aenarete/winchmodels.jl

Winch models (groundstation models) for airborn wind energy systems

WinchModels

Introduction

This package shall implement different models of ground stations for airborne wind energy systems. A ground station has the following components:

• motor/generator
• gearbox (optional)
• drum

Currently implemented is a model of the 20kW ground station from Delft University of Technology. In addition, a generic, torque controlled winch without brake is implemented.

Mathematical background

Torque controlled winch.

Installation

First, install Julia 1.10 or higher. Then launch Julia and install this package using the package manager.

using Pkg
pkg"add WinchModels"

Exported types

AbstractWinchModel
AsyncMachine
TorqueControlledMachine

Main functions

calc_acceleration(wm::AsyncMachine, speed, force;            set_torque=nothing, set_speed=nothing, use_brake = false)
calc_acceleration(wm::TorqueControlledMachine, speed, force; set_torque=nothing, set_speed=nothing, use_brake = false)
calc_force(wm::AsyncMachine, set_speed, speed)

Plot of function "calc_force"

Helper functions

calc_reactance
calc_inductance
calc_resistance
calc_coulomb_friction
calc_viscous_friction
smooth_sign

Plot of function "smooth_sign"

Performance

using WinchModels, BenchmarkTools, KiteUtils

set = se()
wm = AsyncMachine(set)
@benchmark calc_acceleration(wm, 7.9, 8.0, 100.0)

On i7-7700K 17ns for Julia, 1050ns with Python.

See also

• Research Fechner
• The application KiteViewer
• the package KiteUtils
• the packages KiteModels and KitePodModels and AtmosphericModels
• the package KiteControllers and KiteViewers

winchmodels.jl's Issues

Add function calc_power

Add a function to calculate the mechanical and electrical power as function of force and speed.

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Translate missing functions

• calc_coulomb_friction
• calc_viscous_friction
• calc_acceleration
• calc_force

Add continues integration

run tests automatically

Add model of torque-controlled winch

The current winch model assumes a speed controlled asynchronous generator. But modern winches often use a torque-controlled motor/generator, which reacts much faster. A model of such a winch should be added.

Register package

https://github.com/JuliaRegistrator

Verify agains Python code

• Add unit tests
• Add plot of function smooth_sign(x)
• Add plot of tether force vs speed for different values of the synchronous speed

Add test for brake

brake of TorqueControlledMachine not yet tested