HE AIM OF WIND TURBINE SYSTEMS DEVELOPMENT is to continuously increase output power. A few years ago, the rated output power of production-type units reached 200 kW. By 1999, the average output power of new installations climbed to 600 kW. The largest series production units today are specified to deliver 1.5-MW output power (Table 1). It is anticipated that in the near future, power rating of ...

The stratification of the atmospheric boundary layer (ABL) is classified in terms of the M-O length and subsequently used to determine the relationship between ABL stability and the fatigue loads of a wind turbine located inside an offshore wind farm. Recorded equivalent fatigue loads, representing blade-bending and tower bottom bending, are combined with the operational statistics from the ins...

The contribution of foundation damping to offshore wind turbines (OWTs) is not well known, though researchers have back-calculated foundation damping from “rotor-stop” tests after estimating aerodynamic, hydrodynamic, and structural damping with numerical models. Because design guidelines do not currently recommend methods for determining foundation damping, it is typically neglected. This pape...

The problem of robust H∞ dynamic output feedback control design with pole placement constraints is studied for a linear parameter-varying model of a floating wind turbine. A nonlinear model is obtained and linearized using the FAST software developed for wind turbines. The main contributions of this paper are threefold. Firstly, a family of linear models are represented based on an affine param...

We probe the reliability of monopile support structures designed to support industrial scale turbines along the coastal United States using stochastic models for the wind and wave loadings, and representations of the uncertainty associated with soil properties. The turbine support structure investigated is that promulgated by the National Renewable Energy Laboratory as typical of a monopile sup...

Breaking wave impacts on a monopile at 20 m depth are computed with a VOF (Volume Of Fluid) method. The impacting waves are generated by the second-order focused wave group technique, to obtain waves that break at the position of the monopile. The subsequent impact from the vertical run-up flow on a horizontal inspection platform is computed for five different platform levels. The computational...

Fatigue design and certification of OWT is a special challenge. As the turbine manufacturers are reluctant to share detailed turbines information and the offshore contractors have not full knowledge of integrated OWT design, integrated and non-linear time domain simulations are too cumbersome. A simplified approach is proposed, that requires complete separation between turbine and support struc...