| With the continuous development of my country’s economy and society,the demand for water for urban and industrial and agricultural development continues to grow,and some areas even sacrifice agricultural water to meet urban domestic and industrial water use.The normal operation and protection of the economy,society,and environment have been seriously affected by water shortages.The shortage of water resources has become increasingly prominent.Therefore,a number of large-scale water transfer projects have been built in China.The completion and operation of such projects have effectively alleviated the problem of uneven distribution of water resources in time and space,promoted the rational allocation of water resources,and effectively guaranteed the needs of social and economic development.The first phase of the East Route of the South-to-North Water Diversion Project is 1,467km long.It draws water from the Yangtze River from Yangzhou,Jiangsu Province in the lower reaches of the Yangtze River,and uses the Beijing-Hangzhou Grand Canal and its parallel natural channels to carry water to the north step by step.It also connects Hongze Lake,Luoma Lake,Regulatory storage reservoirs such as Nansi Lake and Dongping Lake.After leaving Dongping Lake,there are two roads for water delivery:one way goes north,crosses the Yellow River,and delivers water to Tianjin;the other way goes east,and delivers water to Shandong Peninsula through the main water delivery line in Jiaodong area.A total of 13 cascades and 34 pumping stations have been set up across the line,with a total lift of 65m,a total installed number of 160 sets,and a total installed capacity of 366,200kW.The project is mainly equipped with low-lift water diversion pump stations,which have long running time for annual water diversion,large single-machine flow rate,and high annual energy consumption.In the current actual dispatching operation process,the project dispatching operation plan is usually determined according to the operation management experience.When the upstream and downstream water levels change,the length of water lifting and the total amount of water are variable,the unit operation plan cannot respond in time under certain working conditions,resulting in water transfer.The overall operating efficiency of the pumping station is low.Under the current double "carbon" background,it is very important to carry out the research on the optimal operation of the pumping station system with the goal of saving energy and reducing consumption.At the same time,relevant studies have shown that during the optimal operation of the pumping station,the pump unit adjusts the blade placement angle(or unit speed)in real time to adapt to the upstream and downstream water level changes,resulting in large differences in water flow between time periods and units,which is easy to be lost in the pumping station.The effluent pool forms a large backflow area or folded water flow,resulting in certain wall erosion,which is not conducive to the stable and safe operation of the pump station.In addition,at present,the pump unit of the large variable angle operation pump station can not fully adjust the blade placement angle according to any angle in the actual operation process,so that the blade placement angle of the pump unit in the same period of the previous optimization calculation can not be completely consistent,and it is difficult to really apply to the actual operation of the pump station.If the blade placement angle of each unit is completely consistent in each period,the actual water extraction during the water diversion period will be higher than the target water extraction,resulting in an increase in the cost of water extraction and power consumption.Aiming at the multi-objective optimization operation problem of single pumping station and parallel pumping station group for cross-basin water transfer,this paper mainly carries out the following aspects of work:(1)Aiming at the multi-objective optimization operation of a single pumping station,the objective function is to take the lowest water-lifting power consumption and the smallest flow difference between units within the pumping station’s operation cycle,and the water-lifting volume and motor power of the pumping station are constrained to construct a model that considers the span The multi-objective optimization operation of the complex nonlinear mathematical model for the water transfer pumping station in the basin is proposed,and a multi-objective genetic algorithm(NSGA-II)solution method based on Pareto theory is proposed.At the same time,considering that the Pareto solution set directly output by the algorithm contains multiple operation schemes and cannot be directly applied,an evaluation method for each scheme in the Pareto solution set is proposed.Taking Jiangdu No.4 pumping station,the source of the east line of the South-to-North Water Diversion Project as an example,the optimal operation scheme under different daily average lifts and different water lifting loads was obtained.The results show that when the average daily water lifting head is 3.8m,4.8m,5.8m,6.8m,and 7.8m,the unit water lifting cost of the optimized operation is lower than that of the conventional operation at 100%,80%and 60%of the water lifting load,respectively.The average savings are 12.44%,14.26%and 3.69%,and the corresponding flow unevenness increases by 9.67m~3/s,8.56m~3/s and 8.36m~3/s on average compared with the conventional operation,but compared with the operation plan corresponding to the minimum cost point in the Pareto front The average reduction of 100%,80%and 60%water lifting load is 64.82%,58.12%and 56.27%respectively,which provides theoretical support for realizing the optimal operation of parallel pumping station groups.(2)For the cross-basin water transfer parallel pumping station group that undertakes the joint water transfer task by multiple pumping stations,a pumping station group with the lowest water and power consumption cost and the smallest flow difference between the units of each station within one operation cycle is constructed.,a large-scale system mathematical model with constraints such as the water pumping capacity of the pumping station group and the motor power of each station unit.A large-scale system decomposition-dynamic programming aggregation method based on subsystem multi-objective optimization is proposed.Taking the Jiangdu parallel pumping station group as a research example,in the case of a typical daily average head of 7.8m,the optimal operation unit water pumping costs of each station unit were lower than the conventional operation unit water pumping costs by 3.16%,3.16%,and 0.48%respectively.%and 5.90%.Under the premise of meeting the constraints of the total amount of water pumped,compared with the conventional operation plan,the water pumped by Jiangdu No.1 pumping station and Jiangdu No.2 pumping station increased from 473.07×10~4m~3 to 482.65×10~4m~3,an increase of 9.57×10~4m~3,an increase of 2.02%;The pumping capacity of Jiangdu No.3 pumping station and Jiangdu No.4 pumping station in Jiangdu decreased from 1009.64×10~4m~3 and 1908.85×10~4m~3 in conventional operation to 741.09×10~4m~3 and 1868.24×10~4m~3 respectively,with a drop rate of 26.6%and 2.13%.At the same time,although the flow unevenness of each station increases by 2.16m~3/s,2.16m~3/s.0.60m~3/s and 14.10m~3/s respectively compared with the conventional operation,the increment is small,which can effectively ensure the long-term safe operation of each station.(3)Using the App Designer development tool in MATLAB,a multi-objective optimization operation decision support system module for water diversion and pumping stations was developed.By inputting the curve fitting parameters of the performance of the pumping station,the water lifting target,and the division of time periods,the model solution algorithm described in this paper is used to solve the problem,and the blade placement angles of each unit or the speed of each unit at each time period,and the optimized Pareto solution set can be output,Pumping station pumping water flow rate and water pumping volume and other optimization results in each time period.It can realize the multi-objective optimization calculation of the pumping station with full blade adjustment unit or variable frequency and variable speed adjustment unit,and can provide decision support reference for the management and operation department of large cross-basin water transfer pumping station. |
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