Luchsinger Power Model

A simple, configurable power model for pumping kite airborne wind energy (AWE) systems based on the Luchsinger model.

It takes an awesIO system YAML file and a simulation settings YAML file as input.

Overview

This repository provides a standalone power model for AWE pumping kite systems. It calculates power curves from cut-in to cut-out wind speed, accounting for:

• Aerodynamic forces on the kite
• Ground station generator and storage efficiency losses
• Optimal reeling velocity control
• Three operating regions (force-limited, power-limited)

Purpose

This repository is designed to be:

1. Tested/Used locally using the scripts in the scripts/ folder with configuration from data/
2. Integrated into a larger toolchain where configuration values are set externally and passed to the PowerModel class

When used as part of another toolchain, the wrapper code can create a configuration dictionary programmatically, bypassing the YAML files entirely.

Features

• Simple API: Calculate power at any wind speed or generate full power curves
• Configurable: All parameters via YAML or Python dictionaries
• Reeling-factor optimization: Includes optimal reeling factor calculation
• Standalone: No external dependencies beyond NumPy, SciPy, and PyYAML

Installation

Requirements

• Python >= 3.8
• NumPy >= 1.20.0
• SciPy >= 1.7.0
• PyYAML >= 5.4.0
• Matplotlib >= 3.4.0

Install dependencies

pip install -r requirements.txt

Or using conda:

conda install numpy scipy pyyaml matplotlib

Quick Start

Using the Script

# Generate and plot power curve with an example 100kW configuration
python scripts/calculate_power_curves.py

Using as a Library

from src.power_luchsinger import PowerModel

# Load from YAML configuration
model = PowerModel.from_yaml('data/100kW_system_example.yml')

# Calculate power at a specific wind speed
power = model.calculate_power(windSpeed=10.0)
print(f"Power at 10 m/s: {power:.0f} W")

# Generate complete power curve
power_curve = model.generate_power_curve(numPoints=100)
print(f"Wind speeds: {power_curve['windSpeed']}")
print(f"Power output: {power_curve['power']}")

Using with a Custom Configuration Dictionary

from src.power_luchsinger import PowerModel

config = {
    'kite': {
        'wingArea': 50.0,
        'liftCoefficientOut': 0.8,
        'dragCoefficientOut': 0.12,
        'dragCoefficientIn': 0.06,
    },
    'tether': {
        'maxLength': 500.0,
        'minLength': 250.0,
    },
    'atmosphere': {
        'airDensity': 1.225,  # kg/m³
    },
    'groundStation': {
        'nominalTetherForce': 4000.0,      # N
        'nominalGeneratorPower': 60000.0,  # W
        'reelOutSpeedLimit': 10.0,         # m/s
        'reelInSpeedLimit': 30.0,          # m/s
    },
    'operational': {
        'cutInWindSpeed': 4.0,    # m/s
        'cutOutWindSpeed': 25.0,  # m/s
        'elevationAngleOut': 25.0,  # degrees
        'elevationAngleIn': 45.0,   # degrees
    },
}

model = PowerModel(config)
power_curve = model.generate_power_curve()

Configuration Reference

Required Configuration Sections

Section	Description
kite	Aerodynamic parameters
tether	Tether properties
atmosphere	Atmospheric conditions
groundStation	Ground station parameters
operational	Operating envelope

Kite Parameters

Parameter	Description	Unit
wingArea	Projected wing area	m²
liftCoefficientOut	Lift coefficient during reel-out	-
dragCoefficientOut	Drag coefficient during reel-out	-
dragCoefficientIn	Drag coefficient during reel-in	-

Tether Parameters

Parameter	Description	Unit
maxLength	Maximum tether length	m
minLength	Minimum tether length	m

Atmosphere Parameters

Parameter	Description	Unit
airDensity	Air density	kg/m³

Ground Station Parameters

Parameter	Description	Unit
nominalTetherForce	Maximum tether force	N
nominalGeneratorPower	Maximum generator power	W
reelOutSpeedLimit	Maximum reel-out speed	m/s
reelInSpeedLimit	Maximum reel-in speed	m/s

Operational Parameters

Parameter	Description	Unit
cutInWindSpeed	Cut-in wind speed	m/s
cutOutWindSpeed	Cut-out wind speed	m/s
elevationAngleOut	Elevation angle during reel-out	degrees
elevationAngleIn	Elevation angle during reel-in	degrees

Physical Model

Luchsinger Pumping Cycle Model

The model implements a ground-based pumping kite power system with two phases:

1. Reel-out phase: Kite flies crosswind generating high tether force, pulling out tether and driving the generator
2. Reel-in phase: Kite is depowered (reduced angle of attack), tether is reeled in using the generator

Operating Regions

Region	Description
Region 1	Below force limit - optimal reeling velocities
Region 2	Force-limited - tether force at maximum
Region 3	Power-limited - generator power at maximum

Project Structure

├── src/
│   └── power_luchsinger/
│       ├── __init__.py
│       ├── power_model.py      # Main PowerModel class
│       ├── calculations.py     # Pure calculation functions
│       ├── plotting.py         # Plotting utilities for toolchains
│       └── default_config.yml  # Default configuration parameters
├── scripts/
│   ├── __init__.py
│   └── calculate_power_curves.py  # Main script for generating plots
├── data/
│   └── 100kW_system_example.yml    # Example configuration
├── results/                    # Generated plots and outputs
├── requirements.txt
├── README.md                   # This file
└── LICENSE

References

1. R.H. Luchsinger: "Pumping cycle kite power". In Airborne Wind Energy, Springer, 2013. https://doi.org/10.1007/978-3-642-39965-7_3

License

This project is licensed under the Apache License - see the LICENSE file for details.