Wind Energy Systems

The aim of this lecture course (6 ECTS) is that students understand the physical principles of wind energy and the technology of modern wind energy systems. It consists of lectures and exercises, and is given by Prof. Dr. Moritz Diehl and Nick Harder.

Contents: 

  • global wind energy resource
  • aerodynamic principles of wind turbines
  • design of modern wind turbines
  • control of modern wind turbines
  • the electrical system of wind turbines
  • alternative concepts and airborne wind energy

Course Organization

The course is organized as flipped classroom. We provide recordings of the lectures and will meet once every week for either a Q&A or an exercise session. The detailed time plan for the semester can be found below. We highly recommend to follow the suggesed schedule for the lectures.


Virtual meetings: We will meet every Tuesday, 12:30 PM to 2:00 PM, in a virtual lecture room. These meetings are alternatingly dedicated to either Q&A sessions with Prof. Diehl or exercise sessions with the teaching assistant (see below). We will use Zoom for the meetings. Please note that you can join the meeting via your browser and do not need to install to the Zoom client. 

You can join via this link

Meeting ID: 629 0189 7053

Password: efjnDNpG3

None of the meetings will be recorded. For more information on how the university uses Zoom, a guide for students, and a note on data protection please see here.


Lecture recordings: The lecture recordings were already created in a past semester.

Course manuscript: The lectures are accompanied by a detailed course manuscript, which you may find here.

Q&A sessions: Every second week there will be a virtual Q&A session with Prof. Diehl, where you can ask any questions about the course content. The format is meant to be highly interactive and depends strongly on your participation. We would recommend that while watching the video lectures or reading the course script, you write down any questions that come to your mind, such that you have them readily available for the Q&A sessions.


Exercises: The exercises are voluntary (though of course we strongly recommend to solve them). Nonetheless we offer the possibility to hand them in to receive feedback, but for this please respect the deadlines you can find in the calendar below. If you would like feedback on a specific part of the exercise especially, you can state so on your solution sheet. To hand them in, send them in an email to: nick.harder@inatech.uni-freiburg.de.

Exercise sessions: Every other week we will meet for the exercise sessions. They will not be used to show the solutions, but to discuss any questions related to the exercises. These can either be questions about the current exercise sheet or questions about the solution to the last sheet. As the Q&A sessions, this format depends heavily on your participance.

Final evaluation: The final exam is a written exam. This final exam is 'closed-book,' which means that ONLY pens, a calculator, and one A4 page (that is, two sides) of notes can be used. The questions will be partially multiple-choice and partially short-answer.


Schedule

Week

What

Tuesday 12:30 PM

Content Recordings Deadline
19.04 - 25.04.2021 Introduction

Chapter 1: Introduction

Section 1.1: Introduction (Slides)

Section 1.2: Energy content of the wind

Section 1.3: Power density of blade area

 

Section_1_1

Section_1_2

Section_1_3

 

 

 

26.04 - 02.05.2021 Q&A

Section 1.4: Components of modern wind turbine

Section 1.5: Blade & Airfoil nomenclature

 

Chapter 2: The Wind Resourse

Section 2.1: Origins

Section 2.2: Global patterns

Section 2.3: Mechanics of wind

 

Exercise Sheet 1

Section_1_4

Section_1_5

 

 

Section_2_1

Section_2_2

Section_2_3

 

 

 

 

 

 

 

 

03.05 - 09.05.2021 Q&A

Section 2.4: Stable and unstable atmospheric stratification

Section 2.5: Statistics of wind

Section 2.6: Spectral properties of wind

Section_2_4

Section_2_5

Section_2_6

 
10.05 - 16.05.2021

 

Exercise

Chapter 3: Aerodynamics of Wind Turbines

 

Section 3.1: Wakes (Wind_wakes_image)

Section 3.2: Actuator disc model and the Betz' limit

 

Exercise Sheet 2

 

Section_3_1

Section_3_2_Part1

Section_3_2_Part2

 
17.05 - 22.05.2021

Q&A

Section 3.3: Wake rotation & rotor disc theory

Section 3.4: Blade element momentum (BEM) theory

Section_3_3

Section_3_4_part1

 
31.05 - 06.06.2021

Exercise

Section 3.4: Blade element momentum (BEM) theory

 

Exercise Sheet 3

Section_3_4_part2

Section_3_4_part3

 

 
07.06 - 13.06.2021

Q&A

Section 3.4: Blade element momentum (BEM) theory

Section_3_4_part4

Section_3_4_part5

Section_3_4_part6

 
14.06 - 20.06.2021

Exercise

Chapter 4: Mechanics & Dynamics of Wind Turbines

Section 4.1: Steady loads in normal operation

Section 4.2: Stress and strain

 

Exercise Sheet 4

Section_4_Intro

Section_4_1

Section_4_2

 
21.06 - 27.06.2021

Q&A

Section 4.3: Static beam bending

Section 4.4.1: Intro: spring-mass-damper system

Section 4.4.2: Eigenmodes

Section 4.4.3: Rayleighs method

Section 4.4.4: Dynamic beam equation

Section 4.4.5: Tower eigenmodes

Section 4.4.6: Stiff & soft towers

Section_4_3

Section_4_4_part1

Section_4_4_part2

Section_4_4_part3

 

Section_4_4_part_4_5

Section_4_4_part_6

 
28.06 - 04.07.2021

Exercise

Section 4.5: Blade oscillation & centrifugal stiffening

 

Chapter 5: Control of Wind Turbines

Section 5.1: Sensors and Actuators in wind turbines

 

Exercise Sheet 5

Section_4_5

 

 

Section_5_1

 
05.07 - 11.07.2021

Q&A

Section 5.2: Control system architecture

Section 5.3: Control of variable speed turbines

Section_5_2

Section_5_3

 
12.07 - 18.07.2021

Exercise

Section 5.4: Torque control at subrated power

 

Section 5.5: Thrust jump at nominal wind speed

Section_5_4_part1

Section_5_4_part2

Section_5_5

 
19.07 - 25.07.2021

Q&A

Chapter 6: Alternative Concepts

Section 6.1: Vertical axes wind turbines

Section 6.2: Airborn Wind Turbines

Section_6_1

Section_6_2_part1

Section_6_2_part2

 

 


Special Events

  • The tour to the wind turbines on Rosskopf will take place on Juny 11 afternoon. All information TBA.


Resources

Wind Energy Handbook is available here.

Wind Energy Explained: Theory, Design and Application is available here.


Links of interest

2020-05-12 Report on renewable power generation costs in 2018 (by IRENA(PDF)

2020-05-19 Which way a wind turbine turns might not seem to matter (by the Economist(screenshot)

2020-05-19 Atmospheric circulation patterns (from wikipedia)

2020-05-26 Article on the Global Energy Transition (by the Economist)

2020-06-02 Albert Betz: Wind-Energie. Cover, Turbine Illustrations, Concluding Sentence