Grid-connection strategies of the doubly-fed variable speed constant frequency wind power generators with/without load

It is pointed out in this paper that the connection between DFVSCF (doubly-fed variable speed constant frequency) wind power generator and the grid is flexible, which means that by excitation regulation, the stator output voltage can fulfill the condition of grid-connection and the generator can be safely connected to the grid at variable speed. Using the method of field-oriented vector control, the grid-connection principle of DFVSCF wind power generator was investigated in this paper, and two control strategies of the generator for grid-connection with load and without load were established based on stator flux oriented vector control technique. Finally, the experimental research was conducted, whose results verified the correctness and feasibility of the strategies proposed by this paper.