离网型双馈异步风力发电机组最大风能捕获控制研究

摘要

针对离网型双馈异步风力发电机组( DFIG)不能实现最大风能跟踪问题,提出一种基于可变负载的最大风能捕获控制方案. 基于风机最优功率曲线,检测转子转速计算转矩参考值与发电机电磁转矩反馈值比较,所获误差信号用于控制可变负载,实现最佳功率捕获. 同时,针对定子电压易受负载投切的影响,采用定子磁链强迫定向方法,考虑励磁电流暂态过程的影响,结合前馈补偿设计双电流闭环控制器,抑制定子电压扰动. 为验证控制策略有效性,在MATLAB/Simulink环境下建立兆瓦级仿真模型,结果表明可变负载可有效实现最大风能捕获,定子输出电压幅值及频率稳定.%In order to solve the problem of maximum wind energy capturing in stand-alone wind turbines based on doubly-fed induction generators(DFIG), an maximum wind energy capturing method based on variable load was proposed. Based on the optimal power curve of wind turbine, the demanded generator torque could be calculated by measuring the rotor speed, compared with electromagnetic torque of generator, the variable load could be controlled by error value, and realize the function of tracking the maximal power point of wind power. Meanwhile, the voltage of DFIG was easily affected by load switches, apply a forced orientation of stator flux, considering the influence of dynamic exciting current, combined with feed-forward compensation design the double-loop current controller to suppress voltage disturbance. The simulation model of the stand-alone megawatt level DFIG was established in MATLAB/Simulink environment to verify the scheme. The simulation results showed that the variable load can capture the maximum wind power and output stable stator voltage.