A Novel Framework for Floating Offshore Wind Farm Layout and Cable Routing Optimization In the Mediterranean Sea

Floating offshore wind energy is expected to grow significantly in the next years, as new commercial projects are developed in deep waters, where bottom-fixed turbines become economically unfeasible. The reduction of the cost of energy is essential for enabling this growth. However, due to the relative immaturity of floating offshore wind technology, currently no standardized framework for the floating offshore Wind Farm Layout Optimization Problem (WFLOP) has been established. Most current research addresses either layout optimization or cable routing optimization separately, with limited efforts to integrate both. This study addresses this gap by presenting a comprehensive framework that integrates layout optimization, cable routing, and substation positioning, while accounting for bathymetry and geographical data. The framework was specifically designed to minimize computational costs. It approximates the impact of bathymetry on cable length by considering a lazy wave shape for the dynamic cable sections and uses a techno-economic cost function based on industry and literature data. The framework was tested in a case study off the west coast of Sardinia, a site characterized by medium wind speeds and a steep bathymetric profile. Three different farm sizes (300 MW, 660 MW, and 990 MW) were analysed using the IEA 15 MW reference turbine. The study compared two optimization algorithms, COBYLA and Random Search, for solving the WFLOP. The initial layout for both was generated using a Smart Start Algorithm. The results consistently showed that the Random Search algorithm outperformed COBYLA, although small improvements were achieved with respect to the initial layout. The study also identified and addressed specific challenges in the larger 660 MW and 990 MW projects.