Abstract
Pumped storage units improve the stability of the power grid, and the key component is the pump−turbine. A pump−turbine usually needs to start and shutdown frequently, and the operating head varies greatly due to changes in the water level of the reservoir, which makes the dynamic behavior of a pump−turbine runner extremely complex. This paper investigates the effects of operating head on the dynamic response characteristics of a pump−turbine runner in turbine mode. The flow characteristics of the pump−turbine at maximum head, rated head and minimum head are analyzed, and the dynamic response characteristic of the pump−turbine runner are numerically studied. The results show that operating head can affect the pressure pulsation and dynamic stress characteristics of the pump−turbine runner, but it has little effect on the frequency spectra. The conclusions of this paper intend to improve understanding of the effects of the operating head on the dynamic behavior of the pump−turbine runner, therefore providing a theoretical reference for safe and stable operation of the pump−turbine unit.