Hydraulic stability analysis of a pumped turbine with wide load operation in part-load turbine mode

Abstract Pumped storage units with stable operation in wide load areas play an important role in effectively absorbing new energy sources such as wind power and photovoltaics. Wide load pumped storage units generally refer to the area where the stable operation of power generation conditions can be extended to less than 50 % load. A pump turbine with wide load operation with a five-splitter-blade runner was chosen for unsteady simulation. The SST-CC turbulence model is used to carry out three-dimensional numerical calculation of the pump turbine with wide load operation, and the unsteady flow characteristics and pressure fluctuation of the pump turbine under the working condition of the turbine are explored. The results show that the flow is more disordered under lower load and lower efficiency. With the unstable evolution of the flow, the pressure fluctuation amplitude in each component shows an inconsistent distribution. The hydraulic loss and flow cause of the pump turbine under small opening (low load) conditions are analysed in detail. In addition, the amplitude and spectrum characteristics of pressure pulsation are analysed.