Study of wake effects for offshore wind farm planning

The main task of a wind farm is to get as much energy as possible from the minimal number of wind turbines and with a minimal space between the turbines due to the economy of land in onshore and connections costs in offshore. However, minimization of the distance between single wind turbines within a wind farm causes an increase of the so called wake effect, which is introduced by the shadowing of some wind turbines by the other units within the farm and as a consequence causes a turbulent flow. This leads to the reduction of energy yield in the shadowed units. For the offshore wind farms which consist of 100 and more wind turbines is this effect especially significant. In this paper the aspects of wake effects will be discussed. In the first step the wake phenomena will be characterized and the analysis and comparison of the existing mathematical models for wake effects will be performed. Then, the planning tasks for wind farms with an incorporation of the wake model in order to maximize the energy yield, such as optimal farm configuration, will be discussed. The modeling of an exemplary wind farm for wake effect simulation will be described and some exemplary simulations will be performed in order to show the influence of wake effect on energy yield.