Optimal control for minimizing power consumption during holding patterns for airborne wind energy pumping system

Airborne Wind Energy (AWE) concerns systems capable harvesting energy from the wind, offering an efficient alternative to traditional wind turbines by flying crosswind with a tethered airfoil. Such concepts involve a system more difficult to control than conventional wind turbines. These systems generally cannot be operated efficiently in very low wind conditions, necessitating intervention by launching and landing. In contrast to this approach, this paper proposes to continue flying holding patterns which minimize power consumption. Efficient holding patterns are determined by solving an optimal control problem. The model is specified as a set of differential algebraic equations and an approximation of the tether drag is taken into account. Finally, an evaluation in terms of energy is performed by means of statistical approach.