额定风速以上风力发电机组的恒功率H∞鲁棒控制

风力发电机组由于机械结构以及电气负荷承受能力的限制存在着转速限制和功率限制, 额定风速以上时,需要通过控制桨距角来实现额定恒功率输出, 同时保持转速在额定转速处. 本文建立了风力发电机组的详细机理模型, 将H_∞控制理论应用到额定风速以上时风力发电机组的恒功率输出的控制器设计, 建立了标准H_∞恒功率控制问题. 利用LMI方法求解, 得到了桨距角的H_∞控制器. 仿真结果表明该H_∞控制器能够成功实现额定风速以上时的恒功率输出控制, 并且具有良好的鲁棒性.     

风力发电系统的恒功率非线性H∞鲁棒控制

风力发电系统传统控制器的缺点在于, 基于某一工况点的局部线性化方法无法实现全局范围的精确控制, 且传统的控制理论无法应对内外干扰. 本文将精确反馈线性化方法与线性H∞理论相结合设计非线性H∞控制器. 首先用微分几何精确线性化方法将非线性风电模型全局线性化, 然后运用线性H∞控制理论对此线性系统设计控制器, 将两者结合有原风电系统的非线性H∞变桨距控制器. 最后对12 m/s至24 m/s阶跃风, 12 m/至22 m/s骤变风, 18 m/s至20 m/s随机风, 以及风力机转动惯量下降10%的情况进行仿真, 能实现风机转速及输出功率的恒定. 验证了该控制器在全风速段的精确控制, 并且具有良好鲁棒性.     

变桨距风力发电机组恒功率反馈线性化控制

在额定风速以上时,为保证风电机组的安全稳定运行,需要降低风力机捕获风能,使风力机的转速及功率维持在额定值,基于微分几何反馈线性化方法,提出变桨距风力发电机组恒功率控制策略.建立了风力机的仿射非线性模型,采用微分几何反馈线性化变换实现全局精确线性化;根据新的线性化模型,以风力机转速为输出反馈变量,叶片桨距角为输入控制变量,设计桨距角控制器;在风速高于额定值时调节风力机维持在额定转速,从而实现额定风速以上的恒功率控制.仿真结果表明,所提控制策略能较好地解决变桨距风力发电机组额定风速以上的恒功率控制问题,控制方法具有较好的适应性和鲁棒性.     

风力发电机组桨距角鲁棒控制器的设计与仿真

在空气动力学原理基础上建立了变浆距风力发电机组非线性数学模型,以此为基础采用基于动态逆的非线性内模控制方法设计了风力发电机组在额定风速以上工作时的桨距角鲁棒控制律,以使输出功率维持在额定值附近。设计是针对风力机的非线性数学模型进行的,克服了基于局域近似线性化模型设计方法的缺点,适应工况点大范围变动的情形,而且对系统参数摄动具有良好的鲁棒性,求解过程相对比较简单。以一台额定功率为300kW的实际风力发电机组为实例进行了对比仿真,结果表明了该方法能够满足控制要求,具有较好的动、静态特性和鲁棒性。     

基于微分几何的风力发电机组恒功率控制

当风速超过额定值时, 可以通过降低风力机的转速实现恒功率控制从而避免使用复杂的变桨距机构, 本文基于微分几何理论设计了非线性控制器, 实现了变速风力发电机组的恒功率控制. 首先, 分析了风力机的空气动力学特性, 这是所提出的恒功率控制方法的理论依据; 然后, 通过微分几何反馈线性化变换, 将风力机的非线性模型全局线性化; 最后, 基于新的线性化模型设计了非线性控制器, 实现了变速风力机的全局精确线性化控制. 仿真结果表明, 所提出的控制方法在风速大范围变化的情况下能有效的实现变速风力发电机组额定风速以上的恒功率控制.     

额定风速以上风切变场中风力发电系统独立变桨鲁棒控制

研究了风切变场中风力发电系统的独立变桨鲁棒控制问题.针对风切变对额定风速以上恒功率控制的影响,设计了一种额定风速以上独立变桨距鲁棒控制器,该控制器由基于自抗扰控制的集中桨距角控制器和基于扰动补偿的独立桨距角控制器叠加而成,其中统一变桨控制器能及时补偿由于风速变化,风力机参数变化导致的系统模型不确定性,并且能有效抑制电磁转矩扰动;独立桨距角控制器能有效抑制风切变引起的转速波动以及叶片拍打方向的机械载荷,对统一变桨信号的频率和幅值变化的鲁棒性较好.理论分析和仿真结果表明了本文所提方法的有效性.     

风电系统的非线性模糊恒功率控制器的设计

研究了风速高于额定值时风电系统的非线性模糊恒功率控制。由物理分析得出风电机组的二阶数学模型,采用微分几何的精确反馈线性化理论,对该二阶模型进行全局线性化,得到适用于全局范围的线性模型。应用模糊控制理论对新的系统写出模糊控制规则,进而得到原系统的恒功率控制器。在MATLAB/Simulink中搭建含该非线性模糊变桨距控制器的风力发电机组模型。对阶跃风和随机风分别进行仿真,均能实现风机转速及输出功率的恒定,由此验证了该控制器在额定风速以上的良好控制。     

大型风力发电机组变桨距控制技术研究

在研究风力发电控制技术中,变桨距控制因其特有的技术特点,常被用在大型风力发电机组中,以保证额定功率点以上输出功率的恒定和机组的安全运行.由于大型风力发电机组的非线性、时变、强耦合等特征,为进一步提高系统的稳定性,用加入单个神经元在线调整模糊控制查询表的变桨距控制算法;并用MATLAB软件对机组控制进行仿真.仿真结果表明,变桨距控制算法具有良好的静、动态特性,能较好地将功率限定在额定值附近.     

国内最大功率风力发电机组在北海市下线

日前,目前国内功率最大的风力发电机组AV928机组在北海市下线,该机组的下线标志着我国拥有自主知识产权的风机技术与世界风机强国的主流技术实现了同步,将对我国风电装备产业及地方经济发展产生重大影响。     

风力发电机组的变论域自适应模糊控制

建立了变速变浆距风力发电机组的简化模型。在此基础上,将变论域自适应模糊控制应用到风力发电机组的转速和浆距控制系统中,改善风力发电机组的风能捕获性能。变论域自适应模糊控制器在保持规则形式不变的前提下。论域随着误差的变化而变化。这种控制器不但具有经典模糊控制的优点,如不需要精确的数学模型,产生非线性控制动作,良好的动态性能等．而且具有较高的控制精度。仿真结果证明该方法改善了风力发电机组的控制性能。     

An LMI approach to robust H-infinity control for uncertain singular time-delay systems

The problem of robust H-infinity control for a class of uncertain singular time-delay systems is studied in this paper. A new approach is proposed to describe the relationship between slow and fast subsystems of singular time- delay systems, based on which, a sufficient condition is presented for a singular time-delay system to be regular, impulse free and stable with an H-infinity performance. The robust H-infinity control problem is solved and an explicit expression of the desired state-feedback control law is also given. The obtained results are formulated in terms of strict linear matrix inequalities （LMIs） involving no decomposition of system matrices. A numerical example is given to show the effectiveness of the proposed method.     

Modelling and control of a wind energy conversion system

The dynamical model of a novel low power wind energy conversion system consisting of a wind turbine, an induction generator, a PWM a.c. inverter and a d.c. battery group is obtained. A feedback control law is developed to provide optimum power conversion and arbitrarily fast responses at steady-state. The feedback does not require measurement of the wind speed and therefore is suitable for real applications. The stability of the closed-loop system is analysed using a Liapunov-type practical stability criterion, and it is shown that the system remains stable for wind speed variations that are not both large and fast at the same time. Digital computer simulation studies on a 1 kVA test system verify the theoretical results.     

Adaptive fault diagnosis and active tolerant control for wind energy conversion system

The fault mathematic model of the transmission part of wind energy conversion system (WECS) is established, and adaptive fault observer is constructed in the presence of unknown disturbance, it can detect the faults of the system, and estimate these faults. Then, based on fault observer, an active tolerant controller is designed to ensure the stability of the transmission part of WECS with fault.The simulation results of different type faults of generator show the effectiveness and feasibility of adaptive fault diagnosis methods.     

Design of robust non-fragile H-infinity controller based on Delta operator theory

Considering that the controller parameters are of additive norm-bounded uncertainties when realized, a design method of robust non-fragile H-infinity controller for uncertain systems based on Delta operator theory is illustrated in this paper. A sufficient and necessary condition of the existence for the controller is given, which is presented in LMI forms. Finally, the designed method is used in the speed control system of a permanent magnet linear synchronous motor （PMLSM）. With the designed controller, the resulting speed closed-loop system is still stable and has the expected Hinfinity performance even if the sample period is reduced and the parameters of the controller and the controlled object are varied. The results show that the designed method is effective.     

Pitch angle control in wind turbines above the rated wind speed by multi-layer perceptron and radial basis function neural networks

In wind energy conversion systems, one of the operational problems is the changeability and discontinuity of wind. In most cases, wind speed can fluctuate rapidly. Hence, quality of produced energy becomes an important problem in wind energy conversion plants. Several control techniques have been applied to improve the quality of power generated from wind turbines. Pitch control is the most efficient and popular power control method, especially for variable-speed wind turbines. It is a useful method for power regulation above the rated wind speed. This paper proposes an artificial neural network-based pitch angle controller for wind turbines. In the simulations, a variable-speed wind turbine is modeled, and its operation is observed by using two types of artificial neural network controllers. These are multi-layer perceptrons with back propagation learning algorithm and radial basis function network. It is shown that the power output was successfully regulated during high wind speed, and as a result overloading or outage of the wind turbine was prevented.     

Delay-dependent H-infinity control for continuous time-delay systems via state feedback

The delay-dependent H-infinity analysis and H-infinity control problems for continuous time-delay systems are studied. By introducing an equality with some free weighting matrices, an improved criterion of delay-dependent stability with H-infinity performance for such systems is presented, and a criterion of existence and some design methods ofdelay-dependent H-infinity controller for such systems are proposed in term of a set of matrix inequalities, which is solved efficiently by an iterative algorithm. Further, the corresponding results for the delay-dependent robust H-infinity analysis and robust H-infinity control problems for continuous time-delay uncertain systems are given. Finally, two numerical examples are given to illustrate the efficiency of the proposed method by comparing with the other existing results.     

具有非线性扰动的广义系统的鲁棒H∞控制

研究具有非线性结构扰动广义系统的鲁棒H∞控制和鲁棒H∞保性能控制问题,该不确定性为时间和状态的函数.且满足Lipschitz条件.目的是分别设计系统的鲁棒H∞控制器和鲁棒H∞保性能控制器.应用线性矩阵不等式方法,分别给出了系统的鲁棒H∞控制器和鲁棒H∞保性能控制器存在的充分条件.当这些条件可解时,分别给出了鲁棒H∞控制器和鲁棒H∞保性能控制器的表达式.最后通过一个仿真算例说明了所给出方法的应用.     

Energy-based approach to the output feedback control of wind energy systems

Wind energy systems can be classified into constant speed and variable speed ones. In constant speed schemes, the generator is directly connected to the electric grid. On the other hand, variable speed operation can be accomplished interposing a static converter in the energy flow between the generator and the grid, permitting a high control flexibility. The main control objectives are the maximization of the conversion efficiency and the elimination of torque oscillations propagated through the drive train. It is assumed in this paper that the most flexible part of the system lies on the turbine, constraining the control solutions to generator speed feedback. The control task is addressed from a passivity-based control viewpoint. The drive train dynamics is modelled as a port-controlled Hamiltonian system with dissipation. Then, stabilization of the desired operating point is achieved through energy shaping and damping injection. Depending on the damping matrix assignment, different control solutions are recovered. Finally, a dynamic feedback controller which preserves the system structure is proposed to improve the system performance without measuring the wind velocity.     

永磁同步发电机风能转换系统滑模控制仿真

针对由于风速的随机波动性而使基于线性定常控制器的风能转换系统稳定性较差的问题,提出了一种基于滑模控制的永磁同步发电机风能转换系统的设计方案;分析了该系统中风力机模型、传动装置模型和永磁同步发电机模型的建立原理,介绍了滑模控制策略的具体实现。仿真结果表明,该系统具有较好的速度跟踪特性,实现了最大风能捕获。