基于双PWM变换器并网的双馈式风电系统谐波研究

发布时间：2018-03-29 20:19

本文选题：双PWM变换器　切入点：双馈感应发电机　出处：《西南交通大学》2017年硕士论文

【摘要】：基于双馈感应发电机(Doubly Fed Induction Generators,DFIG)的双馈风电机组是我国当前风电市场的主流发电设备。背靠背式双PWM变换器作为双馈风电系统中应用最为广泛的交流励磁变换器,是实现双馈风机转子侧和电网之间频率转换的装置,同时也是系统中最主要的谐波源。随着国内外风电产业的迅猛发展以及风电机组装机容量的不断增加,风电谐波标准不断提高,研究基于双PWM变换器并网的双馈式风电系统谐波问题具有十分重要的理论指导意义。论文结合风电发展现状及特点,分别对风电系统和电力电子变换器的谐波研究现状进行了全面的综述,并分析了现有研究的特点及存在的不足。论文指出目前对双馈风电系统谐波产生机理的研究还相当匮乏,有必要建立具有针对性的谐波研究体系。论文首先分析并研究了电网电压三相平衡状态下双馈风电系统的谐波产生机理。考虑背靠背式双PWM变换器结构及调制方式的特点,基于功率平衡理论,对其直流侧和网侧低频谐波进行分析,并运用双重傅里叶变换算法,实现转子电流的高频谐波建模。在网压平衡谐波研究的基础上,论文进一步分析了网压不平衡下风电系统的谐波产生机理。采用对称分量法和空间坐标变换,对网压、网流进行建模;结合变换器功率平衡理论和迭代递推法,推导得到变换器网侧、直流侧以及风机转子侧、定子侧低频谐波的解析表达式;基于双重傅里叶变换算法,建立变换器闭环传递函数的数学模型,结合迭代递推法,实现变换器网侧、直流侧以及风机转子侧的高频谐波建模。最后,论文采用RTDS实时数字仿真平台,搭建了基于背靠背式双PWM变换器并网的双馈风电系统仿真模型,获取了电网电压三相平衡和不平衡状态下的谐波数据,并对谐波数据进行了频谱仿真。仿真结果与理论分析结果近乎完全吻合,由此验证了理论分析的准确性和可信性。
[Abstract]:Doubly-fed wind turbine based on doubly-fed Fed Induction generator generator is the mainstream equipment in wind power market in China. Back-to-back double PWM converter is the most widely used AC excitation converter in doubly-fed wind power system. It is a device to realize the frequency conversion between the rotor side of a doubly-fed fan and the power grid, and it is also the main harmonic source in the system. With the rapid development of wind power industry at home and abroad and the increasing installed capacity of wind turbine, Since the harmonic standard of wind power is improving continuously, it is of great theoretical significance to study the harmonic problem of double-fed wind power system based on grid-connected double PWM converters. The harmonic research status of wind power system and power electronic converter is summarized, and the characteristics and shortcomings of the existing research are analyzed. It is pointed out that the research on harmonic generation mechanism of doubly-fed wind power system is still scarce. It is necessary to establish a targeted harmonic research system. Firstly, the harmonic generation mechanism of doubly-fed wind power system under three-phase voltage balance is analyzed and studied. The characteristics of back-to-back double PWM converter and modulation mode are considered. Based on the theory of power balance, the low frequency harmonics of DC side and grid side are analyzed, and the high frequency harmonic modeling of rotor current is realized by using double Fourier transform algorithm. In this paper, the harmonic generation mechanism of wind power system under unbalanced grid voltage is further analyzed. The symmetrical component method and spatial coordinate transformation are used to model the network voltage and current, and combined with the power balance theory of the converter and iterative recursive method, the harmonic generation mechanism of wind power system is analyzed. The analytical expressions of low frequency harmonics on the grid side, DC side, rotor side and stator side of the converter are derived, the mathematical model of the closed-loop transfer function of the converter is established based on the dual Fourier transform algorithm, and the iterative recursive method is used to establish the mathematical model of the closed-loop transfer function of the converter. The high frequency harmonic modeling of converter grid side, DC side and fan rotor side is realized. Finally, the simulation model of doubly-fed wind power system based on back-to-back double PWM converter grid-connected is built by using RTDS real-time digital simulation platform. The harmonic data under the condition of three-phase voltage balance and unbalance of power network are obtained, and the harmonic data are simulated in the frequency spectrum. The simulation results are in close agreement with the theoretical analysis results, which verifies the accuracy and credibility of the theoretical analysis.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614;TM711

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