异步风力发电机组小干扰稳定性机理

Mechanism of Small Signal Stability of Asynchronous Wind Turbines

传统的电力系统稳定性分析的定义与分类主要是针对同步发电系统的动态。采用物理过程分析与特征模态分析相结合的方法,由简入繁的思路,逐步对笼型异步发电机、笼型异步风力发电机组及双馈异步风力发电机组的小干扰稳定性进行了探讨。分析结果表明,笼型异步风力发电机组的小干扰稳定性是由同转速相关的非振荡模式决定的,而双馈异步风力发电机组则是由同转子暂态电势及转子侧变频器控制器相关的振荡模式决定的。尽管主导模式不同,但电压降低是导致其特征值穿越虚轴的共同主因,因此,认为异步风力发电机组的小干扰稳定性从物理机理上讲属于电力系统电压稳定性范畴。

The definition and classification of stability analysis on conventional power system is mainly aimed at the dynamics of synchronous generator system. Based on the method combining physical process analysis and characteristics modal analysis, as well as the rule ＂from simple to complex,＂ the small signal stabilities of squirrel-cage induction generator, squirrel-cage induction wind turbine and doubly-fed induction wind turbine are discussed. The results show that： the small signal stability of squirrel-cage induction wind turbine is determined by the non-oscillation mode correlated with rotor speed, whereas the small signal stability of doubly-fed induction wind turbine is determined by the oscillation mode correlated with rotor transient voltage and rotor-side converter controller. Although the dominate mode differs with each other, it is the low voltage that causes the eigenvalues to cross the imaginary axis. Therefore, from the point of the physical process, the small signal stability of induction wind turbines is suggested to be one type of voltage stability of power system.