Distributed control system and novel power take off method for pumping-mode airborne wind energy

peer-reviewed
The robotic control of tethered parafoils enables a number of exciting applications, primarily a novel approach to wind energy generation. The airborne wind energy (AWE) paradigm aims to reduce greatly the mass and cost of materials required to generate electrical power from the wind. With innovative, distributed control systems and advanced materials, free flying tethered wings can replace the tower and blades of a conventional wind turbine, with the power take off system relocated to ground level. The critical enabling challenge faced by such systems, is the development of suitable control system hardware and software architectures with robust controllers maintaining the safe and optimal operation of the system. Suitable power take off methods form an integral part of AWE systems, as the mechanical power is produced on a periodic cycle. A holistic approach to the design, development and testing of a distributed control system for the flight of tethered kites has been undertaken. The airborne control element must operate harmoniously with the ground based power take off unit. A series of flight tests of a prototype control system developed has been carried out in the field. A detailed analysis of results and outcomes is provided. Paralleling the prototype development a mathematical model and simulation tool for the power take off synchronisation of multiple AWE systems has been developed with analysis of the performance and requirements for such a system. Continuous power output is achieved from multiple interconnected cyclical sources in a model that presents one feasible AWE farm topology. Having gained low cost access to altitude, additional payload applications for the automatic flight of parafoils emerge such as aerial sensor and observation platforms or ‘over the horizon’ communications links.