状态反馈线性化控制下DFIG低电压穿越研究

发布时间：2019-03-13 12:16

【摘要】：随着电网中风力发电渗透率的不断提高，风电机组运行状况对电网的影响也越来越大，世界各国电网导则对风电场并网的标准也愈加严格，尤其是对风电机组在电网故障下的低电压穿越（LVRT）能力的要求也越来越高。双馈异步感应发电机（DFIG）因其良好的经济性和控制性能在风力发电机中应用最广。同时，由于DFIG定子直接并网，转子励磁变换器容量较小，使得风电机组对电网故障非常敏感。因此，研究DFIG低电压穿越方法，提高DFIG低电压穿越能力具有非常重要的意义。本文首先建立了双馈型并网风力发电机及其背靠背励磁变换器在三相静止ABC坐标系和两相旋转dq坐标系下的数学模型，分析了其工作原理及传统矢量控制策略。然后设计了基于状态反馈线性化的控制方法，并且在MATLAB/Simulink环境下搭建了一台2MW双馈风力发电机模型，进行了状态反馈线性化控制与传统矢量控制的仿真对比，表明状态反馈线性化控制在电网轻微对称故障时具有更好的动态性能，更强的鲁棒性。然后对电网对称故障条件下DFIG暂态特性进行了分析，，设计了针对不同故障程度的低电压穿越方案：电网电压小幅跌落下通过状态反馈线性化控制实现DFIG不间断运行；大幅跌落下通过增加转子侧Crowbar和直流Crowbar的硬件保护来实现低电压穿越。重点推导了转子侧Crowbar的旁路电阻取值范围及其最佳投切时刻选取，通过仿真验证，获得了良好的低电压穿越效果。最后搭建了一台基于dSPACE的10kW双馈型并网风力发电系统实验平台。进行了网侧变换器分别在传统矢量控制和状态反馈线性化控制下的实验对比，结果显示状态反馈线性化控制无论在稳态性能还是动态性能都优于传统矢量控制，验证了理论分析的正确性。然后对转子侧变换器进行了调试，实现了双馈电机的并网运行。
[Abstract]:With the increasing permeability of wind power generation in power grid, the operation condition of wind turbine has more and more influence on the power grid, and the standards of grid connection of wind farms in various countries in the world are becoming more and more strict. Especially, the requirement of low voltage traversing (LVRT) capability of wind turbine under power grid fault is higher and higher. Doubly-fed asynchronous induction generator (DFIG) is the most widely used wind turbine because of its good economy and control performance. At the same time, because the DFIG stator is directly connected to the grid and the rotor excitation converter capacity is small, the wind turbine is very sensitive to the fault of the power grid. Therefore, it is very important to study the low voltage traversal method of DFIG and improve the low voltage traversal ability of DFIG. In this paper, the mathematical models of double-feed grid-connected wind generator and its back-to-back excitation converter in three-phase static ABC coordinate system and two-phase rotating dq coordinate system are established. The working principle and traditional vector control strategy are analyzed. Then the control method based on state feedback linearization is designed and a 2MW doubly-fed wind generator model is built in MATLAB/Simulink environment. The simulation comparison between state feedback linearization control and traditional vector control is carried out. It is shown that the state feedback linearization control has better dynamic performance and stronger robustness when the power network is slightly symmetric. Then the transient characteristics of DFIG under symmetrical fault condition are analyzed, and the low voltage traversal scheme for different fault levels is designed. The low voltage traversal scheme is realized by state feedback linearization control under the small voltage sag of the power network, and the uninterrupted operation of DFIG is realized under the control of state feedback linearization. Large sags achieve low voltage traversal by increasing the hardware protection of rotor-side Crowbar and DC Crowbar. The range of the by-pass resistance and the selection of the optimal switching time of the rotor-side Crowbar are derived. The simulation results show that the low-voltage traversing effect is good. Finally, an experimental platform of 10kW double-feed wind power generation system based on dSPACE is built. Compared with the traditional vector control and the state feedback linearization control, the results show that the state feedback linearization control is superior to the traditional vector control in both steady and dynamic performance. The correctness of the theoretical analysis is verified. Then the rotor side converter is debugged to realize the grid-connected operation of doubly-fed machine.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM315

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