改进的双馈风力发电系统小干扰模型

An Improved Small Perturbation Model for Doubly Fed Wind Power System

基于双馈风力发电机转子运动方程,对双馈风力发电机组接入无穷大系统引发的负阻尼型低频振荡进行机理分析,寻找产生负阻尼的系统运行条件,以及影响系统阻尼的各个运行参数。基于李亚普诺夫原理,建立了改进的双馈风力发电机组小干扰稳定性模型,相比传统的双馈风力发电机组小干扰稳定性模型。该模型将风机的机械特性、轴系传动特性、发电机电磁特性以及定、转子侧的控制特性全部反映到风机的状态方程里,可以更加准确地反映风机接入系统后的振荡模态。仿真结果验证了上述模型的有效性,并对比了双馈风电机组处于不同运行模式不同控制方法下的系统模态。

Based on rotor motion equation of doubly fed induction generator（DFIG）, the mechanism of low-frequency oscillation with negative damping caused by connecting DFIGs to infinite bus system is analyzed to find out the grid operating conditions leading into negative damping and operational parameters impacting system damping. Based on Lyapunov theory an improved small perturbation model of DFIG is established. Different from traditional small signal stability model for DFIG, in the established model the mechanical characteristics of wind turbine, the drive characteristic of shafting, electromagnetic properties of induction generator and control characteristics at rotor side and stator side are totally reflected in the state equations of the DFIG, thus the oscillation modal of power grid after connecting induction generator to it can be reflected more accurately. The validity of the established model is verified by simulation results, on this basis, the system modals under different operating modes and different control approaches of double fed induction generator are compared.