基于频率扫描的双馈风电机组次同步控制相互作用分析

摘要

双馈风电机组中存在较多与次同步振荡频率范围耦合的控制环路,容易引发控制环路与线路串联电容补偿之间的次同步控制相互作用(SSCI).其中双馈风电机组转子侧内环比例参数对SSCI影响显著,但由于其稳定阈值较小,在抑制SSCI时的可调范围有限,因此有必要探寻控制环路中的其他参数对SSCI的影响.在建立完善的含双馈风电机组控制环路的并网系统阻抗模型的基础上,通过波特图与灵敏度分析详细对比控制参数对系统阻抗的影响大小,采用频率扫描法揭示了控制参数对系统阻抗的影响机理.结果表明:转子侧内环积分参数直接影响系统的谐振频率与线路的临界串联电容补偿度大小,积分参数的减小能够增加比例参数的可调范围,从而有利于降低并网系统发生SSCI的风险.%Doubly-fed wind turbines have many control loops that are coupled to the sub-synchronous oscillation frequency range,which may lead to Sub-Synchronous Control Interaction (SSCI) between the control loop and series compensated transmission line.Although inner loop proportional parameter has a significant effect on the SSCI,because of the limit of stability threshold,it is necessary to find out the effects of other parameters in the control loop on the SSCI.On the basis of the establishment of the impedance model contains control loops of DFIG,bode plot and sensitivity analysis are adopted to compare the influence of different controller parameters on the system impedance and frequency scan is used to reveal the impact mechanism of system impedance at different control parameters.The results show that the integral parameter of the rotor side directly affects the resonance frequency and series compensation degree of the transmission line.The reduction of the integral parameter can increase the adjustable range of the proportional parameter,which is beneficial to reduce the risk of SSCI in grid-connected system.