Reservoir Multi-year Regulating Strategy And Hedging Optimal Dispatching Method Under Multi-water Demand

With the development of economy and society,the shortage of water resources becomes more and more serious.How to utilize and allocate the limited water resources is very important.As one of the effective methods of water resources comprehensive utilization,reservoir optimal operation becomes one of the hot issues.Based on the analysis of reservoir runoff characteristics,stochastic simulation and prediction,this paper takes Danjiangkou Reservoir as an example to study the reservoir multi-year regulating strategy and hedging optimal dispatching method under multi-water demand.The research achievements in this paper mainly include the following aspects:Firstly,based on the analysis of annual runoff characteristics of Danjiangkou reservoir,the non-periodic components and periodicity components of the historical annual runoff are identified.A stochastic simulation model of annual runoff based on EEMD-AR is proposed and applied to stochastic simulation of annual runoff in Danjiangkou Reservoir.Through the EEMD decomposition,the problem that the historical runoff sequence of Danjiangkou reservoir is nonstationary sequence and can not be directly applied to the stochastic simulation of AR model is solved.The simulation results show that EEMD-AR model can well simulate and predict the annual runoff sequence of Danjiangkou reservoir and keep the statistical characteristics of the original historical sequence.Secondly,based on the EEMD-AR runoff simulation model of Danjiangkou Reservoir,the multi-year runoff sequence with different frequencies is obtained,and a multi-year optimal operation model is established by taking the uncertainty of runoff and the water demand of the middle line of South-to-North Water Transfer Project(SNWTP)into account.According to the evaluation of cumulative power generation,storage rate and integrated water shortage index SI,the influence of inflow uncertainty,starting water level(SRL),flood control level and water level at the end of year(WLE)on the multi-year operation of Danjiangkou Reservoir is derived.Finally,the optimal SRL and of the recommended range of WLE under the multi-year schelduling after the heightening are proposed,and the reservoir regulating strategies under different inflow scenarios are summerized.Thirdly,based on the traditional two-stage hedging dispatching model,the calculation of water anomaly index,the consideration of time factors and the division of drought severity in Palmer are introduced into the evaluation of water supply in reservoir operation.The water supply anomaly index Z_i,the accumulated water shortage index X_i and the water shortage severity classification are put forward.Through the adjustment of the weighting factor w,which corresponds to the different severity of water shortage,the improvement mechanism of parameters and a multi-stage optimal hedging dispatching model which considers the cumulative effect of water shortage are established.Fourthly,the optimized hedging dispatching model considering the cumulative effect of water deficit is applied to the Danjiangkou Reservoir.Based on the evaluation of multi indexes,some operation suggestions on Danjiangkou Reservoir with multi-water supply demand under dry inflow condition are proposed.The main conclusions are as follows:(1)In the typical dry year and the historical driest year,the initial optimal w is 0.7 and 0.15,the SRL should be greater than 158m.The delivery rate of the SNWTP water should be controlled at 0.85 and 0.4 respectively.(2)Using the available water is an effective way to relieve the serious degree of water shortage by combining the forecasting runoff results,the current adjustment level SRL and the expected final water level.(3)For multi-water supply reservoirs,the reasonable order of water supply should be determined on the basis of unit water supply economic benefit of each water user.