机械不平衡及轴瓦间隙对水轮机运行稳定性的影响分析

机械不平衡及间隙过大等问题是水力机械不平衡的主要原因,通过对45 MW轴流转桨式水轮机进行稳定性试验,包括空载、变转速以及变负荷试验,并对监测到的振动和摆度数据进行频谱分析以及主轴轴心轨迹分析,发现机组同时存在转子质量不平衡问题及间隙过大问题。为降低机组振动及摆度幅值,通过键相位法快速确定机组的质量不平衡点,并进行配重;又根据轴心轨迹特性逐步调整上导及水导间隙。通过三次配重试验,最终确定配重质量为36 kg,结合轴瓦间隙调整,上机架、顶盖等部位的振动幅值以及上导和水导的摆度幅值均有效降低至安全运行范围,提高了机组的运行稳定性。通过试验,验证了联合分析振摆特性和轴心轨迹对于综合判断机组多重因素引起振动问题的有效性,介绍了剔除干扰因素并确定直接影响因素的试验和分析方法,能够有效降低试验次数,快速确定故障原因,并提高故障诊断的准确率。

Analysis of the Influence of the Mechanical Imbalance and the Bearing Clearance on the Operating Stability of Hydro-power Unit

The operating instability of the hydro-power units is often caused by the mechanical imbalance and the excessive bearing clearances. In order to identify the reasons for the vibration of a 45 MW Kaplan turbine, the stability test is done to obtain the vibration and swing information. Through the spectrum and shaft orbit analysis, the reason for the vibration is found out to be the mechanical imbalance and the excessive bearing clearances. The clearances are adjusted and the balancing test is taken using the key phase point method to reduce the amplitude of the vibration and swing. After the clearance is adjusted and 36 kg balance weight is added to the rotor, the amplitude of the vibration and the swing are all reduced into the allowable range. Which means the joint analysis method is appropriate for the vibration problems caused by multiple factors. The spectrum and shaft orbit joint analysis can reduce the number of tests and improve the accuracy of fault diagnosis. And the step by step test and analyze method which can quickly identify the main reason among a lot of reasons is clearly introduced.