Wind Energy Systems

Lecture: Prof. Dr. Moritz Diehl

Tutor: 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 Thursday, 2:00 PM to 3:30 PM in the Building 101, Room HS-026. These meetings are alternatingly dedicated to either Q&A sessions with Prof. Diehl or exercise sessions with Nick Harder. For a detailed plan see the table below.

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

When	Content	Recordings
Week 1 10.04 - 14.04	Chapter 1: Introduction Section 1.1: Introduction (Slides) Section 1.2: Energy content of the wind	Section_1_1 Section_1_2
13.04 2:00 PM	No session
Week 2 17.04 - 21.04	Section 1.3: Power density of blade area Section 1.4: Components of modern wind turbine Section 1.5: Blade & Airfoil nomenclature	Section_1_3 Section_1_4 Section_1_5
20.04 2:00 PM	Introduction session
Week 3 24.04 - 28.04	Chapter 2: The Wind Resource Section 2.1: Origins Section 2.2: Global patterns Section 2.3: Mechanics of wind Exercise Sheet 1	Section_2_1 Section_2_2 Section_2_3 Exercise_01 Exercise_01_Solution Exercise_01_Code
27.04 2:00 PM	Exercise session
Week 4 01.05 - 05.05	Section 2.4: Stable and unstable atmospheric stratification Section 2.5: Statistics of wind Section 2.6: Spectral properties of wind Exercise Sheet 2	Section_2_4 Section_2_5 Section_2_6 Exercise_02 Exercise_02_Solution Exercise_02_Code
04.05 2:00 PM	Exercise session / Q&A session
Week 5 08.05 - 12.05	Chapter 3: Aerodynamics of Wind Turbines Section 3.1: Wakes Section 3.2: Actuator disc model and the Betz' limit Exercise Sheet 3	Section_3_1 Section_3_2_Part1 Section_3_2_Part2 Exercise_03 Exercise_03_Sol
11.05 2:00 PM	Q&A session
Week 6 15.05 - 19.05	Section 3.3: Wake rotation & rotor disc theory Section 3.4: Blade element momentum (BEM) theory	Section_3_3 Section_3_4_part1
18.05 2:00 PM	Holiday (no session)
Week 7 22.05 - 26.05	Section 3.4: Blade element momentum (BEM) theory	Section_3_4_part2 Section_3_4_part3
25.05 12:30 PM	Hike to wind turbines on Rosskopf
Week 8 29.05 - 02.06	Holidays
01.06 2:00 PM	Holiday (no session)
Week 9 05.06 - 09.06	Section 3.4: Blade element momentum (BEM) theory Exercise Sheet 4	Section_3_4_part4 Section_3_4_part5 Section_3_4_part6 Exercise_04 Exercise_04_Sol
08.06 2:00 PM	Holiday (no session)
Week 10 12.06 - 16.06	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	Section_4_Intro Section_4_1 Section_4_2 Section_4_3
15.06 2:00 PM	Exercise session
Week 11 19.06 - 23.06	Section 4.4.1: Intro: spring-mass-damper system Section 4.4.2: Eigenmodes Section 4.4.3: Rayleighs method	Section_4_4_part1 Section_4_4_part2 Section_4_4_part3
22.06 2:00 PM	Q&A session
Week 12 26.06 - 30.06	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 Exercise Sheet 5	Section_4_4_part_4_5 Section_4_4_part_6 Section_4_5 Exercise_05 Exercise_05_Sol
29.06 2:00 PM	Exercise session
Week 13 03.07 - 07.07	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 Practice exam	Section_5_1 Section_5_2 Section_5_3 Practice_exam Practice_exam_sol
06.07 2:00 PM	Q&A session / Guest Talk by Prof. Dr. Jens Geisler
Week 14 10.07 - 14.07	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
13.07 2:00 PM	Exercise session
Week 15 17.07 - 21.07	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
20.07 2:00 PM	Summary session
11.09 9:00-12:00	FINAL EXAM

Special Events

The tour to the wind turbines on Rosskopf will take place on May 25th, 2023, in the afternoon. We will start from Kanonenplatz at 12:30, the excursion at the wind turbines will be from 14:00 till 15:00. We will meet with Andreas Markowsky and Thomas Schuwald, the managing directors of Ökostromgruppe Freiburg (the company operating the wind turbines), who give technical and administrative details on the turbines. Afterwards we will head back and you can expect to be back in Freiburg at around 17:30.
On July 6th at 14:00 we will have an invited guest in the lecture room, Prof. Dr.-Ing. Jens Geisler, Hochschule Flensburg University of Applied Sciences, who will give a guest lecture on the industrial practice of wind turbine control.

Resources

Wind Energy Handbook is available here.

Wind Energy Explained: Theory, Design and Application is available here. This book should be your number one reference if you don't understanding something from the handbook.