【作者】 霍菲阳；

【导师】 张奕黄；

【作者基本信息】 北京交通大学 ， 电气工程， 2013， 博士

【摘要】 大型发电机的温度状况直接影响着电机的性能,因此发电机的散热问题一直备受关注,发电机的通风结构成为了研究的重点。采用不同的通风结构直接影响着发电机内部的风路及风量分配,进而对电机的散热状况产生很大的影响。发电机内部的发热与冷却问题一直是电机设计研究中的重点问题,尤其是如何确定发电机的温度分布和最高温升位置,不仅可以为发电机内绝缘等级的选取,还可以为发电机安全和稳定运行提供参考。因此,对发电机内温升分布的准确计算具有实际的工程意义。本文根据电磁场理论,建立了大型汽轮发电机端部实体模型,通过对发电机端部三维瞬态电磁场求解,确定了发电机空载和额定负载端部区域漏磁分布及端部铜屏蔽、压圈、压指的涡流损耗,对比研究了发电机端部铜屏蔽相对压圈位置改变及空实心铜屏蔽内、外层铜屏蔽之间风道宽度对端部区域漏磁分布及端部各结构件涡流损耗的影响。通过将三维瞬态涡流场计算得到的结构件损耗结果作为热源,结合大型汽轮发电机的实际结构和流体力学、传热学理论,建立了大型汽轮发电机三维端部区域流体与传热耦合的数学模型,给出了相应的基本假设和边界条件,基于有限体积法对该发电机三维端部区域耦合场进行求解,确定了端部区域各构件的温度分布,并将铜屏蔽温度计算结果与实测值进行比较,验证了计算方法的准确性与可靠性。还对端部构件铜屏蔽与压圈之间不同距离和空实心铜屏蔽时端部区域内流体速度分布和端部构件铜屏蔽、压圈、压指温度分布的变化规律进行了数值分析,为大型汽轮发电机通风系统结构设计提供了可靠的依据。此外以一台全空冷水轮发电机为例,根据该电机特殊的通风冷却结构,确定了转子旋转情况下的计算区域,建立了三维流体场和温度场的计算模型,给定相应的基本假设与边界条件,采用有限体积法对其通风和发热问题进行计算,得到转子支架、磁轭通风沟、磁极间隙以及定转子气隙内冷却气体的流速分布与转子各部分的温度分布,详细分析了极靴表面和磁极中心线处流体流速和温度沿轴向的变化趋势,并将转子表面温度的计算结果与运行试验数据进行比较,验证了该计算结果的可靠性。图76幅,表13个,参考文献136篇。更多还原

【Abstract】 The thermal condition of the large generator affects the performance of machine directly, so the heat dissipation problem of the generator has aroused considerable concern, and the ventilation structure of the generator has become the focus of research. The ventilation structure affects the internal wind road and air distribution of the generator directly, and then has a great influence on generator heat dissipation. The internal heating and cooling problem have always been the key problems in the study of the electric machine design, what is especial is how to determine the highest temperature rise position of the generator accurately, and this may provide a reference for not only the selection of generator’s insulation class, but also the safe and stable operation of the generator.In this dissertation, according to the theory of electromagnetic field, the calculation model of the end region in large turo-generator is established. By solving the transient magnetic field in end region, the three-dimensional transient electro-magnetic field distribution and eddy current loss is obtained under no and rated load. Meanwhile, the influence of metal screen position and the width of ventilation between inner and outer screens on three-dimensional transient magnetic field distribution and eddy current loss are investigated. Using the eddy current loss, which is gained from numerical calculation of electromagnetic fields as heat source, combined with the actual large turbo generator structure and the theories of fluid mechanics and heat transfer, the three-dimensional multi-physics fields coupling mathematical models of large turbo-generator end region is established. After the determinations of related basic assumptions and boundary conditions, the multi-physics fields of this generator three-dimensional end region are coupling analyzed by using the Finite Volume Method, and the temperature distributions of each structure end component region is obtained. The calculated temperature distribution in copper shield is compared with the measured values, by which the accuracy and reliability of the calculation method are verified. By using the same analysis method, the fluid velocity distributions in end region with different distances between the copper shielding and clamping plate and the empty solid copper shield structure are investigated, as well as the variation of temperature distribution in copper shield, clamping plate and press fingers. The obtained results could provide a reliable basis for large turbo ventilation system design. In addition, the heat transfer and the cooling mechanism in a fully air-cooling hydro-generator are studied. According to the special ventilation cooling structure of the machine, considering the rotor rotating the calculation region is determined, and a three-dimensional fluid field and temperature field calculation model is proposed. Then, the corresponding basic assumptions and boundary conditions are given, and the Finite Volume Method is adopted for the cooling and heat transfer analyses. The cooling air flow velocity distribution in the rotor bracket, in yoke ventilating grooves, in gap between magnet poles, and in air-gap between stator and rotor are studied, and the temperature distribution in rotor components are obtained. The flow velocity of fluid in the pole shoe surface and the magnetic pole center line, and the change trend of temperature along the axial direction are analyzed in detail. From the comparison of the calculated rotor surface temperature with the test data, the reliability of the calculation results is verified.更多还原