Research On Vibration Characteristics Of Hydropower Plants Induced By Flood Release

With the rapid development of the hydropower industry,high dams or ultra-high dams with large flow and high flow rate have become the main trend of water conservancy construction in my country.The high dams currently planned and under construction in my country are in the leading position in the world in terms of dam height and discharge volume.However,due to the huge discharge drop of the high dam,the phenomenon that the high-speed water flow of the flood discharge induces the vibration of the discharge structure and other hydraulic structures frequently occurs.As an important place for converting water energy into electrical energy in a hydropower station,the powerhouse of a hydropower station has higher requirements for vibration control.The vibration of the powerhouse structure will not only affect the normal production and life,worsen the working environment,and even lead to the destruction of the powerhouse structure.In fact,some high-head,large-capacity hydropower stations that have been built in my country have already experienced the problem that the vibration of the powerhouse increases significantly during flood discharge.In view of these practical problems,it is necessary to study the vibration of the hydropower plant’s powerhouse induced by the discharge of the hydropower station.In this paper,a large hydropower station is taken as a case study,and the finite element numerical analysis method is used to study the vibration characteristics of the powerhouse vibration of the hydropower station induced by the spillway and the flood discharge and sand bottom hole discharge.The main research contents are as follows:(1)A three-dimensional finite element model including a spillway dam section of a hydropower station,a right-side flood discharge and sand bottom hole dam section and a unit section was established.and mode shape characteristics were analyzed respectively,and the calculation and post-processing command flow compilation based on Ansys APDL language was completed.(2)The pulsating loads were applied to the spillway and the sand-scouring bottom hole respectively,and the harmonic response was calculated,and the dynamic responses of the hydropower plant under the pulsating loads of the spillway and the sand-scouring bottom hole with different frequencies were obtained.The results show that: under the action of low-frequency pulsating load of 0.5Hz～2Hz,the dynamic displacement amplitude of the powerhouse increases with the increase of frequency.In addition,it is also found that although the flood discharge and sand bottom hole on the right is closer to the powerhouse,the same frequency The vibration displacement amplitude of the powerhouse caused by the pulsating load of the lower spillway is larger.(3)Divide the spillway and the flood discharge scouring sand bottom hole into sections,apply pulsating loads to each section respectively,and calculate the vibration response caused by the pulsating pressure load of each section of the spillway and the scouring sand bottom hole under the pulsating load of different frequencies,which accounts for the overall response.The vibration source of the powerhouse vibration induced by the pulsating load of the spillway and the scouring bottom hole was analyzed.The results show that the contribution percentage of each section of the spillway and the sand flushing bottom hole to the vibration of the powerhouse is mainly related to the magnitude of the pulsating pressure on each section and the relative position of each section and the powerhouse.Section 3 is the main vibration source of the powerhouse vibration induced by flood discharge from the spillway,and the main vibration source of the powerhouse vibration induced by flood discharge from the sand bottom hole on the right is the chute between No.1 and No.3 aeration sills.