Modeling and periodic optimal control of an Airborne Wind Turbine

Jochem De Schutter

University of Freiburg

Monday, September 19, 2016, 14:00

Room 01-012, Georges-Köhler-Allee 102, Freiburg 79110, Germany

The experimental concept of an “airborne wind turbine” (AWT) can be understood as an intermediate stage between single- and dual-airfoil airborne wind energy systems with pumping cycle. Whereas single-airfoil systems suffer from significant efficiency losses due to tether drag, dual-airfoil systems can reduce these losses by connecting two airfoils to a shared tether. However, the system and trajectory design for the dual-airfoil configuration is much more intricate than for single-airfoil systems. An AWT has much simpler dynamics dan dual kites, because it has the different airfoils fixed to each other, with only the 'pitch' degree of freedom remaining (similar to a regular wind turbine). At the same time it preserves the advantage of a small tether drag. The disadvantage of this concept is that it is only interesting for small-scale applications due to the additional weight of the system. In this talk I will first present a physical model, and then discuss how stable, periodically stationary solutions can be found for this system with periodic optimal control. Going from there, I will show how reel-in and reel-out phases of a possible power cycle can be generated by solving a periodic optimal control problem as well.