Effect of turbine's torque and speed variation on hydraulic vibration analysis during transient processes

• Published in: Energy science & engineering Vol. 12; no. 3; pp. 1137 - 1147
• Main Authors: Shen, Aili, Cui, Weijie, Zhou, Jianxu, Cai, Fulin
• Format: Journal Article
• Language: English
• Published: London John Wiley & Sons, Inc 01.03.2024; Wiley
• Subjects: Boundary conditions; Flow rates; Flow velocity; Forced vibration; Free vibration; Guide vanes; Hydraulic impedance; hydraulic turbine; Hydraulic turbines; hydraulic vibration analysis; Hydraulics; Hydroelectric power; Hydroelectric power stations; Impedance; Impedance method; Mathematical analysis; Matrix methods; Power plants; Pressure head; Pumped storage; Simulation; Stability analysis; Torque; Transfer matrices; Turbines; unit's dynamic characteristic; Vibration; Vibration analysis; Vibration damping; Vibration mode; Water conveyance
• ISSN: 2050-0505; 2050-0505
• DOI: 10.1002/ese3.1704

With the rapid development of large‐capacity hydraulic turbines and pumped‐storage power stations, hydraulic vibration analysis attracts increasing attention nowadays. To explore the influence of torque and speed variation on hydraulic vibration characteristics during transient processes and ensure the stability of hydropower stations, an improved analytical formula of turbine impedance involving the torque and speed variation was then derived. The free vibration analysis and forced vibration analysis using the transfer matrix method and the hydraulic impedance method were carried out. According to the numerical simulations, the obtained attenuation factors show differences in magnitude which illustrates that the torque variation and speed variation in transients do affect the damping rate of the vibration. In addition, the results indicated the natural angular frequencies of hydropower system were mainly dependent on the length of water conveyance system and pipe characteristics. It can be inferred form vibration mode shapes that for some specific frequencies, the magnitude of oscillatory pressure head and flow rate along the downstream tail tunnel are influenced by the hydraulic turbine. The correlation between the turbine impedance and guide vane openings tells that the hydraulic impedance is getting smaller as the opening increases. What's more, the corresponding free vibration analysis shows that the absolute value of the damping rate is closely related to the value of the flow rate. Exploration of turbine's torque and speed variation effect on hydraulic vibration characteristics during transients in hydropower stations.