Comparison of computational fluid dynamics and mass-conserving approaches for annual energy production (AEP) evaluation: Part I: analysis of a standard wake model and wind speed/power curve implementations

Abstract

A variety of microscale numerical approaches are available nowadays for high-resolution local flow characterization, differing on accuracy according to the application and on computational effort. In this study, a mass-conserving and a computational fluid dynamics wind flow model were compared using openWind and WindSim tools. The flow over an idealized terrain, perfectly flat with uniform surface roughness, was simulated with equivalent setup in both models to evaluate the implementation of turbine power curve and of a wake model, avoiding terrain effects. In this flat terrain, both approaches provided the same (uniform) speed-up field. Wind turbines were distributed over the domain in different arrays and spacing layouts. The power curve implementation, analyzed through gross annual energy production estimates, showed similar results in these tools. For net annual energy production, a maximum difference of 2.6% was found, showing small sensitivity regarding the same wake model implementation. The models herein employed may be considered equivalent for terrain-independent cases.