基于内模的双馈风力发电机组滑模电流控制策略研究

发布时间：2018-12-08 18:13

【摘要】：变流器是双馈异步风力发电机组的重要组成部分,是实现风电机组变速恒频发电的关键,其控制策略影响着机组的稳定运行。同步旋转坐标系下,转子d、q轴电流耦合项中含有定转子电感、电阻等电机参数,而电机参数会随工况变化而改变,造成常规的矢量控制策略无法完全消除d、q轴电流耦合。因此,本文在内模控制结构基础上,结合滑模控制策略对风电机组d、q轴电流进行解耦控制。首先,根据双馈发电机的结构和工作原理,得到电机等效电路,建立三相静止坐标系下的数学模型,通过三相静止到两相旋转的坐标变换,并且采用定子磁链定向的矢量控制,推导出两相旋转坐标系下双馈发电机的数学模型。其次,根据内模控制原理与特点,结合双馈发电机同步旋转坐标系下的数学模型,对解耦项进行拉氏变换,得出内模结构的基本传递函数,按照内模控制器的设计步骤,给出内模控制器结构,通过内模参数的匹配,获得了满足系统要求的动态响应性能;利用滑模控制原理,结合双馈发电机的数学模型,定义了d、q轴滑模面和电流滑模控制律,采用李雅普诺夫稳定性理论,分析了系统的稳定性,在内模控制器的基础上,给出了基于内模的滑模电流控制结构。最后,搭建了基于内模的滑模电流解耦控制的双馈风力发电系统仿真模型,分别对亚同步、同步、超同步三种风电机组运行工况进行了仿真研究,并与常规控制策略仿真结果进行对比分析。在风速变化时,定子输出有功和无功功率、转子d、q轴电流等主要物理量超调量小、响应时间快、调节时间短;在电机参数变化时,以上物理量与各自原来电机参数不变时相比偏差小、能更好跟随参考值。由此可见,所提控制策略不仅提高了风电机组的动态性能,而且也具有更加优良的鲁棒性。
[Abstract]:Converter is an important part of doubly-fed asynchronous wind turbine and the key to realize variable speed constant frequency generation of wind turbine. Its control strategy affects the stable operation of wind turbine. In the synchronous rotating coordinate system, the current coupling term of the rotor dnq axis contains the motor parameters such as stator and rotor inductance, resistor and so on, but the motor parameters will change with the change of working conditions, resulting in the conventional vector control strategy can not completely eliminate d. Q axis current coupling. Therefore, based on the internal mode control structure and sliding mode control strategy, decoupling control of dq-axis current of wind turbine is carried out. Firstly, according to the structure and working principle of the doubly-fed generator, the equivalent circuit of the motor is obtained, and the mathematical model in the three-phase static coordinate system is established, and the vector control based on the stator flux orientation is adopted through the coordinate transformation from the three-phase static to the two-phase rotation. The mathematical model of doubly-fed generator in two phase rotating coordinate system is derived. Secondly, according to the principle and characteristics of internal model control, combined with the mathematical model of synchronous rotation coordinate system of doubly-fed generator, the decoupling term is transformed by Laplace transform, and the basic transfer function of internal model structure is obtained, according to the design steps of internal model controller. The structure of the internal model controller is given, and the dynamic response performance of the system is obtained by matching the internal model parameters. Based on the sliding mode control principle and the mathematical model of doubly-fed generator, the sliding mode surface and current sliding mode control law are defined. Based on Lyapunov stability theory, the stability of the system is analyzed. A sliding mode current control structure based on internal mode is presented. Finally, the simulation model of double-fed wind power generation system based on sliding mode current decoupling control based on internal mode is built, and the sub-synchronous and supersonic wind turbine operating conditions are simulated. The simulation results are compared with those of the conventional control strategy. When the wind speed changes, the stator output active and reactive power, rotor dnq axis current and other main physical quantities overshoot small, the response time is fast, the adjustment time is short; When the motor parameters change, the deviation of the above parameters is smaller than that of the original motor parameters, so it is better to follow the reference value. Therefore, the proposed control strategy not only improves the dynamic performance of wind turbine, but also has better robustness.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM315

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