26 Jun 2020

26 Jun 2020

Review status: a revised version of this preprint is currently under review for the journal WES.

A fully integrated optimization framework for designing a complex geometry offshore wind turbine spar-type floating support structure

Mareike Leimeister1,2, Maurizio Collu1, and Athanasios Kolios1 Mareike Leimeister et al.
  • 1Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, 100 Montrose Street, Glasgow G4 0LZ, United Kingdom
  • 2Division System Technology, Fraunhofer IWES, Institute for Wind Energy Systems, Am Luneort 100, 27572 Bremerhaven, Germany

Abstract. Spar-type platforms for floating offshore wind turbines are considered suitable for commercial wind farm deployment. To reduce the hurdles of such floating systems to become competitive, a fully integrated optimization framework is applied to design an advanced spar-type floater for a 5 MW wind turbine. Three cylindrical sections with individual diameters and heights, as well as the ballast filling height are the modifiable design variables of the optimization problem. Constraints regarding the geometry, ballast, draft, and system performance are specified. The optimization objective to minimize the floater structural material shall represent the overall goal of cost reduction. Preprocessing system simulations are performed to select a critical design load case, which is used within the iterative optimization algorithm. This itself is executed by means of a fully integrated framework for automated simulation and optimization and utilizes a genetic algorithm. The presented design optimization example and approach emphasize the complexity of the optimization problem and lead to the recommendation to consider safety factors for other more critical and design-driving performance criteria. For the applied methodology and conditions it is shown that the required material for an advanced spar-type platform supporting an offshore wind turbine can be reduced by more than 31 % and, at the same time, the performance of the floating system – expressed by the maximum system inclination, maximum tower top acceleration, and mean translational motion – improved in some respect.

Mareike Leimeister et al.

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Mareike Leimeister et al.

Mareike Leimeister et al.


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Short summary
Floating offshore wind technology has high potential, but still faces challenges for gaining economic competitiveness to allow commercial market uptake. Hence, design optimization plays a key role, however, the final optimum floater obtained highly depends on the specified optimization problem. Thus, by considering alternative structural realization approaches, not that stringent limitations on the structure and dimensions are required. This way, more innovative floater designs can be captured.