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.