Short-term Optimal Scheduling Of Cascade Hydropower Stations Considering The Influence Of Head-sensitive

During the past two decades,China has formed a large-scale hydropower dispatching system,which is mainly concentrated in southwest China.The cascade hydropower stations not only include a large number of hydropower plant with multiple turbines in one tunnel with high water head and large head variation,but also include hydropower plant with head-sensitive,which has a significant role in frequency control and peak load regulation tasks.The short-term load distribution problem has always been a hot and difficult research.Modelling and solving the short term load distribution problem for these stations is extremely difficult due to mutual interference between water head and complication in hydraulic and electric constraints of cascade hydropower stations.In this paper,the short-term optimal operation of the key problems faced by the cascade hydropower stations under sensitive water heads in southwest China,and takes the cascade hydropower stations on Nanpanjiang of Hongshuihe as the background.The main work completed and the conclusions obtained are as follows:(1)Short-term load dispatching MILP model for a hydropower plant with multiple turbines in one tunnel with head-sensitive.Many large hydropower stations adopt long-distance water diversion power generation mode with multiple turbines in one tunnel.These stations are characterized by large installed capacity,high water head,the complication of head loss and multi-hydroturbine sets sharing a common penstock.The MILP model considering the combined load distribution of the tunnel and the unit is constructed,and the reasonable piecewise linear head loss was obtained by introducing the 0-1 integer variable to actually indicate the limit of unit start and shut,and the existing three-dimensional difference method was used to better realize the relationship between output,head and power release,and the influence of head was comprehensively considered.According to the typical daily example of a hydropower station in Hongshuihe,the method can effectively guide the short-term load distribution of the hydropower plant with multiple turbines in one tunnel with sensitive water head,and provide an effective guarantee for the economic operation of the hydropower station.(2)Short-term load distribution method for diversion hydropower plant with multiple turbines in one tunnel using a two-stage model.In view of such problems as large head variation,complex hydraulic interference between units and low efficiency of MILP model,two-stage modeling is adopted in this paper: In the first stage,units on/off model considering duration constraints is established,and then be solved by the heuristic searching method and progressive optimal algorithm to determine the combination of start-up tunnel and unit on/off status.In the second stage,load distribution model using the criteria of determining water consumption by generation is established and then be solved by dynamic programming for optimal load distribution given the achieved on/off status of tunnel and units in the first stage.The proposed method is tested in the load distribution problem for the hydropower station of Basin Hongshuihe in dry-season under different typical load rates.Results could meet the practical operation requirements and demonstrate the practicability of the proposed method.(3)Research on short-term peak load peak regulation optimization model for cascade hydropower systems based on power control.In view of the problem that the cascade hydropower stations under head-sensitive can adjust the peak load reasonably under the multiple constraints of the power grid and the power station,the peak load peak regulation maximization model of cascade hydropower stations based on power control is constructed and the corresponding solution method is proposed.The contract electric quantity distributed to each power station is taken as electric quantity control constraint and solved by progressive optimal algorithm.The example for the cascade hydropower stations case of Nanpanjiang in Hongshuihe gives full play to the peak regulation function of the cascade power station under the daily optimal electric quantity and control constraints.At last,a brief summary is summarized and the future work is prospected.