Numerical Models for the Static Analysis of Cable Structures Used in Airborne Wind Turbines

In this work, the authors present two different multibody models for static analysis of airborne wind turbines (AWTs) cables. These wind turbines are composed of three main components: a buoyant blimp with a standard turbine rotor fixed within its shell, tethers connecting the system to earth ground, and a rotating base station. The tethers (or cables) are critical parts due to their multiple functions (aerostat control and power electric transmission, among others). The models/procedure presented in this article allows determining equilibrium points of the space tethers, which can be used for starting a global dynamic analysis of the complete system. An accurate initializing solution is essential for the convergence of the successive numeric non-linear aeroelastic analysis of AWTs. On these bases, the authors present two models of increasing complexity: i) a lumped-parameter model formulated in $$\mathbb {R}^{3}$$ , and ii) a finite element model based on a kinematically exact formulation of beams in SE(3). Both models are validated comparing results against well-documented problems (e.g. the elastic catenary).