Vibration Test And Numerical Analysis Of Floor Of Pumped Storage Power Station

Because of the characteristics of high speed,high hydraulic head,frequent change of pumping and generating conditions,the vibration problems of pumped storage power stations are larger than those conventional hydropower stations.Moreover,the vibration is a kind of comprehensive response,which is stimulated by many factors such as structure,hydraulic,mechanical,electromagnetic,and so on.At present,the vibration is mainly studied by model test,numerical simulation and field measurement,but the mechanism of vibration is still unclear,and there is no unified vibration control standard for floor of pumped storage power stations.In order to research the floor vibration law of the pumped storage power station,the vibration of the floor is tested under various conditions;and the time and frequency domain of vibration acceleration,velocity and displacement are analysed.These testing conditions include power on and off conditions,pumping and phase adjustment conditions,steady-state operation of different loads,load rejection and accident shutdown conditions.The harmonic response method is used to simulate and calculate the vibration of the power station by the finite element software ANSYS,and the results are compared with the measured ones.The main contents and results are as follows.(1)On the whole,the vibration of the floor is smaller under the steady state condition,while the vibration of the floor is larger under the unsteady state condition.For 75% and 100% load rejection condition and pumping accident shutdown condition,although the process only lasted for a few seconds,because of its large vibration,these conditions should be avoided,so as to prevent damage of the floor.The vibration of turbine layer and middle layer is larger than that of volute layer and generator layer.(2)The laws of vibration acceleration,velocity and displacement have both similarities and differences.Under steady-state operation conditions of different load,with the increase of the proportion of low frequency frequencies,the positions,where the maximum value of vibration-related physical quantities appears,d ecrease gradually.Under different load rejection conditions,the vibration increases with the increase of lost load;and the positions of the maximum values mostly appear on the turbine layer.(3)The frequency components of vibration acceleration mainly include high frequency,mainly double the blade frequency(112.5Hz),vibration displacement,low frequency,and vibration velocity,both high frequency and low frequency.From the three-dimensional spectral,it can be seen that the frequency composition of the steady-state working condition changes little with time;and the frequency composition is very stable.However,for unsteady conditions,the frequency composition is very complex,which changes constantly;and the vibration amplitude increases sharply in the process.The changing process of rotational speed of turbine can be seen from the three-dimensional spectrum of 100% load rejection condition.(4)According to the pulsating pressure experiment of the model machine,six kinds of calculation schemes are designed.Through analysis,it is found that there exists some difference about values and laws between the results of numerical calculation and field measurements.The similar relationship between the model machine and the prototype should be studied in depth;and the numerical simulation calculation scheme should be optimized.It can be seen from the vibration contours that the locations of selected measuring points may not be the largest vibration positions.And the location of the measuring points should be optimized.