As the core for energy conversion in pumped storage plants, the pump turbine is also a key component in the process of building a clean power grid, owing to its fast and accurate load regulation. This paper introduces the current status of research and development of pump turbines from the perspectives of significance, design and optimization, operational performance, advanced research methods, etc. Internal and external characteristics such as transient flow evolution, structural vibration, flow-induced noise, etc., not only reflect operational performance (hydraulic, cavitation, sediment abrasion, and stability performance, etc.) but also directly affect the safe and efficient operation of the system. It is worth mentioning that the space-time evolution of internal and external characteristics is an emerging research direction, the results of which can be used to predict the operational conditions of pump turbines. Moreover, the development and application of intelligent condition monitoring and fault diagnosis aim to prevent failures and accidents in pumped storage plants.

The load regulation capability of hydropower station ensures power system efficiency and stability while supporting the development of renewable energy-integrated smart grids. Seeking a better way to study internal fluid characteristic and performance of turbine is a long-standing subject, numerical simulation demonstrates significant advantages due to its cost-effectiveness and fully visualization capabilities, with turbulence models playing a pivotal role in ensuring simulation precision. A dynamically defined MPANS (Modified Partially Averaged Navier Stokes) turbulence model is developed in this work by integrating considerations of real-time turbulence scale and mesh size. Comparative analyses between experimental data and numerical results reveal that the MPANS model exhibits a higher degree of agreement with experimental data. Compared with RNG (Renormalization Group) k-ε model, MPANS significantly reduces the maximum deviations in torque, efficiency, and water head. Under steady conditions, the vortex volumes captured in the runner and draft tube are increased by 18% and 126% with MPANS, respectively, relative to those predicted by the RNG k-ε model. Under load-increasing condition, the vortex volumes in the runner and draft tube show increases of approximately 6% and 87% with MPANS, respectively. Parameter like eddy viscosity is considered based on flow characteristic, MPANS demonstrates enhanced capability in resolving intricate details of vortex structure and offers a more comprehensive depiction of dynamic vortex evolution, under both steady and transient condition of Francis turbine.

This study proposes the water hammer energy difference (WHED) method based on unsteady flow energy and continuity equations, as well as the propagation laws of water hammer in closed pipes, and verifies its accuracy. Additionally, the parameter evolution patterns of typical transient conditions in pumped storage power plants are investigated based on WHED. The application of WHED in the transient processes of hydropower plants (HPs) is validated by experiments, showing a maximum error of about 7% between numerical and experimental results under conditions of initial load increase followed by decrease (H_R = 184 m). Additionally, WHED was validated under two critical conditions in pumped storage plants (PSPs): 90% load rejection in generating mode and emergency power-off in pumping mode. In PSPs, the results of WHED are consistent with those obtained using the method of characteristics (MOC), with a maximum fault tolerance rate Δ < 3%. Notably, WHED offers superior time efficiency when analyzing hydraulic transitions in complex pipe networks, as it directly considers boundary conditions at both ends of the pipeline and hydraulic machinery, whereas MOC requires dividing the pipeline into multiple segments with a series of boundary points. Lastly, WHED’s energy parameters are used to describe flow stability from a physics perspective, explaining the causes of pressure fluctuations during transient periods in HPs and PSPs. These findings offer valuable references and guidance for the safe operation of PSPs and HPs.