Abstract
Transient analysis in diversion pipelines should be performed to ensure the safety of a hydropower system. After the establishment of a three-dimensional (3D) geometric model from the part upstream reservoir to the diversion pipeline end in a pumped storage hydropower (PSH) station, the hydraulic characteristics of the diversion system were solved by Reynold average Navier–Stokes (RANS) equations based on a volume of fluid (VOF) method under the condition of simultaneous load rejection of two units. The variations of the water level in the surge tank, the pressure at the pipeline end, and the velocity on the different pipeline sections with time were obtained through the calculation. The numerical results showed that the water level changing in the surge tank simulated by VOF was consistent with the field test data. These results also showed that a self-excited spiral flow occurs in the pipeline when the flow at the end of the pipeline was reduced to zero and its intensity decreased with the flow energy exhaustion. The discovery of the self-excited spiral flow in the study may provide a new explanation for the pressure wave attenuation mechanism.
Highlights
The increasing popularity of renewable energy in power systems requires large-scale energy storage technology to compensate for their intermittency [1]
3D numerical of the was longcarried water diversion with a surge tank during the load The rejection process ofsimulation the pumped storage hydropower (PSH) station out using system a volume of fluid (VOF) two-phase flow model, and it load rejection process of the station was carried out using a two-phase flow model, and it can intuitively reflect the change of water level in a surge chamber at any time
The numerical results can intuitively reflect the change of water level in a surge chamber at any time
Summary
The increasing popularity of renewable energy in power systems requires large-scale energy storage technology to compensate for their intermittency [1]. Station is an ideal peaking and emergency appliance because of its flexible operation and quick response. It is suitable to use as the peaking load shifting, and has several performances and dynamic benefits such as frequency and phase modulation, emergency reserves, black startup, and load adjustment, among others [2,3]. In the PSH station and diversion power station, a long pipeline is always connected to the front of the unit spiral case and the tail of draft tube [4]. It is necessary to investigate the changing process of the water flow in a pipeline to ensure the safety of the hydropower systems [8]
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