Author(s): Zhaowei Liu; Manjie Li; Yongcan Chen
Linked Author(s): Yongcan Chen, Zhaowei Liu
Keywords: Hydropeaking; Hydropower Plants Cascade; Hydraulic Simulation; Boundary Condition
Abstract: In regulated rivers, hydropeaking is a common phenomenon caused by the rapid increase or decrease in the release of water from upstream reservoir hydropower stations when there is a great fluctuation in the demand for power. For a hydropower plants cascade, the flow in the downstream reservoir is significantly affected by upstream hydropeakings. In the present paper, we discuss associated problems and counteraction related with downstream boundary conditions when trying to simulate such artificial flows with a one-dimensional hydraulic model. Usually, the downstream boundary condition may be flows, stages or a rating curve. But none of them can be easily and correctly used in the simulation of hydropeaking flows in a reservoir: the flow at the downstream boundary is not easily available; stage errors at downstream boundary may be propagated throughout most of the domain due to a pretty small hydraulic gradient in reservoirs; a rating curve measured under natural conditions is not suitable for such artificial flow. A modified rating curve is proposed for solving the problems, by assuming a virtual broad crest existed at the downstream boundary. This method is used in the simulation of a hydropeaking flow in the Three Gorges Reservoir resulted from the planning upstream hydropower station. The computed results are compared and discussed with the ones obtained by using a constant water stage at the downstream boundary.
Year: 2015