Research On Optimization Method And Aided Design Software For Pipe Network System

China’s total agricultural water consumption accounts for more than 60% of the total water all year round,and it is mainly used for agricultural irrigation.Accelerating the largescale application of efficient water-saving technologies in agriculture is an important measure to alleviate the contradiction between supply and demand of domestic water resources and ensure the stable development of agriculture and national food security.The infrastructure in rural areas of China is relatively backward,and the development of pipeline irrigation system and water supply pipe network system can not fully meet the production and living needs in rural areas.The design of pipeline irrigation system in rural areas is still lack of intelligent means.In addition,there are few studies on water supply network in rural areas of China,which is characterized by long water transmission distance and lack of maintenance for a long time.In addition,there is no general auxiliary software in the pipe network design in China,and there are many difficulties in the design work,which restrict the rural construction in China.In this paper,aiming at the problems that the low-pressure pipeline irrigation network is not universal,it is difficult to consider the division of rotating irrigation groups and the rural water supply network less considers accident conditions,the optimization method and auxiliary design software of the pipe network system are studied on the basis of summarizing the research at home and abroad.The main achievements are as follows:(1)For complex irrigation pipe network.The layout of irrigation pipe network is relatively complex,and the pipe diameter of the pipe network is mainly optimized.Taking the economic index as the optimization objective and combined with the constraints,the optimization model is established.Using MATLAB software,the model is solved by using genetic algorithm based on non line capital,and the pipe diameter calculation results are obtained.Then,the pipe network calculation method in line with agricultural hydraulic characteristics is used to design the pipeline.Because the design of irrigation pipe network needs to consider the engineering experience artificially,this paper specially designs a userfriendly form as the user input source in the code design,and introduces the designer’s engineering experience in the design of wheel irrigation group.In the case study,the pipe diameter of complex pipe network is optimized by Matlab using improved genetic algorithm.In the self pressure irrigation pipe network,when the water supply pressure is large,the pipe diameter of each section of the surface irrigation pipe network system is generally small.With the increase of self pressure water supply pressure,the total construction cost of main pipe and sub main pipe decreases,which also shows that the algorithm is stable and reliable on the whole.After the optimization of mechanical pressure irrigation pipe network system,the total annual cost,total pipeline construction cost,total main pipe cost,total sub main pipe cost,pumping height and annual pumping cost are significantly reduced,among which the sub main pipe construction cost decreases the most,mainly because the variable diameter pipe is adopted in the optimization scheme,which is more economical and reasonable.The pump head is also reduced from 24.81 M before optimization to 17.29 m after optimization.It also shows that the model and optimization algorithm are scientific and reasonable,and the calculation results are robust.(2)For water supply network in rural areas.The single objective and multi-objective optimization design method of rural water supply network considering accident conditions is proposed,and the automatic optimization of pipe diameter of rural water supply network is realized.The improved genetic algorithm and NSGA-II algorithm are used to solve the single objective and multi-objective models respectively.The single objective optimization model takes the lowest annual cost as the optimization objective,and the optimization objective of the multi-objective optimization model comprehensively considers the annual cost and the average node surplus head.The method of integer coding is adopted to realize that each pipe diameter under the multi-objective optimal model of rural pipe network is an integer,and the head of pump station is coded by binary coding.By using Pareto curve in NSGA-II algorithm,the optimization results of pipeline can be obtained,and the relationship between pipe diameter and flow can be obtained by combining LM algorithm.This can effectively reduce the cost and operation cost of the pipeline.The example shows that this scheme can not only fully consider the economy and reliability of water supply,but also better adapt to the water supply demand in case of emergencies.Using this method,the basic data such as elevation and node water demand provided by users can be used to provide basis for reasonable and economic pipe diameter planning.It is found that under the condition of comprehensive multi-objective and accident conditions,although the annual cost of the multi-objective function and the optimization method considering accident conditions is higher than that of the single objective optimization model,this method can better take into account the reliability index of the water supply network,so as to effectively reduce the probability of pipe network failure,which is more feasible in practice.(3)Research on CAD software.The secondary development of Auto CAD based on Auto LISP language has preliminarily realized the automatic drawing of the optimization results of irrigation and water supply network.This paper focuses on the secondary development of Auto CAD,using Auto LISP language for programming.It can automatically read the txt file stored by matlab calculation results and obtain the pipe diameter optimization results.In the CAD drawing of the project area,the pipeline position is automatically identified according to the pipeline number,and the pipe diameter is intelligently marked.This work provides a general CAD drawing method for the optimization and CAD of complex irrigation network,and a new method for the CAD system in the future.