Research On The Generator-Side Converter Of Asynchronous Wind Power Generator

The rapid and stable development of the converter for wind power is the sources which make wind power industry get new and developing. At present, 90% of the converters, which are used by domestic wind power industry, depend on imports, so it is essential that the inverters should be localized. This paper relies on the small and medium sized VSCF AC asynchronous wind turbine generator as the background produced by the automatic control technology institute of Shenyang University of Technology to research on the generator side converter. With the direct torque control technology, it is realized to adjust the torque and rotational speed of the generator accurately and quickly by the generator side converter, which can make the synchronous speed of the generator always slower than its rotor speed and maintain the generator working at the best generating state.According to the disadvantages of the direct torque control technology, such as the flux and torque ripple, we propose an improved direct torque control approach in this thesis. Firstly, the SVPWM technology, which has concise algorithm and outstanding control performance, is used to substitute for the traditional method, which relays on switching voltage vector table. Secondly, which replaces the traditional hysteresis comparator with torque fuzzy PI controller and flux PI controller, essentially avoids tolerance settings of traditional hysteresis comparator on system performance influence. The simulation results show that the performance based on the SVPWM AC asynchronous wind power generator with improved direct torque control method is better than the performance with traditional direct torque control method, such as the stator flux linkage trace is more closer to round and the torque, the better robustness, higher response rate, the flux and the current ripple are smaller relatively, which verifies the effectiveness and feasibility of this improved method.The hardware experiment platform of the direct torque control system of the AC asynchronism wind turbine is putted up based on the model simulation, which includes the main control system with the core of dsPIC30F6010 DSC and the driving system with the core of intelligent power module PS21865. The main program and interrupt service routine of this system are designed with a mixed programming way using c language and assembly language under the integrated development environment of MPLAB IDE. The experimental results show that the wind power converter designed in this paper has steady output voltage, adjustable frequency and the phase relations between each voltage is 120°, and keeps asynchronous motor working in generation mode which reaches the design objective.