节点文献
大功率双馈风力发电机的控制策略研究
Research on Control Scheme of High-Power DFIG for Wind Turbine
【作者】 刘思佳；
【导师】 庄圣贤；
【作者基本信息】 西南交通大学 ， 电力电子与电力传动， 2009， 硕士
【摘要】 本论文主要针对大功率双馈风力发电机的控制策略进行研究,使风电机组达到变速恒频发电的效果。同时介绍了双馈风力发电机系统在低压穿越时的运行模式,并对其运行效果进行仿真分析。文中通过与其它风力发电机系统的比较,介绍了双馈风力发电机系统的结构特点。并采用双馈发电机的T型等效电路对其运行控制原理进行了分析。双馈发电机可通过控制转子侧转差功率的方式实现定子侧输出功率的有效控制。文中还对双馈发电机变速恒频发电的原理及双馈风力发电机系统的其它部分进行了介绍。文中通过双馈发电机系统的数学模型对其控制策略进行了设计研究。这是一种基于定子电压定向的转子电流矢量控制的控制方式,可实现双馈发电机输出有功功率、无功功率的独立控制。与定子磁链定向的方式相比,这种方式省略了磁链测量部分。并根据此控制方法,使用Matlab/Simulink软件构建了一个用于1.5MW双馈风力发电机的控制系统,仿真验证了当输出有功功率、无功功率改变时,该控制策略的有效性。当电网电压出现骤降时,风力发电机需保持并网实现低压穿越,这是对风电机组的新要求。对双馈风力发电机系统而言,低压穿越时会遇到许多问题,目前常用的解决方式是采用主动式Crowbar电路,其作用是在发电机并网的状态下保护转子侧的变流器。文中对不同类型的Crowbar电路进行比较分析,并对其在双馈风力发电机系统中的运行效果进行了仿真研究,仿真中仍采用上述的功率控制策略。
【Abstract】 This thesis deals with the control scheme of doubly-fed induction generator (DFIG) in wind power conversion system, which can make power generation in Variable Speed Constant Frequency (VSCF) mode. Furthermore, the operation mode of DFIG system in low voltage ride through (LVRT) condition is investigated and simulated in detail.The structure characteristic of DFIG system is described by comparing with other kinds of wind generators. The power characteristic of DFIG is analyzed by using the T- type equivalent circuit, which means the stator-side output power of DFIG can be controlled by adjusting the rotor-side slid power. Also the principle of VSCF mode on DFIG is described, and the other parts of DFIG system is introduced briefly.The control scheme of DFIG system is designed based on its mathematical model, which is a kind of rotor current vector control in stator-voltage-oriented frame, and can control active and reactive output power of DFIG independently. Compared to the stator-flux-oriented frame, this control method doesn’t need stator-flux measurement. The control system is simulated by Matlab/Simulink for 1.5MW DFIG. The simulation results show the effectiveness of the control scheme during variations of active power and reactive power.LVRT is a new and necessary request to wind turbines, which means the generator should keep connecting to the grid when grid voltage sag happens. There are many problems to DFIG system in LVRT operation, and the general answer to these problems is active crowbar circuit, which can protect rotor-side converter and keep generator connecting to the grid during LVRT. The different types of active crowbar circuit are investigated in this thesis, and the operation effect is simulated based on the control scheme mentioned above.