzed by means of simulations, using finite elements method calculation software, and by experimental measurements. The introduced results allow selecting an optimal arrangement and the best screening material in order to reduce the magnetic fields in those directions required to protect. 相似文献
4.
为了提高军用移动电站的电磁防护能力,需要研究电磁场对屏蔽电缆的影响,从而提高屏蔽电缆的电磁防护能力.总结了国内外在屏蔽电缆耦合电磁场问题方面的研究情况;介绍了常用的研究方法以及某些方法的最新发展;指出了电磁场对屏蔽电缆耦合问题的研究发展方向. 相似文献
5.
近年来,利用电力电缆屏蔽层载波通信传输配电自动化数据,是最经济、便捷和有效的一种可靠通信方式。城市小区普遍采用P型环网结构供电,采用电力电缆高频网桥耦合技术实现利用P型环网结构的电缆屏蔽层载波组网通信,是一种新的尝试,文章根据应用实例,通过现场测试多级分段电力电缆的屏蔽层信道的传输特性,分析载波组网通信效果,结果显示,利用多级分段电力电缆的屏蔽层载波通信传输配电自动化数据是可靠的。 相似文献
6.
Increasing electrification brings increased human exposures to electric and magnetic fields, commonly called EMFs, and growing evidence suggests that exposure to even low frequency, low energy, electric and magnetic fields may be related to adverse health effects. This paper focuses on magnetic fields and strategies that address them. The challenges faced by scientists in understanding magnetic field interactions with humans, and of mitigating their effects, are discussed. The management of magnetic fields created by power systems are discussed including shielding and interference technology 相似文献
7.
The proper shielding of control cables in an industrial control system is an important part of the system's design. With the advent of direct digital and analog process control in large industrial facilities such as steel mills and power plants, the minimumization of interference induced in the communication link between the in-plant transducers and analog or digital controller becomes an important problem. The communication link may be very short, or run for several miles, depending upon the installation. In most cases, this link is a pair of electrical conductors. It is often necessary to shield these control and instrumentation cables. This paper describes a series of tests that were developed to determine the shielding efficiency of cable trays made of various types of material. Tests are described for both electromagnetic and electrostatic fields. As in most engineering decisions, the final choice of material must be the result of a compromise. 相似文献
8.
《Industry Applications, IEEE Transactions on》2008,44(6):1834-1840
9.
针对一种新型的器身磁屏蔽——肺叶磁屏蔽自身以及其在变压器中的设计问题,以一台容量为334MV?A、带有肺叶磁屏蔽的单相自耦变压器为研究对象,首先应用三维频域非线性有限元法分析了肺叶磁屏蔽对变压器结构件、绕组区域漏磁场以及杂散损耗的影响;然后,以漏磁场分析以及杂散损耗计算为手段,以变压器油箱、夹件、拉板、油箱屏蔽以及肺叶磁屏蔽的磁感应强度(或损耗密度)作为观测目标,研究肺叶磁屏蔽安装位置以及尺寸对变压器漏磁场的影响,并通过负载损耗试验将有限元计算所得结果与实验值进行对比,验证分析的有效性;最后,针对肺叶磁屏蔽自身可能出现的局部过热问题,设计三种不同的肺叶磁屏蔽油路结构,基于有限体积法对比分析不同油路结构下肺叶磁屏蔽的油流、温升特性。对肺叶磁屏蔽特性的系统分析可为其设计以及其在变压器中的设计提供指导,具有重要工程意义。 相似文献
10.
11.
Carrescia M. Profumo F. Tartaglia M. 《Industry Applications, IEEE Transactions on》2000,36(5):1206-1211
Electric and magnetic fields produced by transmission systems have received strong interest both for biological effects and for interference with electrical and electronic devices, measuring sets, computers, control systems, etc. A deeper attention has been more recently devoted to magnetic fields which are difficult to screen and which can be significant when produced by transmission, but also by distribution and utilization systems. This paper proposes a simplified approach which seems to be useful in the case of lines set up by cables and, in particular, when more cables are connected in parallel, considering currents affected by significant harmonics content. Complete simulation results for several selected cases to analyze the electromagnetic field under quasi-stationary conditions in a multiconductor system are reported and discussed in detail, and the main results are summarized. It was found that the parallel connection of conductors can amplify or reduce magnetic field amplitude with respect to the single conductor case and that this effect depends on the harmonics order 相似文献
12.
Xiao-Mei Yang Xiao-Bang Xu 《Power Delivery, IEEE Transactions on》1996,11(2):644-649
The investigation of the magnetic field produced by power lines has drawn a lot of attention from researchers. Since sharing space by buried power lines and pipelines has become commonplace, it is of interest to investigate the influence of the pipeline. In this paper, we study the change of the magnetic field produced by buried cables, due to an additional steel pipe nearby. A Fourier series technique is used to calculate the magnetic field. An iterative procedure is employed to handle the nonlinear characteristics of the steel pipe and to determine the varying permeability in it. The calculated results of the magnetic field are compared with those produced by buried cables without the additional pipe. The comparison shows that the steel pipe close to buried cables may significantly alter the magnetic field 相似文献
13.
The Insulated Power Cable Engineers Association voltage limits differ from those permitted by the 1975 National Electrical Code for nonshielded extruded insulated conductors rated 2001 to 8000 V. These differences have created among cable users a renewed interest in the subject of power cable shielding. A brief history of shields has been employed as an introduction to a review of shielding. Electric field patterns in nonshielded versus shielded cable are described along with reasons for shielding and the several functions performed by shields. It is shown how electric stresses can create tracking or surface discharge in typical nonshielded cable installations Also reviewed are methods of minimizing shield losses in single-conductor shielded cables 相似文献
14.
Weiming Chen Weiguo Lu Xi Wang 《International Journal of Circuit Theory and Applications》2019,47(2):294-303
It is an effective way to use magnetic shielding scheme in magnetic coupled wireless power transfer (WPT) system to reduce magnetic flux leakage. However, the additional shielding material would affect the equivalent circuit model and the power transmission efficiency of WPT system. Although the impact of some common shielding materials on the transmission efficiency has been studied using finite element simulation, there is still a lack of understanding about the impact to the equivalent model in theory. In this paper, the equivalent circuit and transmission efficiency of WPT system are analyzed theoretically under the influence of different shielding materials, and the relationship between material electrical characteristics and transmission efficiency is presented. In our WPT prototype with two 166-mm diameter coils under ferrite shielding and aluminum shielding, the achieved maximum transmission efficiencies are 95.7% for 100-kHz resonant frequency and 97.9% for 1-MHz resonant frequency under the ferrite shielding, and the efficiency errors between the analytical and experimental results are less than 5% for 100-kHz resonant frequency and 10% for 1-MHz resonant frequency. 相似文献
15.
随着数字通信网络不断地向多功能、大容量、高频率和高速率发展,对数字通信电缆抗电磁干扰的屏蔽性能提出了更高的要求。论述了数字通信电缆屏蔽原理,提出了几种屏蔽电缆选择和应用的前提条件;介绍了各种屏蔽技术和结构;对屏蔽电缆的接地系统也作了详细介绍,以便使通信电缆更好地应用于通信网络。 相似文献
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17.
An improved functional approach for designing MRI (magnetic resonance imaging) main magnets with active shielding is presented.
By nulling one or two external moments as well as a certain series of internal moments of the magnetic field, new designs
with improved shielding in combination with or without shorter magnet lengths are obtained. The improved method can be employed
to design short and practical superconducting magnets at any given field strength. The resulting designs yield the desired
field homogeneity inside the region of interest without using superconducting shim coils. This approach requires only a modest
amount of computing power. One of the design steps, a contour plot of the continuous current solutions, can be utilized to
study stretch goals for favorable design parameters. 相似文献
18.
Takashi Kurihara Kenichi Kimura Takuya Watanabe Tomoyuki Sato 《Electrical Engineering in Japan》2023,216(4):e23447
Corrosion and breakages of shielding layers are one of the factors for degradation of extruded three-layer (E-E type) 6.6 kV cross-linked polyethylene (XLPE) cables. Tohoku Electric Power Network has been measuring electrical resistances of shielding layers in E-E type 6.6 kV XLPE cables, and recently has found breakages of shielding layers. The authors performed an accelerated degradation test for shielding layers of E-E type 6.6 kV XLPE cables by taking account of aqueous solution, temperature, heat cycles, bending stress, frequency of an applied voltage, and water-proof layer in the test conditions, and investigated factors affecting corrosion and breakages of shielding layers. Corrosion, cracks, and breakages were found on shielding layers in the cables without water-proof layer, but no crack was found in the cables with water-proof layer, when heat cycles were applied to the cables, and shielding layers were supplied with artificial sea water. We investigated the suppressive effect of the cables with water-proof layer on cracks and breakages of shielding layers by measuring tensile strengths of copper tapes obtained from the shielding layers of the cables with and without water-proof layers. 相似文献
19.
Barras R.E. Bow K.E. Snow J.H. Volz D.A. 《Industry Applications, IEEE Transactions on》1997,33(5):1321-1330
In recent years, environmental issues have had a profound influence on power cable designs and materials used in cable construction. This paper addresses the issues concerned with the effects of cables on the environment, as well as the effects of environmental conditions on cable performance and reliability. Effects on the environment include release of toxic materials and contamination of ground water. Environmental effects on cables are related to the presence of moisture, chemicals, ions, oils or solvents. All such issues must be considered in the evolution of environmentally-safe cables. This also extends to the manufacturing processes for producing cable insulation, jacketing and sheathing materials, as well as the cable manufacturing process itself. New cable designs and materials have been developed to mitigate many of the more serious environmental issues now associated with cable applications. Such designs and associated materials are reviewed in this paper. Emphasis is placed on the safeguards protecting the environment and on extending cable life and performance. These safeguards include technological advances in insulation, shielding, jacketing and sheathing materials, as well as new cable designs that cable specifiers should take into consideration when properly selecting and applying power cables for petroleum and chemical plant installations. Other user concerns that include cable diameter, short-circuit withstand, mechanical performance, installation, splices and terminations are briefly reviewed as they relate to current cable technology 相似文献
20.
20kV架空绝缘电缆防雷措施的研究 总被引:6,自引:0,他引:6
20 kV电压等级作为一种新型的配电电压等级,目前已在世界范围内被公认为可以取代10 kV电压等级。工程应用表明,20 kV线路多采用架空绝缘电缆,但架空绝缘电缆的雷击事故率却明显高于传统的架空裸导线。针对上述状况,全面分析了架空绝缘电缆雷击事故的特点,计算了20 kV线路多种情况下的感应雷过电压幅值。计算结果表明,感应雷过电压幅值可大于450 kV,超过现有20 kV线路的绝缘水平。基于10 kV线路以往的防雷经验和措施,分析并提出综合运用氧化锌避雷器、过电压保护器、屏蔽分流线等防雷措施来保护20 kV架空绝缘电缆线路。该研究为20 kV配电网安全供电提供了参考。 相似文献