基于磁通密度分布特征的水轮发电机低频振动评估与精确处理方法探究

Evaluation and Precise Treatment of Low-frequency Vibration of Hydro-generator Based on Magnetic Flux Density Distribution Characteristics

大中型水轮发电机的低频振动问题近年频发,未得到系统性解决。针对里底水电站2号水轮发电机低频振动问题,本文提出一种改进的基于磁通分布特征评估方法,通过电磁仿真结合实测气隙磁通密度的方法建立评估模型,对振动问题进行分析。分析表明,当气隙磁场呈椭圆分布时,可能诱发定子低频振动。根据振动评估结果应用遗传算法寻优,通过电磁仿真进行预分析,进而制订针对性较强的改造方案。改造效果明显,具有较强的普遍适用性和推广价值。

The problem of low-frequency vibration of large and medium-sized hydro-generator occurs frequently in recent years,which has not been systematically solved.In view of the low frequency vibration of Unit 2 hydro-generator in Lidi Hydropower Station,an improved method based on magnetic flux distribution characteristics evaluation is put forward in this paper,in which,the evaluation model is established based on electromagnetic simulation combined with air gap flux density measurement to analyze the vibration problem.The analysis shows that the low frequency vibration of the stator will be easily induced when the air gap magnetic field is elliptic.According to the vibration assessment results,the genetic algorithm is used to optimize and the electromagnetic simulation is used for pre-analysis,and then a more targeted transformation plan is formulated.The vibration is greatly weakened after the transformation,which shows that this method has strong universal applicability and promotion value.