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In recent years, there have been several reports of blade damage caused by lightning strikes on wind turbines. A few of these accidents have resulted in more serious secondary damage owing to the continued rotation of the damaged blades. To prevent the initial damage from spreading in this manner, wind farms in the regions of Japan vulnerable to winter lightning were required to introduce lightning detection systems, which can accurately detect when lightning strikes the wind turbine and then immediately stop the rotation of the blades. Normally, when the system detects a lightning strike to a wind turbine and stops operation, the process of restarting is initiated only after the soundness of the blades is confirmed by visual inspection. However, in bad weather, it is often difficult to check the soundness of the blade visually, and the resulting delay in the restart process prolongs the downtime and reduces the availability of the wind turbine. In this paper, we report the results of using the supervisory control and data acquisition (SCADA) system data to check the soundness of the blades after a lightning strike to resume operations more quickly, thereby increasing up-time. [ABSTRACT FROM AUTHOR]

Examines the results of lightning current measurement on transmission lines in Japan. Publication of the characteristics of lightning current amplitude in papers written on the issue; Methods used for conducting field investigations of lightning current in Japan; Results of lightning current measurement using magnetic links on transmission lines.

Proposes a novel calculation method of multiphase back flashover occurrence on the Okushishiku Test Transmission Line in winter lightning season in Japan. Role of winter lightning in the cause of most transmission line outages in Japan; Identification of several methods used to analyze transmission line outage; Procedure used for measuring lightning surges.

A network of lightning location systems covering the entire Japanese Archipelago has been operational since the late 1980s. However, the operational records appear to be distorted relative to winter lightning flash densities. The maximum flash density registered was 0.3 flashes/km² per one winter season, a mere one-tenth of the corresponding figure for severe summer lightning anywhere along the archipelago. On the other hand, the fault frequencies of overhead transmission lines constructed in the severe winter lightning districts are comparable with those of severe summer lightning districts. The author submits to resolve the apparent disparity by introducing two analytical parameters, namely 1) the propagation velocity of the return strokes of the winter lightning, and 2) the seasonal difference in the altitude of the lightning charge in the cloud. Consequently, the author proposes a certain seasonal modification of the threshold level applicable to the operation of lightning location systems. [ABSTRACT FROM AUTHOR]

The transmission line exposed to thunder storms in the winter manifests a series of unique behaviors substantially different from those observable during the summer season. The share of multiphase simultaneous faults as a percentage against the total number of faults is more numerous for winter than for summer. In addition, simultaneous flashing occurs onto different towers on several occasions. Since most of the transmission lines, including 500-kV ones, are built on a double circuit principle in Japan, these Lines are vulnerable to double-circuit faults during the winter. Exhaustive effort has been made to trace the origin. The author examined statistical data on the lightning performance of transmission lines as well as results of various field investigations, and established a fault probability estimation theory, which may be utilized to formulate pertinent countermeasures. [ABSTRACT FROM AUTHOR]

Investigates the incidence of ground lightning between the period of 1992-1995 in Japan. Establishment of the rational insulation design of power transmission systems; Information on lightning location systems in Japan; Description of the dispersion of lightning flash density in Japan; Examination of the relationship between the number of lightning strokes and thunderdays.