Understanding of Lift Kite Operation Requirements of a Rotary Kite Wind Turbine

A rotary kite airborne wind energy (AWE) system is equipped with a tensile rotary power transmission (TRPT) unit for torque transmission from the tethered airborne components to the ground generation station. A lift kite is attached to the rotor and TRPT system playing crucial functions during system launching, landing and in-air operations. The aim of this work is to investigate the operation requirements of the lift kite through steady-state analysis at equilibrium points of given wind speeds and a selected elevation angle. The equilibrium model includes the balance of forces in the TRPT axial direction to enable the torque transmission from the turbine rotor to the ground electrical generator and the moment equilibrium in the direction perpendicular to the rotation axis of the TRPT. These two conditions together determine the lift kite operation requirements meant to provide the structural stiffness for torque transmission, prevent the system from over-turning and maintain the system positioning to achieve most efficient power generation. Simulation studies are conducted using a model developed for a prototype system manufactured and field tested.