双馈型风电机组低电压穿越技术研究

发布时间：2019-04-20 11:48

【摘要】：随着人们环保意识的增强，风能作为一种清洁的可再生能源，受到了世界各国的高度重视，风力发电已成为各国能源发展战略的重要方向。随着风电穿透功率的急剧增加，风力发电对地区电网稳定性的影响不容忽视。双馈感应发电机以其调速范围宽、有功和无功功率可独立调节以及所需励磁变流器容量较小等优点而成为主流机型。双馈型风电机组经过背靠背双PWM（Pulse WidthModulation，PWM）变流器跟电网相连，，由于双馈风电机组的机构特点，当电网电压跌落时，风电机组脱网运行会对电网的稳定性造成严重影响。因此，低电压穿越技术的研究成为热点问题，势必对电网短路故障下双馈机组不间断运行能力进行深入研究。本文以变速恒频双馈感应发电机组为对象展开研究。首先，分析了双馈风电机组的运行特性及相关控制原理，介绍了网侧PWM变流器的矢量控制策略；其次，针对电网发生三相短路故障，机端电压跌落时双馈感应电机的暂态过程进行了分析；然后，详细介绍了对电压大值跌落最有效的低电压穿越方法--转子Crowbar电路。细致列出了各国电网对风电并网的要求，针对Crowbar保护，讲述了其运行原理，并对其电阻阻值进行了整定。仿真分析了Crowbar保护电阻阻值不同和切除时间不同对机组低电压穿越的影响，结果表明，在合理的取值范围内，Crowbar的取值越大，对机组的低电压穿越性能越好；Crowbar保护在故障切除一个周波后退出运行，对机组的低电压穿越性能越好；最后，根据Crowbar保护投入后网侧变流器的不同运行方式，制定了网侧变流器低电压穿越的控制方法，并与Crowbar保护相结合，提出了低电压穿越的协调控制策略，通过仿真对其可行性进行验证。
[Abstract]:With the increasing awareness of environmental protection, wind energy, as a clean and renewable energy, has been paid great attention by many countries in the world. Wind power generation has become an important direction of energy development strategy in all countries. With the rapid increase of the penetration power of wind power, the influence of wind power generation on the stability of regional power grid should not be ignored. Doubly-fed induction generator has become the mainstream model because of its wide range of speed regulation, independent regulation of active and reactive power and small capacity of excitation converter. The double-fed wind turbine is connected to the grid through the back-to-back dual-PWM (Pulse WidthModulation,PWM converter. Due to the characteristics of the doubly-fed wind turbine, when the grid voltage drops, the off-grid operation of the wind turbine will have a serious impact on the stability of the grid. Therefore, the research of low-voltage traversal technology has become a hot issue, and it is bound to carry on in-depth research on the uninterrupted operation capability of doubly-fed units under short-circuit fault in power network. In this paper, the variable-speed constant-frequency doubly-fed induction generator set is studied. Firstly, the operation characteristics and related control principle of doubly-fed wind turbine are analyzed, and the vector control strategy of PWM converter on the network side is introduced. Secondly, the transient process of doubly-fed induction machine is analyzed when there is a three-phase short circuit fault in the power network, and then the rotor Crowbar circuit, which is the most effective low voltage traversal method for large voltage sag, is introduced in detail. The requirements of wind power grid in various countries are listed in detail. According to the Crowbar protection, the operation principle is described, and the resistance value of the wind power grid is adjusted. The influence of different resistance value of Crowbar protection and different cutting time on the low voltage traversal of the unit is analyzed by simulation. The results show that the larger the value of Crowbar is, the better the low voltage traversal performance of the unit is. The better the low voltage traversal performance of the unit is, the better the Crowbar protection will be when the fault is removed after a cycle of fault is removed from operation. Finally, according to the different operation modes of the grid-side converter after the Crowbar protection is put into operation, the control method of the low-voltage traversal of the network-side converter is formulated, and combined with the Crowbar protection, the coordinated control strategy of the low-voltage traversal is put forward. The feasibility of this method is verified by simulation.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614

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