风力发电机组的自适应转矩控制及载荷优化

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降低传动链载荷进行研究。低风速时在研究了传统风能追踪控制策略的基础上,文中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。同时针对风力发电机组传动链的扭转振动,提出了基于发电机转速反馈滤波的转矩纹波控制方式。以2MW变速变桨风力发电机组为验证对象,基于Blade软件平台对所采用的控制策略进行仿真研究。结果表明：所提出的自适应转矩控制策略能够更好的追踪最大功率点,同时采用转矩纹波能够降低传动链载荷     

额定风速附近变速变桨风力发电机组功率优化控制

详细分析导致功率波动和功率损失的原因,提出一种转矩优化控制策略。该转矩优化控制方法结合查表法和非线性PI控制器,在低风速区仅启用查表法以追踪最优功率;额定风速附近及以上时运用非线性PI控制器使转矩输出形成滞环,来抑制额定风速附近的功率波动;采用基于转矩误差及误差变化率的桨距角模糊调节器,实现转矩和变桨控制解耦;给出一种功率平均值限制算法,可抑制阵风时(包括额定风速以下和以上)引起的转速短时过速和功率损失,同时也可减少变桨机构的疲劳载荷。以风力机设计专业软件Bladed为工具,结合C语言编写外部控制器,对风力发电机组转矩及变桨控制策略进行仿真研究,仿真结果表明所提出的优化方案可行。     

风电机组电液比例变桨距技术研究

针对风力机功率控制的重要性,设计了电液比例变桨距执行机构,并结合风力机设计软件Bladed组建成半物理仿真试验台。在此试验台上对提出的分段PID变桨距控制算法以及变速恒频和变桨距切换设定的控制策略进行试验研究。试验结果表明在风速高于额定值时,通过分段PID变桨距控制发电机输出功率稳定性高于常规PID,当风速在额定值左右变化时,变桨距和变速恒频切换正常,满足功率控制和最大风能捕获的要求。     

基于功率灵敏度因子的风力机变速变桨距控制研究

针对大型变速变桨风力机在高风速区的气动性能随桨距角变化而改变的特性,文章提出了一种功率-桨距角变化的灵敏度控制策略。通过设计功率灵敏度因子调节PID变桨距控制器,建立输出功率偏差与风轮转速偏差的闭环系统。将提出的策略应用到某5 MW风机的参数模型中,利用MATLAB平台进行仿真验证。结果表明,提出的控制策略抑制了高风速区的扰动风速对系统的影响,使输出功率和风轮转速保持在额定值附近且波动很小,提高了系统的动态性能和稳态性能,同时提高了发电质量,并为风电机组并网需求奠定了理论基础。     

基于风轮气动特性的风力机变桨优化控制策略研究

当风速大于额定风速时,风电机组通过控制变桨机构调整桨距角来减小风能捕获,从而使机组的输出功率保持在额定功率附近。变桨系统一般采用PI(比例积分)控制算法,但由于风轮气动转矩与风速、风轮转速、桨距角呈高次复杂非线性关系,单一控制参数的变桨控制器难以满足风电机组在额定风速以上的运行性能要求。为了解决单一变桨控制性能不足的问题,提出一种基于风轮气动特性的风力机变桨优化控制策略,该策略通过测量桨距角当前值来动态调整变桨控制器参数,可有效提升变桨系统随风动作连续性,减小由变桨控制引起的转速与功率波动,削减机组由变桨动作引起的动态载荷。     

风电机组变速与变桨距控制过程中的动力学问题研究

讨论了额定风速以下的变速运行控制和额定风速以上的变桨距控制以及变速与变桨距两种控制策略的相互耦合关系;分析了风电机组主要部件包括叶轮、传动系统、塔架的各阶振动模态以及它们之间的相互影响力;提出了转矩控制对传动系统扭转振动和变桨距控制对塔架前后振动的影响力及控制方案;应用BLADED和MAT- LAB软件对主要控制环节进行设计及参数调整,并对机组的控制效果进行仿真。结果表明,所采用的控制策略和控制算法能够满足控制要求,并能有效地解决动力学问题。     

基于混沌优化PID风力发电机组变桨距系统研究

变桨距控制是永磁直驱同步风力发电系统在额定风速以上限制功率输出的主要控制手段,文章基于风力机功率输出特性曲线,分析了永磁直驱风力发电系统变桨距控制在全风况下对应的控制策略。在额定风速以上时利用转速和功率相结合的双闭环变桨距控制系统,并在传统的PID控制器的基础上运用了混沌优化技术,用来减小在额定风速附近引起的输出功率波动及载荷突变的不利影响。通过Matlab仿真软件对混沌优化变桨距进行验证,仿真结果表明该变桨距控制策略响应速度快且鲁棒性强。     

风电机组低电压穿越转矩和变桨控制策略分析

针对低电压穿越时转速幅值波动大的问题,提出一种以限制吸收风能为目标的控制策略。综合运用高速桨距角调整和快速转矩给定来达到这一目标。文章结合1.5MW双馈机组张北基地测试实例,通过对不同电压跌落深度时的风速、转速、转矩、桨角等数据进行分析,提出利用桨距角的快速调整并配以合理的转矩输出,可完成解决转速(功率)波动大的问题。     

变速风力机变桨距系统建模与仿真

变速风力发电机组一般采用变桨距控制来稳定输出功率,但是桨距角的改变会引起攻角的改变,从而引起叶片气动性能的改变,所以在变桨距控制过程中,必须保证合适的攻角,以确保风力机具有良好的气动性能。采用统一变桨距控制方法,在matlab/simulink环境下,通过预测攻角仿真研究了变速风力发电机组的变桨距控制过程,结果表明,该控制模型能正确模拟各种风速下风力发电机组变桨距的动态过程,为进一步研究变速风力发电机的功率控制奠定了基础。     

减小风力机1P气动载荷和3P气动转矩脉动的独立变桨距控制策略研究

为研究风切变和塔影效应对三叶片风力机气动载荷、气动转矩以及输出功率的影响,根据风切变和塔影效应的风速模型,引入等效风速模型,推导分析风力机1P(P为风轮旋转频率)气动载荷和3P气动转矩脉动的形成机理,并基于GH Bladed仿真平台验证这2种脉动的存在性。为减小这2种脉动对风力机产生的影响,基于变桨控制,设计带通滤波器过滤出风力机输出功率的3P脉动分量,并结合方位角信号将其转换为每支叶片的桨距角调节信号,与统一变桨控制的桨距角参考信号叠加,实现基于输出功率和方位角联合反馈的独立变桨距控制。仿真结果表明,所提独立变桨距控制策略不仅能有效缓解风力机1P叶根挥舞载荷脉动,还能明显减小气动转矩和输出功率的3P分量,从而在减小风轮疲劳载荷的同时提高风电机组输出电能质量。     

Gain scheduling control of variable speed WTG under widely varying turbulence loading

Probabilistic paradigms for wind turbine controller design have been gaining attention. Motivation derives from the need to replace outdated empirical-based designs with more physically relevant models. This paper proposes an adaptive controller in the form of a linear quadratic Gaussian (LQG) for control of a stall-regulated, variable speed wind turbine generator (WTG). In the control scheme, the strategy is twofold: maximization of energy captured from the wind and minimization of the damage caused by mechanical fatigue due to variation of torque peaks generated by wind gusts. Estimated aerodynamic torque and rotational speed are used to determine the most favorable control strategy to stabilize the plant at all operating points (OPs). The performance of the proposed controller is compared with the classical proportional-integral-derivative (PID) controller. The LQG is seen to be significantly more efficient especially in the alleviation of high aerodynamic torque variations and hence mechanical stresses on the plant drive train. Simulation results validate the effectiveness of the proposed method.     

Multivariable control strategy for variable speed, variable pitch wind turbines

Reliable and powerful control strategies are needed for wind energy conversion systems to achieve maximum performance. A new control strategy for a variable speed, variable pitch wind turbine is proposed in this paper for the above-rated power operating condition. This multivariable control strategy is realized by combining a nonlinear dynamic state feedback torque control strategy with a linear control strategy for blade pitch angle. A comparison with existing strategies, PID and LQG controllers, is performed. The proposed approach results in better power regulation. The new control strategy has been validated using an aeroelastic wind turbine simulator developed by NREL for a high turbulence wind condition.     

极端风况下双转子风力机降载复合控制策略

为降低双转子风力机在极端风况下的大波动载荷,基于双转子风力机气动与控制仿真系统,提出了基于独立变桨自抗扰控制器和偏航模糊控制器的降载复合控制策略,并分析了正常风况和极端风况下该策略的控制效果。结果表明：与传统PID独立变桨控制相比,在极端运行阵风和极端湍流模型下,独立变桨自抗扰控制方法使叶根挥舞弯矩标准差减小18%以上;与传统恒速偏航控制相比,在极端风向变化下,偏航模糊控制方法使偏航轴承滚动力矩标准差减小约27%。降载复合控制策略有效降低了极端风况下双转子风力机的大载荷,抑制了功率波动。     

Regulation of WTG dynamic response to parameter variations of analytic wind stochasticity

Although variable‐speed operation can reduce the impact of transient wind gusts and subsequent component fatigue, this is still an unknown factor that must now be quantified. Reduction in drive‐train stresses caused by fatigue loads in high wind turbulence is fundamental to realizing both output power leveling and long service life for a wind turbine generator (WTG). This paper presents an evolutionary controller comprising a linear quadratic Gaussian (LQG) and neurocontroller acting in tandem to effect optimal performance under high turbulence intensities, for a variable‐speed, fixed‐pitch WTG. The control objectives are maximum energy conversion and reduction in mechanical stresses on the system components. The proposed paradigm utilizes generator torque in controlling the rotor speed in relation to the highly turbulent wind speed, thereby ensuring the extracted aerodynamic power is maintained at a constant value, while shaft moments are regulated. The performance of the proposed controller is compared with that of the LQG and it is found that the former is more efficient in maintaining rated power, minimizing shaft torque variations, and shows robustness to parameter variations. Copyright © 2007 John Wiley & Sons, Ltd.     

Analysis and synthesis of sliding mode control for large scale variable speed wind turbine for power optimization

The problem of designing a nonlinear feedback control scheme for variable speed wind turbines, without wind speed measurements, in below rated wind conditions was addressed. The objective is to operate the wind turbines in order to have maximum wind power extraction while also the mechanical loads are reduced. Two control strategies were proposed seeking a better performance. The first strategy uses a tracking controller that ensures the optimal angular velocity for the rotor. The second strategy uses a Maximum Power Point Tracking (MPPT) algorithm while a non-homogeneous quasi-continuous high-order sliding mode controller is applied to ensure the power tracking. Two algorithms were developed to solve the tracking control problem for the first strategy. The first one is a sliding mode output feedback torque controller combined with a wind speed estimator. The second algorithm is a quasi-continuous high-order sliding mode controller to ensure the speed tracking. The proposed controllers are compared with existing control strategies and their performance is validated using a FAST model based on the Controls Advanced Research Turbine (CART). The controllers show a good performance in terms of energy extraction and load reduction.     

基于5MW风机模型的变初值模糊PI变桨控制技术研究

针对传统PID变桨控制器参数自调整性能较差,适应性不强的问题,文章提出了风电机组变初值模糊PI变桨控制算法。通过模糊控制算法实现了PI参数的自动调节,根据风速大小设计了合理的变初值调整算法,实现了模糊控制器初值的在线调节。基于FAST风机软件中5 MW陆上风电机组非线性模型,分析了风电机组在额定风速以上运行时变桨系统的动态特性,从算法结构出发,设计了合适的模糊规则和量化、比例因子以及变初值调整算法,在Matlab/Simulink中搭建了变初值模糊PI变桨控制策略。通过仿真验证了控制策略在抑制转速波动和风机叶片、塔基受力力矩波动方面具有较好的效果。     

The Design of closed loop controllers for wind turbines

This article reviews the design of algorithms for wind turbine pitch control and also for generator torque control in the case of variable speed turbines. Some recent and possible future developments are discussed. Although pitch control is used primarily to limit power in high winds, it also has a significant effect on various loads. Particularly as turbines become larger, there is increasing interest in designing controllers to mitigate loads as far as possible. Torque control in variable speed turbines is used primarily to maximize energy capture below rated wind speed and to limit the torque above rated. Once again there are opportunities for designing these controllers so as to mitigate certain loads. In addition to improving the design of the control algorithms, it is also possible to use additional sensors to help the controller to achieve its objectives more effectively. The use of additional actuators in the form of individual pitch controllers for each blade is also discussed. It is important to be able to quantify the benefits of any new controller. Although computer simulations are useful, field trials are also vital. The variability of the real wind means that particular care is needed in the design of the trials. Copyright © 2001 John Wiley & Sons, Ltd.