Objectives and problems to be solved:
The main objective of the STABCON project is to develop reliable design tools for analysis and optimisation of large wind turbines with respect to aero elastic stability and active control.
Derived guidelines describe how to:
- Identify important parameters for aero elastic stability, and optimise them for increased damping to passively suppress instabilities and reduce loads.
- Identify the potentials of active aero elastic control to reduce loads by suppressing instabilities and alleviating gusts, and enhance power production.
- Perform integrated design studies of active-stall and pitch-regulated turbines to allow control of lifetime consumption and adaptation to specific conditions.
Description of the work:
The objectives are achieved through project activities divided in two parts:
Part 1 concerns the aero elastic stability of wind turbines that have active power regulation but no active aero elastic control. Instabilities involve rotor whirling due to stall induced vibrations, blade flap/lead-lag vibrations and flutter, low damped tower vibrations and drive train vibrations. New stability tools are developed and used to predict the stability limits for an existing 2.5 MW turbine. The damping characteristics of this turbine are measured using a newly developed test method. Measured and predicted stability characteristics are compared to evaluate and refine the stability tools. This is supported by advanced aero elastic predictions based on Computational Fluid Dynamics. Part 1 leads to a common understanding of turbine instabilities, development of design tools and design guidelines for passive (built-in) suppression of these instabilities, without active use of the control system for load reduction.
Part 2 concerns the active aero elastic control of wind turbines. A morphological study of possible wind turbine control systems is performed. The wind turbine industry already considers collective and individual blade pitch variations to control power, thrust and rotor bending moments. These and other concepts are considered to achieve the three objectives. The active coupling between component loads is used for damping of vibrations. Aero elastic codes and stability tools are developed to include these control systems, and optimisations are performed for each of the three objectives (instability suppression, turbulence- and gust alleviation and power enhancement) independently and by conditional weighting, respectively. Part 2 leads to design guidelines for active aero elastic control systems that can reach an optimum combination of the objectives.
Milestones and expected results:
Milestones of the project are:
- Mapping of the aero elastic stability of a 2.5 MW turbine based on theoretical and experimental analysis.
- Validated aero elastic stability tools.
- Knowledge of the important non-linearities for large wind turbines.
- Establishment of a firm basis to evaluate and further develop different concepts.
- Aero elastic control systems for gust alleviation, instability suppression and power enhancement.
- Integrated design of aero elastic control based on site, grid and turbine specific conditions.
Optimisation of large wind turbines with respect to aero elastic stability and active control will strengthen the position of the European wind turbine industry and research community and help to form a European Research Area on these fundamental issues.
Funding SchemeCSC - Cost-sharing contracts
19009 Raphina (Pikeermi)
2628 CN Delft