Fr., 26.4.2013 10:30 Uhr
Simulation eines Offshore Windparks

Abstract:

We report on a fully dynamic simulation of Vattenfall's Lillgrund offshore Wind Farm, with a focus on the wake effects of turbines on the performance of individual turbines, and of the farm as a whole.

The modelling approach was to solve the fluids equations using the finite Element LES Computational Fluid Dynamics package Fluidity from Imperial College, London. Embedded in the fluid domain are dynamic representations of the wind turbines according to the manufacturer's specifications to simulate interaction between the wind and the turbine rotors. Based on the instantaneous velocity field in the turbine domains, the operating conditions (drotation rate, yaw direction, and blade pitch) are adjusted towards their nominal values. The interaction between the wind and rotors is then based on the lift and drag coefficients which both translate into a power output from the turbine and reaction forces on the fluid.

This model was applied to the wind farm for a selection of key wind speeds and directions, to investigate cases where a row of turbines would be fully aligned with the wind or at specific angles to the wind. The simulation results were then compared to actual performance measurements from the wind farm spanning several years of operation. These results demonstrate that time-resolving LES simulations are able to reproduce realistic wake structures, including wake meandering and wake recovery, as well as the effect of wakes on turbine performance.