Making use of analytical wake models for large scale power system models by generation of generic efficiency fields

Hereby a modelling approach for wind power in large scale power system models is presented. Therefor a generic wind farm layout is implemented and an analytical wake model is applied to it. The generic layout is organized as a square grid in resolution of the rotor diameter matching the given area. The wind turbines are placed in a fixed pattern matching the total given power and aiming to match rules of ideal placement. From that an efficiency field in dependence of wind speed and wind direction is obtained. The efficiency is defined as the total power of the wind farm considering wake losses for a certain wind speed and direction divided by the power a single turbine would produce given that respective wind speed times the number of turbines. This efficiency field is then introduced into a power system model. The power system model is therefore able to model the wind power generation not only in dependence of wind speed, but also the wind direction with comparatively low computational effort. This allows maintaining a physically sensible interpretation of a wind power plant and keeping the performance factor to availability and uncertainty losses only.
For the generation of the efficiency field the CharL model is used. As an exemplary power system model the TransiEnt Library is used. For the validation of the approach the German wind power generation at a municipal level is modelled using the characteristic lines of a small and a large wind turbine. The efficiency fields are then generated for each turbine with a generic farm layout for three power densities (30, 60 and 90 MW/km²). The area of the wind farms is set to accompany 40 turbines at 60 MW/km². The resulting power profiles are scaled according to the installed power in each municipality, whereby the choice of turbine and efficiency field is made appropriately. For all farms the main wind direction is set to western. The wind power feed – as published by the TSOs – is used as reference for the validation.
With this approach the wind generation profile can be modelled closely and the impact of the wind direction can be shown as an additional parameter by successfully modelling power generation drops that relate to changes in wind direction.