Cascade Brushless Doubly Fed Induction Generator

Nowadays, renewable energy source becomes more and more important to our global energy consumption. Wind power as a kind of adequate and clean renewable energy source is drawing more and more attention. Cascaded Brushless Doubly-Fed Generator (CBDFG) which has no electrical-brush and can run for Variable-Speed Constant-Frequency (VSCF) generation system is very suitable for wind power generation.This thesis has done all-around investigation on a VSCF electricity generating system of CBDFG. First of all, the mechanical structure and the working principle of CBDFG are introduced. By using voltage equations of asynchronous motors and transformation theory of reference frame, a rotating reference frame dq0 model based on rotor asynchronous speed and another MT model based on stator synchronous speed of CBDFG were deduced in detail.Secondly, based on the dq0 model of CBDFG some related simulations are achieved. Detailed curves of these simulations demonstrate the capability of CBDFG for VSCF power generation.Third, a mathematic model of a grid-side converter and a further control strategy of it using grid voltage vector oriented control method are deduced. Based on the MT model and stator flux vector oriented control method a kind of VSCF control strategy of a motor-side converter is derived. The results of the simulations under three typical running conditions conclude many important conclusions which will be very helpful to construct an experimental platform of this VSCF wind power generation system.Finally, based on the theoretical analysis, simulation results and control strategy the author designs an experimental system of CBDFG including hardware platform and software program. The hardware platform design consists of devices choosing, function circuit design, PCB board manufacture and test. The software program design includes system flow chart, SVPWM waves generated by DSP, other function subprogram detailed design, etc. All of the design work that had been done founds the basis of the experimental platform of CBDFG wind power generation system.