In today's highly information-based society, lightning damage has a significant impact on an increasing number of electric appliances such as personal computers and facsimile machines. Lightning surge protection devices for electric appliances are on the market and concern for lightning protection has been increasing, but there are still many unknown aspects of lightning surges that propagate into residences. To provide effective lightning protection measures, clarification of surge propagation patterns is needed. The Tokyo Electric Power Company has observed the patterns of lightning surge propagation into houses using lightning surge waveform detectors installed at ordinary residences and obtained data on 30 lightning surge current waveforms between 2008 and 2009. This paper discusses various aspects of lightning surge currents propagating into low-voltage appliances, including home electric appliances, based on the lightning surge current waveform data obtained from lightning observations. The result revealed the patterns of lightning surge currents propagating into the ground and lines of low-voltage appliances. © 2011 The Institute of Electrical Engineers of Japan.

Abstract

This paper deals with a decentralized autonomous control strategy of a super‐distributed energy system with a hierarchical structure in order to reduce the complexity of control. In this paper, distribution systems are assumed to be composed of multiple small‐scale power systems in which many customers with dispersed generators exist. A small‐scale power system can be considered as a unit with a generator state and a load state, or as a customer with dispersed generators. Control components of small‐scale power systems are interconnected with each other and are used to operate distribution systems. An expanded decentralized autonomous control method for a super‐distributed energy system with a hierarchical structure is proposed on the basis of the Hopfield neural network. It is demonstrated that super‐distributed energy systems with a hierarchical structure can be controlled autonomously by applying the proposed method. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.