摘要
风力机是承受复杂随机载荷的动力系统,其动态气动弹性问题涉及随机动态气动力与结构动力响应之间的相互作用,是一个含大气边界层湍流风场、风轮动态空气动力学、叶片及机组结构动力学的多学科交叉问题。本文基于国家自然科学基金项目“考虑叶片柔性变形的风力机气动弹性问题研究”,针对现代大型水平轴风力机自身的结构,结合外部运行特点和国际设计标准,应用现代模态分析理论和有限元数值分析相结合的方法,以1.5MW水平轴风力机为对象,研究了大型风力机在空气动力载荷和机械载荷作用下的结构动力学响应分析方法。
本论文采用以叶素动量理论为基础的动态气动分析方法来得到气动载荷,建立结构动力学响应模型分析随机气动载荷作用下的结构动态响应及气动弹性载荷。考虑塔架结构变形对叶片的动态反馈作用,并通过模态综合法,实现风轮和塔架的耦合。最后,利用Palmgren Miner线性累积损伤理论来计算风力机的安全疲劳寿命。
论文主要包括以下几个方面的内容:
(1)分析风力机基本的空气动力特性。根据修正后的叶素动量理论对作用在风轮叶片上气动载荷进行估算。
(2)将叶片和塔架简化为变截面悬臂梁,采用二节点梁单元建立其有限元模型。利用多自由度拉格朗日方程建立运动方程,通过模态分析得到固有频率和振型。考虑风轮旋转频率,避免风力机固有频率和激振频率重叠引起共振。
(3)运用模态叠加理论和Newmark法来求解运动方程,获得叶片和塔架在载荷作用时的动态响应,并编制相应的计算程序。
(4)研究风轮和塔架的耦合方法,考虑塔架变形对风轮动态气动特性影响。计算低阶主导模态,通过模态综合法建立风轮模态和塔架模态的相互联系。考虑它们之间气动弹性的影响,叠加时序的变化,运用迭代算法求得主模态的响应结果。
(5)利用雨流计数法统计风力机随机载荷谱和Palmgren-Miner线性累积损伤法则进行叶片疲劳寿命的估算。
Wind turbine is a dynamic system that bears complex random load. The problem about aeroelasticity is related to the interaction of stochastic dynamic aerodynamic and structure dynamic response. And it is a multidisciplinary issue about atmospheric boundary layer turbulent wind field, rotor dynamic aerodynamics and blade and unit structural dynamics. In this paper, aimed at the configuration, operation characteristic and international standard of the modern large scale horizontal axis wind turbine, using the method which combines modern modal analysis theory and finite element numerical analysis, targeting a 1.5MW horizontal axis wind turbine, the analysis method of the large scale wind turbine dynamic response caused by the aerodynamic load and mechanical load is investigated based on the NSFC project“Research on the aeroelasticity problem of wind turbine considering the flexible deformation of the blade”.
Using blade element momentum theory to calculate aerodynamic load and establishing the structural dynamics model, the structure dynamic response and aeroelasticity load under random aerodynamic load are analysed. At the same time, it should be considered that tower structure deformation has a dynamic feedback to the blade. With the modal synthesis method, the coupling of rotor and tower is achieved. Finally, the security fatigue life of wind turbine based on the Palmgren Miner linear fatigue damage accumulation rule is estimated.
The main content of this paper includes the following respects:
(1) The basic aerodynamic characteristics of the wind turbine are analysed. According to revised blade element momentum theory, the aerodynamics load on the blade is estimated.
(2) The rotor and tower are considered as a cross-section cantilever and appied two-node beam element to the finite element modeling. Multi-DOF Lagrange equations based on the generalized coordinate system is used to build the motion equation. And the modal analysis is used to get natural frequencies and mode shapes. The frequency of the rotating rotor is given and the resonance should be avoided that is caused by the overlap in natural frequency and excited frequency.
(3) Mode-superposition method and Newmark method are used to compute the motion equation and determine the dynamic response of the blade and tower under loads. In addition, the numerical programs are developed.
(4) Considering that the tower deformation affects the dynamic aerodynamic characteristics of the rotor, the coupling method of the rotor and tower is studied. Low-level lead modes are calculated and the relation between the rotor and tower is established by modal synthesis method. Considering the impact of the aeroelasticity, overlying the timing changes and applying iterative algorithm the response results of lead modes are obtained.
(5) The stochastic load spectrum is counted by the rain flow count method. And the fatigue life of the blade is estimated by the Palmgren Miner linear fatigue damage accumulation rule.
引文
[1].中国风能信息网.风能的利用,http://www.zgwp.net/,2010.03
[2].许洪华.世界风电技术发展趋势和我国未来风电发展探讨.电力设备,2005年,第6卷(10):106-108.
[3]. GWEC. Global wind Report– annual market update 2010. Belgium:GWEC,2011. 12-18.
[4].李俊峰,施鹏飞,高虎.中国风电发展报告2010.海南:海南出版社,2010. 6-12.
[5].中国风能协会. 2010年中国风电装机容量统计.北京:中国可再生能源学会风能专业委员会,2011.
[6].贺德馨等.风工程与工业空气动力学.北京:国防工业出版社,2006. 80-82.
[7].刘雄,陈严,叶枝全.水平轴风力机气动性能计算模型.太阳能学报,2005,26(6):792-800.
[8].刘雄,张宪民,陈严.基于BEDDOES- LEISHMAN动态失速模型的水平轴风力机动态气动载荷计算方法.太阳能学报,2008,29(12):1449-1455.
[9].刘雄.水平轴风力机气动与结构CAD系统集成研究.汕头大学.硕士论文. 1999. 10-14.
[10]. Robert E.Wilson, Peter B.S.Lissaman, Stel N.Walker. Aerodynamic Performance of Wind Turbines. Oregon State University:Department of Mechanical Engineering,1976. 65-73.
[11].刘雄,张宪民,陈严.基于动态入流理论的水平轴风力机动态气动载荷计算模型.太阳能学报,2009,30(4):412-419.
[12]. David-P.Molenaar, Sjoerd Dijkstra. Modeling the Structural Dynamics of Flexible Wind Turbines. France:Proc of 1999 EWEC,1999. 234-237.
[13]. Molenaar D P. Modeling the Structural Dynamics of the Lagerwey LW-50/750 Turbine. Netherlands:Delft Univ of Tech,1998. 16-18.
[14]. Friedmann P P. Aeroelastic Modeling of Large Wind Turbines. Journal of American. Helicopter Society,1976,21(4):17-27.
[15].窦修荣,黄珊秋,宋耕宪.大型水平轴风轮转子/塔架耦合系统的气动弹性稳定性分析.太阳能学报,1997,18(3)7:278-280.
[16]. WarmbrodtW, Friedmann P. Aeroelastie. Response and Stability of a Coupled Rotor/Support System with Application to Large HAWT. UCLA-ENG-7881,1978,32-57.
[17]. J.W.Larsen, S.R.K.Nielsen. Non-linear Dynamics of Wind Turbine Wings. International Journal of Non-Linear Mechanics,2006,41:629-643.
[18]. David J.Malcolm. Modal Response of 3-Bladed Wind Turbines. Transactions of the ASME,2002,124:372-377.
[19]. M.H.Hansen. Aeroelastic Stability Analysis of Wind Turbines Using an Eigenvalue Approach. Wind Energy,2004,7:133-143.
[20]. Hou SN. Review of Modal Synthesis Techniques and a New Approach.40th Shock and Vibration Symposium. Virginia:Hamp ton,1969. 124-128.
[21]. Donghoon Lee, Dewey H.Hodges, Mayuresh J.Patil. Multi-flexible-body Dynamic Analysis of Horizontal Axis Wind Turbines. Wind Energy,2002,5:281-300.
[22]. Molenaar D P, Kijistra S. Modeling the Structural Dynamics of Flexible Wind Turbines. Proc of 1999 EWEC.Nice,1999:234-237.
[23]. Kane TR, Levinson DA. Dynamics: Theory and Applications. New York:McGraw-Hill,1985. 154-159.
[24]. K.Holm-J?rgensen, S.R.K.Nielsen. A component mode synthesis algorithm for multibody dynamics of wind turbines. Journal of Sound and Vibration,2009,326:753-767
[25]. P.J.Murtagh, B.Basu, B.M.Broderick. Along-wind response of a wind turbine tower with blade coupling subjected to rotationally sampled wind loading. Engineering Structures,2005,27:1209-1219.
[26]. Nithian Ti Sivaneri. Dynamic stability of a rotor blade using finite element analysis. AIAA J,1981,20(5):716-723.
[27]. Bauchau O H. Finite element approach to rotor blade modeling. J Ame Helicopter Soc,1987,21(1):73-96.
[28]. Anders Anlstrm. Aeroelastic Simulation of wind Tuthine Dynamies. Royal Institute of Technology Department of Mechanics. Doctoral Thesis. 2005. 85-88.
[29]. Baumjohann F, Hermanski M, Dickmann R, Kroning J. 3D-multi body simulation of wind turbines with flexible components. DEWI Magazine,2002,21:63-66.
[30]. Hans Ganander, Teknikgruppen AB. The use of a Code-generating System for the Derivation of the Equations for Wind Turbine Dynamics. Wind Energy,2003,6:333-345.
[31]. Ye Zhiquan, Li Deyuan, Chen Yan. Numerical Analysis of the Rotating Blade of Horizontal Axis Wind Turbine Based on Flexible Multi-body dynamics theory. Proc of 3rd WWEC,China,2004.
[32].陈彦.大型水平轴风力机结构动力响应与稳定性研究.清华大学.硕士论文. 1999. 24-28
[33].王介龙,陈彦,薛克宗.风力发电机耦合转子/机舱/塔架的气弹响应.清华大学学报(自然科学版),2002,42(2):211-215.
[34].陈严,杜明慧.变转速风力机全系统性能分析.汕头大学学报,2005,20(3):41-47.
[35].凌爱民,黄斌根,韩普祥.应用直升机动力学设计方法分析大型风力发电机组动力学特性.直升机技术,2001,1:7-13.
[36].李声艳.大型风力发电机组的动力学特性计算分析.天津工业大学.硕士论文. 2007. 5-12.
[37].邵金华.风力发电机系统动力特性仿真研究.重庆大学.硕士论文. 2007. 18-22.
[38].金鑫.风力发电机组系统建模与仿真研究.重庆大学.博士论文. 2007. 34-56.
[39]. R.克拉夫,J.彭津.结构动力学.北京:高等教育出版社,2006. 143-150.
[40].梁君,赵登.模态分析方法综述.现代制造工程,2006,8:139-141.
[41].张雄,王天舒.计算动力学.北京:清华大学出版社,2007. 53-59.
[42]. Bladed for Windows. User Manual.Version3.82. Denmark:Garrad Hassan,2008. 69-72.
[43]. Bladed for Windows. Theory Manual.Version3.82. Denmark:Garrad Hassan,2008.
[44]. DNV/Ris?. Guidelines for Design of Wind Turbines. Second Edition. Denmark:Jydsk Centraltrykkeri,2002. 58-60.
[45].李本立,宋宪耕,贺德馨,安玉华.风力机结构动力学.北京:北京航空航天大学出版社,1999. 176-195.
[46]. Tony Burton, David Sharpe, Nick Jenkins, Ervin Bossanyi. Wind energy handbook. England:John Wiley & Sons Ltd,2001. 276-280.
[47].傅志方,华宏星.模态分析理论及应用.上海:上海交通大学出版社,2000. 60-62
[48].张子明,周星德,姜冬菊.结构动力学.北京:中国电力出版社,2009. 212-215.
[49].刘胜祥,李德源,黄小华.风波联合作用下的风力机塔架疲劳特性分析.太阳能学报,2009,30(10):1250-1256.
[50].单光坤,关新,宋世东. 100KW风力发电机叶片疲劳分析.可再生能源,2010,28(2):20-25.
[51].汤炜梁.大型风力机疲劳计算方法研究.电力技术,2010,19(17):125-136.
[52].陈余岳.风力机玻璃钢叶片疲劳分析.玻璃钢,2001,4:1-4.
[53].李德源,叶枝全,陈严等.风力机玻璃钢叶片疲劳寿命分析.太阳能学报,2004,25(5):592-598.
[54].任国栋,孙文磊,任秀玲.基于协同仿真的风力发电机叶片的疲劳研究.机床与液压,2010,38(7):99-102.
[55]. Herbert J. Sutherland. A Summary of the Fatigue Properties of Wind Turbine Materials. Wind Energy,2000,3:1-34.
[56]. Dick Veldkamp. A Probabilitistic Evaluation of Wind Turbine Fatigue Design Rules. Wind Energy,2008,11:655-672.
[57].李德源,叶枝全,陈严等.风力机叶片载荷谱及疲劳寿命分析.工程力学,2004,21(6):118-123.
[58].王国军. Msc fatigue疲劳分析实例指导.北京:机械工业出版社. 2009. 24-26.