Abstract:The optimal dispatching for flood control of reservoir can reduce floods

achieve floodwater utilization and improve the operating efficiency of reservoirs.However

the previous studies on combined flood control dispatching of cascade reservoirs only give calculation of flood discharge capacity of reservoirs without the consideration of the specific opening of gates.The gate opening and closing conditions of hydropower stations are summarized and the digital forms of flood discharge gates are prepared in accordance with the operation requirements of gates.The digital forms of gates are used to solve the constraints of flood discharge of gates.The preparation of digital forms requires calculation of several sub-units

each of which is composed of gate combinations within a specific range of flow rate at a given water level.Each unit contains a number of different ways of combination

each of which includes a number of representative gate combinations.The application of digital forms can depends on the expected let-down flow rate of hydropower stations.Dichotomy can be used to seek for gate combination scheme

and the minimum sum of squares of deviations of gate opening and the minimum change of gate opening can be used as the objective functions.Correction can be made to the error between the let down flow rate of gate and the flow rate calculated with the multi-step progressive optimality algorithm so as to make real time allocation for the flood discharge capacity of hydropower stations and adjust the gate opening in a quicker and more accurate way.A sample calculation is conducted based on the optimal dispatching for flood control of cascade reservoirs at the downstream of a river basin.The opening times of gate of hydropower stations are reduced after considering the fact that the let-down flow rate of optimal dispatching for flood control of gates in operation is more uniform than that of the original hydropower station inactual operation and through comparison and optimization of the gate openings in two adjacent time intervals

thus obtaining the optimal dispatching of gates in operation superior to the actual dispatching.The results indicate that the method using digital forms of flood discharge gates is correct.