Inflow-Dependent Sensitivity of Layout Optimization Performance: A Case Study of the Lillgrund Wind Farm

Layout optimization is one of the most effective approaches to reduce the power loss induced by turbine wakes. However, the performance of a wind farm is strongly affected by the inflow direction. This paper conducted a sensitivity analysis on a realistic wind farm, Lillgrund Wind Farm, to investigate the sensitivity of inflow direction on the power production of the initial layout and optimal limits. A wake model considering ambient turbulence intensity is adopted together with the wake superposition method to efficiently resolve the flow field in the wind farm. The results indicate that the power production of the initial layout had a significant discrepancy under different inflow directions, and relies on the consistency of inflow direction and layout array directions. The feature of the two main directional sectors is observed from a realistic wind rose. Therefore, two-sector wind roses are adopted in optimization, and the angles of sectors vary among 51 cases. After optimization, the fin-shape layout trends are observed. More importantly, the optimal limits of the layout are similar under different sector angles. The normalized power performance of the initial layout has an average of 72% and a variation of 24%. Meanwhile, the optimal layout can reach an average of 80% with a variation of 7%. The results indicate that the design boundaries of Lillgrund Wind Farm do not have a significant constraining effect on the optimal limit of layout limit.