KiteModels

Kite power system models, consisting of tether and kite

The model has the following subcomponents, implemented in separate packages:

• AtmosphericModel from AtmosphericModels
• WinchModel from WinchModels
• KitePodModel from KitePodModels

This package is part of Julia Kite Power Tools, which consists of the following packages:

News

October 2024

• the orientation is now represented with respect to the NED reference frame
• azimuth is now calculated in wind reference frame. This allows it to handle changes of the wind direction during flight correctly.
• many unit tests added by a new contributor
• many tests for model verification added; they can be accessed using the menu2.jl script
• the documentation was improved

August 2024

• a new kite model, KPS3_3L was contributed. It uses three lines to the ground and three winches for steering a ram-air foil kite.
• a first ModelingToolkit based model was added, which shows a much better performance and easier to read code
• a new KCU model was added which assumes a linear relationship between the depower settings and the depower angle and thus is easier to configure than the original model.
• the drag of the KCU is now taken into account
• the drag of the bridle is now taken into account correctly, also if the real kite has more bridle lines than the model
• the function to find the initial state is now much more robust

July 2024

• a new groundstation / winch type is now supported, the TorqueControlledMachine. It can be configured in the section winch of the settings.yaml file. It uses a set torque as input.
• a Python interface is now provided, see: pykitemodels

April 2024

• added support for the native Julia DAE solver DFBDF. It is much more accurate and faster than the IDA solver that was used before.

What to install

If you want to run simulations and see the results in 3D, please install the meta package KiteSimulators . If you are not interested in 3D visualization or control you can just install this package.

Installation

Install Julia 1.10 or later, if you haven't already. On Linux, make sure that Python3 and Matplotlib are installed:

sudo apt install python3-matplotlib

Before installing this software it is suggested to create a new project, for example like this:

mkdir test
cd test
julia --project="."

Then add KiteModels from Julia's package manager, by typing:

using Pkg
pkg"add KiteModels"

at the Julia prompt. You can run the unit tests with the command:

pkg"test KiteModels"

You can copy the examples to your project with:

using KiteModels
KiteModels.install_examples()

This also adds the extra packages, needed for the examples to the project. Furthermore, it creates a folder data with some example input files. You can now run the examples with the command:

include("examples/menu.jl")

Advanced installation

If you intend to modify or extend the code, it is suggested to fork the KiteModels.jl repository and to check out your fork:

git clone https://github.com/USERNAME/KiteModels.jl

where USERNAME is your github username. The compile a system image:

cd KiteModels.jl/bin
./create_sys_image --update

If you know launch julia with:

cd ..
./bin/run_julia

you can run the examples with

include("example/menu.jl")

One point model

This model assumes the kite to be a point mass. This is sufficient to model the aerodynamic forces, but the dynamic concerning the turning action of the kite is not realistic. When combined with a controller for the turn rate it can be used to simulate a pumping kite power system with medium accuracy.

Four point model

This model assumes the kite to consist of four-point masses with aerodynamic forces acting on points B, C and D. It reacts much more realistically than the one-point model because it has rotational inertia in every axis.

Tether

The tether is modeled as point masses, connected by spring-damper elements. Aerodynamic drag is modeled realistically. When reeling out or in the unstreched length of the spring-damper elements is varied. This does not translate into physics directly, but it avoids adding point masses at run-time, which would be even worse because it would introduce discontinuities. When using Dyneema or similar high-strength materials for the tether the resulting system is very stiff which is a challenge for the solver.

Further reading

These models are described in detail in Dynamic Model of a Pumping Kite Power System.

Replaying log files

If you want to replay old flight log files in 2D and 3D to understand and explain better how kite power systems work, please have a look at KiteViewer . How new log files can be created and replayed is explained in the documentation of KiteSimulators .

Licence

This project is licensed under the MIT License. Please see the below WAIVER in association with the license.

WAIVER

Technische Universiteit Delft hereby disclaims all copyright interest in the package “KiteModels.jl” (models for airborne wind energy systems) written by the Author(s).

Prof.dr. H.G.C. (Henri) Werij, Dean of Aerospace Engineering

Donations

If you like this software, please consider donating to Flood in Kenya .

See also

• Research Fechner for the scientic background of this code
• The meta-package KiteSimulators
• the package KiteUtils
• the packages WinchModels and KitePodModels and AtmosphericModels
• the packages KiteControllers and KiteViewers

Documentation Stable Version --- Development Version

Author: Uwe Fechner (uwe.fechner.msc@gmail.com), Bart van de Lint