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https://doi.org/10.5194/wes-2018-58
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Research articles 17 Sep 2018

Research articles | 17 Sep 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Wind Energy Science (WES).

A comparison study on jacket substructures for offshore wind turbines based on optimization

Jan Häfele, Cristian G. Gebhardt, and Raimund Rolfes Jan Häfele et al.
  • Leibniz Universität Hannover/ForWind, Institute of Structural Analysis, Appelstr. 9a, 30167 Hannover, Germany

Abstract. The structural optimization problem of jacket substructures for offshore wind turbines is commonly considered as a pure tube dimensioning problem with given topology, minimizing the entire mass of the structure. However, this approach goes along with the assumption that the given topology is fixed in any case. The present work contributes to the improvement of the state of the art by utilizing more detailed models for geometry, costs, and structural design code checks. They are assembled in an optimization scheme, in order to consider the jacket optimization problem from a different point of view that is closer to practical applications. The objective function is replaced by a sum term comprising several cost terms. To address the issue of high demand of numerical capacity, a machine learning approach based on Gaussian process regression is applied to reduce numerical cost and enhance the number of considered design load cases. The proposed approach is meant to provide decision guidance in the first phase of wind farm planning. A numerical example for a NREL 5MW turbine under FINO3 environmental conditions is computed by two effective optimization methods (sequential quadratic programming and an interior-point method), allowing for the estimation of characteristic design variables of a jacket substructure. In order to resolve the mixed-integer problem formulation, multiple subproblems with fixed integer design variables are solved. The approach shows reasonable and promising results, useful both for further research and technical applications.

Jan Häfele et al.
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Jan Häfele et al.
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Latest update: 17 Oct 2018
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Short summary
To reduce the levelized costs of offshore wind energy, capital expenses of substructures have to be decreased significantly. Therefore, structural optimization approaches were proposed in the recent past, mainly to improve the design of jackets. This work proposes a holistic approach to jacket optimization, which addresses some problems arising from methods that were presented in literature.
To reduce the levelized costs of offshore wind energy, capital expenses of substructures have to...
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