多源激励及多因素相关的风电传动系统动态可靠性及疲劳寿命研究

Aiming at the characteristics of the varying working condition and the high flexibility of wind turbines and the problems of high-failure rate of gear transmission system under the condition of multiple-source excitation，the random wind load acting on the wind rotor incited by random wind speed changing，the dynamic load caused by vibration of tower and nacelle，and the dynamic load caused by power grid impact are imported the transmission system of wind turbines，the coupling relationship between the multiple excitation sources and the mapping relationships between the each excitation sources and dynamic performance and fatigue life will be researched. On that basis，the non-linear dynamics model will be established under the multiple source excitations，and the influence of multiple excitation sources coupling effect on non-linear vibration response and the actual loading history of each gear and each bearing of transmission system will be researched. The random processes theory will be adopted to describe the random behavior of the fatigue load，the extreme load and the strength degradation，the Copula theory will be introduced to describe the failure-dependence of transmission system，the statistical relationships between the whole performance and the each independent element degradation will be revealed，and the dynamic reliability and fatigue life model of gear transmission system considering the multifactor correlation will be built under the condition of multiple-source excitation load coexist，the design theory and method of dynamic reliability and fatigue life of wind turbines gear transmission system under multiple-source excitation and multilayer correlation condition will be formed, and the effective way will be provided for our country to establish and perfect the dynamic reliability assessment and fatigue life prediction theory and method of wind turbines gear transmission system.

针对风力发电机变工况和整机高柔性的特点以及传动系统承受多源复杂激励、失效率高等问题，将由随机风速变化引起的作用在风轮上的随机风载荷、塔架和机舱振动引起的动载荷以及电网冲击引起的动载荷引入传动系统，研究各激励源之间的耦合关系及对传动系统动态性能及疲劳寿命的映射关系。在此基础上，建立多激励源条件下的传动系统非线性动力学模型，研究多激励源耦合作用对传动系统各轮齿和轴承的非线性振动响应及实际载荷历程的影响。采用随机过程理论描述疲劳载荷、极端载荷及强度退化的随机行为，引入Copula 理论描述传动系统失效过程的相关性，揭示系统整体性能与各独立元件性能之间的统计学关系，建立多源激励载荷共存环境下多因素相关的传动系统动态可靠性及疲劳寿命模型。形成多源激励及多层次相关的风电齿轮传动系统动态可靠性及疲劳寿命设计理论与方法，为建立和完善我国风电齿轮传动系统的动态可靠性评估及疲劳寿命预测理论与方法提供有效途径。

风力发电机齿轮箱是风力发电机组的重要部件，在多源激励及多因素耦合的作用下是风力机中失效率较高的部件之一，严重制约着风力发电机的性能及寿命。针对这一问题，项目以大型风力发电机齿轮传动系统为研究对象，采用理论分析、数值仿真和试验验证的方法，开展了大型风力发电机齿轮传动系统外部载荷计算、动力学特性、动态可靠性以及疲劳寿命等方面的研究。其主要工作如下：.(1)建立了风力发电机整机耦合动力学模型和多源激励作用下风电齿轮传动系统齿轮-轴承耦合动力学模型，得到传动系统内部关键零部件齿轮和轴承的动载荷，相比传统的将零部件所受载荷近似处理为静载荷的方式，更准确的反映了风力发电机齿轮传动系统在多源载荷作用的实际情况。.(2)将载荷作用过程视为随机过程，零件强度视为随机变量，建立传动系统动态可靠性模型，研究系统零部件和系统的可靠性指标及可靠度随时间的变化规律。.(3)考虑零件失效相关性和强度随时间退化对传动系统可靠性的影响，从系统的角度应用应力强度干涉模型建立传动系统动态可靠性模型，研究了系统的可靠性和失效率随时间的变化规律，与以往假定零件失效相互独立且忽略强度退化规律的可靠性模型相比，具有一定的创新性。.(4)基于随机风速模型和传动系统齿轮-轴承耦合动力学模型，结合有限元方法和数理统计理论，利用Palmgren-Miner线性累积损伤法则和零件的P-S-N曲线，估算了风电齿轮传动系统各齿轮和轴承的疲劳寿命，该方法与采用无限寿命估算法相比更符合实际且简单可靠。.这些研究结果，为大型风电齿轮传动系统的动态性能分析和动态可靠性设计提供理论基础，较好的解决了风电齿轮箱设计中由于多源载荷和多因素耦合作用带来的寿命不高的难题。