Scheduling optimization of drainage pumping stations in urbanization polders

Abstract: For guaranteeing flood control security, the drainage pumping stations with large installed capacity were distributed densely at urbanization areas set with embankments. Conducting optimization research on operation scheme under different precipitation conditions lower than drainage standard should effectively decrease energy consumption. The main difficulty of operation scheme optimization of urban drainage pumping stations was that with the increase of pumping station quantity and single station's installed capacity, the combination number of feasible schemes increased too fast to be difficult to calculate. This paper proposed an optimization method which selected the lowest total energy consumption from multiple schemes with orthogonal test and eliminated unqualified schemes with controlling river water level outside the polder. Using this method, pumping stations in the drainage area were divided into different groups according to their actual layout, and a certain quantity of start-up schemes combined with practical experience were established for each group of pumping stations under different precipitation conditions. Then, taking pumping station group as the test factor, start-up scheme as the test level, and the lowest total electric power consumption as the objective function, the orthogonal experiment was carried out. The sequence of influence extent of various test factors and levels as well as the best test lever of each test factor to the target function could be obtained by conducting orthogonal analysis on test results. Thus the sequence of multiple optimized operation schemes including theoretically the best one could be obtained. Using the unsteady flow model to calculate each level of river water for each optimization scheme, and if each level of river water was within the allowable variation amplitude, the scheme was optimal and feasible, otherwise, the scheme could be crossed out. The operation scheme which met the requirement of the lowest total electric power consumption was found out from all of the feasible schemes, and taken as the best optimized scheduling method under the specific precipitation condition. Taking certain area of Shanghai as a study case, the optimized scheduling schemes under four common precipitation conditions lower than the drainage standard were worked out respectively for the two hydrological conditions, i.e. self-draining via the tide outside the river and self-draining that cannot utilize the tide outside the river. On the most unfavorable hydrological condition that could not utilize the tide outside the river for self-draining, the total electrical power consumption of the optimized scheduling scheme could be saved about 12% compared with the current operation scheme. By comparing energy-saving benefit between optimal scheduling schemes and current schemes, the rationality of current scheme had been verified, and the optimization suggestion was proposed in this paper as well. The method proposed in this paper was a beneficial attempt to enrich and improve the method of optimizing operation scheme of pumping stations.