基于电网虚拟磁链的变速恒频风力发电机柔性并网技术

Flexible grid-connection technology based on grid virtual flux linkage for VSCF wind generator

利用双馈风力发电机与电网的"柔性连接"特性,基于合理的转子侧交流励磁控制可实现发电机柔性并网。在推导双馈风力发电机空载数学模型基础上,提出了电网虚拟磁链的概念,给出了柔性并网中双PWM励磁变换器的控制方法:基于电网虚拟磁链定向的机侧变换器矢量控制策略和基于电网电压定向网侧变换器矢量控制策略。设计了具有初始磁链估计、不需电压传感器的虚拟电网磁链观测器,该观测器实现简单,精度较高。实验研究表明,柔性并网技术安全稳定,电流冲击小,满足双馈风力发电机的变速恒频运行需要。

According to the characteristics of ＂flexible connection＂ between DFIG （Doubly-Fed Induction Gene- rator） and grid,the flexible grid-connection of generator is achieved by valid AC excitation of rotor. The mathematic model of DFIG with no-load is deduced and the concept of grid virtual linkage is put forward. The control scheme of back- to-back PWM converter for grid- connection is analyzed,which includes the grid virtual linkage oriented vector control strategy of rotor-side converter and the grid voltage oriented