Model-Based Efficiency Analysis of Wind Power Conversion by a Pumping Kite Power System

Airborne Wind Energy is gaining increasing attention. Compared to conventional wind turbines, this class of innovative technologies can potentially generate more energy at a lower price by accessing wind at higher altitudes which is stronger and steadier. In this chapter, first a theoretical system model of a kite power system in pumping mode of operation is presented. Then it is validated with electrical and mechanical measurement results. The model is used to predict the electrical power output and the size of the major components. The terms pumping efficiency, cycle efficiency and total efficiency are introduced. It is shown that the kite power demonstrator of Delft University of Technology currently achieves a maximum total efficiency of 20 %. The analysis indicates that it will be possible to design small to medium sized kite power systems with a total efficiency of 50 to 60 %. The terms nominal power of a ground station and system power of a kite power system are introduced, noting their particular difference: the nominal power is the installed electrical generator power whereas the system power is defined as the average net electrical power output at nominal wind velocity.