Research On Dispatching Of Cascade Hydropower Stations During Water Storage Period Adapted To Grid Demand

With the construction and operation of large-scale hydropower stations in each basin,the pattern of joint operation of cascade hydropower stations under regional power grid has been formed in China.However,the mode of separation of power plant and grid makes it difficult for each hydropower station to respond to the change of grid load,not only to make full use of water resources,but also to unify the operation mode of hydropower and grid demand.Especially in the impoundment period,the original planned impoundment operation scheme at the end of flood season will cause the competitive impoundment problem among the reservoirs,hinder the normal operation of the power station,and further intensify the impact on the safe and stable operation of the power grid.It is difficult for the traditional optimal dispatching method to solve the peak load regulation problem under the situation of grid interconnection,so it is urgent to find new theories,models and methods to carry out research.Therefore,focusing on the key scientific problems faced by the downstream of Jinsha River and the Three Gorges cascade hydropower station to adapt to the needs of central China Grid,this paper has carried out in-depth research on the efficient solution method of the medium and long-term peak load regulation and scheduling model of hydropower station,the peak load regulation and scheduling of the Three Gorges Hydropower Station during the impoundment period with multi frequency inflow runoff,and the impoundment period scheduling of the cascade hydropower station to meet the needs of the grid,with the main work content and innovation The research results are as follows:(1)Aiming at the peak load regulation demand of the power grid during the impoundment period of the hydropower station,the medium and long-term peak load regulation model of the hydropower station is established with the minimum mean square deviation of the remaining load of the receiving power grid as the goal.In this paper,the water level corridor method is used to deal with the constraints of medium and long-term optimal operation of hydropower stations.The case study of Three Gorges power station and central China power grid shows that the improved Stochastic Fractal Search algorithm(SFS)is larger than the actual operation and heuristic load shedding method in peak valley difference reduction degree and residual load mean square deviation reduction degree,which realizes the water storage peak regulation of Three Gorges power station,verifies the applicability,superiority and stability of the algorithm in the model solution,and provides a kind of medium and long-term peak regulation dispatching for hydropower station A new solution.(2)In order to explore the influence of the uncertainty of the inflow during the Three Gorges impoundment period on the impoundment and peak regulation effect of the Three Gorges,the frequency distribution curve of the inflow runoff during the impoundment period of the Three Gorges is fitted,and the inflow process of each runoff frequency during the impoundment period of the Three Gorges is deduced.In order to ensure the power generation during the impoundment period of the Three Gorges,the correlation between the average inflow flow and the power generation is analyzed,and the quantitative relationship between them is obtained.On this basis,a medium and long-term peak load regulation model of hydropower station is established,which is controlled by the end water level and the total generating capacity at the same time.The case study of Three Gorges power station and central China power grid shows that the peak regulation effect is the best when the frequency of inflow runoff is 40%-60%,while the peak regulation effect is relatively limited in the extremely high and low seasons.Based on the contradiction between Xiluodu,Xiangjiaba and the Three Gorges power station,and the influence of the Three Gorges output mode on the central China power grid,the peak load regulation model of cascade hydropower stations is established.Combined with the improved SFS and successive approximation method,an efficient model solving method(SA-SFS)is proposed.The case study results of Xiluodu,Xiangjiaba and the Three Gorges cascade hydropower stations show that the optimal operation of peak regulation of cascade hydropower stations can not only meet the water storage task of cascade reservoirs,but also achieve better peak regulation effect than single station,which effectively responds to the peak regulation demand of central China power grid.It provides a reference for the operation of cascade hydropower stations during the impoundment period and has a certain engineering application value.