Study And Design Of Direct-driven Permanent Magnet Synchronous Wind-Energy Generation Control System

With the aggravation of the energy crisis and the worsening of environment, the development and utilization of renewable energy are concerned by many countries around the world. As a way to use the renewable and clean energy, the wind-energy generation is developed rapidly. Comparing with doubly-fed AC excited wind-energy generation system, the direct-driven permanent magnet synchronous wind-energy generation system has features of simpler structure, higher generation efficiency and higher operation reliability. The control of the direct-driven permanent magnet synchronous wind-energy generation system includes the control of both the generator-side converter and the grid-side converter. The output active power of the generator, the fluctuation of the torque and the wind-energy utilization efficiency are influenced by the control strategy of the generator-side converter. On the other hand, the active power transmission and the reactive power regulation are influenced by the control strategy of the grid-side converter. So, it is the key that an appropriate control strategy should be adopted to improve system performance.The direct-driven permanent magnet synchronous generation system with the back-to-back PWM converter used as the grid-connected main circuit is studied in this thesis. Firstly, the mathematical model of the permanent magnet synchronous machine and coordinate transformation is analyzed, and the control strategy of the generator-side converter based on the vector control is studied. The maximum wind-energy tracking control strategy with the optimal reference power is studied from the characteristics of the wind turbine. The optimal setting value of the output active power is calculated according to the generator rotation speed and the maximum wind-energy tracking control is realized by closed-loop regulation. Secondly, the control theory of the grid-side converter is analyzed and the mathematical model is built, and the control strategy of the grid-side converter is studied. The output active power of generator is transmitted to the grid by stably controlling DC-link voltage. The reactive power of the grid-side converter is regulated by controlling the reactive current of the grid-side converter. Lastly, the hardware of the direct-driven permanent magnet synchronous generation system is designed by using high speed digital signal processor TMS320F2812 and intelligent power module (IPM) and the software is accomplished according to the control model. The good performance of the generation system and the control strategy are validated through experimental research. The maximum wind-energy tracking control, the independent control of grid-connected active power and reactive power, and variable speed constant frequency (VSCF) generation are realized.