Purpose

Owing to the salient pole structure and stator slots of hydro-generator, the air gap magnetic field in the generator is unevenly distributed. High-frequency harmonic components contained in the inhomogeneous air gap magnetic field will have a negative impact on the generator performance. The purpose of this paper, therefore, is to improve the distribution of air gap magnetic field by using appropriate magnetic slot wedge, thereby improving the generator performance.

Design/methodology/approach

Taking a 24 MW, 10.5 kV bulb tubular turbine generator as an example, the 2 D electromagnetic field model of the generator is established by finite element method. The correctness of the model is verified by comparing the finite element calculation data with the experimental data. The influences of the permeability and thickness of the magnetic slot wedge on the generator performance are studied.

Findings

It is found that the intensity and harmonic content of the air gap magnetic field will change with the permeability of slot wedge and then the performance parameters of the generator will also change nonlinearly. The relationship between the eddy current loss, torque ripple, output voltage and other parameters of the generator and the permeability of slot wedge is confirmed. In addition, the variation of losses and torque with wedge thickness is also obtained.

Originality/value

The influence mechanism of magnetic slot wedge on the performance of hydro-generator is revealed. The presented results give guidelines to selecting suitable magnetic slot wedge to improve generator performance.

中文翻译：

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磁槽楔对球管式涡轮发电机性能的影响

目的

由于水轮发电机的凸极结构和定子槽，发电机中的气隙磁场分布不均匀。不均匀气隙磁场中包含的高频谐波分量将对发电机性能产生负面影响。因此，本文的目的是通过使用合适的磁性槽楔来改善气隙磁场的分布，从而提高发电机的性能。

设计/方法/方法

以一台24 MW，10.5 kV灯泡形管状涡轮发电机为例，通过有限元方法建立了发电机的二维电磁场模型。通过将有限元计算数据与实验数据进行比较，验证了模型的正确性。研究了磁槽楔的磁导率和厚度对发电机性能的影响。

发现

研究发现，气隙磁场的强度和谐波含量会随着槽楔的导磁率而变化，进而发电机的性能参数也会发生非线性变化。确认了涡流损耗，转矩脉动，发电机输出电压等参数与槽楔磁导率之间的关系。另外，还获得了损耗和扭矩随楔形厚度的变化。

创意/价值

揭示了磁槽楔对水轮发电机性能的影响机理。给出的结果为选择合适的磁性槽楔提高发电机性能提供了指导。