Wind resource modelling of entire sites using Large Eddy Simulation

Abstract

Accurate wind speed, direction, shear and turbulence information are key inputs for wind farm energy yield and turbine suitability assessment. Met-mast measurements offer limited coverage both in horizontal and vertical directions, with few locations on the site and heights typically limited to below turbine hub-height. Simulation becomes an increasingly appealing option to mitigate these shortcomings. Current flow models used in wind resource assessment (WRA) rely heavily on assumptions to simplify complex atmospheric physics and reduce computing expense. As a result, they cannot resolve turbulence, and output average or annualized statistics. A new generation of models utilizing high-performance-computing now allows for high-fidelity simulation of sites with fewer modelling assumptions. In this work, we demonstrate and validate a computationally feasible large eddy simulation (LES) approach to generate high-fidelity time series of relevant quantities for WRA - including resolved turbulence - at sites in the order of 1000 square kilometres. The capability of the LES to produce insights in complex terrain is presented. A validation of the approach is performed by comparison of raw model results against met-mast measurements in a wide range of sites with varied complexities. Results show good agreement with measurements, with further error reduction expected through downstream adjustment of the model results with met-mast data on sites. Overall, the approach enables high-fidelity time-series based modelling for wind resource characterization and value addition to the WRA tool chain.