Floating Offshore Wind Farm Array Optimization considering Mooring Lines, Anchors, and Array Cables: Paper No. OTC-35814-MS

Offshore wind presents an opportunity to increase the domestic energy supply in the United States, but cost reductions are needed. To minimize the levelized cost of energy, we developed an optimization toolset for array design, considering layout, wake effects, mooring design, anchor selection, and cable routing. Real-world data, including lease area shapes, bathymetry, and seabed and metocean conditions, are used to inform the model. Our design optimization couples the optimizer with MoorPy for mooring systems, algorithms for cable routing and sizing, FLORIS for wake effects and annual energy production, and anchor capacity models for anchor sizing. Two layout types are considered: free and uniformly gridded wind farms. We optimize turbine x and y coordinates and anchor sizing for soil gradients, and we adjust mooring lines independently based on depth. Ground conditions and load components guide anchor type selection and are assessed for capacity using soil-structure interaction models. Cable routing is optimized using clustering, a minimum spanning tree algorithm, and conductor sizing to minimize cost. Real-world conditions from the Maine Research Array in the Gulf of Maine are used for three 10-turbine optimizations: one uniform grid optimization using particle swarm optimization and a pair of free optimizations using a gradient-based optimizer. The free optimizations specifically explore the effect of including multiple anchor types in the optimization process. It was found that annual energy production was a significant driver for all optimizations; however, cable, mooring, and anchor costs varied significantly from initial to final layouts, supporting their inclusion in the optimization process. The free optimizations showed a significant difference in the optimized layouts when multiple anchors were sized compared to the use of a single anchor.