Optimal Schedule Methods Of Reservoir Flood Control And Refill Operation

As many large reservoirs have been built in China during past thirty years, the main issure of water resources project has begun to transform from construction to management. Therefore, how to strengthen the reservoir group management to maximize the comprehensive benefits of flood control, power generation, nevegation and ecology protection, and to achieve the optimal scheduling and economic operation is the primary task and technical problem for water resources management. In this paper, Three Gorges Reservoir (TGR) and Qingjiang cascade reservoirs were selected as case studies. Optimal scheduel methods of reservoir flood control and refill operation were proposed and discussed. Main research and achievements are summarized as follows:(1) The reservoir operation theories, methods and the development progress were reviewed. Research progress of the reservoir flood control forecast operation, optimal operation and real-time scheduling were presented. In addition, the existing problems durin reservoir refill, including flood control risk, siltation, environmental and ecological problems were summarized(2) In order to overcome the phenomenon of premature convergence which is prevalent in swarm intelligence algorithm, a new algorithm named PDP (Parallel DE and PSO) algorithm was proposed. It is mainly based on the DE and PSO algorithm. The whole population is divided into two parts to keep parallel searching at early period, which can ensure the convergence rate. The convergence factor is introduced at later period to determine whether the populations fall into a local optimum and achieve the populations to escape from the local optimum district by extended operations.10standard test functions with different typical mathematical features were selected and100independent simulation experiments were carried on to verify the superiority of the algorithm.(3) To solve the problem of flood control system of joint operation for the Three Gorges and Qingjiang cascade reservoirs, separate and joint cascade operation flood control models were proposed. The models were solved by a modified progressive optimality algorithm according to the procedure of "optimization-verification-adjustment" and its constraint conditions are treated by dynamic penalty function. The results show that the proposed method of generating the initial solution can accelerate the convergence rate of the POA algorithm greatly. The flood control standard in the Jingjiang River reach can be raised to118-year and136-year design flood respectively based on1982typical flood. (4) There are mainly two difficulties in the process of solving the optimal flood control operation for the cascade reservoirs, which are the uncertainty of reservoir inflow forecasts and the complexity of solution for the optimization model. To solve these problems, a joint distribution function of upper and interval basin floods was established by using copula function and inflow hydrographs of cascade reservoirs were obtained by stochastic simulation method. Furthermore, a flood control optimization model for cascade reservoirs and a new algorithm, named Paralleled DE and PSO (PDP), were proposed. The proposed method not only can consider the variety and randomness of regional flood composition, but also can easier gain the optimum global solution than traditional optimal algorithms, which provides a new approach for flood control operation of cascade reservoirs.(5) The necessity of refill earily of the TGR was analyzed.30different schemes of impounding water in advance were proposed based on scheme of optimal operation and experimental impounding water for the TGR. A procedure coupled a flood control risk module with utilization benefits analysis module is then developed to derive the optimal refill rule. The application results show that the optimal rule is that refill begins on September1with storage level reaching160m on September30linearly.(6) A joint distribution function and conditional probability distribution of this samples using copula was build and inflow series in September were obtained by stochastic simulation method. Furthermore, a refill operation optimization model for the TGR was established to derive the optimal refill scheme. The results show that the optimal refill scheme depends on the reservoir inflow in late August. In the wet year, refill begins on late September with storage level reaching166m on September30linearly; In the normal year, refill begins on middle September with storage level reaching166m on September30linearly; In the dry year, refill begins on early September with storage level reaching166m on September30linearly by strengthening real-time monitoring.