Flight trajectory optimization of Fly-Gen airborne wind energy systems through a harmonic balance method

Abstract. The optimal control problem for flight trajectories of Fly-Gen airborne wind energy systems (AWESs) is a crucial research topic the field, as suboptimal paths can lead to drastic reduction in power production. One novelties present work expression frequency domain through harmonic balance formulation. This allows potential size by solving only main harmonics and implicit imposition periodicity solution. trajectory described Fourier coefficients dynamics (elevation azimuth angles) inputs (onboard turbine thrust AWES roll angle). To isolate effects each physical phenomenon, are presented with an increasing level representation from most idealized case: (i) if mean (mechanical linked dynamics) considered objective function, characterized constant velocity over loop circular shape. done converting all gravitational into electrical energy. At low speed, onboard turbines then used propellers ascendant part loop; (ii) shaft after momentum losses) converted kinetic rest Therefore, fluctuates (iii) never because conversion efficiency. Optimal case have shape squashed along vertical direction. be generally modeled one two angle without significant loss power, demonstrating that absence high-frequency not detrimental generated AWESs.