The Research On Influence Of Peaking Operation Of TGP Hydropower Station In Flood Period On The Upstream Navigation Conditions

The research on influence of peaking operation of TGP hydropower station in flood period on theupstream navigation conditions.According to TGP preliminary design, the TGP power station will be regulated during the dryseasons only. There are many researches and analyses on the influence of peaking flow to thenavigational conditions, and it is focused on the 38km river between the three Gorges project andGezhouba project. With the rapid development of national economy, the power station should beregulated during flood period daily in order to supply high quality electric energy for the market.Water level of three Gorges reservoir is 175m at dry reason and 145m in flood period. Unsteadyflow movement upper formed by daily peaking operation is more violent in flood period than dryreason. For the shipping safety of Three Gorges Project, a physical model (1:100) experimenthas been implemented from 2002 to 2003.The physical model is to evaluate the daily peakinginfluence on upper flow conditions for navigation and it is supposed that the Three GorgesProject have been operated 50+4 years and 70+6 years under aggrading conditions.The research shows that, when power station unit opened negative wave is formed in reservoirand water discharge from channel and former cross current at the entrance area; when powerstation closed, phenomenon of water current is exactly the opposite. The amplitude of wave andcross current at entrance area is increasing with regulated discharge increasing, which almosthave nothing to do with initial discharge and regulated time (not more than 6min) of powerstation unit on-off. Berthing dolphin local slope is related to regulated discharge and regulatedtime, but there are no relationships with initial discharge. Under the condition that the dailyregulation discharge is maximal, the restriction for navigation of upstream approach channel isthe cross flow at entrance area right route and the wave amplitude behind ship-lift surpass TGPnavigation standards. By means of the experiments, the relationships between the amplitude oflock fore-wave, maximal cross current at entrance area and regulated flow of power station havebeen set up. Depend on this, we can analyze any possible flow condition in given daily regulatedcurve and can bring forward limiting conditions of navigation on daily regulated according tonavigation standards. When regulated discharge is fixed, amplitude of water level is responsewith section shape. Uncork guiding dividing duke can decrease the wave height in approachchannel during daily regulated. Power station units batch-stagger operating can markedlydecrease cross flow velocity at entrance area. The most disadvantageous operating mode is thattwin lock watering and closing power station (or swing load) are operating at the same time.Initial numerical model calculation and analyse indicated that with the silting years increasing,daily regulated flow condition for navigation gradually become more disadvantageous.The mobility mechanism of positive and negative wave has been proved further by means of theresearch of way of model inlet wave absorption of the reservoir. Wave reflection at inlet of dailyregulation is reduced by changing of discharge of inlet, then improved efficiency accurate of theexperiment, and founded the basis of improving experiment of daily regulation in reservoir.