【作者】 刘国强；

【导师】 王长德；

【作者基本信息】 武汉大学 ， 水利水电工程， 2013， 博士

【摘要】 水是生命之源、生产之基、生态之要。我国人多水少,水资源时空分布不均,水资源短缺、水污染严重、水生态恶化问题十分突出,已成为制约我国经济社会可持续发展的主要瓶颈,因此必须提高水资源的利用效率,并对水资源进行合理配置。修建长距离跨流域输调水工程是优化水资源配置最为有效的的工程措施之一。长距离输水工程采用自动化运行控制技术,可以大大提高渠系的运行调度水平,改善输水效率,降低运行管理费用,实现适时、适量供水,最终达到提高水资源利用率并为用水单位提供良好服务的目的。但同时,长距离输水渠道系统具有大滞后性、高度非线性、强耦合性和未知扰动性,水流的控制非常复杂。研究渠道的运行调度问题不仅需要考虑输水渠道的水力学特性,同时又要研究运行控制理论在此基础之上的应用。因此,对于长距离输水渠系运行控制理论和应用方面的研究具有十分重要的意义。本文建立了长距离输水渠系运行控制仿真模型,对长距离输水渠系的运行控制相关问题和冬季输水进行了深入的研究,主要成果包括以下几个方面的内容：分析论述了渠道运行控制自动化的必要性以及渠道自动化、渠系运行和渠系控制的基本内容,总结了国内外现有的渠系运行控制方法、理论和典型工程实例。对长距离输水渠系的渠道和渠系建筑物进行了概化处理,并对典型渠段进行了数学建模。分析了恒定流模拟和非恒定流模拟,并提出采用一维圣.维南方程组描述非恒定流,总结了该方程组的几种数值解法,并提出采用Preissmann隐式差分法对一维圣.维南方程组进行数值求解。对长距离输水渠系总干渠的配水方式、运行控制技术和节制闸运行技术进行了研究,并设计了流量前馈和水位反馈相结合的带有死区设置的渠道控制系统。在此基础上,建立了长距离输水渠系运行控制模拟仿真模型。对长距离输水渠系建模和运行控制中常采用的模糊控制、状态空间法和时域频域分析法进行了总结和比较,得出了各自的特点和局限性,并进一步提出本文建立的基于明渠非恒定流与动态边界相结合的数值仿真模型的优势和特点,并利用该模型对典型工况进行了数值模拟。对弧形闸门闸孔淹没出流的基本原理进行了分析,并总结和比较了常用的各种计算公式。然后结合南水北调中线一期工程总干渠安阳-北京明渠段,进行了闸门过流能力的校核计算,拟合了李炜《水力学》公式和武汉水利电力学院公式的σs曲线,并根据计算结果提出了建议。针对长距离输调水工程在冬季面临冰期输水的问题,从定义、特点、成因等几个方面研究了冰塞和冰坝,分析论述了冰期输水特性和输水模式。对冰期输水进行了阶段划分,并提出了各个阶段的运行控制方法。从工程和管理两个方面提出长距离输水渠系冬季运行安全措施。最后总结了国内外调水工程冰期运行经验。提出了判断长距离输水渠系在冰期形成平封冰盖的两个判定标准,即流速判定标准和弗劳德数判定标准,并建议控制渠系采用流速判定标准。在此基础上,研究了渠系下游和分水口冰期取水方案、流速判定标准取值大小和闸前常水位运行方式下闸前控制点目标水位取值对长距离输水渠系冰期输水能力的影响。基于建议的冰期在平封冰盖下输水的模式,提出了根据提前三天的气象预报,通过降低渠池输水流量和分水口取水流量将渠池内流速在三天内降低至0.4m/s,进而得到长距离输水渠系在三天内从常态下的明渠大流量输水向冰期平封冰盖下小流量输水的过渡模式,并研究了该过渡阶段分水口的调控方式和渠系运行策略。研究了确定PI控制器参数和实时整定参数的方法。同时,还对PI控制器的鲁棒性进行了分析,得出在相同的PI控制器参数下,渠系的糙率和渠池的长度会影响渠道系统的控制效果,弧形闸门过闸流量系数小幅度变化时,基本不影响渠系的控制效果。更多还原

【Abstract】 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.更多还原