Research On Variable Speed Constant Frequency Squirrel-cage Induction Generator For Wind Power System

With the social and economic rapid development, the energy shortage is more serious, at the same time the energy consumption make environment pollution worsen. And among all of the renewable energy sources, wind energy exist significant advantages, so the development of wind power technology is greatly paid attention by home and abroad. Therefore, in this paper Variable Speed Constant Frequency (VSCF) squirrel-cage inductor generator (SCIG) wind power system which is based on dual-PWM converter is researched.Firstly, this paper describes the development situation and future trends of domestic and foreign wind power generation. A detailed contrast analysis of four kinds of typical VSCF wind power generation systems is introduced.Secondly, the basic structure and principle of SCIG wind power system are introduced. on the basis of the analyzing the wind turbine characteristics and operating region, control method of system maximum power capture is researched.Using the mathematical coordinate transformation, the mathematical models of SCIG at the three-phase stationary coordinate, two-phase synchronous coordinate and two-phase stationary coordinate are detailedly analyzed.Thirdly, the control strategy of SCIG wind power system based on dual-PWM converter which contains the rotor side converter and the grid side converter is researched. For the former, this paper is based on SCIG rotor flux oriented control, a dual-closed-loop PI control scheme is developed to achieve decoupled control of active and reactive power, so its strategy is derived; For the latter, several commonly used control strategies which contain Voltage-based direct power control(V-DPC), Virtual-flux oriented control(VFOC) and Voltage oriented control(VOC) are briefly introduced, through the analysis of them the grid voltage oriented control strategy is adopted and a dual-closed-loop PI control scheme is also developed. In addition, the grid side converter is further researched, and a new control strategy of it is also proposed under unbalanced grid.Furhermore, this paper builds a complete SCIG wind power system simulation model with Matlab7.0, the operating characteristics of wind power system is analysed through this model simulation. And the experimental results are analyzed to prove the effectiveness of the control strategy.Finally, on the basis of simuliation this paper studies and designs the SCIG wind power analog system, which uses dual-DSP(TMS320F2812) to control the motor-side and grid-side converter, the hardware circuit and the software flow chart of the control system are preliminarily designed.