What Stock Prices and Wind Loads Have in Common
Extreme loads that occur only once or a few times in the life of a wind turbine play an important role in the design process. The time series of loads typically look like a mixture of oscillations and random fluctuations, the latter caused by the turbulent wind. From the fluctuating time series we need to be able to determine reliable loads equipped with probabilistic properties like ‘exceeded on average once within 50 years’. For a long time the methods used to determine ultimate loads for wind turbines have been relatively simplistic. However, nowadays, because of increasing turbine size and value, more sophisticated methods are recommended. In this article we give an introduction to extreme value theory that provides the tools to determine ultimate loads and also introduce our computer program GumbelWind as a tool for the practical application of the theory.
By M. Hänler and U. Ritschel, Windrad Engineering GmbH, Germany
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