弱电网对称短路故障期间DFIG风电系统动态稳定性分析

Dynamic stability analysis of DFIG-based wind power generation system during symmetrical short circuit fault of weak grid

文章建立了弱电网短路故障期间,考虑锁相环和电网传输线路的双馈风力发电系统小信号状态空间模型。基于小信号状态空间模型,研究了双馈风电系统在低电压穿越过程中的动态特性,从机理上阐明弱电网对称短路故障期间系统的振荡失稳原因,并对故障期间的双馈风力发电系统进行了全面模态分析,确定了系统最弱阻尼的振荡模态。通过特征根轨迹,综合评估了电压跌落程度、锁相环带宽、转子电流环带宽对双馈风力发电系统小信号稳定性的影响。最后,通过Matlab/Simulink仿真验证了理论分析的正确性。

In this paper,the small signal state space model of the DFIG system taking into account the phase-locked loop(PLL)and transmission lines impedance under the weak grid fault is established.Based on the small signal model,the dynamic characteristics of the DFIG wind power system during low voltage ride through(LVRT)is investigated.The mechanism of the oscillation instability during symmetric short-circuit fault of weak grid is revealed.A comprehensive modal analysis of DFIG wind power system during the short-circuit fault of weak grid is carried out,and the oscillation mode of the weakest damping of the system is determined.In addition,the influence law of voltage dips degree,PLL bandwidth and rotor current loop bandwidth on the small signal stability of the system is explored through the characteristic root locus.Finally,the time-domain simulation model of DFIG wind power system is established in Matlab/Simulink,and the correctness of the theoretical analysis is verified by the simulation results.