AC excited synchronous generator for DC connected offshore wind farm

This paper presents the possibilities of using the negative frequency excitation for the doubly fed induction generator system for DC connected wind power generation. For DC output, the output frequency of the generator can be selected arbitrarily. This paper investigated the optimum excitation condition for the doubly-fed induction generator connected to the dc output. The excitation frequency is changed from positive to negative to search the change of the power condition at the stator and the rotor side. The simulation results show that there is the optimum frequency of the negative sequence excitation for minimizing the rating of the excitation converter.