Abstract
As the offshore wind industry develops, more lease sites in the intermediate water depth (50–85 m) are being released to developers. In these water depths floating wind turbines with chain catenary systems and fixed-bottom turbines with jacketed structures become cost prohibitive. As such, industry and researchers have shifted focus to floating turbines with taut or semi-taut synthetic rope mooring systems. In addition to reducing the cost of the mooring systems, synthetic systems can also reduce the footprint compared to a chain catenary system which frees areas around the turbine for other maritime uses such as commercial fishing. Both the mooring systems component cost and footprint are pertinent design criteria that lend themselves naturally to a multi-objective optimization routine. In this paper a new approach for efficiently screening the design space for plausible mooring systems that balance component cost and footprint using a multi-objective genetic algorithm is presented. This method uses a tiered-constraint method to avoid performing computationally expensive time domain simulations of mooring system designs that are infeasible. Performance metrics for assessing the constraints of candidate designs are performed using open-source software such as Mooring Analysis Program (MAP++), OpenFAST and MoorDyn. A case study is presented providing a Pareto-optimal design front for a taut synthetic mooring system of a 6-MW floating offshore wind turbine.
Highlights
The global pipeline for floating offshore wind more than tripled in 2020 and as a result new floating technologies are needed as the industry looks to lease sites in deeper waters [1]
Fixed bottom jacket structures or monopiles are used in shallow waters and floating offshore wind turbines (FOWTs) with chain catenary mooring systems are used as the water gets deeper
Time-domain simulations are computationally expensive so the constraints are posed in such a way that inadequate designs can be screened out which prevents running time domain simulations unnecessarily
Summary
The global pipeline for floating offshore wind more than tripled in 2020 and as a result new floating technologies are needed as the industry looks to lease sites in deeper waters [1]. Depending on the type of mooring system, for example a chain catenary system, neglecting these nonlinear loadings can greatly under-predict the tension in the mooring lines [7] Another approach that has been attempted is to train a surrogate-model using many time domain simulations [8,9,10]. For this approach a tiered method for evaluating constraints is used to prevent running time domain simulations on undesirable designs In this process progressively more restrictive constraints are evaluated to determine the effectiveness of a mooring system based on criteria like the platform natural periods which are computationally trivial compared to time-domain simulations used for determining peak mooring line tensions. The tiered constraint approach is applied in this work to optimize a taut synthetic mooring system for a 6-MW FOWT
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
