【作者】 陈思哲；

【导师】 吴捷；

【作者基本信息】 华南理工大学 ， 控制理论与控制工程， 2010， 博士

【摘要】 由于化石能源的逐渐枯竭和环境污染的日益严重,开发以风能、太阳能为代表的各类可再生能源,已经成为人类社会实现长期可持续发展的必然选择。在众多可再生能源发电方式中,风力发电是发展最快、最成熟且最适合规模化开发的方式之一。在风力发电领域,目前应用最广泛的是基于双馈感应电机的变速恒频风力发电机组。本文对双馈感应电机在不同工况下的控制技术展开了深入的研究,且取得了具体的创新性成果。首先调研了国际和国内风力发电产业的发展现状和趋势,介绍了目前最主要的几种变速恒频风力发电机组的结构和特点,并对双馈感应风力发电机组的主要控制技术进行了详细的评述。介绍了双馈感应电机变速恒频运行的机理,给出了其在静止坐标系和同步旋转坐标系中的模型,并推导了电网电压不平衡工况下其在正、负序同步旋转坐标系中的正、负序模型,依此作为研究工作的理论基础；在实验室中搭建了双馈感应电机硬件实验平台,为研究工作提供实验基础。考虑到双馈感应电机是一个多变量强耦合系统,以寻求控制效果最佳且最易实现为原则,本文采用相对增益阵列(relative gain array, RGA)方法以选择最合适的输入输出控制关系,在控制算法方面采用滑模变结构控制以提高系统的鲁棒性。具体表现在如下几个方面：提出一种新颖的积分变结构单环直接电压控制方法,用于实现双馈感应电机的并网控制。该方法的创新性主要体现在以下两个方面：采用RGA方法分析双馈感应电机内部各变量之间的相关程度,建立了转子电压对定子电压的直接控制关系,从而消除了转子电流控制环；在控制器设计过程中充分考虑了参数不确定性和外部扰动的影响,从而提高了系统的鲁棒性。仿真和实验结果表明,所提出的控制方法有效实现了双馈感应电机的并网控制,并且对参数误差和外部扰动具有鲁棒性。率先提出电网电压不平衡工况下双馈感应电机的并网控制方法。将并网控制器分解为主控制器和协控制器,主控制器控制正序定子电压跟踪正序电网电压,协控制器控制负序定子电压跟踪负序电网电压。仿真和实验结果表明,所提出的控制方法可有效控制双馈感应电机的定子电压精确跟踪不平衡电网电压。将积分变结构控制与空间矢量调制结合,提出一种开关频率固定的积分变结构直接转矩控制方法。该方法的创新性主要体现在以下三个方面：通过转子电压直接控制双馈感应电机的电磁转矩和无功功率,无需转子电流控制环；在控制器设计过程中充分考虑参数误差的影响,从而提高了系统的鲁棒性；采用固定的开关频率,从而避免了传统直接转矩控制固有的电流畸变问题。仿真和实验结果表明,所提出的控制方法可有效调节双馈感应电机的转矩和无功功率,并且具有良好的参数鲁棒性和输出电能质量。提出电网电压不平衡工况下双馈感应电机的直接转矩控制方法,在独立调节电磁转矩和无功功率的同时,消除不平衡电网电压造成的转矩和功率波动。通过RGA方法建立正、负序转子电压对正、负序转矩和无功功率的直接控制关系,在此基础上分别设计正、负序控制器。与现有电网电压不平衡工况下的控制方法相比,本文提出的方法无需进行转子电流测量、正负序分解和坐标变换,简化了控制器结构。仿真和实验结果表明,所提出的控制方法有效地消除了不平衡电网电压造成的转矩和功率波动。本文的研究工作得到国家自然科学基金重点项目(60534040)和国家863计划项目(2007AA05Z244)的资助,提出的所有控制方法均通过硬件实验验证,为进一步的产业化奠定了基础,也为现代控制理论的工程化和推广应用提供了可借鉴的经验。更多还原

【Abstract】 Because of the gradual depletion of fossil energy resources and the increasingly serious issue of environmental pollution, it has become the inevitable choice to develop renewable energy represented by wind energy and solar energy for the sustainable development of human society. Among many renewable power generation methods, wind power generation is one of the methods which are the most mature and suitable for large-scale development. In the field of wind power generation, the variable-speed-constant-frequency (VSCF) wind turbines based on the doubly-fed induction generator (DFIG) is the most popular kind. In this thesis, the researches about the control technology of the DFIG under different operating conditions are carried out, and some innovative fruits are achieved.The international and domestic development status and trends of wind power generation industry are survey. The structure and characteristics of several kinds of VSCF wind turbines are introduced. Main control technologies about wind turbine based on DFIG are summarized.The VSCF operation principle of the DFIG is introduced.The model of the DFIG in the stationary and synchronous reference frame is described, and the model of the DFIG in the positive and negative sequence synchronous reference frames under unbalanced grid voltage is derived, which is the theoretical basis for the research. A hardware experimental platform is developed in the lab, which provides experimental basis for the research.Because the DFIG is a multi-variable strong coupling system, in order to achieve the best control effect, the relative gain array (RGA) methodology is introduced to choose the most suitable input-output control pairs, and sliding mode variable structure control is introduced to improve the robustness of system. It is specifically manifested in the following aspects:A novel single loop direct voltage control scheme using integral variable structure control is proposed to synchronize the DFIG to the grid. The RGA methodology is used to analysis the degrees of relevance among the variables of the DFIG and develop direct control relationship between rotor voltage and stator voltage, which eliminates the control loop of rotor current. The parametric uncertainty and external disturbances are adequately considered in the design procedure of the controller, which improves the robustness of the system. Both simulation and experimental results show that the proposed control scheme effectively achieves the grid synchronization control of DFIG,and it has satisfied robustness against parametric errors and external disturbances.A grid synchronization control scheme of DFIG under unbalanced grid voltage is firstly proposed. The grid synchronization controller is divided into main controller and auxiliary controller. The main controller is used to control the positive sequence stator voltage to follow the positive sequence grid voltage, while the auxiliary controller is used to control the negative sequence stator voltage to follow the negative sequence grid voltage. Both simulation and experimental results show that the proposed control scheme effectively controls the stator voltage of the DFIG to follow unbalanced grid voltage accurately.An integral variable structure direct torque control scheme of DFIG with constant switching frequency is proposed by combining integral variable structure control with space vector modulation. The torque and reactive power of DFIG are directly controlled by the rotor voltage, which eliminates the control loop of rotor current. The parametric errors are adequately considered in the design procedure of controller, which improves the robustness of the system. The constant switching frequency avoids the inherent current distortion problem in traditional direct torque control. Both simulation and experimental results show that the torque and reactive power of the DFIG can be effectively controlled by the proposed control scheme, and the parametric robustness and generated power quality are satisfied.A direct torque control scheme of DFIG under unbalanced grid voltage is proposed to independently control the torque and reactive power, and simultaneous eliminate torque and power pulsations caused by unbalanced grid voltage. The RGA methodology is used to develop the direct control relationships among the positive and negative sequence rotor voltage and the positive and negative sequence torque and reactive power, based on which positive and negative sequence controllers are designed, respectively. Comparing to existing control schemes under unbalanced grid voltage, the proposed control scheme eliminates the measurement, coordinate transformation and symmetrical component extraction of rotor current, which simplified the controller. Simulation and experimental results shows that the proposed scheme effectively eliminates torque and power pulsations caused by unbalanced grid voltage.This work was supported by the National Natural Science Foundation of China under Grant 60534040 and the National High Technology Research and Development of China under Project 863 Program 2007AA05Z244. All the proposed control schmes are validated on the hardware experimental platform, which establishes basic for further industrialization and provides experience for the engineering applications and extensions of modern control theory.更多还原