A New Formulation for Equivalent Wind Speed and Comparison of Results for Onshore and Offshore Cases using the High Resolution Doppler Lidar

A new formulation for equivalent wind speed is presented that accounts for the combined effect of wind speed shear, wind direction shear, turbulence and direction fluctuations on the expected power output from a turbine. The power estimated from this formulation is compared to that estimated from hub-height wind speed and to the formulation by Wagner et al. (2009). Results are compared using onshore data gathered during the Turbine Wake and Inflow Characterization Study (TWICS) conducted in April 2011 at the National Wind Technology Center (NWTC) at National Renewable Energy Laboratory (NREL). During this field campaign, the High Resolution Doppler Lidar (HRDL) took spatially and temporally resolved measurements of the inflow to a 2.3 MW wind turbine. This data will be used to characterize the effect of the inflow on the expected power output using the new formulation for equivalent wind speed.

A similar study will be done using offshore data gathered during the New England Air Quality Study (NEAQS) conducted in June-August 2004. During this experiment, the motion compensated HRDL was deployed on R/V Ronald Brown along with other surface based instrumentation. Data gathered from this experiment will help understand the effect of inflow conditions for offshore wind turbines. Recommendations for future studies are made based on the results.