Unsteady wind farm simulations and short-term power forecasting using actuator disk model in OpenFOAM coupled with WRF

Önel, Hüseyin Can
In this study, a numerical framework is developed for coupling mesoscale atmospheric flow simulations with Weather Research and Forecasting (WRF) to microscale Navier-Stokes simulations using OpenFOAM. First, an unsteady, nested WRF solution over the terrain of interest is obtained, utilizing Global Forecast System (GFS) meteorological input data for the desired time frame. The velocity field from the innermost nest of the WRF solution is extracted as a time series. These velocity data are then utilized as inflow boundary conditions at the outer boundaries of the OpenFOAM solution domain during the unsteady flow simulation. To accurately represent complex terrain topographies, a high-resolution computational grid that conforms to the terrain is employed. The microscale flow field is obtained using the incompressible unsteady Reynolds-Averaged Navier Stokes (URANS) solver, pimpleFoam, which provides a high-resolution wind field. The unsteady wind speed and the direction computed are validated against the field measurement data at the Flatirons Campus of NREL in Colorado, USA. It is first shown that the framework accurately captures near-ground wind fields within the atmospheric boundary layer, and forms the foundation for short-term wind power forecasting by means of wind turbine models to be placed into the simulation domain. Automatic blade pitch, rotor speed and yaw controllers are integrated into the rotating actuator disk model, which is used to simulate the wind turbines within time-varying wind fields. Once the turbine model parameters are calibrated and validated, the methodology developed is applied to the La Haute Borne wind farm in France. It is finally shown that the coupled flow solutions over the wind farm together with the wind turbine models capture wake interactions between the wind turbines and the resulting power losses successfully. The developed framework provides high-fidelity wind fields and short-term power forecasts for wind farms.
Citation Formats
H. C. Önel, “Unsteady wind farm simulations and short-term power forecasting using actuator disk model in OpenFOAM coupled with WRF,” Ph.D. - Doctoral Program, Middle East Technical University, 2023.