Research On Optimal Scheduling Of Multistage Pumping Stations Based On Transient Flow Calculation And Safety Analysis

The common features of large multistage pumping stations are long distance, large discharge, long operation time and large operation costs, so it has an excellent optimized possibility not only in the operation scheduling, but also in the safe start-up and efficient operation of units. Because of the influence of vibration characteristics, start-up charactristics and start-up frequency for the units operation, to research the optimal scheduling of multistage pumping stations need to analyze the operation reliability of units, and optimize the start-up process, which is helpful to improve the feasibility of optimal scheduling results. Based on the transient flow therory and safety analysis, the research on the optimal scheduling of large multistage pumping stations provides powerful theoretical basis for making reasonable, economical and reliable operation scheduling, and it has great academic significance and practical value.Based on the theories of pumping sations economical operation, fluid mechanics, signal analysis, the nonlinear dynamics and intelligent optimization algorithm, the research on the optimizing scheduling of multistage pumping stations is carried out, and the main contributions of this dissertation are summarized as follows:1. Research on the real-time scheduling is conducted. Based on the unsteady flow equations of channel and pressure pipeline, the method of characteristics is used to analyze the hydraulic transient induced by discharge changing of first pumping station, and then combined with scheduling experience, the discharge hysteresis relationship between pumping stations is determined.2. Research on the relationship between reliablility operation of pumps and optimal scheduling is conducted based on the vibration analysis. By the HHT and rotor dynamics, the abnormal virabition causes of all-adjusted vertical mixed flow pumps are analyzed from the signal analysis and the numerical simulation, and then the vibration influence for pumps efficiency is discussed. The results show that, the abnormal vibration is caused by the rotor misalignment, which is mainly induced by the impact force with the start-up process; and the impact force with start-up process is closely related to the intensity of the vibration, the strong impact force is more likely to induce the severe vibration, and severe vibration can induce the pumps efficiency to decrease obviously. Therefore, to improve unit start-up mode and reduce the impact force can weaken vibration effectively.3. Research on the start-up parameters optimization of all-adjusted vertical mixed-flow pumps is conducted. The start-up process of pumps is divided into two stage, i.e, exhausting process and butterfly valve opening process. The VOF model and dynamic grid technology are used to calculate the water hammer, and the start-up parameters of pumps are optimized using the orthogonal test. The results show that, with increasing electric motor start-up time, the maximum pressure in the start-up process decreases gradually; but with increasing butterfly valve opening time, the maximum pressure increases gradually. Besides, considering the effect of saddle region, the-3°blade angle of pumps is chosen.4. Research on the single objective optimal scheduling is conducted. The optimal operation model of multistage pumping stations is built, which is based on the transient flow caculation and safety analysis. The optimal target is determine the minimum operation costs. In order to overcome the slow convergence of particle swarm optimization algorithm(PSO), which is easy to be trapped in local optima, the immune algorithm is adapted to improve the PSO. The new method is used to solve the optiaml scheduling of Dongshen water supply project. The results show that the new method not only enhances the activity of particles,but also improves the search precision.Thus the "premature" of PSO is enhanced. The applocation of optimal scheduling for Dongshen water supply project saves the costs of29,900yuan per day, which improves the economy of the project.5. Research on the double-objectives optimal scheduling is conducted. In consideration of the influence of operation costs and maintenance costs, the model of the double-objectives optimal scheduling is established, and the two optimal targets are the minimum usage of pumping electricity and the minimum maintenance costs (smallest units start-up times). Two different hybrid particle swarm optimization algorithms, combined with the linear weighting method and Pareto optimal solution separately, are used to solve the optimal problems. The research results show that, the double-objectives optimal model is changed into single-objective model based on the first method, and the solution will change with the weight of objectives; but using the second method to solve the optimal model, a group of optimal schedulings are gotten, and the relationship between the minimum usage of pumping costs and the smallest unit start-up times are complicated. The minimum pumping costs firstly decreases, and then increase with increasing the units start-up times, but in a specific region(contain the minimum pumping costs of Pareto solution), with the change of start-up times, the change of pumping costs is not obvious, this region is the optimal choice for scheduling.