【作者】 郭家虎；

【导师】 龚幼民；

【作者基本信息】 上海大学 ， 电力电子与电力传动， 2008， 博士

【摘要】 由于能源危机和环境恶化问题的日益严重,风能作为最重要的替代能源之一引起了越来越多的重视,风力发电技术在世界范围内得到了巨大的发展。随着电力电子器件制造与应用技术的进步,由交流励磁双馈风力发电机构成的大型变速恒频风力发电机组已经成为目前风电开发的主流机型,它突破了传统机电系统必须严格同步运行的传统观念,变机电系统之间的刚性连接为柔性连接,而且和转子绕组相连的交流励磁电流仅需处理双馈发电机的转差功率,使得变频器的容量变小,成为目前国际上风力发电方面的研究热点和必然的发展趋势。本文以双馈风力发电系统为研究对象,基于非线性控制理论从系统集成的角度对其构成及相关的控制技术进行了详细地研究。首先针对目前对双馈风力发电系统的控制均是采用分离控制技术,未考虑双馈发电机,网侧变换器以及转子侧变换器之间的关联,从而无法获得高性能控制这一缺点,本文从整体出发、以系统的眼光将网侧变换器,转子侧变换器,电网以及双馈发电机内部运行机制有机地结合起来,从电力电子装置与电机系统集成的角度建立了变速恒频双馈风力发电系统的统一数学模型,并在此模型基础上详细分析了双馈发电机系统的功率特性,确定了双馈风力发电系统的有功功率和无功功率的运行边界。为了最大限度地利用风能,微风发电技术引起了越来越多的注意,而其关键技术之一就是要降低风电机组的损耗,所以本文还研究和分析了双馈风力发电系统的损耗问题,并就如何降低损耗提出了一些解决方案。为了克服目前广泛研究和使用的双馈风力发电机基于近似线性化模型的分离控制方法动态性能较差,抗干扰能力弱的缺点,本文从一般非线性系统的相对阶的定义出发,基于双馈风力发电系统的统一模型,使用非线性控制理论将双馈发电系统进行精确线性化解耦,实现了对双馈发电机的高性能解耦控制,提出了双馈风力发电系统的逆系统内模控制策略,详细分析了在此控制策略下,系统的稳定性,抗扰性以及鲁棒性,并在MATLAB\SIMULINK平台下作了详细的仿真研究。然后根据并网型双馈发电系统的特殊工况,讨论了逆系统内模控制算法可能的简化形式。设计并构建了一套由风力机模拟系统,双馈风力发电系统,风电机组主控制器以及虚拟仪器系统等四大部分组成的完整的160KW的变速恒频双馈风力发电系统的实验平台。并在该实验平台上进行了风场模拟,风力机模拟,最大功率跟踪,空载并网控制,双馈风力发电系统逆系统内模控制的实验研究。仿真和实验结果都验证了该控制策略的有效性及先进性。根据双馈风力发电系统的统一数学模型,采用数学和仿真分析两种方法详细地研究了双馈风力发电系统在电网对称故障和不对称故障时的动态响应特性,以及电网故障恢复时间对双馈风力发电系统的动态特性的影响。在上述研究内容的基础上,从双馈风力发电系统在电网故障穿越的基本要求出发提出了一种新的双馈风力发电系统电网故障穿越技术,这种控制技术基于考虑正序和负序分量的双馈风力发电系统的统一动态模型,控制发电机转子电流及其产生的磁场抵消定子磁场暂态直流分量与负序分量对转子侧的影响。仿真结果表明,该故障穿越技术适合于各种电网故障状态下的双馈风力发电组的不脱网运行,暂态冲击小,响应速度快,有利于提高电网电压及频率的稳定性。更多还原

【Abstract】 Due to the crisis of energy and the environmental pollution, clean and renewable energy resources are attracting more and more interesting, especially wind energy. With the great development in manufacture of power electronic converter and its application technology, the variable speed wind turbine with doubly-fed induction generator(DFlG) has turned into mainstream machine in the field of exploring wind energy in the world now, it only deal with the slip power of DFIG and can flexibly join wind turbine to power system, It is important to study the technology, operation characteristics, safety and stability in an electric power system with the type wind turbine. In this dissertation, the AC excitation control law is studied for wind energy generation system with DFIG.At presence, the control scheme of DFIG is to control the grid side converter and machine side converter independently; it can not obtain the good dynamic performance because of separating physical relation between the DFIG and converter. To avoid the defection, the unified model is founded, which consider the DFIG, grid side converter and machine converter as the all and the one, and take their affection each other into account. Base on the unified model of DFIG system, the power characteristic is analyzed in detail, and make sure the active and reactive power limit of DFIG system. To compare the energy efficiency with other types wind turbine, the loss including the converter and DFIG is analyzed too.Because the control law of DFIG which based on the simply dynamic model has not good dynamic performance, and anti-jamming ability, multi-variable nonlinear control law is studied. The inverse system theory is used to design the decoupled control of active and reactive power of DFIG system. With the pseudo linear system obtained by state feedback, the internal model control is developed to construct the decoupled control system to increase the robustness. The control system is modeled on MATLAB/SIMULIND, and the simulation shows its availability and good performance. According to special state of DFIG, the simply law based on inverse system theory is studied too.A 160kW VSCF wind energy generation system with DFIG and back to back PWM converter is designed and established, which consists of a laboratory emulation of wind turbine, DFIG system, the control system of wind generation system and a virtual instrumental system based on Labview. Systematic experimental study of VSCF generation operation has been carried out on this laboratory platform, such as DFIG output active and reactive power decoupled control, grid-connection control, the maxim wind power capture operation and control law of DFIG system based on inverse system theory. The experimental results testify the validity of the strategy proposed by this dissertation.The behavior of DFIG system during and after grid fault such as symmetrical fault, single-line-to-ground fault, two-line-to-ground fault, and line-to-line fault is investigated combined with the analytic and simulation analysis. Based on the deeply understanding of the DFIG system transient under grid fault, a dynamic model with separated positive and negative sequence is developed, and proposed a novel control of DFIG system under the grid fault, which controlled the rotor voltage to counteract the effect of the harmful components in the stator flux, at the same time the stator side resistance is used to weaken the harmful stator flux field. The validity work has been done by system simulations.更多还原