Study On Long-term Optimal Scheduling And Combined Dispatching Chart Of Cascade Hydropower Stations

As a major initiatives advantageous to the public of economic development and structural adjustment, the state attaches great importance and vigorously support to the construction of large water conservancy project, putting the development of hydropower cause in a prominent position in the energy construction. Cascade rolling development is being designed or has already bean realized among a number of basin. The constitution of cascade hydropower system becomes more complex of the basin and inter basin. Inter basin management, centralized power supply and comprehensive coordination will be the overall trend of hydropower station group in the future development. The existing mode of the operation of producting and the management of dispatch has been difficult to meet the actual demand, and only the implementation of joint optimization scheduling and compensation adjustment can realize the comprehensive benefits of the cascade.This paper comprehensively considering the issue of joint optimization scheduling and the compensation of all sub cascades inside the system of cascade hydropower station group, combined with runoff relations between different sub cascades, establishing mathematical model and putting forward the corresponding solving methods with conventional scheduling, optimization scheduling and dispatching graph scheduling method respectively, in order to maximize the generation efficiency of the whole basin hydropower system. The main achievements of this dissertation are as follows:(1) Study on comprehensive evaluation of annual runoff based on Set Pair Analysis. Due to the deficiency of existing methods for evaluating annual runoff based on Set Pair Analysis, an improved method for appraising the abundance characteristic was presented, considering uncertainty in classification of annual river runoff. Firstly, an effect weighting factor and evaluation attribute matrix was adopted to make clear the influence of the annual amount of runoff and its features of distribution in a year on the evaluation. Then the difference of distinct degrees was described by grade deviation coefficient based on frequency analysis. Afterwards, the abundance level of annual runoff was evaluated and classified by Set Pair Analysis.(2) Study on long-term optimal generation scheduling of cascade hydropower stations. Fully considering hydraulic and electric contact of cascade hydropower stations, long-term joint optimization dispatching model of cascade hydropower stations is established, with a hybrid nested algorithm combined by the dynamic programming algorithm and progressive optimization algorithm to implement efficient solution of model. Taking the hydropower system of Ertan-Tongzilin, Xiluodu-Xiangjiaba and Three Gorges-Gezhouba cascade hydropower stations as a case study, according to the history long series of annual and classification results runoff in different dry level, the method is applied to the joint optimization calculation of cascade, revealing compensation characteristics and operation rules of different scenarios in different dry level of joint dispatching of cascade hydropower station, to significantly improve the power generation efficiency and provide theoretical guidance and scientific basis for the actual operation of cascade hydropower stations.(3) Study on combined dispatching chart of basin cascade hydropower stations. Based on the initial normal single dispatching charts of Ertan, Xiluodu, Xiangjiaba and Three Gorges hydropower stations, an approach was proposed to achieve the combined dispatching chart of cascade hydropower stations for the joint scheduling of the whole basin hydropower stations, separately in the type of Level-Output and Enerty-Output, with the leading station at upper reaches as the main controlling object of each sub-cascade. The combined dispatching chart was optimized by output allocation and adaptive discrete differential progressive optimality algorithm to maximize the generating capacity of the cascade hydropower stations and the whole basin hydropower system separately, by means of simulation calculation with history runoff data. Finally, the combined dispatching chart of the hydropower system of Ertan-Tongzilin, Xiluodu-Xiangjiaba and Three Gorges-Gezhouba cascade hydropower stations under different circumstances are provided and simulation results indicates that the optimized combined dispatching chart can significantly improve the power generation benefit of the hydropower system guaranteeing the output of each sub-cascade, successfully to provide reference for practical engineering application.