Wind Energy Systems

Lectures: Prof. Dr. Moritz Diehl,          Exercises: Nick Harder

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.


Sessions: We will meet every Tuesday, 12:30 PM to 2:00 PM, in the Mensa building 82, in lecture hall 82-00-006 ("Kinohörsaal") (not anymore in SR 03-026, building 051). Please enter from the side from outdoors. These meetings are alternatingly dedicated to either Q&A sessions with Prof. Diehl or exercise sessions with Nick Harder. 


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.

Forum: In Ilias, we provide a forum for discussion of any questions you have related to the course, be it organization, content or exercises. Please feel free to open new topics and to answer questions of your fellow students. Link to the forum.


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.

The final exam date - 12.09.2022 09:00 - 12:00 G.-Köhler-Allee 101, SR 00-017/19.


Schedule

When

Content

Recordings

Week 1

02.05 - 06.05

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 1.4: Components of modern wind turbine

Section 1.5: Blade & Airfoil nomenclature

 

Section_1_1

Section_1_2

Section_1_3

Section_1_4

Section_1_5

10.05 12:30 PM

Introduction session (Slides)

 

Week 2

09.05 - 13.05

Chapter 2: The Wind Resource

Section 2.1: Origins

Section 2.2: Global patterns

Section 2.3: Mechanics of wind

Section 2.4: Stable and unstable atmospheric stratification

Section 2.5: Statistics of wind

Section 2.6: Spectral properties of wind

 

Exercise Sheet 1

 

Section_2_1

Section_2_2

Section_2_3

Section_2_4

Section_2_5

Section_2_6

 

Exercise_1

17.05 12:30 PM

Q&A session

 

Week 3

16.05 - 20.05

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

Exercise_2

24.05 12:30 PM

Exercise session 1

Exercise_1_Sol

Week 4

23.05 - 27.05

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 12:30 PM

Q&A session

 

Week 5

30.05 - 03.06

Section 3.4: Blade element momentum (BEM) theory

 

Exercise Sheet 3

Section_3_4_part2

Section_3_4_part3

Exercise_3

14.06 12:30 PM

Exercise session 2

Exercise_2_Sol

Week 6

13.06 - 17.06

Section 3.4: Blade element momentum (BEM) theory

Section_3_4_part4

Section_3_4_part5

Section_3_4_part6

21.06 12:30 PM

Q&A session

 

Week 7

20.06 - 24.06

Chapter 4: Mechanics & Dynamics of Wind Turbines

Section 4.1: Steady loads in normal operation

Section 4.2: Stress and strain

Section 4.3: Static beam bending

 

Exercise Sheet 4

Section_4_Intro

Section_4_1

Section_4_2

Section_4_3

 

Exercise_4

28.06 12:30 PM

Exercise session 3

Exercise_3_Sol

Week 8

27.06 - 01.07

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 4.5: Blade oscillation & centrifugal stiffening

 

Mock exam

 

Section_4_4_part1

Section_4_4_part2

Section_4_4_part3

 

Section_4_4_part_4_5

Section_4_4_part_6

Section_4_5

Mock_Exam

05.07 12:30 PM

Q&A session

 

Week 9

04.07 - 08.07

Chapter 5: Control of Wind Turbines

Section 5.1: Sensors and Actuators in wind turbines

Section 5.2: Control system architecture

Section 5.3: Control of variable speed turbines

 

Section_5_1

Section_5_2

Section_5_3

12.07 12:30 PM

Hike to wind turbines on Rosskopf

Details

Week 10

11.07 - 15.07

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 12:30 PM

Exercise session 4

 

Week 11

18.07 - 22.07

Chapter 6: Alternative Concepts

Section 6.1: Vertical axes wind turbines

Section 6.2: Airborne Wind Turbines

 

 

Section_6_1

Section_6_2_part1

Section_6_2_part2

26.07 12:30 PM Summary session or Exercise session on mock exam  

12.09.2022

09:00 - 12:00

FINAL EXAM Location: TF 101, SR 00-017/19

 


Special Events

  • The tour to the wind turbines on Rosskopf will take place on July 12 afternoon. All information can be found here.


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