Multidimensional coupling characteristics of "flow-structure-life" and damage assessment of pumped storage units in new power systems

In response to the severe structural safety challenges faced by pumped-storage units due to frequent operating condition transitions and unsteady operation under the new power system, this paper constructs a “Flow-Structure-Life” multi-dimensional coupling assessment system for pumped-storage units. Firstly, by establishing a full flow passage fluid-structure interaction model, the unsteady flow field and structural dynamic response under pump mode and turbine mode were simulated. Subsequently, spectral and coherence analysis techniques were employed to elucidate the distinct mechanisms governing the transmission of fluid excitation energy to the structure across different operating modes. Finally, a fatigue life prediction model for critical components considering the operational weights of typical running conditions was proposed, quantifying the nonlinear sensitivity of fatigue life to flow regulation strategies in pump mode, and revealing a pronounced disparity between the fatigue-life sensitivities of pump mode and turbine mode operational strategies. The results demonstrate that reducing the annual proportion of operation under partial flow conditions from 20% to 1% via optimized control can significantly mitigate structural cumulative damage, indicating a potential order-of-magnitude extension in the relative fatigue life trends of the runner and guide vanes. These findings provide critical theoretical support and an evaluation framework for the scientific dispatching and refined operation and maintenance of pumped storage power stations.