Simulation for Airborne Wind Energy
Airborne Wind Energy is an emerging field in which simulation has an important role to play with system being more complex than encountered in classical wind power.
The first step toward simulation is defining a model, which can then be used for analytical computations or for simulation based on numerical computations.
The first level corresponds to static flight.
The second level enables to make some power estimation based on simple formula. The most famous one is Lloyds' formula based on a quasi-static approach.
The third level corresponds to kinematic simulator, for which parts of the effects of mass is neglected (inertia, but not necessarily weight).
The fourth level corresponds to dynamic simulator in which inertia are taken into account.
Simulators can also be categorized by the number of degrees of freedom or the number of bodies in the case of multibody simulation.
Multibody simulation might be needed for some aspects of system which are using flying pods for example.
Multibody simulation might be needed as well.
Static flight
Static symmetric flight.
Equilibrium
When in static flight, the forces are balanced.
Aerodynamic force and line tension have to be considered. Weight might be neglected.
If weight and wind gradient are neglected, the behavior of the system is invariant by rotation around the wind axis.
The system can then be reduced to only two degrees of freedom which are the pitch of the kite and position with respect to the center of the wind window.
If gravity is taken into account, a symmetric kite has only two equilibrium positions which are at zenith or at nadir.
Stability analysis
Stability analysis was conducted by Bryan back in 1915[1]
Asymmetric static flight on the side of the wind window
Other equilibrium positions can be reached if an asymmetry is created, either by moving mass away from plane of symmetry of kite, or if kite is not symmetric anymore.
Quasi-static model
Mile Lloyds studied in 1980 the crosswind flight using a quasi-static model.[2]
http://edge.rit.edu/edge/P15462/public/CAD/crosswind_kite.pdf
Dynamic flight
2D model
Nonlinear dynamics of a kite in flight was studied by Monica Geist in her master of science at University of Colorado Denver[3]
http://digital.auraria.edu/AA00003180/00001
A more recent study was done by Gonzalo Sanchez in 2006[4], and results applied in the field of Airborne Wind Energy by Filipo Trevesi[5]
3D model
Moritz Diehl proposed a 3D model in 2001.[6]
Simulators
Here are a few open sources simulators which can be used to model AWE systems:
Specialized simulator:
- FreeKiteSim, by Uwe Fechner
- KiteSimulators.jl by Uwe Fechner
- megAWES: 3DoF & 6DoF kite dynamics, initially developed by Dylan Eijkelhof
- awebox[7]
- openkite: OpenKITE is a ROS package for simulation, estimation and control of rigid-wing airborne wind energy kites. Developed at the Automatic Control laboratory EPFL as part of the AWESCO project.
- kitesim: real time dynamic model of a tethered kite which can be useful for visualisation, parameter estimation, flight controller development and so forth for airborne wind turbines.
- laksa: LAgrangian Kite SimulAtor, developed at Universidad Carlos III de Madrid by Gonzalo Sánchez-Arriaga and Alejandro Pastor-Rodríguez
- KiteEnergySystems: simulation framework for kite energy system using C++ language
- TetheredKiteUAV_Simulink
- rawsome : RAWESOME Airborne Wind Energy Simulation, Optimization and Modeling Environment
| Simulator | Degrees of freedom | Language | Winch model | Kite network |
|---|---|---|---|---|
| megaAWES | 3/6 | Matlab/simulink | Yes | No |
| FreeKiteSim | Python | Yes | No | |
| KiteSimulators.jl | Julia | Yes | No | |
General purpose simulators:
- Bullet
- Mujoco
- Exudyn
- ↑ The small oscillations of a kite, The aeronautical journal, October/December 1915 by Bryan
- ↑ Crosswind kite power, Miles Lloyds, The journal of Energy 1980
- ↑ Non linear dynamics of a kite in flight, Monica Geist, Master of science. University of Colorado 1996
- ↑ Dynamics and Control of Single-Line Kites , Gonzalo Sanchez-Arriaga 2006
- ↑ Flight Stability of Rigid Wing Airborne Wind Energy Systems by Filipo Trevesi in Energies, 2021
- ↑ Real-Time Optimization for Large Scale Nonlinear Processes, Moritz Diehl, Phd thesis at University of Heidelberg, 2001
- ↑ "De Schutter, J.; Leuthold, R.; Bronnenmeyer, T.; Malz, E.; Gros, S.; Diehl, M. AWEbox: An Optimal Control Framework for Single- and Multi-Aircraft Airborne Wind Energy Systems. Energies 2023, 16, 1900. https://doi.org/10.3390/en16041900"
