Investigation Of A Brushless Doubly-fed Wind Power Generator System

As is known to all, Variable speed and constant frequency (VSCF) system is a better solution for wind power generation than constant speed and constant frequency (CSCF) system due to its higher efficiency to draw energy from wind. Brushless doubly-fed generation (BDFG) system is one of hopeful VSCF solutions. In this system a generator can be connected to a windmill without any gears, and the converter used to control the frequency of the system output may be quite more economical than in others.In this thesis, a cascade BDFG is the core of the BDFG system discussed. After the analysis of its structure and its VSCF electricity generating principle, the BDFG's mathematical model is deduced. Based on this model, some programs are designed to simulate typical running situations.The modeling and simulation founds the basis of researches on control strategy of BDFG. The generator will be excited by a converter. And the converter will work on the strategy of vector control with the definitive direction of the stators magnetic field. Also, the thesis develops the algorithm to corroborate the magnetic field's direction by the state's current and voltage.To validate the theory analysis of BDFG. a lab platform is designed and implemented. The platform includes a DC motor with its control device which works as a windmill, a BDFG with its control equipment which is the study object and a centric PC which control and monitor the whole system.The thesis discusses principle issues of the BDFG system such as mathematical modal, control strategy and the simulation of its steady operations, etc. By the theoretical analysis, computer simulation and experimental investigation, some valuable experiences and significant conclusions are given, which found the basis of the project for the further studies.