Key Technology Research Of Megawatt Three-level Double-fed Wind Power Converter

Using wind effectively is one of the effective ways to solve the energy and environment problems. It has important significance to research high performance wind power converter for perfecting country's wind power industry chain and promoting the overall level of wind power industry. As the own advantages of three level topological structure, it can adapt to a higher voltage grade and provide more green electricity. Therefore, adopting three level topology instead of traditional two level topology for wind power converter is one of the important research directions.Based on the three level topological structure, several key technologies of MW double fed wind power converter are researched deeply. Overall design scheme of double fed wind power converter and LQRI control strategy are proposed in this dissertation. Effective control of Grid side converter is realized under unbalance grid conditions. On the basis of sliding mode control with fuzzy approach, rotor current inner loop control strategy is proposed to inhibit adverse effects as a result of the mathematical model change before grid connection and after. Grid voltage tracking before grid connection and power given tracking after grid connection are also realized effectively. Double fed converter is controlled with speed sensorless. Experiments on wind field verify the control strategy correctly and effectively.