Analysis On Vibration Of Small-scale Francis Hydro Turbine Generating Units Test

Vibration is a ubiquitous phenomenon in all of the rotating machinery. As a kind ofrotating machinery, the hydroelectric generating set has many differences from the otherrotating equipment. There are a variety of forms vibration in the operation process ofthe hydroelectric generating set, and the causes of the vibration is very complex. It ismainly influenced by many factors such as electromagnetic, mechanical and hydraulic.The harm caused by the vibration of the hydroelectric generating set is very serious.Itnot only can cause structural damage, also affect the stability of power system, and evena threat to life safety of the operators. Therefore, the monitoring and analysis ofvibration of the turbine units have a positive and practical significance.In the hydropower industry of our country, the large-scale hydropower enterprisesattach great importance to the stability of hydroelectric generating set. They put intomore technology investment, and their technology is relatively mature. However, manyof the small hydropower station in our country all have vibration problems. On the onehand，because the operation income is relatively low, less investment and so on, thesmall hydropower stations generally have no run vibration monitoring equipments; Onthe other hand, the operating personnel’s quality is not high, they can not understand theharm of hydroelectric units vibration enough and lack the awareness of the hydropowerunit vibration. Besides, their lack of technical strength, and can not found unit operationproblems in time caused many units to run in spite of illness.The No.2hydroelectric generating set in the Xida hydropower station was theresearch object in this paper,it was a small hydroelectric generating set and it’s ratedpower is500kw. It built in the late1980s.In running process the vibration was existedand the temperature of the bearing oil rise after adding excitation recently. Do the fieldtest of the No.2hydroelectric generating set based on the condition of the hydropowerstation available. In the test,10working conditions were set and5groups of sensorswere installed to respectively monitor the great shaft’s pendulum of the turbine and thevibration of the upper frame, the lower guide bearing, the water-guide bearing and thehead cover. DASP-V10，as a software of vibration analysis,has been used to analysesthe signals and the data collected in the test. And it can compare the test date with thenational standard and evaluated the data. The causes of vibration was studied based on the related parameters, and found the shaft oscillation of the No.2hydroelectricgenerating set was beyond the national standard when it was running in most cases. Theaxle center trail in the process of increasing excitation and load change all in a widerange of the deviation. The main reasons for these problems is unbalanced magnetic pullinside the generator, the axis of the unit is not straight，and the hydraulic imbalancecaused by the change of the gate opening. The vibration on the upper frame, the lowerguide bearing, the water-guide bearing and the head cover of the hydroelectricgenerating set was beyond the national standard only in the process of startup andshutting down the turbine. The analysis of the vibration also can explain the causes ofthe vibration is consists of mechanical factors, electromagnetic factors and hydraulicfactors. The conclusion through the test and analysis, and the received conclusions willbe used to provide theoretical basis and guidance for the maintenance of thehydroelectric generating set in the future.