| Eastern Route of South-to-North Water Transfer Project is a large and complex step pumping station system. Because of large installed capacity and long operation time, optimal operation of the project is significant to reducing the cost of diverting water. At present, the factors and the optimal range have not been considered comprehensively in pumping station optimal operation, and the optimizing effect could be advanced. Optimal operation has not realized in most of the pumping stations. The operation cost is high and the energy is extravagant seriously. The constitutions of large pumping station system and energy losses were analyzed in the paper. Quantitative optimal selection methods of operation duty adjusting modes were researched for large pumping stations. Single pumping station system, parallel pumping station system and step pumping station system of the Eastern Route in South-to-North Water Transfer Project were calculated respectively based on multi-factors. Optimum operation schemes were obtained, and the operation cost was saved. The main works and the achievements are as follows:(1) The concept of pumping station system was put forward. Pumping station system is constituted by power transmission and transformation engineering, pumping stations and water transmission engineering. Energy losses of each part of step pumping station system were analyzed. Also, energy losses and system efficient of typical pumping station systems were calculated. The characteristics of pumping station system efficiency were revealed for the first time. The results indicated that the efficiency of pumping station system is according with the law of increasing at first and then decreasing with the pump assembly head increasing. Under the circumstances of certain pump assembly head, with the number of running pump units increasing, system efficiency of Baoying pumping station and Jiangdu 4th pumping station is increased at first, and then decreased. System efficiency of Jiangdu 2nd pumping station and Datao 3rd pumping station is increased continuely, and the system efficiency reaches the maximum when all the units are running.(2) On the basis of technical analysis on adjusting modes for large pumping station, several factors such as head variety, operation time, equipment investments and operation cost were considered comprehensively. Quantitative optimal selection methods of adjusting modes for pump unit operation duty were put forward. Aiming at 6 typical pump types, optimal operation of different adjusting modes were calculated and analyzed. The results indicated that under the premise of normal starting, the optimal adjusting mode is half adjusting blade angles when pumping station average head is locating high efficiency area, and also the head variety range is small. When pumping station average head is more deviated from high efficiency area or the head variety range is large, adjusting pump blade angles or rotational speeds by frequency is necessary to adjust operation duties. Because the variable frequency device consumes power and the equipment cost is high, its practicable range is very small. Time density distribution of pumping station annual operation head has a few influences on selecting adjusting modes. The effect of pumping station optimal operation by adjusting operation duties is more obvious with the decrement of the equipment cost.(3) Aiming at pump assemblies of constructed Linjiaba pumping station and Huaiyin 3rd pumping station of South-to-North Water Transfer Project, adjusting modes were selected with the quantitative optimal selection methods, which was put forward in the paper. The results indicated that the best adjusting modes of the two pumping station are both adjusting rotational speed by frequency conversion. This is because the relative variable ranges of the two pumping station head are large. Aiming at waiting for construction Jinhu pumping station, three feasible pump types were selected, and optimal operation schemes of different adjusting modes were calculated and analyzed. The results indicated that the adjusting mode by adjusting pump blade angles is suitable for Jinhu pumping station.(4) Genetic algorithms (GA), particle swarm optimization (PSO) and simulated annealing-particle swarm optimization (SA-PSO) were applied to calculate optimal operation of Jiangdu pumping station system in South-to-North Water Transfer Project. The results indicated that the operation costs by adjusting pump blade angles are 0.99%-4.22%less than that of the conventional schemes under design blade angles. And among the three optimum schemes, SA-PSO is more suitable for solving large pumping station optimal operation.(5) Under the circumstances of pumping certain volume water per day, considering pump assembly head varying along with the time, time-varying electrical price and regulating frequency by adjusting pump blade angles, optimal operation schemes of source Jiangdu 4th pumping station system were determined aiming at the least system operation cost. The results showed that the higher the regulating frequency by adjusting pump blade angles, the more the number of time periods per day is, while the optimal effect is obvious, and pumping station operation cost is decreased, which tends to some const. Considering the influences of frequently regulating on the reliability of regulating mechanism, the proper times of adjusting pump blade angles is 6-8. Compared with not adjusting pump blade angles, the operation cost is saved about 5.76%-17.63%by adjusting blade angles 8 times per day. Operation cost of the optimum schemes by adjusting pump blade angles and considering time-varying electrical price is 5.64%-12.13%less than that of design blade angles without considering time-varying electrical price.(6) Under the circumstances of pumping certain volume water per day, considering pump assembly head varying along with the time, time-varying electrical price and adjusting operation duties by adjusting pump blade angles, and optimal operation schemes of adjacent parallel Jiangdu pumping station system were determined aiming at the least system operation cost. Compared with the schemes of operation on design blade angles without considering time-varying electrical price, the operation cost of the optimum schemes is saved by 5.79%-18.64%.(7) Optimal operation for single line water transfer system was researched for the first time, which is starting from Sanjiangying of Yangtze River to Huai’an pumping station, passing by Jiangdu pumping station, including water channel, transmission and substation facilities. Under the circumstance of certain water level and discharge of Huai’an pumping station, system operation cost by adjusting blade angles are separately 0.62%-2.26%, 0.33%～3.26%and 0.22%-0.83%less than that of design blade angles with the maximum, average and minimum Sanjiangying tidal range of three typical days.(8) Optimal operation for double line water transfer system was researched, which is starting from Sanjiangying of Yangtze River to Huai’an pumping station, passing by Jiangdu pumping station and Baoying pumping station. Optimal models were built for the first time, and optimal discharge ratio of the two lines and system optimal operation schemes were solved by gradually approaching algorithm and two layer direct iteration. The results indicated that system input power of optimal discharge ratio is about 0.2%-2%less than that of design discharge ratio.(9) Optimal operation of the first section step pumping station with 3 steps was researched for the first time, which is starting from Yangtze River to Hongze Lake of Eastern Route in South-to-North Water Transfer Project. Optimal models were built and calculated by four layer iteration. When the water levels of Sanjiangying of Yangtze River and Hongze Lake are 2.19 m and 13.5 m respectively, and inflow discharge of Hongze Lake is 450 m3/s and 300 m3/s, optimal operation schemes were determined (including optimal head distribution among steps, optimal discharge distribution between parallel water diversion line, and pumping discharge, the number of running pump units and operation duties of each pumping station). The results indicated that when inflow discharge of Hongze Lake is 450 m3/s and 300 m3/s, system input power of the optimal operation schemes is 6.83%and 2.27% less than that of original design schemes. |
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