1、摘 要-I-摘 要风能作为可再生能源，受到了世界各国的关注。风力发电成为近年来发展最快的能源，在电网中的比重越来越大。交流励磁双馈电机变速恒频风力发电技术被认为是最有前景的风电技术方案之一，对此，本文从理论与实践上进行了深入全面的研究。本文建立了双馈电机在三相静止坐标系和同步旋转坐标系里的数学模型，推导并分析了双馈电机定转子之间的功率传递关系(有功功率和无功功率)。在此基础上，研究了双馈电机电网电压定向矢量控制策略，针对转子位置初始误差造成的转子电流矢量定向偏差降低矢量控制性能的问题，提出了一种补偿控制策略，可以在不需要知道转子初始位置的情况下，实现转子电流矢量的准确定向。结合风电系统并网控制
2、的实际情况，提出了双馈电机分段并网控制策略，给出了各个控制器的一种设计方法，并对各个阶段控制策略的切换问题进行了讨论，避免了因切换容易引起的冲击问题。双 PWM 变换器的控制技术是双馈电机变速恒频风力发电技术的核心，其中，网侧变换器为转子侧变换器提供恒定的直流电压，网侧变换器的控制性能关系到整个系统的稳定问题。为了提高网侧变换器的抗干扰能力，本文基于输入输出的功率平衡关系，提出了一种改进的前馈控制策略，增强了系统对于电网电压幅值变化（三相对称）和负载变化的抗干扰能力。将该控制策略的思想应用于双 PWM 变换器的协调控制，给出了计算电流环 参考的具体办法。LCL 型滤波器在大功率三相电压型 PW
3、M 变换器中应用越来越广泛。本文分析了 LCL 型滤波器在开关频率处各支路电流之间的关系，根据参数选择的约束条件推导出了一个方程组，将滤波器设计的各个约束条件转换为对方程求解的约束条件。提出了一种实用的设计方法，给出了程序式的设计步骤，大大简化了 LCL 型滤波器的设计过程。针对双馈电机风电系统无功功率的给定问题进行了研究。在分析双馈电机风力发电系统功率关系的基础上，提出了考虑网侧变换器无功发生能力时系统无功功率发生极限的计算方法。考虑网侧变换器在其功率允许范围内的无功发生能力，系统动态无功极限为定子与网侧变换器的无功极限之和。在此基础上，对双馈电机风电场无功功率分析及控制策略进行了研究。提出
4、了强电网条件下双馈电机风电场对当地用户进行就近无功补偿的策略，给出了相应的风电场无功功率分配原则。从而使双馈电机风电场在实现风电机组变速恒频优化运行的哈尔滨工业大学工学博士学位论文-II-同时，充分发挥了整个风电场的无功处理能力，参与所连电网的无功调节。最后，对双馈电机高性能的矢量控制以及网侧变换器控制策略进行了实验研究。为此，本文研制开发了以双 PWM 变换器为核心的交流励磁双馈电机变速恒频风力发电系统的实验室模拟平台，对所提出的控制策略作了系统实验研究。该平台以双 DSP 为控制核心，可以实现系统的统一协调控制。关键词 风力发电；变速恒频；双馈电机；交流励磁；双 PWM 变换器Abstra
5、ct-III-AbstractWind energy has drawn worldwide attention for being renewable resource and wind power of today has become the worlds fastest growing energy. Penetration level of wind power into the grid becomes higher and higher. AC excited Doubly Fed Induction Generator (DFIG) Variable Speed and Con
6、stant Frequency (VSCF) wind power scheme is considered as one of the most dominant schemes, on which this paper researches theoretically and experimentally. Mathematical model of DFIG in three-phase stationary coordinate system and synchronous coordinate system were made and power relationship betwe
7、en stator and rotor was analyzed, including active power and reactive power. Furthermore, grid voltage oriented vector control strategy was implemented to control DFIG. In order to compensate initial error of rotor position from the encoder, which may deteriorate performance of vector control, a con
8、troller was proposed and no initial position information is necessary for rotor current vector orientation. Applying the compensation controller to DFIG wind power generation system, stagewise control strategy was proposed for connecting DFIG to the grid. Overall controllers were designed and implem
9、ented and the problem led by switching between different controllers was solved, which makes smooth transition of every stages.Successful control of dual PWM converter is most important for DFIG wind power generation system. As the front-end of dual PWM converter, grid-side converter provides consta
10、nt DC link voltage for the rotor-side converter and makes great contribution to the stability of overall system. An improved feedforward control strategy was proposed based on the power balance between the input and the output. The proposed method can improve the robustness of grid-side converter to
11、 disturbances from both grid voltage amplitude fluctuation (symmetry) and load variation. Applying such a principle to the overall control of dual PWM converter, the method calculating current reference was derived.LCL type filter is commonly used in high power applications as grid interface of thre
12、e-phase voltage source PWM converter. Based on relationship between currents through branches of the filter at switching frequency, a set of equations were got according to the constraints of the filter parameter selection. The design process of 哈尔滨工业大学工学博士学位论文-IV-the filter becomes that of solving
13、the equations. A novel design method was proposed and step-by-step design procedure was given, which makes the task very straightforward.Determination of reactive power reference of DFIG wind power generation system was investigated. A method is proposed to calculate the reactive power limit of the
14、system based on the power relationships of overall system. Considering the reactive power capacity of the grid-side converter, total reactive power includes that of both stator and the converter. Furthermore, reactive power analysis and control of wind farm made up of DFIG wind power generation unit
15、 were studied. A reactive power compensation strategy for the local user using DFIG wind farm was developed and the distribution algorithms of reactive power demand were given. With VSCF optimized operation of each generation unit, DFIG wind farm contributes to the reactive power regulation in the g
16、rid at its full reactive power capacity.Finally, for the purpose of experimental research on high performance vector control of DFIG and control strategy of grid-side converter, a simulation platform of AC excited DFIG VSCF wind power generation system was built, of which dual PWM converter is main
17、part. With Dual DSPs as the heart of the control part, overall control strategy of the converter can be implemented.Keywords wind power; VSCF; DFIG; AC excitation; dual PWM converter目 录-V-目 录摘要 IAbstract III第 1 章 绪 论 11.1 课题的背景 11.2 风力发电技术国外研究现状 31.2.1 风力发电系统常用的拓扑结构 31.2.2 风力发电技术的发展趋势 71.3 风力发电技术国内研
18、究现状 101.4 交流励磁双馈电机变速恒频风力发电相关技术 131.4.1 双馈电机交流励磁用变换器技术 131.4.2 双馈电机交流励磁控制技术 151.4.3 双馈电机风电场的无功功率控制技术 171.4.4 风力发电机组的并网控制技术 181.5 本论文研究的目的和主要内容 20第 2 章 双馈电机矢量控制及并网技术研究 222.1 引言 222.2 双馈电机的数学模型 222.2.1 双馈电机三相静止 abc 坐标系下的数学模型 232.2.2 双馈电机同步旋转 dq 坐标系下的数学模型 252.3 交流励磁双馈电机的变速恒频运行原理 262.4 双馈电机功率传递关系 262.4.1
19、 双馈电机定转子有功功率传递关系 262.4.2 双馈电机定转子无功功率传递关系 282.5 交流励磁双馈电机电网电压定向矢量控制 302.6 双馈电机转子位置初始误差的补偿策略 312.6.1 转子位置初始误差的定义 312.6.2 误差补偿控制器的提出 322.6.3 补偿原理 332.7 交流励磁双馈电机分阶段并网控制策略研究 34哈尔滨工业大学工学博士学位论文-VI-2.7.1 转子位置初始误差的补偿阶段 352.7.2 定子电压的建立阶段 352.7.3 双馈电机的并网阶段 362.7.4 控制策略切换问题 372.7.5 实验结果 372.8 本章小结 40第 3 章 双馈电机交流
20、励磁用双 PWM 变换技术研究 413.1 引言 413.2 网侧变换器的数学模型 413.2.1 采用开关函数描述的数学模型 413.2.2 采用占空比描述的数学模型 433.2.3 同步旋转 dq 坐标系下网侧变换器的数学模型 443.3 稳态条件下网侧变换器交流侧的矢量关系 483.4 网侧变换器控制策略研究 503.4.1 网侧变换器电网电压定向矢量控制 503.4.2 电流环控制器的设计 503.5 提高网侧变换器抗扰动性能的研究 543.5.1 传统的前馈双闭环控制 543.5.2 改进的前馈控制策略 553.5.3 实验结果 563.6 双 PWM 变换器的协调控制 593.7
21、本章小结 59第 4 章 双馈电机风电场无功功率分析及控制研究 604.1 引言 604.2 双馈电机风电场的功率分析 614.2.1 双馈电机风力发电系统的功率关系 614.2.2 双馈电机风电场的功率关系 634.3 双馈电机风电场无功功率极限的分析 634.3.1 双馈电机风电系统的无功功率极限 634.3.2 风电场无功功率极限 664.4 双馈电机风电场无功功率控制策略 664.4.1 控制方案 664.4.2 无功功率的分配问题 68目 录-VII-4.5 风电场无功功率控制策略的仿真研究 694.5.1 仿真算例及模型建立 694.5.2 仿真结果 694.6 本章小结 72第
22、5 章 双馈电机风力发电实验室平台及系统实验 735.1 引言 735.2 交流励磁双馈电机风力发电系统模拟平台 735.3 驱动电路设计 745.4 网侧变换器 LCL 型滤波器的设计 765.4.1 设计原则 775.4.2 设计实例及实验结果 835.5 转子侧变换器输出滤波器的设计 855.5.1 滤波器的拓扑结构及参数设计 865.5.2 设计实例及实验结果 885.6 系统实验结果及分析 905.6.1 稳态实验结果及分析 905.6.2 系统动态实验及结果分析 935.7 本章小结 95结论 96参考文献 98攻读博士学位期间所发表的论文 107哈尔滨工业大学博士学位论文原创性声
23、明 108哈尔滨工业大学博士学位论文使用授权书 108致谢 109个人简历 110哈尔滨工业大学工学博士学位论文-VIII-ContentsAbstract (Chinese)IAbstract (English)IIIChapter 1 Introduction 11.1 Research Background11.2 Inernational Research Status of Wind Power31.2.1 Generally Used Wind Power Schemes31.2.2 Wind Power Technology Trends71.3 Domestic Researc
24、h Status of Wind Power101.4 Related Technology of AC Exicted DFIG VSCF Wind Power Scheme131.4.1 Converters for AC Exictation of DFIG 131.4.2 AC Excitation Technology of DFIG151.4.3 Reactive Power Control Strategy of DFIG Wind Farm171.4.4 Grid Connection Control of Wind Power Generator181.5 Purpose a
25、nd Main Contents of Research20Chapter 2 Research onVector Control and Grid Connection of DFIG222.1 Introduction222.2 Mathmatical Model of DFIG222.2.1 Mathmatical Model of DFIG in 3-phase abc Stationary Frame 232.2.2 Mathmatical Model of DFIG in Synchronous Frame252.3 VSCF Operation Principle of DFIG 262.4 Internal Power Transfer of DFIG 262.4.1 Actice PowerTransfer between Stator and Rotor
