A new lightning protection system for wind turbines using two ring‐shaped electrodes

Abstract

AbstractWind turbines are often struck by lightning because of their special shape, their tall structure and their being placed in the open air. Besides seriously damaging the blades, lightning results in accidents in which low‐voltage and control circuit breakdowns frequently occur in many wind farms worldwide. Although some reports, such as IEC TR61400‐24 and NREL SR‐500‐31115, have indicated a methodology for protection against such accidents, a standard solution to these problems remains to be established.The author, focusing on a method for protection of low‐voltage and control circuits in a wind tower, proposed a new lightning protection system with two ring‐shaped electrodes attached to the wind turbine. The proposed system has two ring‐shaped electrodes of several meters diameter, one vertically attached to the nose cone and the other laterally placed at the top of the wind tower lying just below the nacelle. The pair of rings is arranged with a narrow gap of no more than 1 m in order to avoid mechanical friction during rotation of the blades and the nacelle's circling. When lightning strikes a blade, the current reaches the upper ring from a receptor through a conductive wire. Then, the electric field between the two rings becomes high and finally sparks over and the lightning current flows downwards. The current propagates along the lower ring and the grounding wire, which is arranged outside of the wind tower rather than inside, and is safely led to a grounding electrode placed far enough away from the tower's grounding system.In this paper, the author describes a basic experiment using a 1/100 downsized model, and also discusses the concept behind the present system. The result of the downsized experiment provides evidence of an effective advantage for lightning protection. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.