直驱永磁同步风电系统低电压穿越的研究

Low voltage ride-through of directly driven wind turbine with permanent magnet synchronous generator

【目的】研究直驱永磁同步风电系统的控制策略,以提高其低电压穿越的能力。【方法】建立经背靠背双PWM变流器并网的直驱永磁同步风力发电系统的仿真模型,采用电流前馈控制实现两侧变换器的有功和无功功率的解耦控制。将电网电压信号引入机侧整流器参考功率的计算,提出按电网电压跌落幅度减小发电机输出功率的低电压穿越控制策略。【结果】仿真结果表明,电网电压跌落时,文章所提控制策略限制了变流器直流侧过电压和网侧逆变器过电流;辅以桨距角调节可以抑制发电机功率减小时机组机械转速的升高。【结论】保持发电机功率平衡和变流器直流侧功率平衡,可提高直驱永磁同步风电系统的低电压穿越能力,同时向系统提供无功功率支持,帮助电网电压恢复。

【Objective】 The control strategy for directly driven wind turbine with permanent magnet synchronous generator（D-PMSG） was investigated to enhance its capacity of low voltage ride through（LVRT）.【Method】 A D-PMSG model comprising of a host AC power grid with two back-to-back PWM voltage source converters（VSCs） and a common DC link was established.The active and reactive powers of the two VSCs were independently controlled by the PI current controllers with feedforward decoupling.The real-time grid voltage was introduced into the reference power calculation of gen-side rectifier. The control strategy with reducing generator power based on the ratio of actual and rated grid voltage was proposed. [Result] Simulation results showed that during voltage dip, the proposed strategy could limit both the DC voltage and inverter current. The rotational speed was limited at its reference by pitch angle controller. [Conclusion] The power balance of generator and DC-link of the converters could be maintained through the employment of the proposed control strategy, thus the LVRT capacity of D-PMSG was enhanced, and the reactive power to the grid could also be supplied.