Simulation of Hydropeaking Flows in downstream Reservoir of Hydropower Plants Cascade.

Zhaowei Liu, Manjie Li, Yongcan Chen

Wednesday 1 july 2015

9:00 - 9:15h at Europe 1 & 2 (level 0)

Themes: (T) Water engineering, (ST) Computational methods

Parallel session: 8E. Engineering - Computational

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 measures 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. We propose two methods for solving the problems. One is extending the simulated domain downstream with a large hydraulic gradient reach and specifying a constant stage at the downstream boundary. The other is using a modified non-reflecting boundary condition as the downstream boundary condition. Both methods are used and compared in the simulation of a hydropeaking flow in the Three Gorges Reservoir resulted from the planning upstream hydropower station.