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Keywords:

  • downbursts;
  • turbine loads;
  • turbulence;
  • thunderstorms;
  • FAST

ABSTRACT

The simulation of thunderstorm downbursts and associated loads on a utility-scale wind turbine is the focus of this study. Using a deterministic–stochastic hybrid model, downburst-related wind fields are generated separately from non-turbulent and turbulent parts. The non-turbulent part builds on available analytical models developed from field data that include recorded downburst events; the turbulent part is simulated as a stochastic process using standard turbulence power spectral density functions and coherence functions adjusted by information on parameters such as the downburst's translation velocity. Key thunderstorm downburst-related parameters include the maximum radial velocity, the height and radial distance to the maximum radial velocity, the downburst intensity, the downburst translation velocity and the downburst translation direction. In addition, the streamwise ambient (environmental) velocity and the downburst touchdown location relative to the wind turbine are also important in turbine load computation. A utility-scale 5-MW wind turbine model is selected, and loads are generated using stochastic simulation of the aeroelastic response. Information available in the literature on recorded downbursts is used to define the cases studied. A single downburst simulation and associated turbine response simulation is first discussed to illustrate loads computation and highlight downburst-related parameters of interest. Next, a Monte Carlo simulation study is performed to investigate the influence of touchdown locations and translation direction on turbine extreme loads. Copyright © 2014 John Wiley & Sons, Ltd.