Design og kontrol af effektkonverter til dobbelt-fødet asynkrongenerator i vindmølleapplikationer / Design and Control of power converters for a doubly-fed induction generator in a wind turbine application

In this project, the variable speed wind generator is realized by the use of a doubly-fed induction generator, where the stator is connected directly to the grid. To obtain a variable speed generator a four quadrant power converter is inserted between the rotor of the doubly-fed induction generator and the supply grid. An advantage of the doubly-fed induction generator compared to the squirrel cage induction generator is that the power converter only needs to handle a fraction of the total power to achieve full control of the generator. The purpose of the project is to investigate different converter topologies for use in this system. A number of subjects are of interest: * The dynamics of the converter * The efficiency of the converter * The harmonic spectra at the input and the output of the converter * The ratings of the components * The number of components. The project includes a detailed simulation study of the converters considered, - a realization of the most promising converter topology and finally an investigation/development of a suitable modulation and control strategy. (Lars Helle, Stig Munk-Nielsen, Frede Blaabjerg;  Vestas Wind Systems)