Assignments

The assignments will be uploaded in time on this page.

Assignment 1: Wind Data Analysis

• Assignment (PDF)
• Necessary data (Matlab and Excel format) and Matlab files
• Time for questions: See schedule.
• Hand in latest Friday, 31 January, 13.00.
• Important results and mistakes will be presented and discussed in an exercise session, see schedule.

Assignment 2: Generators

• Assignment
• Time for questions: See schedule.
• Hand in latest Tuesday, 18 February, 13.00.
• Important results and mistakes will be presented and discussed in an exercise session, see schedule.

• Key to the comments in the marked assignments:

  • a) Stator, power supply, magnetic field
  • b) Induction
  • c) Rotor current
  • d) Magnetic fields of rotor and stator interact
  • e) Interaction leads to changes in stator current
• These five steps are essential when explaining how a sqirrel-cage induction machine works; for example, one cannot explain that the generator feeds active power into the grid without explaining that the rotor exhibits a magnetic fields that interacts with the stator field. To explain that the rotor exhibits a magnetic field when rotating faster than synchronous speed, one needs to explain why there is a current flowing in the rotor bars. That one can only be caused by a voltage. Therefore one cannot get around induction. Because induction requires a changing magnetic flux, one needs to explain how the magnetic field of stator looks like. And to explain that it is a rotating field of constant magnitude one needs to tell how the stator windings are connected to to a three-phase voltage suppöy (grid).
• Hence, the two main challenges of the assignment were to identify and to explain all steps that are necessary for understanding.
• Properly explaining those important steps gained 0.5 points per step (a-d). Because the last step is quite difficult we decided that all solutions that did not already receive maximum amount of points (2.5 points) gain 0.5 points in addition.
• Here you will find a good picture that I would have liked to show you when we discussed how to connect the stator of an induction machine. Now, it should be clear where the current "enters" and "exits" a coil if the voltage of the specific phase is positive. E.g. if the current of phase U is positive, the current enters coil U at U and exits it on the opposite side. If the current  is negative, it will be the other way round.

Assignment 3: Grid integration

• Assignment (PDF)
• Static Analysis of Power Systems (PDF) (password: hornsrev)
• Time for questions: See schedule.
• Hand in latest Wednesday, 5 Mars, 10.00.
• Important results and mistakes will be presented and discussed in an exercise session, see schedule.

Assignment 4: Blade design + Assignment 5: Hybrid systems

• Time for questions: See schedule.
• Hand in latest Friday, 11 April, 15.00.
• Important results and mistakes will be presented and discussed in an exercise session, see schedule.