| Water is the source of life, basis of production, and essence of ecology. However, China has large population and inadequate water, and the spatial and temporal distribution of water resources is extremely uneven in our country. Also, problems of water shortage, water pollution and water ecological deterioration are very serious, severely restricting the sustainable development of the economy and society in China. Thus utilization efficiency of water resources must be improved and reasonable allocation must be made. Constructing long distance inter-basin water delivery projects is one of the most effective engineering measures to optimize allocation of water resources. Besides, automatic operation and control technology can greatly enhance the quality of canal system operation and scheduling, improve water delivery efficiency, reduce the cost of operation and management and achieve timely and adequate water supply, eventually to improve water utilization efficiency and provide good service for water units. But also, due to the characteristic of large time delay, high nonlinearity, strong coupling, unknown disturbance and time-varying for the long distance water delivery projects, control of water flow is very complicated. Research on operation and control of long distance water delivery canal system not only needs to consider the hydraulic characteristics of canal system, but also the applications of operation and control theories on this base. Therefore, the research work is of great significance.This paper aims to develop a simulation model of long distance water delivery canal system operation and control. Moreover, some research was done on the related issues of canal system operation and control and water delivery in the winter. The main results include the following aspects:The essentiality and necessity of automatic operation and control of canal system was analyzed and discussed. Then basic knowledge of canal automation, canal operation and canal control were introduced. Besides, the development history of canal operation and control was reviewed, and the methods and theories of canal operation control and some typical engineering projects at home and abroad were summarized.The mathematic models of the canal system, important inline structures (aqueducts and inverted siphons) and turnouts and check gates were developed by generalized methods based on respective hydraulic characteristics. Simulation for steady flow and unsteady flow was analyzed, and one-dimensional Saint Venant equations, which are expressions for conservation of mass and momentum, were adopted to describe unsteady flow in open channels. Then several common numerical methods solving these equations were summarized and compared. In this paper, Preissmann’s implicit difference method was employed to establish discrete equations owing to its high accuracy and good numerical stability.Delivery concepts, methods of operation, control theory, basic characteristics of automatic control, canal system control methods, control algorithms and check gate operating techniques for long distance water delivery canal system were studied and summarized. The combination of feed-forward and feedback control was used in this work-or rather, discharge was used as the feed-forward controlled variable and water level as the feedback controlled variable. Also, a dead band was set in the comparator of the control system. On this basis, the simulation model of long distance water delivery canal system operation and control was developed. Then, several common methods used in modeling and operation control of long distance canal system, such as fuzzy control, state space method and analysis method in frequency domain and time domain, were summarized and compared. Consequently, features and limitations of each method were obtained. Our numerical simulation model was based on the unsteady flow in open channel with dynarnic boundary conditions, and the advantages and characteristics of this model different from conventional control theory and model were summarized, and the numerical simulations of three typical working conditions were carried on.The basic principle of radial gate with submerged outflow was analyzed, and several common calculation formulas were summarized and compared. A check calculation was performed to the flow capacity of the main canal of the diddle route of the South-to-North Water Transfer Project from Anyang to Beijing. Besides, σs curves in the Liwei formula and Wuhan Hydraulic&Electric College formula were fitted. Moreover, some suggestions were given according to the calculation results.In view of water delivery during ice period in winter, ice jam and ice dam were studied from several aspects such as definition, characteristics, causes and so on. Characteristics and mode of water delivery in ice period were analyzed and discussed. Also, the ice period was divided into several stages and respective methods of operation and control at each stage were put forward. Then safety measures for canal operation in winter were given from the point of engineering and management, and operating experiences in ice period of long distance water delivery projects were summarized.Two criterion s were given to judge whether a juxtaposed freeze-up ice cover formed in the ice period:velocity criterion and Froude criterion. And the velocity criterion was suggested to be used as the judgment for controlled canal system. On this basis, influences of scheduled discharges of downstream and turnouts, target water levels before each check gate with constant downstream depth method of operation and standard velocity value of velocity criterion on water conveyance capacity in ice period were studied.Based on the suggested mode of delivering water under the juxtaposed freeze-up ice cover, flow velocities were reduced to less than0.4m/s by decreasing discharges of canal pools and turnouts in terms of3days’cold current forecast in advance and then the transition mode from open-channel water delivery state to a low flow ice-forming state was proposed. Also, regulation rules of turnouts and operation strategy of canal system in the transition stage were studied.Giving and real-time tuning methods of PI controller parameters were studied. Besides, robustness of PI controller was analyzed. With the same PI controller parameters, roughness and length of canal pools will affect the control effect of canal system, while small changes of discharge coefficient of radial gates seldom affect the control effect of canal system. |
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