No. 1335
	Lightning Protection for Wind Power considering Lightning Properties
	Investigating R&D Committee on lightning protection technology for wind power generation considering lightning properties
	Keyword : Wind power, Lightning properties, Winter lightning, Risk management
	With less carbon emission than thermal power generations and lower cost than other renewables, wind energy has rapidly expanded in Europe and the United States since 2000s to mitigate the global warming. On the other hand, wind power development in Japan has not been lively so much because of environmental and legislative barriers. As many standards for wind turbines have been established mainly for the natural environment in Europe and North America, where only normal summer lightning is considered. On the other hand, many of wind power plants in Japan are installed in costal areas of the Sea of Japan and suffered from so-called "winter lightning". The winter lightning has special properties like upper flash leader and high electric charge, both of which threaten wind turbine very much. The main purpose of the present report is to investigate the relationship between the properties of the winter lightning and damage aspects of wind turbine due to lightning. Another goal is to identify the direction of countermeasures for lightning protection of wind turbines in Japan. The main contents and results of the report are as follows; (1) investigation on lightning protection measures for wind power in Japan and other countries, (2) investigation on damages suffered from winter lightning in wind power plants, (3) examination on estimation methodology of strike frequency of winter lightning against wind turbines and shielding effect by an independent lightning tower, (4) study on surge propagation paths and their electric charges due to winter lightning, (5) consideration on selection methodology of surge protection devices (SPDs) and arresters taking into account winter lightning current and earth impedance and (6) development of risk management for winter lightning taking into account mitigation of repairing costs. After above investigations, damage aspects in wind turbine components, power lines and communication line due to lightning has been clarified. It became also evident how the winter lightning in Japan gives serious influence to wind turbine incidents and power and communication lines due to back flow surge from wind turbine.
	©2007. The Institute of Electrical Engineers of Japan