The interaction of power-line electromagnetic fields with the humanbody

The possible deleterious effects on human health due to exposure to the 50-60 Hz electromagnetic fields of power lines have been of concern for over 30 years. This important problem in biophysics has recently generated much activity. In the following sections of this article, the validity of the physical principles that underlie the reasoning and conclusions in previous articles is examined in the light of recent research work. Important misconceptions, errors, and omissions are pointed out. Topics covered include: natural sources of exposure; exposure to 60 Hz electromagnetic fields; thermal noise; epidemiological studies; and electric and magnetic fields in houses     

Electric and magnetic field exposure

The possible health hazards of low-level, power line frequency (50/60 Hz) electric and magnetic fields are considered. The historical background to this concern is briefly discussed. The types of studies being carried out and the results so far are summarized. It is concluded that while the scientific evidence on field effects is inconclusive, inferences of health effects justify further evaluation     

消除SPQC对电力系统不良影响的新方法

通过研究串联电能质量补偿器(SPQC)在投入和退出瞬间,对电力用户、电网及其本身产生的不良影响,分析了引起此不良影响的根本原因,找出了消除此不良影响的新方法,一是采用特种变压器改善SPQC各方面特性,二是提出了一种非投入和退出的控制策略,完全解决了这些问题。大量的仿真实验和模拟环境测试证实了该方法的正确性。     

A review of studies of the biological effects of electromagnetic fields in the intermediate frequency range

Concerns have been raised regarding the relationship between electromagnetic fields and human health. Compared to the research on extremely low frequency (ELF) and radio frequency (RF) electromagnetic fields, very few studies have addressed the biological effects of the electromagnetic field with intermediate frequency (IF) from 300 Hz to 10 MHz. This paper reviews the biological effects of IF electromagnetic fields with around 20 kHz from in vivo and in vitro studies. In contrast to studies on the effects of ELF and RF electromagnetic fields, few studies on biological effects of IF elecromagnetic fields have been carried out. From a short review based on published articles, it is seen that the available research data is inadequate for health risk assessment of IF electromagnetic fields. In future, it will be very important to conduct biological effects studies and evaluate the effects on human health from exposure to IF electromagnetic fields. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

AC Corona Charging of Particles

Measurements of the mobility statistics of dioctyl-phthalate (DOP) particles leaving an ac corona charger with various electrode configurations are reported. Mobilities are determined using a laser-Doppler velocimeter (LDV) to measure particle migration velocities in response to a transverse electric field imposed downstream of the charger. Charging models, which do not include effects of finite ion transit times, nonuniform fields, or differences between the distributions of positive and negative wire coronas, predict some of the mobility statistics, especially below 100 Hz, but cannot explain the high-frequency charging. In the turbulent flow with significant corona wind effects the disparate corona current distributions are shown to have a significant effect on the ac corona charging processes.     

The possible biological effects of low-frequency electromagneticfields. Supplement to the Public Affairs Board Report No. 10 June 1994

The IEE survey found no evidence to justify the high level of media speculation concerning the possible harmful effects of low-frequency electromagnetic fields or the needless public concern it generates     

Electromagnetic field effects and mechanisms

The author discusses the following topics: exposure vs. dose; known mechanisms; thermal effects vs. nonthermal effects; membrane excitation; electric fields (charge interactions; permanent dipole interactions; induced dipole interactions); magnetic field effects; free radical effects; human perception of 60 Hz magnetic fields; cyclotron resonance; microwave auditory effect; blood-brain barrier effects     

Evaluation and measurement of magnetic field exposure over human body near EHV transmission lines

Power frequency (50/60 Hz) magnetic field exposure still draws the attention of many researchers worldwide to investigate its harmful effects on living bodies. In light of this attention, as the population increases, the overlap between the power transmission lines and the settlement areas causes a problem (as in the case of exposure in random, residential, commercial and other areas, which lie very near or under the power transmission lines). In this paper, the power frequency magnetic fields, over a human body, at different positions, near extra high voltage (EHV) transmission lines are demonstrated, both analytically and practically. For the analytical part, the human body is approximately simulated as a parallelepiped. Two different positions for a human are selected near 500 and 220 kV power transmission lines. The magnetic field intensity along the vertical center line of the human is calculated. The effects of two different line configurations (for 220 and 500 kV power systems) and human positions, with respect to the transmission line, are considered. The paper also presents the actual practical magnetic field values measured near actual power transmission lines (220 and 500 kV) using a magnetic field measuring instrument. These transmission lines represent parts of the transmission network of the Egyptian united power system, near Cairo and El-Asher of Ramadan, under the actual loads. The results obtained, from the analytical studies and practical measurements, are compared with the international standards of the magnetic field exposures.     

带磁芯的罗柯夫斯基线圈及其应用

介绍带磁芯的罗柯夫斯基线圈(以下简称罗氏线圈)的研究结果及其一些典型的应用,研究表明,带磁芯的罗氏线圈的频带为20Hz～100MHz,灵敏度可在1V/A～1V/kA范围内选择,方波响应上升时间可达1ns左右。     

Response of dairy cattle to transient voltages and magnetic fields

Stray voltages in dairy facilities have been studied since the 1970s. Previous research using steady-state AC and DC voltages has defined cow-contact voltage levels which may cause behavioral and associated production problems. This research was designed to address concerns over possible effects of transient voltages and magnetic fields on dairy cows. Dairy cow response to transient voltages and magnetic fields was measured. The waveforms of the transient voltages applied were: 5 cycles of 60 Hz AC with a total pulse time of 83 ms, 1 cycle of 60 Hz AC with a total pulse time of 16 ms, and 1 cycle of an AC square wave (spiking positive and negative) of 2 ms duration. Alternating magnetic fields were produced by passing 60 Hz AC fundamental frequency with 2nd and 3rd harmonic and random noise components in metal structures around the cows. The maximum magnetic field associated with this current flow was in excess of 4 G. A wide range of sensitivity to transient voltages was observed among cows. Response levels from 24 cows to each transient exposure were normally distributed. No responses to magnetic fields were observed     

电力电缆的现场试验与诊断

本文介绍电力电缆现场试验和诊断的现状和发展。直流电压试验作为一种对油浸纸绝缘电缆非常有效的方法应用至今 ,但它对塑料绝缘电缆是无效而且有害的。文中讨论了近几年以来开发的 0 .1Hz VL F法、CDA法、OWTS法以及变频谐振试验系统。用变频谐振试验系统进行的 2 0～ 30 0 Hz交流电压试验已被 IEC确认为高压和超高电力电缆的主要试验方法。     

Evaluating the Effect of Various Walking Conditions on KINECT-based Gait Recognition

Human gait is one of the unobtrusive behavioral biometrics that has been extensively studied for various commercial and government applications. Biometric security, medical rehabilitation, virtual reality, and autonomous driving cars are some of the fields of study that rely on accurate gait recognition. While majority of studies have been focused on achieving very high recognition performance on a specific dataset, different issues arise in the real-world applications of this technology. This research is one of the first to evaluate the effects of changing walking speeds and directions on gait recognition rates under various walking conditions. Dataset was collected using the KINECT sensor. To draw an overall conclusion about the effects of walking speed and direction to the sensor, we define distance features and angle features. Furthermore, we propose two feature fusion methods for person recognition. Results of the study provide insights into how walking speeds and walking directions to the KINECT sensor influence the accuracy of gait recognition.     

Exposure of Pregnant Dairy Heifers to High-Tension Power Lines [Health Effects]

This article investigates the biological effects and potential health hazards to pregant dairy heifers from exposure to extremely-low-frequency (ELF) electromagnetic fields, in the 50/60 Hz range, particularly those associated with transmission lines. It was found that the EMF exposed cattles gained weight.     

Electromagnetics - the uncertain health risks

Considering all the evidences to date in the scientific literature, an association between EM fields at the environmental levels and harmful effects to human is inconclusive or uncertain. However, the available evidences are enough to raise concern by certain segments of the public. In order to manage health risk in the face of scientific uncertainty, authorities may be persuaded to consider precautionary approaches while establishing safety standards and protection guidelines for EM fields. The precautionary principle is another management tool that could be adopted to deal with the health risks associated with EM exposure. It is an extremely conservative decision making principle that leads to prudent actions in the face of uncertainty. Where there is reasonable risk to the public, a prudent action to reduce the risk should be carried out. This procedure should hold even when the scientific proof is inconclusive as long, as the balance of quantitative and qualitative risk, benefit and cost of action justifies it.     

A Clamped AC?AC Frequency Converter for Induction Heating

A clamped load-commutated ac-ac frequency converter for induction heating applications is presented. The converter provides variable frequency, continuous output current with low harmonic distortion, and has an optimum performance in the medium frequency range of 400 Hz to 3 kHz. A steady-state analysis of the converter for a series/parallel compensated load is presented. The effects of changes in circuit parameters on the operation of the circuit are described and preferred operating conditions are established. Test results on an experimental setup are presented.     

低压大电流母线框紧固螺栓的涡流发热问题

文章中用电磁场理论分析了低压大电流母线框紧固螺栓的涡流发热问题，得出了有关的解析表达式，并提出了消除有关发热危害的具体措施。     

新一代人工智能在智能电网中的应用研究综述

智能电网是人工智能 （artificial intelligence, AI） 的重要应用领域之一, 以高级机器学习理论、大数据、云计算为主要代表的新一代人工智能 （new generation artificial intelligence, NGAI） 技术的进步和突破, 将会促进智能电网的发展。首先概述AI的主要方法, 并对NGAI的内涵、特点与技术体系进行论述。之后, 对NGAI在能源供应、电力系统安全与控制、运维与故障诊断、电力需求和电力市场等领域中的最新应用研究情况进行比较系统的综述。最后, 总结NGAI在智能电网中应用的关键问题, 提出人工智能在智能电网中的应用可分为三阶段实施的建议。     

Misinterpretations of some power properties of electric circuits

It might be expected that the meaning of the apparent power S, a quantity of innumerable everyday applications for almost a century, is well understood. It occurs, however, that this meaning is still a matter of discussion and some interpretations hard to accept are published. Also it is suggested in some papers published recently that only oscillations of the instantaneous power may cause an increase of the apparent power S, which is not true. Misinterpretations that refer to fundamental notions such as powers could be particularly harmful for electrical engineering and should be eliminated as much as possible. Therefore, this paper shows that the apparent power does not have the physical meaning suggested recently. Also it shows that load unbalance in three-phase power systems does not cause any oscillation of the instantaneous power. The conclusion that load unbalance causes oscillations of the instantaneous power is a consequence of a substantial misinterpretation of this quantity in three-phase power systems     

高准确度外加20 Hz电源定子单相接地保护的研制

分析了发电机中性点处配电变压器对外加20Hz电源定子单相接地保护的影响。基于许继WFB-800型发变组保护硬件平台，研制了考虑中性点配电变压器参数影响的高准确度定子单相接地保护，试验验证了保护中计算接地故障过渡电阻方法的准确性，并分析和给出了防止20Hz电源及其引线故障误动作的措施。     

Design considerations for powering 415 Hz computer systems

It is noted that the design of 415 Hz power systems for mainframe computer systems requires additional considerations beyond those of conventional 60 Hz systems. The effects of the higher frequency on the wiring, components, and power system design are explored. Voltage drop, line drop compensation, centralized versus distributed power sources, and the special requirements of typical mainframe computer systems are considered. The power quality requirements of 415 Hz computer systems are significantly different from those of 60 Hz computer systems. The steady-state voltage tolerance is generally much tighter while the frequency tolerance is much broader. Because of the effects of the higher frequency on wiring impedance, 415 Hz wiring practices are different from those for a 60 Hz system. Nonmetallic or nonferrous wireways and relatively short wiring runs are recommended. Wire sizes larger than #2/0 are not effective at reducing wiring voltage drop, parallel conductors in parallel conduits are recommended. For best results, multiconductor cable assemblies such as the seven-conductor 400 Hz cable are recommended. Both passive and active line drop compensation techniques are available to help offset wiring voltage drop. Centralized 415 Hz power sources offer the advantages of economies of scale and ease of redundancy, which having the disadvantages of complicated 415 Hz wiring system design, higher installation costs, lack of flexibility, and potential load interactions. Distributed 415 Hz power sources minimize 415 Hz wiring and make it easier to meet the computer system's power requirements