Frequency-dependence of Magnetization of a Slip-ring Induction Generator

Abstract

In this Master's Thesis, a slip-ring induction machine applied to a wind power generating system is studied in detail. The aim of the work is to try to determine the relation between its magnetization and the frequency of rotor current. Further, it is explored whether the reason why its magnetization is relevant to the frequency of rotor current is eddy current or not, so that people can make some modifications for the optimization of the slip-ring induction machine. The work is mainly carried out based on the results of the simulations. Two sorts of simulations are included here. One is the full-load simulation for knowing the distribution of eddy current inside the generator, and the other is the no-load simulation in order to obtain the relation between the magnetization and the frequency of rotor current. In addition, for the convenience of analyzing the frequency-dependence of the magnetization, before the no-load simulation is done, theoretical calculation of the magnetization is carried through so that the theoretical results may be compared with the actual results. Finally, the analysis of the simulations shows that only when the slip-ring induction generator is saturated, is its magnetization frequency dependent, and that the main reason is the eddy current occurring inside the shaft of the generator.