双馈感应风力发电机的负电阻效应研究

INVESTIGATION ON NEGATIVE-RESISTANCE EFFECT OF DOUBLY-FED INDUCTION GENERATOR

为评估双馈风电场经串补送出系统的振荡风险,该文重点对双馈风力发电机的负电阻效应进行研究。首先,结合双馈风力发电机常用的控制结构,通过分析其扰动响应特性建立端口导纳模型。在此基础上,通过等效电路分析建立异步发电机转子回路的等效阻抗模型。进一步地,对转子回路的负电阻特性进行研究,并定义2个特征指标来定性评估系统的振荡风险。最后,通过时域电磁暂态仿真验证所建立模型的准确性和特征指标的有效性。算例分析表明:双馈风力发电机的负电阻效应主要取决于异步发电机的转子回路,会受到运行转速、转子电阻及转子侧换流器控制器参数等的影响。

For the oscillations risk assessment of the double-fed induction generator(DFIG)transmitted by the series-compensated grid,the negative-resistance effect of the DFIG is specially investigated in this paper.Firstly,based on the common control structure,the port-admittance model of the DFIG is established by analyzing its response characteristics to disturbances.On the basis,the equivalent rotor impedance of asynchronous generator is derived based on the equivalent electrical circuit analysis.Subsequently,the negative-resistance characteristics of the rotor circuit are further investigated and two characteristic indexes are defined to evaluate the oscillations risk.Finally,the accuracy of the port-admittance model and the effectiveness of the characteristic indexes are verified through the time-domain electro-magnetic transient simulation.From case studies,it indicates that the negative-resistance effect of the DFIG mainly depends on the rotor circuit of asynchronous generator.It is influenced by the rotating speed of the generator,the resistance of the rotor windings,and the controller parameters of the rotor-side converter.