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This review summarizes the history, the basic theory and application examples of electromagenetic transient analysis by a circuit-theory based approach. Also, key points of handling the electromagnetic transients by the approach, which should be reminded by a user of such a simulation tool, are described in concluding remarks.

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Over the past 20 years there have been several studies examining the impacts of geomagnetic storms on high voltage power systems on the Earth's surface. These were strongly motivated by the blackout of the power grid in Quebec, Canada in March 1989 due to a severe geomagnetic storm created by a coronal mass ejection on the sun several days earlier. This paper evaluates examples of three major types of geomagnetic disturbances that typically occur (auroral electrojets, sudden storm commencements, and high speed streams due to coronal holes on the Sun). In each case the nature of the geomagnetic time variation is discussed along with its typical conversion to electric fields in the Earth. This allows a determination of the potential impact on a power grid. It is important to understand the relative importance of these different types of disturbances, as they have different latitudes of exposure, which are important for the locations of different power grids throughout the world.

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CIGRE maintains its value by delivering unbiased information based on field experience regarding power systems and equipment. Among sixteen Study Committees (SC) in CIGRE, SC A3 is responsible for all high voltage substation equipment not explicitly dealt with by other SC's. It covers all mechanical switching devices, surge arresters, instrument transformers, insulators, bushings and fault current limiters. This scope is well suited to various technical needs of utilities that require technical solutions for emerging problems in changing network conditions. This report will outline the current and planned works of CIGRE SC A3 including new technologies, improved specifications, reliability and life-cycle management of transmission and distribution equipment along with the CIGRE strategic directions and the associated projects.

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A line surge arrester using metal-oxide elements (LSA) has been applied for lightning protection of overhead lines. Externally gapped line surge arrester (EGLA) is a proven technology in Japan, for which an IEC standard was published in 2011. This is the first dedicated IEC standard for LSAs. This paper summarizes the essence, providing a technical background to utilize the IEC standard. Another aspect of the IEC standardization for LSAs includes revision of the surge arrester application guide IEC 60099-5, of which the FDIS (Final Draft International Standard) will be circulated shortly. The revised standard will newly include contents regarding LSAs, and is expected to provide necessary information for their application. This paper also intends to address issues in testing and applying LSAs with these IEC standards.

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The impulse characteristics and breakdown mechanisms of soil are the fundament of grounding design for lightning protection. Photographic investigation using X-ray films is a useful means for studying the impulse characteristics and breakdown mechanisms of soil. Through a large number of tests, three types of streamer discharges, positive streamer, negative streamer, and negative feather and positive retrograde streamer, were found in sandy soil under negative impulse voltage in this paper. Basing on the streamer discharge theory of gas, the developing processes of streamer discharges in sandy soil are preliminarily described. These three types of streamer discharges in soil are very similar to those in gas, thus it strongly supports the electrical breakdown mechanism of soil. On the other hand, using X-ray film imaging technology we observed the discontinuous ionization phenomenon in the soil around the grounding electrode on which a surge voltage was applied. This phenomenon is formed due to the non-uniformities of soil dielectric properties and the shapes and sizes of air apertures. The soil breakdown under lightning impulse is mainly caused by the electrical breakdown of the air among the soil particles.

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This paper has investigated the frequency and time responses of wave/surge propagation characteristics on a pipe-type cable based on a theoretical analysis, EMTP and FDTD simulations, as a function of the separation distance of the inner conductor from the center of the pipe enclosure. It is found that the conductor resistance increases and the inductance decreases as the separation distance increases, i.e. the eccentricity becomes greater, due to the proximity effect. The increase of the resistance and the decrease of the inductance are more pronounced as the frequency increases. Correspondingly, the attenuation increases and the characteristic impedance decreases as the eccentricity increases. Also, a transient voltage becomes smaller and a transient current becomes higher as the eccentricity becomes greater. EMTP simulation results are confirmed to agree satisfactorily with FDTD simulation results.

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In this paper, some of the major lightning troubles in traction power supply system are described. Different from power companies' grid, traction power supply system in urban area adopted D. C. 1500V as a voltage level and it is difficult to detect ground fault which resulted in more critical transport disorders. The troubles of breaking of feeder messenger wires and breaking of silicon rectifier are explained in detail to figure out the peculiarities of traction power supply system.

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Due to the progress of information-oriented societies all over the world, telecommunication cables are often installed on concrete poles along with power distribution lines. When a lightning stroke hits a concrete pole equipped with an overhead ground wire and a telecommunication cable, the lightning current is split into the three paths: the concrete pole, the overhead ground wire, and the telecommunication cable. It is easily estimated that the existence of the telecommunication cable reduces the current through the concrete pole, and thus, reduces the voltages across the insulators which support the phase wires. However, its quantitative study has not yet been carried out. In this paper, we clarified the effect of the telecommunication cable on reducing the voltages across the phase-wire insulators from the both sides of an actual-scale distribution line test and EMTP (Electro-Magnetic Transients Program) analysis.

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Establishment of lightning protection design of household electrical appliances has been an important subject with progress of a highly informative society. As examining lightning protection design of household electrical appliances, the individual measure for power equipment, communication equipment, and household electrical appliances is insufficient. And it is important to evaluate and examine these synthetically as one circuit (low voltage distribution system). This report describes the results of the lightning hazard evaluation for low voltage distribution system.

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With the advent of highly advanced information-oriented society, the appliances connected to the telecommunication line come to be widely used in the house, and it is reported that these appliances are frequently damaged by lightning. The home electric appliances have a built-in SPD (Surge Protective Device), damaged with the excess of the amount of charge passing through. In this paper, the authors estimate the lightning surge on an indoor distribution line by using the VSTL (Virtual Surge Test Lab. ) where the FDTD (Finite Difference Time Domain) method is adopted. The accuracy of the calculated results by the VSTL is verified by comparison with the experimental results. The lightning current resulting in the damage of the SPD of the home electric appliances is investigated in the case of the direct strokes to the concrete pole where not only the 6.6kV distribution line but also the low-voltage line are installed, and it turns out that the estimated damage rate reasonably agrees with the reported rate.

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The assessment of the lightning performance of a compact configuration of MV overhead lines that is expected to be adopted in the near future by an electricity distribution company in a Brazilian region characterized by high keraunic levels is presented. The compact configuration is characterized by the presence of an unenergized wire that has the main function to sustain the spacers of the phase conductors. As the wire could be periodically grounded, the paper analyses its effectiveness in reducing the overvoltages due to indirect lightning. The results are compared with those relevant to a conventional configuration of MV overhead lines now adopted by the same distribution company. The effects of the presence of surge arresters along the line are also analysed.

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The electromagnetic radiations from lightning discharges have been intensively studied for a long time in different frequency ranges. Recent observations of electromagnetic radiations from lightning in the ELF (extremely low frequency) frequency range so-called ELF transients are recognized as a powerful tool to obtain one of the most important properties of lightning discharges; the charge moment changes (Qds). In this paper we demonstrate the spatio-temporal distributions of lightning discharges together with their charge moment change (CMC) around Japan by using our newly developed domestic ELF observation network. This is the first time to obtain such type of distribution by using only ELF observations in the spatial scale of Japan (a few thousands km). We found that the obtained lightning source distributions both over the Pacific Ocean and the Sea of Japan are originated from the thunderstorm active regions confirmed by other measurements such as WWLLN. Statistical properties of the charge moment changes indicate that both number and CMC of positive CGs are superior to those of negative CGs. Moreover considerably large CMC with both polarities are identified for the CGs over the Pacific Ocean as well as those with positive polarity over the Sea of Japan.

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IEC 61083-4, which is to be completed in 2013, defines requirements for a software which analyses a. c. and d. c. waveform parameters distilled from digitally measured data. TDG (Test Data Generator) attached to the 61083-4 simulates digitally recorded data for typical waveforms observed in daily measurement. Any acceptable software can determine waveform parameters within a given margin specified in IEC 61083-4. Authors could successfully analyse all the a. c. waveforms generated by the TDG using techniques, 1) FFT after an interpolation for steady a. c. and 2) a base curve for short-term a. c. The latter involves the least square method and a set of non-linear equations. The distilled parameters for both waveforms are within the specified margins (0.1% in peak value) proposed in IEC 61083-4. The details of the algorithm are to be clarified in the paper. Also mentioned in the paper is a proposed TDG's controversial behaviour in which a current-zero instant is shifted due to a discrete sampling interval.

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In winter of 2010 and 2011, 65 return stroke currents were observed by Rogowski coils at 14 wind turbines in the coastal area of the Sea of Japan. Performance of JLDN, a large-scale lightning location system (LLS), in lightning detection is evaluated by comparison with the ground-truth data. Detection efficiency of JLDN highly depended on the peak current of return strokes, and strokes more than 15kA in their peak values were all detected by JLDN irrespective of the polarity of the current. Absolute values of the peak current estimated by JLDN were on the average about 20% smaller than the directly measured values.

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The Editorial Committee is working in planning and editing of the publication of Power and Energy Society. In this article, activities of the committee of the last term are reported, and recent trend and future problems are also discussed. The process of planning and editing of the publication, and the challenges to reduce the necessary months for reviewing papers and to increase the number of submitted papers are shown.

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