直驱永磁风机轴系弯扭耦合非线性振动机理研究

Lateral-torsional coupling vibration of direct-drive permanent magnet wind turbines shafting is the cause of shafting instability vibration, which is caused by wind speed mutation and rotor eccentric. Lateral-torsional coupling vibration of wind turbines shafting threaten the safety of wind turbines and power grid. For wind power industry, shafting instability vibration is a key technique issue need to be resolved immediately. The research goal of this project is to identify lateral-torsional coupling vibration mechanism of wind turbines shafting which is caused by wind speed mutation and rotor eccentric. Impact torque calculation method caused by wind speed mutation is researched. Imbalance electromagnetic pull force of shafting caused by wind speed mutation and rotor eccentric is also researched. Differential equation of shafting lateral-torsional coupling vibration is established. Action rules between nonlinear term and shafting natural frequency is researched with theoretical analysis and mathematical deduction. Test bench of lateral-torsional coupling vibration of direct-drive permanent magnet wind turbines shafting is developed. Lateral-torsional coupling vibration characteristics of shafting is measured, which is caused by wind speed mutation and rotor eccentric. Based on mathematical model of lateral-torsional coupling vibration of shafting, equilibrium point and stability of periodic solutions are researched. Numerical simulation of the system is carried out with method of numerical integral and Poincaré mapping, and bifurcations and chaos of the system are also researched. With the research of this project, action rules between wind speed mutation and rotor eccentric will be uncovered, generation mechanism of bifurcations and chaos of shafting vibration will be find out, theoretical basis for direct-drive permanent magnet wind turbines design will be provided.

直驱永磁风机轴系在风速突变和发电机转子偏心共同激励下容易引发轴系振荡失稳，威胁风机和电网的安全运行，已成为风电行业亟需解决的关键科技问题。项目以查明风速突变和发电机转子偏心作用下风机轴系弯扭耦合非线性振动机理为目标，研究风速突变导致的冲击力矩计算方法、风速突变和发电机转子偏心共同作用导致的转子不平衡电磁拉力计算方法，建立轴系弯扭耦合非线性振动微分方程，通过数学推导获取非线性项与轴系固有频率的作用规律，研制风机轴系弯扭耦合非线性振动实验台，测取风速突变和发电机转子偏心作用下轴系的弯扭耦合振动特征，基于风机轴系弯扭耦合数学模型，研究其平衡点及周期解稳定性，采用数值积分及Poincaré映射方法对系统进行数值模拟，分析系统的分岔和混沌运动。通过本项目的研究，揭示风速突变幅值和发电机转子偏心量与轴系弯扭耦合非线性振动的作用规律，查明轴系振动分岔和混沌的发生机制，为直驱永磁风机设计提供理论依据。

直驱永磁风机轴系在风速突变和发电机转子偏心共同激励下容易引发轴系振荡失稳，威胁风机和电网的安全运行，已成为风电行业亟需解决的关键科技问题。项目以查明风速突变和发电机转子偏心作用下风机轴系弯扭耦合非线性振动机理为目标，研究风机轴系激振力计算方法，风机轴系弯扭耦合非线性振动响应，风机轴系弯扭耦合非线性振动的分岔特性与控制。.获取了风速突变作用下风轮冲击转矩的工作特性和发电机转子偏心引起不平衡磁拉力的工作特性。建立了风机轴系弯扭耦合振动方程，分别对正常工况、风速突变、发电机转子偏心、风速突变与转子偏心同时作用下四种工况下轴系振动特性进行仿真分析。正常工况下，风机轴系存在低频率小幅值振动，振动幅值趋近于0。风速突变工况下，轴系扭转振动频率主要分布在10-30Hz，轴系扭转振动幅值随着风速突变峰值增大而增大。转子偏心工况下，轴系弯曲振动频率主要集中在66Hz。风速突变与转子偏心同时作用下，轴系产生弯扭耦合振动，振动幅值增大，频率分布变宽，引发共振概率增大。.建立了风机轴系的扭转振动分岔模型，以T为分岔参数，给出了稳定性和稳定域的判定条件。计算求出系统等价一阶方程的两个平衡点A1，A2，利用Hurwitz稳定性理论分析其稳定性。通过构建Lyapunov矩阵方程得到了系统在平衡点A1稳定时发电机转子转角的稳定域。以阻尼为分岔参数，开展了风机轴系非线性扭转振动分析，获取了非线性变化阻尼对轴系扭转振动特性的作用规律。设计了一种非线性状态反馈控制器，适当调整线性增益部分能够扩大轴系稳定范围、降低轴系扭转振动幅值，适当调整非线性增益部分能够改变轴系Hopf分岔类型。.通过本项目的研究，揭示了风速突变幅值和发电机转子偏心量与轴系弯扭耦合非线性振动的作用规律，查明了轴系振动分岔的发生机制。项目发表学术论文10篇，其中SCI/EI论文6篇，出版学术专著1部，授权国家发明专利5项，培养研究生5名。