Master Thesis Presentation: Rotation Compensation for Rotary Kite Systems

Lukas Klein

University of Freiburg

Thursday, August 01, 2019, 14:00

Building 102 - SR 01-012

Rotary-kite airborne wind energy systems generate a torque on their ground connecting tether as a side effect. The resulting tether twisting has to be compensated in order to guarantee a durable and stable operation. The active rotation compensator consists of an electric battery, a computation unit, a servo motor, an inertial measurement unit and is attached directly to the rotor axle. On the other side the tether can then be connected to the rotary stable part of the compensator.

In this thesis a general model to describe the system behavior is derived. Two different state estimation algorithms (Complementary filter and  Kalman filter) to convert the data from an inertial measurement unit to a rotation estimation are compared. To compensate this rotation a model predictive controller with real time capabilities is described and implemented. A prototype of the system is developed and tested with a rotor-kite emulator. The control algorithm (100 Hz) and the state estimator (250 Hz) run simultaneously on an embedded computer. The prototype is actuated using a speed controlled permanent magnet synchronous motor.

It is shown that the system is capable of compensating the tether rotation by the rotor. Thanks to his self-contained design it is adaptable to similar systems suffering from the same problem such as multi-kite airborne wind energy systems.