基于状态反馈解耦控制的含DFIG电力系统低频振荡抑制研究

Research on low frequency oscillation suppression of power system with DFIG based on state feedback decoupling control

由于风力双馈感应发电机(DFIG)内部阻尼转矩不足,导致DFIG接入电力系统时会降低系统阻尼,增加发生低频振荡的风险。文章提出了一种状态反馈解耦的控制方法,该方法依据闭环电力系统状态空间模型,将DFIG视为反馈控制器,对其传递函数阵进行状态反馈解耦,实现对来自同步发电机角速度、功角和阻抗偏差矢量一对一控制,进而对整个含DFIG电力系统数学模型进行降阶,同时调节功角耦合参数C_(g1)、角速度耦合参数C_(g2)以及阻抗耦合参数C_(g3)提高系统阻尼比,抑制公共连接点(PCC)电压幅值变化,提高了对低频振荡的抑制能力。最后,以风电接入四机两区域间降阶模型为例进行仿真,并与传统的状态观测器方法对比,仿真结果验证了所提方法对提高整个系统阻尼比和降低节点电压幅值抑制低频振荡的正确性和有效性。

Due to the insufficient internal damping torque of wind power doubly-fed induction generator(DFIG),the system damping will be reduced and the risk of low-frequency oscillation will be increased when the DFIG is connected to the power system.A decoupling control method using state feedback is proposed in this paper.This method is proposed based on the state space model of the closed-loop power system.DFIG is regarded as a feedback controller,and its transfer function matrix is decoupled by the state feedback.The synchronous generator angular velocity,power angle and impedance deviation vector are controlled by one-to-one,and then the order of the whole mathematical model of DFIG power system is reduced,and the power angle coupling parameter C_(g1),the angular velocity coupling parameter C_(g2)and the impedance coupling parameter C_(g3)are adjusted to increase the system damping ratio and suppress the point of common connection(PCC)voltage amplitude changing to improve the suppressing ability of the low-frequency oscillation.In the end,taking the reduced-order model of wind power connecting to four-machine and two-area as an example,the above method is used for simulation and compared with the traditional state observer method.Simulation results show that the proposed method is correct and effective for increasing the damping ratio of the entire system and reducing the node voltage amplitude to suppress low-frequency oscillations.