基于枚举法和遗传算法的农田灌溉管道系统优化设计研究

发布时间：2018-11-05 12:39

【摘要】：我国是一个水资源严重缺乏的国家,水资源总量虽然位居世界第六位,但过多的人口导致水资源人均占有量仅为世界人均占有量的1/4,水资源的匮乏已严重制约着我国工农业的发展,成为限制我国经济和社会发展的瓶颈。在水资源缺乏的情况下,水体污染、水资源浪费现象日益增多,进一步加剧了水资源供需矛盾和紧缺程度。我国是农业大国,农业用水量居各行业之首,占全国总用水量的63%左右,而灌溉用水量又占农业总用水量的90%以上。随着国民经济的发展,我国农业与水资源短缺矛盾越来越尖锐,许多地区粗放的灌溉方法和落后的灌溉技术已不再适应可持续发展的要求。目前急需解决的问题是在水资源有限的情况下,高效利用农业用水,在保证粮食安全和可持续增产的前提下,减少农业用水损耗。这就需要我们大力发展节水灌溉技术,充分挖掘农业灌溉节水潜力,提高农业灌溉水利用系数,缓解我国用水危机,解决水资源供需矛盾。发展节水农业,管道输水是重要途径之一。而在以往的工程设计中,管道多沿着田间路布置,管径大多根据水源地供给的水量确定,设计、施工标准不一致,有关设计主要凭经验和常规进行,缺乏方案优化比选,工程设计规划难以达到最优状态,致使工程成本和能耗增加,且过高的灌溉供水成本使农民难以支付,水费征收困难,导致实际水价远低于成本水价,严重制约了灌区的运行和发展。本文的研究对象是小型农田水利工程灌溉管道系统,在综合分析国内外有关管网优化的研究和最优化理论技术的基础上,针对目前灌溉管道系统优化设计存在的问题和不足,以管长、管径、水泵扬程为决策变量,以灌溉供水成本最低为目标函数,建立了小型农田水利工程灌溉管道系统的非线性优化模型,分别进行了管网布置优化和管径优化。管网布置优化时,结合设计人员经验和工程实际,根据单点供水原则,采用枚举法进行优化,并采用CodeBlocks软件编写了C++程序。在此基础上采用遗传算法对管径进行优化,采用整数编码方法,得到各管网布置方案下的最优管径组合及水泵扬程,得到的管径为标准商用管径,避免了管径不连续导致的优化结果的偏差,然后选择出灌溉供水成本最低的方案作为最优设计方案,并编写了Matlab程序。最后采用工程实例对本文建立的优化设计模型及优化方法进行验证。结果表明,本文方法可快速有效地确定出灌溉管道系统整体优化方案,在满足农田灌溉要求的同时,有效降低了灌溉供水成本,保障了农民灌溉用水的切身利益。
[Abstract]:China is a country with a serious shortage of water resources. Although the total amount of water resources ranks sixth in the world, but too many people cause the per capita water resources per capita to be only one fourth of the world's per capita. The scarcity of water resources has seriously restricted the development of industry and agriculture in China and has become the bottleneck of restricting the economic and social development of our country. In the case of water shortage, water pollution and waste of water resources are increasing day by day, which further intensifies the contradiction between supply and demand of water resources and the degree of shortage. China is a big agricultural country. Agricultural water consumption occupies the first place in all industries, accounting for about 63% of the total water consumption in China, and irrigation water consumption accounts for more than 90% of the total agricultural water consumption. With the development of national economy, the contradiction between agriculture and water resources shortage is becoming more and more acute. The extensive irrigation methods and backward irrigation techniques in many areas are no longer suitable for the requirements of sustainable development. At present, the urgent problem is to use agricultural water efficiently under the condition of limited water resources, and to reduce the consumption of agricultural water under the premise of ensuring food security and increasing production sustainably. It is necessary for us to develop water-saving irrigation technology, fully tap the potential of water-saving in agricultural irrigation, improve the utilization coefficient of agricultural irrigation water, alleviate the water crisis in China, and solve the contradiction between supply and demand of water resources. To develop water-saving agriculture, pipeline water transmission is one of the important ways. In the past engineering design, the pipelines were mostly arranged along the field roads, and the pipe diameters were mostly determined according to the water supply from the water sources. The design and construction standards were inconsistent. The related designs were mainly carried out on the basis of experience and routine, and there was a lack of optimization and selection of the schemes. It is difficult to reach the optimal state of engineering design planning, resulting in the increase of project cost and energy consumption, and the high cost of irrigation water supply makes it difficult for farmers to pay, and the collection of water charges is difficult, resulting in the actual water price being far lower than the cost water price. Seriously restricted the operation and development of irrigation district. The research object of this paper is the irrigation pipeline system of small-scale irrigation and water conservancy engineering. On the basis of comprehensive analysis of domestic and foreign research on pipe network optimization and optimization theory technology, this paper aims at the existing problems and shortcomings in the optimization design of irrigation pipeline system at present. Taking pipe length, pipe diameter and water pump head as decision variables, taking the lowest cost of irrigation water supply as objective function, the nonlinear optimization model of irrigation pipeline system in small irrigation and water conservancy engineering is established, and the pipe network layout and pipe diameter optimization are carried out respectively. According to the principle of single point water supply, the optimization of pipe network layout is carried out by enumeration method, and the C program is compiled by CodeBlocks software. On the basis of this, genetic algorithm is used to optimize the pipe diameter, and the integer coding method is used to obtain the optimal pipe diameter combination and pump head under each pipe network layout scheme. The pipe diameter obtained is standard commercial diameter. The deviation of optimization result caused by discontinuity of pipe diameter is avoided, then the scheme with the lowest cost of irrigation water supply is selected as the optimal design scheme, and the Matlab program is written. Finally, an engineering example is used to verify the optimal design model and optimization method established in this paper. The results show that the whole optimization scheme of irrigation pipeline system can be determined quickly and effectively by this method, and the cost of irrigation water supply can be reduced effectively while the requirement of farmland irrigation is met, and the vital interests of farmers' irrigation water can be guaranteed.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S274

【参考文献】