Simulation and experimental analysis of doubly-fed induction generator under grid faults

The percentage of wind power in electrical power systems worldwide is increasing rapidly every year because of the some important advantages of wind power. Wind power is not a new energy source in the world. Wind power has been existed since the world was created. Firstly, people started to use wind power with windmills by the 9th century but not for getting electrical power until July 1887. After this date, the popularity of getting electrical power from wind power has been continuously increased in academia and in industry. Especially in a few decades, by means of power electronics, wind turbines and wind farms became widespread. The reports in 2010 show that recently 21% of electricity production in Denmark, 18% in Portugal, 16% in Spain and 8% in Germany are provided by the wind power [1].These countries have the highest rate in wind power. For Turkey, this rate is around at 2% which is very low compare to wind power capacity of the country that is 58 GW. This power is more than the country?s installed electric power capacity (55.4 GW)[2]. The last few years, there are so many appeal for installing wind power turbine or farm in Turkey [3]. But because of the limited capacity of interconnected system, the taking appeal is stopped for some time to organize interconnected system again. The wind power technology in world tends to variable speed wind power technology because it has so many advantages compare to fixed speed systems such as less mechanical stress, higher efficiency, higher power quality, less reactive power consumption and so on. In variable speed technology, two generator types are generally used; doubly-fed induction generator (DFIG) and permanent magnet synchronous generator (PMSG). These two generator types have some advantages and disadvantages between each other. In this thesis, DFIG was selected to analyze the wind power turbine system. The analysis of wind turbine systems consists of two situations; under healthy condition and under fault condition. The wind turbine system model is created in simulation softwares. Simulation results are obtained from coupled simulation that is modeling of turbine components in different simulation softwares and combining all these components together. Analyzing wind turbine systems in coupled simulation is a unique study in the literature. The advantage of this study that provides more realistic results compare to use only one software. Some important parameters are obtained for improving control technique of DFIG during fault condition. The simulation results are also verified with experimental study. Finally, results are discussed and future study is explained.