The Study On Characteristics Of Starting Transient Process Of Shaft Tubular Pumping Station

Large low-head pumping stations are widely used in many important fields, such as waterlogged land drains, flood control, drought resistance, water resources dispatch and allocation and water ecological improvement of economical developed areas like the Middle-lower Yangtze plains and Zhujiang River Delta. Shaft tubular pumping stations are a new-type kind of low-head pumping stations with simple structure, high efficiency and many other advantages yet also exist similar problems like other types of low-head pumping stations. For example, whether the pump assembly can transit to stable running state in the process of starting, including the cooperation of the motor and pump, the speed of starting gate of quick-closing gate in the outlet passage, whether delaying the time of starting the gate and so on, which play a very important role for safe, stable and reliable operation of pumping stations.This paper takes the shaft tubular pumping station as research object. It has deeply researched many features of the process of starting of the shaft tubular pumping station with the tool of simulating software of Simulink, which starts with asynchronous starting characteristics of the three-phase salient pole synchronous motor, combining with hydraulic characteristics, dynamic characteristics and other theories of the shaft tubular pumping station, establishing mathematic models of the pump assembly’s starting transient process. This paper has mainly completed the work as follows:(1) It has analyzed the basis structure, operating characteristics and starting modes of the three-phase salient pole synchronous motor, especially deeply researched the processes of excitation, pulling into synchronism and others in the way of asynchronous starting, and established the mathematical model of electrics of starting characteristics.(2) It has established the torque equilibrium equation of the pump assembly according to the dynamic characteristics of the shaft tubular pumping station and derived the expressions of the hydrodynamic resistance torque and the thrust bearing’s friction torque completely, using the knowledge of mathematic-physics equations. Meanwhile, regarding the starting of quick-closing gate as uniform motion to study the process and establish the mathematical model of starting the gate, using changing rules of gatage.(3) It has got the performance chart of the model pump unit by means of experimental data fitting of the model shaft tubular pumping station and fit the flow-head curve (Q-H curve) of 0° blade angle with the software of Graph, showing the most qualified expression of the flow-head parameters, which has been taken as the hydraulic characteristics model of the pump device.(4) It has used the method of three-dimensional turbulence numerical simulation, modeled three-dimensional geometry on the basis of the CAD drawings, meshed the inlet and outlet flow passages, the impeller and the guide blade, got the whole meshing model by seamless stitching in CFX and calculated the numerical simulation. In the process of obtaining the head loss of the gate, it has got corresponding height of different gatage by calculating, modeled geometry, meshed and calculated the numerical simulation in turn, found out the expression which is the most qualified for points data fitting by importing the final result into Draph software, which has been regarded as the starting characteristics of the quick-closing gate.(5) Adopting the Matlab/Simulink simulation technology, it has shown the established mathematical model intuitively by building modules, simulated the starting transition process of the shaft tubular pumping station under different schemes by inputting given parameters and analyzed the final exporting emulational images.(6) Summarizing and comparing the changing rules of parameters by simulating to conclude general rules, in order to find ways to avoid undesirable conditions and solve problems in the process of starting the pump assembly and provide some reference basises for safe, stable and reliable operation of the pump assembly at the same time.