【作者】 陈辉华；

【导师】 韩华；

【作者基本信息】 中南大学 ， 电气工程， 2013， 硕士

【摘要】 随着全球能源的短缺以及传统能源发电带来的环境问题的突出,风力发电受到了越来越多的关注。当前风力发电的研究绝大部分都侧重于并网型风力发电,但在解决电网无法覆盖地区的供电问题上,离网型风力发电更具优势。双馈电机(DFIG)采用转子励磁控制技术,在变速恒频风力发电系统中优势明显。为此本文对离网型双馈风力发电系统控制策略进行了研究。论文首先介绍了离网型风力发电系统结构,并对离网系统的两个主要部分——双馈电机和背靠背变频器进行了分析建模,在该数学模型的基础上讨论了离网系统平衡负载下的控制策略。背靠背变频器通过中间电容实现两端相互解耦,利用转子侧变换器(RSC)控制建立双馈电机定子电压,即离网系统的母线电压;而利用负载侧变换器(LSC)控制建立中间直流电压。鉴于离网系统负载不平衡的情况时有发生,本文详细分析了不平衡负载对系统的影响,讨论了不平衡负载下的系统控制策略,提出了建立三相平衡定子电压的最终控制目的。出于对双馈电机的保护,本文采用通过LSC来补偿负序电流的策略。并提出利用PI加谐振(PIR)控制在正向旋转坐标系下同时控制电流的正序分量和负序分量。考虑到控制系统的电流传感器过多,对系统经济性及稳定性不利,本文研究提出了一种减少一对电流传感器的控制策略,该控制策略避免了采样负载电流,但能达到同样的控制效果。最后通过仿真和实验验证了该控制策略的有效性和可行性。更多还原

【Abstract】 With the shortage of global energy and the prominent environmental problems caused by conventional energy generation, wind power generation gets more and more attention. Most of current research on wind power generation focus on grid-connect systems, but stand-alone systems have more advantages to solve power supply problems for the areas which grid can not covered. The doubly-fed induction generator (DFIG)adopt rotor excitation technology which makes it more competitive in wind power systems of variable speed constant frequency. For this reason, the thesis do research on control strategy for stand-alone DFIG-based Wind Power Systems.The thesis first introduces the structure of stand-alone wind power system, then analyses and models the two main parts——DFIG and back-to-back converter, and discuss its control strategy under balanced loads. Back-to-back converter has two parts, rotor-side converter (RSC) and load-side converter (LSC), they decoupled via intermediate DC capacitor. RSC controlling is to build DFIG stator voltage which is also the bus voltage of stand-alone systems; LSC controlling is to build intermediate DC voltage. Owing to the frequently unbalanced loads, this thesis detailed analyzed the impact of unbalanced loads on the system, and discussed the system control strategy in this case, and then proposed that the ultimate control purpose is to build balanced three-phase stator voltage. For the protection of DFIG, this thesis employs the strategy that use LSC to compensate negative sequence component of current. Additionally, it make use of PI-Resonant controller to control positive and negative sequence component simultaneously at the forward rotating coordinate system. Taking account of the redundancy of current sensor which brings adversely affect on system’s economy and stability, this thesis proposed a strategy with reduced current sensors. This strategy can avoid load current sampling and reach the same control effect. At last, it was verified effective and feasible through simulation and experiment.更多还原