Fatigue design of large wind energy conversion systems and operational experience from the Swedish prototypes

Abstract The Swedish experience of fatigue problems in large wind energy conversion systems (WECS) is summarized. The two prototypes, Nasudden and Maglarp, are discussed, with emphasis on blade-related topics for the steel and glass-fibre composite blades, respectively. The topics include loads, fatigue design, material properties, structural testing, inspection procedures and environmental effects. In-service fatigue-related experience during 5–6 years of operation is discussed in the light of these topics.