空冷汽轮发电机新型定子齿内冷及端部琴键式屏蔽结构通风系统冷却机理的研究

Ventilation system design ideas of a new inner cold stator teeth and piano keyboard type screen are proposed, and the influence of the new teeth axial ventilation system on the distortion of the magnetic field on the teeth is researched. It reveals the influence of the shape and location of teeth axial ventilation duct on the winding temperature distribution and the teeth cooling capacity. Doing research on influence relationship of the topological structure of teeth ventilation hole on the inhibition of secondary backflow. The ant colony optimization mathematical model of the circumferential choke plate located the teeth section is established, which suppresses parasitic eddy current as the minimum objective function. It reveals the influence law of the radial ventilation chokes plate on inhibiting fluid parasitic eddy current.The influence of topological structures of core teeth and the numbers, shape and structure of choke plate on stator temperatures is studied. Taking the nonlinearity of core material into consideration, the three-dimensional mathematical and geometry models of the nonlinear transient eddy current field with the new piano keyboard type screen is given. The shielding effect of the size and shape of new copper shielding structure on the leakage magnetic field in the end region under leading and lagging operationg states is investigated.Comprehensive evaluation of the influence of new structure eddy current loss on the air temperature is done. Also, the influence of the different end structures, metal screen materials and end winding warping degree on magnetic and loss distribution, and air flow state in the end region are studied. Do research on distributing law of surface heat transfer coefficient on the end windings. The feasibility of the new ventilation structure is verified through the test.

提出新型定子齿内冷和端部琴键式屏蔽结构通风系统的设计思想，研究新型齿部轴向通风系统对齿部磁场畸变的影响程度，揭示齿部轴向通风沟形状和位置对定子绕组温度分布及齿部散热能力的影响规律，探究齿部通风孔拓扑结构对抑制二次回流影响关系。建立抑制寄生涡流为最小目标函数下的齿部分段周向阻风板蚁群优化数学模型，揭示径向通风沟内阻风板对抑制寄生涡流的影响规律，给出齿部不同拓扑结构和阻风板数量、形状、结构对定子温度的影响关系；建立新型琴键式发电机端部计及饱和效应影响的三维非线性瞬态电磁场数学模型，研究发电机进相和迟相运行工况下新型铜屏蔽结构尺寸和形状对端部漏磁场的屏蔽效果，确定新结构下端部结构件涡流损耗的变化对空气温度的影响关系；研究端部不同结构形式、材料特性、定子绕组翘曲度对端部电磁分布、损耗分布规律和端部区域空气流动状态的影响，探究端部绕组表面散热系数的分布规律, 并通过试验测试验证新型通风系统的可行性。

本项目提出新型定子齿内冷和端部琴键式屏蔽结构通风系统的设计思想，研究了齿内冷通风孔的位置、通风孔径大小对发电机的定子齿部磁密，定子铁耗，基波气隙磁密，交直轴饱和同步电抗参数等影响的规律，进而论证了新型定子齿内冷通风方案的可行性，确定了定子齿内冷结构的综合优化方案，为进一步研究汽轮发电机新型通风冷却系统流体场、温度场提供研究基础；建立新型琴键式发电机端部计及饱和效应影响的三维非线性瞬态电磁场数学模型，研究发电机进相和迟相运行工况下新型屏蔽结构尺寸和形状对端部漏磁场的屏蔽效果，确定新结构下端部结构件涡流损耗的变化对空气温度的影响关系；研究端部不同结构形式、材料特性、定子绕组翘曲度对端部电磁分布、损耗分布规律和端部区域空气流动状态的影响, 并通过试验测试验证新型通风系统的可行性；提出一种新的计及铁心饱和、非线性的双域非线性瞬态电磁场的机网协同耦合的数值计算方法，解决了端部复杂的电磁场以往单纯依靠定子侧加载电流而难以计算特殊工况下端部复杂漏磁场、涡流损耗、电磁力分布等难题，能够更加准确地计算复杂瞬态端部电磁场。

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