基于T-S型模糊加权的多模软切换的风电机组变桨控制

变桨控制是确保风电机组在额定风速以上恒功率运行的一种有效的控制方式。变桨控制执行机构的动作频繁且幅度较大,增加了风电机组各部分的机械疲劳载荷,影响发电机的输出电能质量和机组的使用寿命;现有的切换控制方法多数只在某一阈值进行切换,导致切换振荡。针对上述问题,提出了基于T-S型模糊加权的多模软切换变桨控制策略,该方法将智能控制与传统控制相结合,根据风电机组发电机的实时转速与其额定转速的偏差及其变化率,利用T-S型模糊推理,完成基于模糊控制、模糊自适应PID控制和PI控制的多模控制器输出的平滑过渡,实现软切换,其优点是兼顾3种控制方法的优势,解决了切换振荡问题。搭建了永磁直驱风力发电机组变桨的多模软切换控制的仿真模型。仿真结果表明,此方法展现了3种控制方法的优点,克服了切换振荡,减缓了执行机构的频繁动作,使桨距角调节更加平滑,输出功率精度更高,脉动更小。     

Control of variable speed wind turbines: Design task

Owing to concern over the environment, there is much interest in renewable sources of electrical power generation, of which one of the most promising is wind power. There are essentially two types of wind turbines, namely constant speed and variable speed machines. In comparison to constant speed wind turbines, variable speed wind turbines are perceived to have several potential advantages which outweigh the considerable cost of the power electronics required to realize variable speed operation. The two frequently mentioned ones are: additional energy capture below rated wind speed and additional power-train compliance and associated load alleviation above rated wind speed. The purpose of this paper is to investigate the design of the control system (as opposed to the synthesis of the controller) for variable speed wind turbines. The choice of control strategy is investigated and appropriate realizations of the controller, to cater for the implementation issues of accommodation of variation in the plant dynamics over the operational envelope and switching transients, are identified. A thorough investigation of the dynamics and control of both stall regulated and pitch regulated variable speed machines is undertaken.     

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.     

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。     

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.     

编码器原理及其在风电控制系统中的应用

本文主要讨论增量式和绝对式旋转光电编码器如何在风电控制系统中准确测量变桨电机转子旋转速度和位置。以及双馈发电机转子转速的精确测量,实现对桨叶角度控制和双馈发电机的伺服控制。     

Asymptotic Tracking Control for Wind Turbines in Variable Speed Mode

This paper presents a variable speed control strategy for wind turbines in order to capture maximum wind power. Wind turbines are modeled as a two-mass drive-train system with generator torque control. Based on the obtained wind turbine model, variable speed control schemes are developed. Nonlinear tracking controllers are designed to achieve asymptotic tracking for a prescribed rotor speed reference signal so as to yield maximum wind power capture. Due to the difficulty of torsional angle measurement, an observer-based control scheme that uses only rotor speed information is further developed for global asymptotic output tracking. The effectiveness of the proposed control methods is illustrated by simulation results.      

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.     

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...     

并网运行的直驱风力发电系统建模及仿真研究

在PSCAD/EMTDC中建立了包含风速、风力机、直驱同步发电机、轴系扭振模块、变流器及其控制部分的并网直驱风力发电系统模型,提出了基于最大风能跟踪控制结合变桨距控制的策略,研究了在变风速输入和网侧出现单相短路故障时直驱型风力发电系统的动态响应特性,仿真结果表明了并网直驱风力发电系统模型及其控制策略的正确性和可行性。     

Adaptive backstepping control of variable speed wind turbines

Variable speed wind turbines maximize the energy capture by operating the turbine at the peak of the power coefficient, however parametric uncertainties in mechanical and electrical dynamics of the system may limit the efficiency of the turbine. In this study, we present an adaptive backstepping approach for the variable speed control of wind turbines. Specifically, to overcome the undesirable effects of parametric uncertainties, a desired compensation adaptation law (DCAL) based controller has been proposed. The proposed method achieves global asymptotic rotor speed tracking, despite the parametric uncertainty on both mechanical and electrical subsystems. Extensive simulation studies are presented to illustrate the feasibility and efficiency of the method proposed.     

Optimization of variable speed wind power systems based on a LQG approach

This paper focuses on a control application of optimization in wind power systems. An optimal control structure for variable speed fixed pitch wind turbines is presented. The optimality of the whole system is defined by the trade-off between the energy conversion maximization and the control input minimization that determines the mechanical stress of the drive train. The frequency separation of the short-term and the long-term variations, adopted in the wind modelling, has resulted in a two-loop control structure. The optimal problem is treated within a complete linear quadratic stochastic approach, whose effectiveness was tested on an electromechanical wind turbine simulator.     

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。     

An observer-based blade-pitch controller of wind turbines in high wind speeds

The paper focuses on variable-rotor-speed/variable-blade-pitch wind turbines operating in the region of high wind speeds, where blade pitch and generator torque controllers are aimed at limiting the turbine's energy capture to the rated power value. Coupled design is described of an observer-based blade-pitch control input and a generator torque controller, both of which not requiring the availability of wind speed measurements. Closed loop convergence of the overall control system is proved. The proposed control solution has been validated on a 5-MW three-blade wind turbine using the National Renewable Energy Laboratory (NREL) wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code.     

Control of variable speed wind turbines: Dynamic models

Owing to concern over the environment, there is much interest in renewable sources of electrical power generation, of which one of the most promising is wind power. Wind turbines exploit this energy source to directly generate electrical power. There are essentially two types of windturbines, namely constant speed and variable speed machines. The purpose of this paper is to investigate the dynamics of variable speed wind turbines and determine suitable models to support the control design task. A basic but widely used dynamic representation of variable speed wind turbines and the corresponding models of the control plant dynamics are initially discussed. More detailed, yet still simple models, are derived separately for the rotor aerodynamics, the drive-train dynamics and the power generation unit dynamics before being combined to form the complete model of the wind turbine dynamics. The resulting combined model, in addition to supporting the control design task, enables the extent, to which the basic models adequate represent the wind turbine, to be assessed. It is concluded that the basic models of variable speed wind turbines are not adequate and do not exhibit all the relevant aspects of the dynamics necessary to support the control design.     

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.     

Dynamic performance improvement of an isolated wind turbine induction generator

A dynamic model of a variable speed stand alone wind generation system is developed. The transient performance of the system under variable wind gust and other disturbance conditions has been studied. It has been observed that a stand alone generator is very vulnerable to transient disturbances in the system. A variable susceptance excitation control system, installed at the generator terminal, has been shown to improve the dynamic performance of the system following transient disturbances. Additional pole-placement based PI and PID controllers in the excitation control circuit are shown to control the violently oscillating and even growing transients very effectively. The robustness of the proposed controller has been tested for various disturbances and also for a range of operation.     

变桨距风力机特性模拟

变桨距风力机在不同风速下具有不同的运行状态和输入输出关系.文章根据空气动力学理论研究了风力机静动态特性;探讨了不同风速下,变桨距风力机的控制方案及运行状态;根据变桨距风力机不同的运行状态,设计了发电机特性和桨距角控制方案;在matlab/simulink环境下,建立了适应变桨距风力机全状态的模拟系统;在匀速风、阵风、渐...     

基于改进差分算法的变桨ADRC参数优化

自抗扰控制器是一类不依赖被控对象数学模型且具有较强鲁棒性及抗干扰能力的非线性控制器,已成功应用于风力发电机变桨距控制这一多变量、强耦合的非线性系统中,但自抗扰控制器也存在参数众多整定难度大这一明显缺点。现提出了通过智能算法来实现参数的自动整定。分析了改进差分进化算法的原理及步骤,并将改进差分进化算法应用到ADRC的整定过程中,实现参数的自动整定。仿真结果验证了通过改进差分进化算法自动整定ADRC参数的可行性,与传统PID控制器相比,改进差分进化算法整定后的ADRC能较好的满足风力发电机变桨控制要求,有效维持了风力发电机组输出功率的稳定性。     

Passivity-based control for variable speed constant frequency operation of a DFIG wind turbine

A standard passivity based control for a double fed induction generator of a wind turbine is presented. The control problem is posed as a variable speed constant frequency operation with the aim to maximise the generated electric power. The controller is designed in such a way that the dual control objective, unity power factor in the stator side and speed tracking in the mechanical port, are satisfied guaranteeing internal stability. The proposed scheme is the first attempt to approach the speed tracking operation from the energy dissipation (passivity) perspective. Simulation results show good performance of the control scheme for wind speeds in different operating regimes.