Wind farm interference and terrain interaction simulation by means of an adaptive actuator disc

Abstract

Wind turbine wake interference is a relevant phenomenon that involves speed losses and turbulence increments which greatly affect downstream turbines, and power efficiency of wind farms. To precisely simulate wake interaction, the most common simplified wind turbine model, the Actuator Disc (AD) model, is improved adding the capability to adapt the thrust force distribution to a non-uniform velocity field over the disc, and the orientation to different local wind directions. These situations are typically found in wind farm situation where turbines interact with wakes of upstream turbines and the terrain. This development is based on the OpenFOAM open source finite volume parallel software. The improved AD model is first validated against wind tunnel experiments. Then, an onshore wind farm case is presented, in which the complex interaction of the turbines and terrain is studied. Comparing with power efficiency of field measurements, the simulations succeed to capture the characteristic values for low and high wake impact situations, with differences of 2.5% and 1.3%, respectively. Results show that this improved AD model produces a better solution for wake interaction cases. Its usefulness to predict the wind farm power output at feasible computational cost is also evidenced.