大型空冷汽轮发电机端部磁场数值计算

Numerical Calculation of End Region of Large Air-Cooled Turbogenerator

针对空冷汽轮发电机端部磁场计算中存在的问题,采用A,(?)-A三维有限元法建立了大型汽轮发电机端部三维涡流场的数学模型,模型充分考虑了定、转子铁心的端部效应和定子齿压指、压板、磁屏蔽、压圈等端部结构件和定、转子端部线圈的实际几何形状以及材料性质的影响。提出用二维磁场和三维磁场耦合求解的方法确定边界条件,该方法既能够保证计算精度又减少了求解区域,节省了计算时间：并给出了定子绕组端部渐开线模型的网格生成方法,利用该方法能准确模拟电机端部绕组的实际情况：以1台OF—150—2型空冷汽轮发电机为例,计算了计及涡流时汽轮发电机空载、满载端部电磁场,给出了电机端部结构件中磁场的分布和一些有价值的结论,计算结果验证了方法的有效性。

Against to problems existed in calculation of electromagnetic field in the end region of large air cooled turbo-generator. Firstly, a full mathematic model used to calculate end field of large turbo-generator by A, φ-A 3D FEM is presented. The model combined end zone with stepped stator core, expanded solved region into the stator and the rotor core. The end structures spatial location, the actual shape of end coil and theirs influence to end field calculation are considered accurately. Secondly, the method to determine the boundary condition of the solved region are given by combined 2D and 3D magnetic field, which is capable of reducing the required end region and ensure high computing accuracy, and also save the computing time. In addition, a generating mesh method is used to divide the stator end winding evolvent model. This method is good meet the actual structure of stator end winding. Finally, taking QF-150-2 turbo-generator for example, the end field is calculated at no-load and at full load with eddy current taking into account. The magnetic flux density distribution in structures of end region is given and some valuable conclusions are drawn. The calculated results provide and the reliability of the method presented in this paper is verified.