The safe operation of drainage pumping stations, which are core flood-control facilities in eastern coastal areas of China, is paramount due to frequent typhoons and short-duration heavy rainfall. To enhance the operational safety against water hammer during pump trips caused by power failure, a water hammer protection method based on the combined application of flap valves and sluice gates is proposed. Only the scenario of all pumps tripping simultaneously was considered. A one-dimensional simulation model of the pumping station’s hydraulic transient process, which included pumps, pipelines, flap valves, and sluice gates, was established to analyze the system response under three scenarios: (i) only the flap valve closes normally, with the sluice gates remaining open, (ii) the flap valve fails, only the sluice gates operate, and (iii) the combined application of flap valve and sluice gates. In scenario (i), the maximum and minimum channel pressure heads were 13.53 m and −2.22 m, respectively, with no pump reversal occurred. However, continuous pressure fluctuations were observed downstream of the flap valve, posing a threat to the flow channel’s safety. In scenario (ii), the channel pressure heads all met the control requirements. Employing a 60 s single-stage linear closure rule for Gate #1 maintained the pump’s reverse speed within the safe range, peaking at −147.25% of the rated speed, with a reversal duration of 60 s. In scenario (iii), all channel pressure heads met basic control requirements, and no pump reversal occurred. The optimal strategy was found to be the adoption of a 60 s single-stage linear closure rule for both sluice gates. Compared to the scenario (i), the combined application reduced the amplitude of pressure fluctuations and damped these fluctuations rapidly, thus shortening the oscillation duration. The combined approach innovatively utilizes existing infrastructure for water hammer control, providing an economical and reliable solution for water hammer protection in urban drainage pumping stations.

To alleviate the pressure on grid regulation and ensure grid safety, pumped storage power stations need to frequently start and stop and change operating conditions, leading to the pump-turbine easily entering the hump characteristic zone, causing flow oscillation within the unit and significant changes in its input power, resulting in increased vibration and grid connection failure. The spatial distribution of energy losses and the hydrodynamic flow features within the hump zone of a pump-turbine under pumped storage operation are the focus of the study. The SST k-ω turbulence model is applied in CFD simulations of the pump-turbine within this work, focusing on the unstable operating range of the positive slope, with model testing providing experimental support. The model test method combines numerical simulation with experimental verification. The LEPR method is used to quantitatively investigate the unstable phenomenon in the hump zone, and the distribution law of energy loss is discussed. The results show that, at operating points in the hump zone, up to 72–86% of the energy dissipation is attributed to the runner, the guide vane passage, and the double vane row assembly within the guide vane system. The flow separation in the runner’s bladeless area evolves into a vortex group, leading to an increase in runner energy loss. With decreasing flow rate, the impact and separation of the water flow intensify the energy dissipation. The high-speed gradient change and dynamic–static interference in the bladeless area cause high energy loss in the double vane row area, and energy loss mainly occurs near the bottom ring. In the hump operation zone, the interaction between adverse flows such as vortices and recirculation and the passage walls directly drive the sharp rise in energy dissipation.