Control Stategy Reseach Of Motor-side Converter In Wind Turbine System

Due to environment pollution and energy shortage, people is looking for clean renewable energy. Wind energy is a wide existing, clear and renewable energy, so that the research of wind energy application develops rapidly. Recently, many countries make full development and utilization of wind power. In all kinds of wind power generation systems, the full-scale converter wind turbine with SCIG or the part-scale converter wind turbine with DFIG has been widely used because of structure and control advantages. The control strategy is very important in motor-side converter, which act as the key part of motor control and power converter. Vector Control(VC) and Direct Torque Control(DTC) are basic control strategy, and VC can be implemented based on PI-Controller or PR-Controller. Therefore, the control strategy of motor-side converter in SCIG and DFIG wind turbine system has been proposed and studied in detail, including the condition of power grid is normal and fault. The key contents and main work in this paper as follows.(1) VC(based on PI and PR controller) and DTC realization and optimization method has studied and proposed in the wind turbine of SCIG and DFIG. The improved algorithms and control strategies, such as FA-PR and SVM-DTC, have been proposed in this dissertation, which can significantly improve the performance of control and the convenience of use. Simulation and experimental results verify the correctness and effectiveness of the proposed strategy.(2) In addition, these strategies of VC(based on PI and PR controller) and DTC are systematically evaluated and compared from many aspects for the steady state grid operating conditions in this paper, such as control precision, algorithm complexity and system demand. The comparison result provide certain reference significance for the wind turbing control and application.(3) For the ability of Low Voltage Ride Through(LVRT) as the standard of grid connected, the transient characteristic and ride through strategy are systematically analyzed of SCIG and DFIG wind turbine system under voltage drop in this paper. Using the results of theory analysis, SCIG and DFIG simulation model is established and LVRT performance is verified and compared based on different control strategy, including Vector control(based on PI and PR controller) and Direct Torque Control. Comparison results provides basis for the improvement and optimization of LVRT algorithm.