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The number of home electric appliances, such as personal computers and telephones, has been rapidly increasing. Lightning damage to these home electric appliances has a great impact on a highly sophisticated information society. There are cases in which lightning overvoltages in low-voltage distribution lines cause malfunctions in them, even though they are equipped with surge protective devices to protect against lightning overvoltages. Therefore, for lightning protection of low-voltage equipment including home electric appliances, it is important to understand the phenomenon of lightning overvoltages in low-voltage power distribution lines. However, many aspects of this problem are not entirely clear, in particular how they are generated. The Tokyo Electric Power Company carried out lightning observations on low-voltage distribution lines. The observation results provide a statistical distribution of lightning overvoltages in low-voltage distribution lines. A mechanism for generating lightning overvoltages in low-voltage distribution lines is inferred from the observed waveforms and facilities data. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 12-21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21299 [ABSTRACT FROM AUTHOR]

As society becomes ever more dependent on electronics, interest in the patterns of lightning hazards in low-voltage distribution lines including residences is growing. However, there have been few studies on low-voltage distribution lines and many things remain unknown about the propagation patterns of lightning surges in the field, particularly the intrusion of lightning surges into residences. The Tokyo Electric Power Company has conducted field research of phenomena accompanying lightning flashes to actual distribution systems using lightning-activated cameras as well as lightning surge waveform detectors, obtaining invaluable 101 datasets of lightning flashes between 2002 and 2007. This paper analyzes typical observation examples and estimates the lightning surge propagation routes in low-voltage distribution lines. In some examples, it is inferred that a lightning current flowed in the reverse direction from the residence to the low-voltage distribution line caused by ground potential rise due to the nearby lightning to the ground. These results will be useful for clarifying lightning surge propagation patterns in low-voltage distribution lines. [ABSTRACT FROM AUTHOR]

New small-scale dispersed generation systems, such as fuel cells and micro gas turbines, have made remarkable advances lately and they will be applied practically in the near future. Although a large number of researches on the introduction of small-scale dispersed generation systems have been carried out, only a small number of small-scale dispersed generation systems are considered in these researches. Therefore, little is known about problems to be solved when a large number of small-scale dispersed generation systems are introduced into electric power systems. This paper deals with a super-distributed energy system that consists of a great number of dispersed generation systems such as fuel cells, micro gas turbines, and so on. The behavior of a customer with a dispersed generation system is simulated as the Ising model in statistical mechanics. The necessity of a distribution network in super-distributed energy systems is discussed based on the Ising model. The feasibility of decentralized autonomous control using vicinity information is also investigated on the basis of stability analysis of the Hopfield neural network model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(1): 43–55, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10368 [ABSTRACT FROM AUTHOR]

Although power distribution lines are protected by ground wire systems, there are fears that these ground wires may break at their corrosion points. For practical purposes, they have therefore been removed to avoid maintenance in certain areas. The Tokyo Electric Power Company (TEPCO) has continuously observed lightning strokes and obtained 321 datasets to date. The present study has determined the potential for an anticipated lightning stroke attraction effect based on the observed data, despite the fact ground wires are eliminated while ground wire caps are left in place. Furthermore, a verification experiment using facilities simulating the power distribution system has confirmed the problem of insulated wires being struck by lightning and the extent of the impact of the ground wire cap on the lightning stroke attraction effect. These results are expected to provide a new facility-construction menu, which will help rationalize the lightning protection design. [ABSTRACT FROM PUBLISHER]