| With the improvement of scale, water head and capacity of hydropower station, the overall dimensions of units and powerhouse continuously increase. This requires more safety and steady operation of units. So, the study of vibration stability of hydropower station becomes a key topic when it’s researched, manufactured and operation. At home and abroad, there are some obvious vibration problems about the structure of powerhouse in some high-water head and large capacity hydropower stations. Some of them are even destructive. Aiming at these situations, it is imperative to study the vibration principles of powerhouse. Hydropower station is always in such a strong noise working environment, so it is complicated of its measured parameters disturbance. In the vibration system of coupled vibration source and strong non-linear structure, it is a hotspot and difficulty to identify the vibration source component and the specific transmission path.This paper centers on the vibration transmission problems of hydropower station with complicated disturbance. By use of signal analysis theory, random vibration theory and vibration transmission theory, the analytical theory and calculation method about vertical transmission path of hydraulic vibration source are studied in hydropower stations. The problem is discussed about the gradient sorting of hydropower station vibration transmission. The accuracy of disturbance analysis is improved in the problem of random vibration. This study provides a theoretical reference for vibration stability analysis and vibration control. The main research contents and achievements include below:(1) A quadratic integral algorithm about hydropower station vibration test signal is provided in view of the features of hydropower station vibration signal, on account of the drift phenomenon of time domain integral and amounts of accumulated errors of frequency domain. This algorithm is based on EMD decomposition. It gets rid of the trend term error in frequency domain integral by use of the feature of EMD adaptive filtering. This accuracy of the algorithm is well demonstrated by example. This algorithm can reserve the complete frequency-domain characteristics of signal and can be used in practical projects.(2) When hydropower station is in operation, parameters are always accompanied by amounts of uncertain disturbances because that noise pollution is severe. Previous research only consider single disturbance. It is undoubted a shortage. Therefore, this paper probes that dual disturbance is used for describing the parameters’disturbance. The dual disturbance especially means a combination of multiplicative disturbance and additive disturbance.Then, this paper derives corresponding random vibration analysis method. The feasibility and efficiency of this method are verified by example.(3) On the basis of dual disturbance, the problems of structure random vibration are studied when disturbance correlation, parameter correlation and these two types’correlations exist together. The corresponding algorithm is then inferred. The influences of structure are analyzed about every correlation by example. Finally, the algorithm is applied in the analysis of transmission path of vertical vibration of hydropower station. The example illustrated that the correlation of parameter cannot be ignored in the condition of many parameters.(4) A more perfect simplified model of hydraulic vibration source vertical vibration is founded by introduction of head-cover system on the basis of previous model. This simplified model can be used for vibration transmission analysis. In consideration of complex disturbance of mass, stiffness and dampness, theoretical analysis and numerical computation about vertical vibration transmission path are conducted. The transmissibility and its probability characteristics are analyzed about each vertical vibration transfer path in frequency domain. Then, they are mutually verified by means of power flow theory. |
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