A novel multi-excitation transient vibration framework for coupling three- and one-dimensional pumped storage hydropower shafting systems.

The article focuses on developing a hydraulic–mechanical–electric multi-excitation transient vibration calculation framework to analyze the relationship between shafting vibration and internal flow regimes in pumped storage power stations (PSPSs) during transient processes such as load rejection. By coupling one-dimensional (1D) method of characteristics (MOC) models with three-dimensional (3D) computational fluid dynamics (CFD) simulations, the study achieves improved accuracy in predicting turbine speed fluctuations and flow-induced forces compared to traditional methods, with less than 1.2% error relative to field tests. The framework reveals that shaft vibrations in the radial direction correspond closely to runner speed changes and stall rotations, while axial vibrations relate to axial hydraulic thrust, and that multiple excitation factors produce more complex shaft motion, especially under braking and reverse pumping conditions. Limitations include the weak coupling between 1D and 3D models and the exclusion of cavitation effects, suggesting directions for future research to enhance transient vibration modeling in hydropower units.