Compared with conventional offshore wind turbines, “floaters” open up enormous wind energy potential, as they allow development of so many offshore locations in deep waters. The Fraunhofer IWES has been developing a tool for the automated optimization of floating wind turbines since 2017 with the aim of increasing the system’s performance and making it more cost-effective and competitive through improved material usage.
Our scientists are working on and with a modeling tool for floating wind turbines which allows an overall system observation of floaters. This tool is now being continuously further developed and verified. The tool makes it possible to not only simulate a wide range of different site conditions and adapt the floater design automatically to suit them, but also to optimize individual systems components (e.g., the floating support structure or controller) with regard to various aspects (costs, performance, reliability). Alongside detailed optimization of the system during the design phase, the development of the tool also focuses on rapid cost estimation in the floating wind farm project planning stage.
The use of a variety of optimization algorithms and tools developed and programmed in-house for modeling and automated simulation and optimization makes it possible to map and weight various target variables flexibly depending on the optimization problem and requirements. The aim is to bring the optimizer into industrial application and to enable customers such as foundation developers and wind farm operators to create a specific design taking international standards into account.
Optimization algorithms are fundamentally indispensable due to the high complexity of the overall systems and its coupled dynamics. They allow not only calculation of the target variables beyond the static equilibrium state, but also detailed consideration of the fully coupled overall system behavior. Conventional approaches for the optimization of floating wind turbines are predominantly based on simplifications and were developed for special objectives. However, the automated optimization tool allows an analysis of any wind turbine (onshore or offshore, bottom-fixed or floating), which can be flexibly applied to the respective objective. Various aspects can thus be included in the optimization when considering a floating wind turbine: the system behavior due to tower top acceleration, the inclination of the entire turbine and translational movements, the material usage and the costs due to the structural volume, and the manageability and manufacturability due to the external dimensions, either directly as a target value or as boundary values.
The Fraunhofer IWES is currently working with a floating reference system based on Hywind Demo to test the different optimization scenarios. Some basic requirements still need to be met for floating wind turbines to be available on the market more quickly: costs must be reduced, the system behavior must be optimized, and a standardization must be created. The scientists at the Fraunhofer IWES are actively shaping this new market. Alongside the development of the optimizer, the Fraunhofer IWES is also participating in the AFLOWT research project. In addition, research is being performed into topics such as grid integration, grid stability, and the wind farm control of wind turbines, allowing the floating system to be examined holistically.