超大型水轮发电机定子振动超标处理技术探讨

以糯扎渡水电站定子为研究对象,针对大型水轮发电机定子长期高强度振动造成发电部件损坏的问题,从定子刚度、转子不圆度、水轮机尾水压力脉动等方面分析了机组振动的原因,通过对转子支架应力复核计算表明转子支架现有结构的最大综合应力已经接近许用应力,并确定机组增加垫片的最大厚度为0.2 mm,在机组大修中采用增加磁轭与转子支架之间的过盈量、机坑外对转子圆度进行了静态调整、机坑内动态调整等方法使机组运行中定转子空气间隙均匀.通过大修后进行的手动开机、过速试验、动平衡试验和升压试验,发现修后空载状态和带负荷运行下定子机架水平振动均大幅下降,修后机组磁轭与转子支架紧量增大,磁轭状态更加稳定.定子水平振动稳定在91 μm左右,设备的可靠性大大提高,保证了机组的安全稳定运行.

Discussion on over-standard treatment technology of stator vibration of super large hydrogenerator

The stator of Nuozhadu Hydropower Station was taken as the research object. Aiming at the problem of the damage of generating components caused by long-term high-intensity vibration of large-scale hydrogenerator stator, the causes of unit vibration were analyzed from the aspects of stator stiffness, rotor out of roundness, turbine tail water pressure pulsation, etc. The maximum integrated stress of the present structure of the rotor bracket has approached to the allowable stress and the maximum thickness of the gasket added to the unit is determined to be 0.2mm. In the overhaul of the unit, the interference between the yoke and the rotor bracket is increased, the rotor roundness is adjusted statically outside the pit, and the dynamic adjustment is conducted in the pit, so that the air gap between the stator and rotor is uniform during the operation of the unit. Through the manual start-up, overspeed test, dynamic balance test and boost test after overhaul, it is found that the horizontal vibration of the stator frame both under no-load condition and under load operation after overhaul is greatly reduced, and the tightness between the yoke and the rotor bracket is increased, and the yoke state is more stable. The stability of stator horizontal vibration is about 91 μm, and the reliability of the equipment is greatly improved, which ensures the safe and stable operation of the unit.