【作者】 卢奭瑄；

【导师】 夏加宽； 王金铭；

【作者基本信息】 沈阳工业大学 ， 电力电子与电力传动， 2012， 博士

【摘要】 变桨距风力发电机组具备装机容量大、风电转换效率高、控制灵活等优点，现在已成为风力发电的主要发展方向。然而，风场内风速的强度和方向变化的不可预知性，给风力发电系统变桨控制带来了很大的困难。目前，国内外对风力发电系统变桨控制策略的研究多以系统转速的稳定为控制目标，研究主要集中在高风速区。由于风力发电机组单机装机容量越来越大，对机组变桨距控制的效果也提出了更高的要求：需要考虑大型叶片多种气动效应因素对风力发电系统转速的影响；变桨距控制器既要能够抑制系统扰动，还能够降低桨距角调节系统的疲劳程度等。针对这些大型风力发电机组变桨控制研究的热点问题，本文进行如下研究工作：对变桨距风力发电机组气动特性数值模拟与分析方法进行研究。采用直接耦合解法克服了风轮气动载荷分析时，流体力学建模设计中迭代法在求解高维问题时计算量大、收敛速度慢的缺陷。应用Visual Fortran软件编制了相应的计算机程序，对实际算例进行仿真计算。数值模拟结果表明直接耦合解法比传统迭代方法的计算时间减少一半以上，验证了此数值计算方法在风力发电机组气动特性数值模拟中的有效性及可行性。研究了风力发电系统结构特征和建模方法。为了准确描述系统传动链的动态过程，采用分析建模和实验验证相结合的方法，建立了大型风力发电系统的非线性数学模型。模型中所使用的风能利用系数利用最小二乘法对风力发电机组实验采样数据进行曲面拟合，并对拟合曲面进行线性化求解，提出一种辨识风力发电系统风能利用系数的方法。理论分析和实际算例验证表明该方法拟合的风能利用系数曲线具有较好的准确性，适合应用在不同风速条件下的风力发电系统建模和控制方法设计中。研究了风力发电系统数学模型和变桨控制方法。针对控制过程中存在的系统部分参数不确定和随机风速扰动问题，设计了一种用于风力发电系统转速控制的桨距角鲁棒控制器。该桨距角鲁棒控制器设计基于定量反馈理论，与传统PID控制器相比，该方法工程实现非常简单，可以保证较大风速变化范围内风力发电机组的稳定性和输出功率控制所要求的动态性能，并且对风力发电系统中不确定参数的摄动影响具有较好的鲁棒性。研究了风速变化与多种气动效应对风力发电机组的影响，提出了一种以实现风力发电系统转速稳定控制的循环变桨距控制策略。该策略结合了定量反馈鲁棒控制方法和重复控制方法，在实现系统转速稳定控制的同时，针对风力发电机组风轮与气流的气固耦合模型中部分气动效应对风力发电系统的影响，采用重复控制抑制风速扰动带来的周期性转速脉动。更多还原

【Abstract】 Variable speed variable pitch wind turbine has now become the main developmentstream of the wind power due to its advantages of large capacity, efficient wind powerconversion, flexible control and so on. However, it is of great difficulty for variable pitchcontrol of wind turbine because of the unpredictable strength and direction of wind speed.At present, the studies of variable pitch control strategy on the wind turbine at home andabroad are prone to the stability control of wind wheel speed, especially focusing on highwind speed areas. With the increasing unit capacity of wind turbine, new requirements tothe variable pitch control of wind turbine are proposed, such as considering the effect ofthe multiaerodynamic effects of large blade on the wind turbine speed, the capability ofvariable pitch controller on inhabiting system disturbances as well as reducing the fatiguedegree of pitch angle adjustment system, and so on. These have become the hot issues forthe variable pitch control of large wind turbine. The details of this dissertation are asfollows:Through surveying the numerical simulation and analytical methods on theaerodynamic characteristics of variable pitch wind turbine, the direct coupling solution isadopted, which can overcome the defects of large computation and slow convergencewhen using iterative method to solve high dimensional problem during fluid dynamicsmodelling. Practical examples are simulated and calculated by Visual Fortran program.Numerical simulation results show that the computing time using direct coupling solutionis half of that using conventional iterative method, which demonstrates the feasibility andeffectiveness of this method in the aerodynamic characteristics numerical simulation ofwind turbine.The structure features and modelling method of wind turbine are studied. Thenonlinear mathematical model of large wind power system is built by the methodcombining analytical modelling and experimental validation to accurately describe thedynamic process of system drive chain. The wind energy utilization coefficient inmathematic model is obtained by the surface fitting of the experimental sampled data of the wind turbine based on the least square method. A method of identifying and analyzingwind energy utilization coefficient of wind turbine is developed by linearizing the fittingsurface. Theoretical analysis and practical example verification show that the fitted windenergy utilization factor curve is accurate and suitable for modelling and controller designof wind power system under different wind speed conditions.The mathematical modelling and variable pitch control method of wind power systemare studied. Considering the system parameter uncertainties and stochastic winddisturbances, a pitch angle robust controller is designed to achieve speed stable control ofwind power system. The pitch angle robust controller is designed based on the quantitativefeedback theory. Comparing with the conventional PID controller, this method can berealized simply and guarantee the stability and required output power dynamicperformance of wind turbine within the larger wind speed range. Meanwhile, it has goodrobustness to the perturbation of the uncertain parameters in the wind power system.The influence of variable wind speed and multi-aerodynamics on wind turbine isstudied. A loop variable pitch control strategy is proposed to implement speed stablecontrol of wind power system. This control strategy combines quantitative feedback robustcontrol and repetitive control to gain the system speed stable control. The repetitive controlis used to attenuate the periodic speed ripple caused by disturbance, which considers thepartial aerodynamic effects of air-solid coupling model between the wind wheel of windturbine and airflow.更多还原