九开关双馈风力发电系统的恒定开关频率电流滑模控制方法

Constant Switching Frequency Current Sliding Mode Control Method for Nine-switch-converter-based Doubly-fed Wind Generation System

较之基于背靠背变换器的双馈风电系统,基于九开关变换器（nine-switchconverter,NSC）的双馈风电系统所需器件更少,且可通过对NSC直流母线电压及电流容量在机侧与网侧的动态分配实现低电压穿越（low-voltage-ridethrough,LVRT）,并具备无功补偿能力。对九开关双馈风电系统的控制,目前均沿用了传统矢量控制与NSC特殊调制相结合的方法,控制过程复杂,性能提升有限。为简化控制过程并提升控制性能,该文提出适用于NSC双馈风电系统的恒定开关频率电流滑模控制,该方法直接在三相静止坐标系进行电流滑模闭环控制,生成NSC驱动所需占空比。该文对所提方案进行详细分析,并通过实验将其与传统比例积分控制进行对比。实验结果表明,所提滑模控制具有优于比例积分控制的动态响应和LVRT性能。

Doubly-fed induction generator （DFIG） wind power system based on nine-switch converter （NSC） needs fewer switch devices than that based on back-to-back converter, and can achieve low-voltage-ride-through （LVRT） and reactive power compensation by assigning the dc-link voltage and current capacities of NSC to rotor and grid side dynamically. However, recent control strategies for NSC-DFIG system simply combines traditional vector control and special NSC modulation method. Such a control frame is complicated, and limits the performance improvement. To simplify the control process and improve the performance, this paper proposed a constant switching frequency current sliding mode control method for NSC-DFIG system. The proposed method directly adopted equivalent current sliding mode control in the three-phase stationary coordinate system to generate NSC driving duty-cycles. It was also analyzed in detail and compared with the traditional proportional integral （PI） control by experiments in this article. The results show that the proposed method performs better than PI control in dynamic response and LVRT performances.