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.     

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.     

变速风力发电机组最大风能追踪与桨距控制

针对变速变桨风力发电机组(Variable Speed Variable Pitch,VSVP)如何在低风速时最大限度捕获风能以及在额定风速以上稳定输出功率进行研究。低风速时在传统风能追踪控制策略的基础上,提出通过改变最优增益系数来追踪最佳风能利用系数的自适应转矩控制策略。在额定风速以上,依据风机空气动力学原理、风轮扫及面内风速风切特性,提出基于桨叶方位角信号的独立变桨距控制策略。该策略通过权系数将统一变化的桨距角转化为3桨叶独立变化的桨距角。以国产某2 MW风力发电机组为验证对象,基于Bladed软件平台对所采用的控制策略进行仿真验证。结果表明,相对传统控制,所提出的控制策略在低风速时能够更好的追踪最大功率点。额定风速以上时,使风力发电机组能够在额定转速下保持稳定的电功率输出。     

风电机组变桨距模糊遗传控制算法研究

为提高额定风速以上风力发电机组发电机转速和输出功率的稳定性,基于风电机组的运行特性,建立了风电机组变桨距控制仿真模型;针对遗传算法收敛速度慢的缺点,采用模糊遗传算法对PID控制器参数进行整定。仿真结果表明,基于模糊遗传的控制器不仅提高了遗传算法的收敛速度,且在动态性能及系统稳定性方面均优于遗传算法控制器。     

大型风力发电机组控制器优化设计

风力发电机组是复杂多变量非线性系统,具有不确定性和多干扰等特点.目前国内应用的风力发电机组大多采用变桨变速恒频系统,具有风能利用系数高、安全可靠、改善整机受力等优点,然而依然面临载荷过大、功率波动大和变桨过于频繁等问题,因此,在大型风力发电机组系统中,选择最适合控制策略的控制器的优化设计就显得尤为重要.在此提出基于模糊性能评估器的控制方法,建立非线性控制模型并设计模糊控制器,介绍了控制器的优化设计步骤,仿真结果表明了这种方法的有效性.     

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。     

风电机组电动变桨距控制系统的优化研究

由于风速的随机性、不稳定性及气动效应的影响,使得风力发电机组变桨距控制系统具有非线性、参数时变性、强耦合等特点,难于实现高精度控制,导致风电机组输出电能质量较差。为了改善系统在恒功率输出运行区域内的动态性能,分析了风电机组变桨距控制系统的现状,建立了整个风电机组模型,提出了优化的变桨距控制策略,并设计了基于模糊控制的变桨距控制器。仿真结果表明,独立变桨距控制技术的控制效果比统一变桨距好,实现了风力机各叶片的优化独立变桨距控制,优化了风力发电系统在超过额定风速时的恒功率控制,具有抗干扰能力强、控制精度高的特点。     

Intelligent maximum power tracking control of a PMSG wind energy conversion system

A comparative control study for a maximum power tracking strategy of variable speed wind turbine is provided. The system consists of a direct drive permanent magnet synchronous generator (PMSG) and an uncontrolled rectifier followed by a DC/DC switch‐mode step down converter connected to a DC load. The buck converter is used to catch the maximum power from the wind by generating an efficient duty cycle. Distinct Maximum Power Point Tracking (MPPT) algorithms are analyzed and compared: a classical Proportional‐Integral controller (PI) and two based Fuzzy Logic Controllers (FLC), including a conventional Fuzzy‐PI and an Adaptive FLC‐PI. The main aim of the presented study is to develop an advanced control scheme for wind generators to ensure a high level operating of the system and a maximum power extraction from the wind. This is achieved by analyzing the behavior of the system under fluctuating wind conditions employing Matlab Simpower Systems tool. Simulation results confirm that the Adaptive FLC‐PI controller algorithm has better performances in terms of dynamic response and efficiency especially in comparison with the ones of a PI controller under variable wind speed.     

Intelligent control for large-scale variable speed variable pitch wind turbines

Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances. Automatic control is crucial for the efficiency and reliability of wind turbines. On the basis of simplified and proper model of variable speed variable pitch wind turbines, the effective wind speed is estimated using extended Kalman filter. Intelligent control schemes proposed in the paper mchde two loops which operate in synchronism with each other. At below-rated wind speed, the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture. At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power. The simulation shows the effectiveness of the intelligent control.     

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.     

Adaptive back-stepping pitch angle control for wind turbine based on a new electro-hydraulic pitch system

A new electro-hydraulic pitch system is proposed to smooth the output power and drive-train torque fluctuations for wind turbine. This new pitch system employs a servo-valve-controlled hydraulic motor to enhance pitch control performances. This pitch system is represented by a state-space model with parametric uncertainties and nonlinearities. An adaptive back-stepping pitch angle controller is synthesised based on this state-space model to accurately achieve the desired pitch angle control regardless of such uncertainties and nonlinearities. This pitch angle controller includes a back-stepping procedure and an adaption law to deal with such uncertainties and nonlinearities and hence to improve the final pitch control performances. The proposed pitch system and the designed pitch angle controller have been validated for achievable and efficient power and torque regulation performances by comparative experimental results under various operating conditions.     

Optimal gain scheduling controller design of a pitch-controlled VS-WECS using DE optimization algorithm

This paper presents an optimal gain scheduling power controller for a variable-pitch variable-speed wind energy conversion system (VS-WECS). For this purpose a set of linear quadratic Gaussian (LQG) controllers are optimally designed using differential evolution (DE) optimization algorithm. These controllers are then used to form a gain scheduling controller (GSC), aiming to regulate the pitch angle and generator electromagnetic torque, and thus, controlling the VS-WECS output electrical power as well as the shaft speed in the above-rated wind speeds. The designed controller for this multi-input multi-output (MIMO) system also reduces destructive mechanical loads on the rotating parts of the wind turbine, while ensuring fast and accurate regulation of the system's variables within their operational constraints. Simulation results on a VS-WECS subjected to a realistic wind model are provided using MATLAB/SIMULINK, which are compared with those of conventional point design controllers. Results indicate that in addition to being robust against parametric uncertainties, the proposed GSC provides enhanced transient and steady-state performance, as well as reduced mechanical loads in a wide range of above-rated wind speed and turbulence variations.     

基于云模型的变桨距系统积分滑模控制

针对具有参数变化和外加干扰的变桨距风力发电系统,提出了一种基于云模型的积分滑模控制。在滑模控制中引入误差项的积分,并用状态量代替误差的导数,消除传统滑模控制需要期望输出信号导数已知的假设;利用云模型的不确定性推理方法,动态地调节切换增益;利用积分的方法对切换增益进行估计,估计出系统中不确定因素的界,有效地削弱系统的抖振。仿真结果表明:该控制器用于风速高于额定风速以上的变桨距控制系统中,具有较好的控制品质,对系统参数的不确定和外部干扰具有很强的鲁棒性。     

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。     

基于二阶滑模控制的变速双馈风力发电系统最大功率点跟踪

本文提出一种超螺旋二阶滑模控制方案同时实现双馈变速风力发电系统最大风能捕获和无功功率调节.通过设计两个二阶滑模控制器,实现控制目标,降低机械磨损,提高控制精度,通过调节发电机转子电压,跟踪风机最优转速和转子电流设定值,实现额定风速以下的最大风能捕获和无功功率调节.采用二次型李雅普诺夫函数确定控制参数范围、确保系统有限时间稳定性.1.5 MW风机系统仿真实验验证所提方案有效性.     

Adaptive Continuous Neural Pitch Angle Control for Variable‐Speed Wind Turbines

As wind energy becomes one of the fastest growing renewable energy resources, the control of large‐scale wind turbines remains a challenging task due to its system model nonlinearities and high external uncertainties. In this paper, an adaptive neural pitch angle control strategy is proposed for the variable‐speed wind turbines (VSWT) operating in pitch control region. The control objective is to maintain the rotor speed and generator power at the prescribed reference values in the presence of external disturbance, without the need of the information of system parameters and aerodynamics. First, the order of the system dynamics is increased by defining a filtered regulation error. By this means, the non‐affine characteristics of the VSWT model is transformed into a simple affine control problem and thus the feedback linearization technique can be employed. The continuousness of control signal is also guaranteed to relax the requirement on the bandwidth of actuators, and the mechanical load on pitching systems is reduced. Subsequently, an online learning approximator (OLA) is utilized to estimate the unknown nonlinear aerodynamics of the wind turbine and extend the practicability of the proposed adaptive parameter‐free controller. In addition, a high‐gain observer is implemented to obtain an estimation of rotor acceleration, which rejects the need of additional sensors. Rigid theoretical analysis guarantees the tracking of rotor speed/generator power and the boundedness of all other signals of the closed‐loop system. Finally, the effectiveness of the proposed scheme is testified via the Wind Turbine Blockset simulation package in Matlab/Simulink environment. Moreover, comparison results reveal that the introduced solution is able to provide better regulation performance than the conventional PI counterpart.     

变转速风力机额定风速以上的非线性控制 ——恒功率输出控制问题

讨论了额定风速以上时变转速风力机的控制问题,系统采用基于微分几何理论下的浆距角和触发角双输入控制,变转 速风机是一个带有大范围风速的多输入产多输出 非线性系统,通过坐标变换,使非线性系统转化为一个标准的线性系统。     

Multi-model predictive control for wind turbine operation under meandering wake of upstream turbines

In wind farm operation, the performance and loads of downstream turbines are heavily influenced by the wake of the upstream turbines. Furthermore, the actual wake is more challenging due to the dynamic phenomenon of wake meandering, i.e. the turbine wake often demonstrates dynamic shift over time. To deal with the time-varying characteristics of wake meandering, a multiple model predictive control (MMPC) scheme is applied to the individual pitch control (IPC) based load reduction. The coherence function in the spectral method is used to generate the stochastic wind profile including wake meandering at upstream turbine, and a simplified wake meandering model is developed to emulate the trajectory of the wake center at downstream turbine. The Larsen wake model and Gaussian distribution of wake deficit are applied for composing wind profiles across the rotor of downstream turbines. A set of MMPC controllers are designed based on different linearized state-space models, and are applied in a smooth switching manner. Simulation results show significant reduction in the variation of both rotor speed and blade-root flapwise bending moment using the MMPC based IPC by including the wake meandering, as compared to a benchmark PI controller designed by NREL.     

Robust nonlinear control strategy to maximize energy capture in a variable speed wind turbine with an internal induction generator

This paper proposes a control strategy to maximize the wind energy captured in a variable speed wind turbine,with an internal induction generator,at low to medium wind speeds.The proposed strategy cont...     

MW级风电系统的变桨距控制及载荷优化

针对风速的随机性及不确定性的特性,以及大型变速变桨风电机组(Variable Speed Variable Pitch Wind Turbine,VSVP)在桨距控制过程中,由于其大转动惯量造成发电机转速响应延迟的问题,提出了一种基于卡尔曼滤波算法的风轮气动转矩观测器,并将气动转矩与参考转矩偏差作为控制器输入以及时响应外界风速变化.针对变桨过程中普遍存在的塔架前后振动和传动链扭转振动问题,提出了通过在原有控制策略的基础上采用加速度反馈和阻尼滤波的方式得到附加桨距角和转矩,从而抑制振动的控制方式.利用Bladed编制了外部控制嚣对某2MW风力发电机组进行仿真,验证了该算法的可靠性,将所提出的控制策略应用于MW级风力发电机组,能够改善桨距控制的动态特性,并有效降低关键部位疲劳载荷.