Wind Turbine Control

The priority area wind turbine control aims at the improvement of the present control algorithms, and the development of new ones, mainly targeting reduction of the cost of energy. To this end, the following objectives are pursued:

• optimal power and rotor speed control,
• load reduction in the mechanical components of the wind turbine,
• high availability and reliability of the wind turbine,
• easy and robust commissioning of the controller,
• coping with all grid requirements.

ECN Wind Energy has an outstanding position in the field of wind turbine control by offering state-of-the-art industrial wind turbine control solutions and tools on the one hand, and performing research towards the development of advanced control design tools and algorithms for application in future wind turbine systems, on the other hand. The user-friendly ECN Control Design Tool provides the wind turbine control engineer with an excellent set of tools in an open-source MATLAB environment, covering the complete process of turbine modeling, control design, stability analysis and compilation of the final controller into executable code (e.g. a dll) for linking to advanced simulation software for load calculations (such as PHATAS and BLADED), or to dedicated hardware. This enables wind turbine manufacturers to develop and validate their own control algorithms. A real-time process simulation tool, currently under development, will offer the manufacturers an open-source design environment for developing and realtime testing of control systems. 

The leading position of the wind turbine control group has been recently strengthened by the developed ECN software TURBU, a unique MATLAB toolbox for deriving control-oriented linear models as needed for the analysis and synthesis of modern multi-objective wind turbine control algorithms. TURBU provides a broad scale of modeling possibilities, allowing the control engineer to choose the desired model complexity by using the integrated model reduction functionality. It provides a solid foundation for the development of an integral design approach for the control system of offshore wind turbines, as aimed in the research project Sustainable Control (SusCon). This integral approach comprises the following four major control components

• Optimized feedback control (OFC), aiming at removing limitations for up-scaling of wind turbines, such as high turbine loads and stability problems,
• Extreme event control (EEC), dealing with prevention of unnecessary standstill and/or increased loads due to extreme events,
• Fault-tolerant control (FTC), having the task of detection of minor (sensor) faults followed by recovery actions,
• Optimal shutdown control (OSC), for preventing the accumulation of damage in cases of a turbine shut-down caused by a severe failure.

Finally, the Wind Turbine Control group is currently exploring the possibilities of using closed-loop system identification for improving the performance of the wind turbine controller, or achieving additional control functionality, during operation. Performance improvement could be gained by reducing the conservative stability margins that are conventionally used due to the uncertainty of first-principles models, or by reconfiguring the controller parameters due to changing environmental conditions. Additional functionality might include load-reduction control loops, such as drive-train damping, tower damping, etc.