基于干扰抑制的双馈风机低电压穿越控制策略

低电压穿越要求风力发电系统在电网电压突降下保持连续运行并为电网提供无功功率支撑。为提升双馈风力发电系统的低电压穿越能力，提出基于状态相关Riccati方程技术的干扰抑制控制方法。所提干扰抑制控制目标为：确保转子侧换流器在暂态期间为系统提供所需的无功功率支撑；控制网侧换流器以维持直流母线电压恒定。基于上述控制目标构建相应的干扰抑制控制问题，并采用状态相关Riccati方程技术获得反馈控制律。在设计权重矩阵时，充分考虑了控制目标、控制效果与控制成本的影响。为了保证转子电流和直流母线电压在低电压穿越过程中处于安全范围，设计转子电流抑制机制，并采用串联动态电阻保护电路。最后，与传统比例-积分（PI）控制、基于粒子群优化的PI控制、滑模控制以及精确线性化控制的仿真结果进行对比，结果表明所提出的控制策略具有更好的暂态性能，能够有效地提升双馈风力发电系统的低电压穿越能力。

Low Voltage Ride-through Control Strategy for DFIG-based Wind Turbine Based on Disturbance Attenuation

Low voltage ride-through (LVRT) requires wind power generation systems to remain continuous operation during the sudden grid voltage sag and provide reactive power support for power grid. To enhance the LVRT capability of wind power generation systems using doubly-fed induction generators (DFIGs), this paper proposes a disturbance attenuation control (DAC) method based on state-dependent Riccati equation (SDRE) technique. The DAC objectives are as follows: the rotor side converter should provide required reactive power support for power grid during the transient period; the grid side converter should keep the DC-link voltage constant. Based on the above control objectives, the corresponding DAC problems are constructed, and the feedback control laws are obtained by using SDRE technique. The influence of control objectives, control effect and control cost are fully considered in the design of weighing matrices. To ensure the rotor current and DC-link voltage are within the safe range in the LVRT process, a rotor current limiting mechanism is proposed and a protection circuit using series dynamic resistor is adopted. Compared with the simulation results of the conventional proportional-integral (PI) control, the PI control based on particle swarm optimization (PSO), the sliding-mode control, and the exact linearization control, the proposed control strategy has better transient performance and can effectively improve the LVRT capability of wind power generation systems using DFIGs.