基于电流补偿策略的DFIG系统低电压穿越研究

Research on low voltage ride-though of DFIG system based on current compensation strategy

为了研究双馈异步风电机组定转子之间的故障特性,在RTDS中建立了低电压故障下双馈异步风电机组励磁变流控制系统,利用拉普拉斯变换分析DFIG系统状态方程在约束条件下的输出响应,给出了三相短路故障下发电机定转子电流各自暂态分量。通过分析定转子暂态分量衰减特性,得到定子直流磁链对定转子电磁暂态响应的主导作用。进一步通过转子电流补偿的改进空间矢量控制消除定子直流磁链,同时配合直流母线Crowbar卸载电路提高DFIG风电系统的低电压穿越能力。RTDS的仿真结果验证了电流补偿和Crowbar电路组合控制策略的有效性。

For studying the failure feature between the stator and rotor of doubly fed induction wind turbine （DFIG）, field converter control system of DFIG during low voltage fault using RTDS is established. Based on Laplace transform and inverse transform analysis of the state equation of DFIG system in the output response under constraint, each transient component of the stator and rotor under three-phase short-circuit fault is given. On the basis of attenuation characteristics in the stator and rotor transient components analysis, the stator DC flux is obtained to be the dominant role in the system electromagnetic transient. The space vector control of rotor current compensation is used to eliminate the stator DC flux, and the ride through capability of DFIG wind power system is enhanced by coordinating with the DC bus Crowbar. RTDS simulation results verify the effectiveness of the proposed combination control strategy.