Reliable Wind Turbine Control Design

Abstract

Wind power has proven to be one of the most versatile forms of renewable energy. Similarly, offshore wind is currently emerging as the most promising method of meeting the global target for low cost of renewable energy production, given the massive potential of wind at sea. However, from the wind turbine design point of view, the requirement of having a low cost offshore plant implies both that the energy yield of the system is maximized and that the associated operational and maintenance costs are minimized over its entire lifespan. Control systems, while certainly required for safe wind turbine operation, can also help in addressing these challenges. Offshore wind turbines are especially subject to large variations of their physical parameters due to heavy environmental conditions and the pronounced passage of time. This report provides an overview of the research approach taken towards ensuring that wind turbine control system performance, while always affected by several introduced factors that cause deviations of the model parameters from their nominal values, remains in some sense optimal. An analysis of the extent to which typical control loops within a wind turbine control system are affected by design uncertainty is first presented; subsequently, an improved design problem is formulated based on the analysis results and solved within the framework of linear parameter-varying control theory; the presented design methodology for the formulated practical problem has the potential of reducing typical design safety factors considerably thus allowing for a decrease in wind turbine production costs by up to 9%. The document is concluded with several qualitative remarks and possibilities for further development resulting from the presented information.