Study On Leakage Location Ofwater Supply Network Based Onhydraulic Model

The water supply network is the most heavily invested part of the urban water supply system.The pipeline is laid long and connects the water supply plants with thousands of households in the city.Most of the domestic water supply pipe network was built in the 1970 s.At that time,the quality standard of the pipeline was relatively low,the construction technology was deficient,also the pipeline was facing the problem of aging.All of the causes led to frequent pipeline leakage.Moreover,the urban water supply pipe network is generally laid underground,traditional manual leakage monitoring is difficult to detect and locate the leakage in time.The leakage of urban water supply pipe network not only leads to the waste of a large amount of high-quality water resources and economic losses,but also induces the invasion of pathogenic bacteria to form the secondary pollution of water supply.With the expansion of the city and the passage of time,the layout of underground water supply pipe network is increasingly complex.Therefore,how to effectively and timely locate the leakage of pipe network is a subject worth studying.With the development of economy,more and more water supply networks are equipped with SCADA system.Leakage may cause abnormal changes in flow and pressure monitoring values of SCADA system.In theory,the leakage can be located by the change data.However,the actual measured data of leakage in the actual pipe network are very scarce,so it is impossible to conduct effective leakage location research.Therefore,this paper uses the hydraulic model to simulate the actual pipe network leakage,and uses the simulated data to analyze the leakage location.The following aspects are studied in this paper:1)Establishment of hydraulic model for water supply network and leakage simulation.Firstly,the hydraulic model of water supply network is summarized,including the purpose,use and modeling steps of constructing the hydraulic model of water supply network.Then the leakage simulation model of water supply network is introduced,and the Shinozuka leakage model is finally selected to realize the leakage simulation of water supply network through comparison.The flow and pressure monitoring values of the pipe network model are collected as the monitoring signalsof the SCADA system.2)The leakage flow of water supply network based on accumulation and control chart is estimated.The principle of accumulation and control chart is to carry out real-time monitoring of the studied data,and accumulate the small deviations in the process to achieve the amplification effect,so as to detect the abnormal changes of the data.This method is simple in calculation and highly sensitive,and can detect small abnormal fluctuations in time during the monitoring process.Therefore,it is very suitable for detecting abnormal flow changes caused by leakage in the water supply pipe network.When the accumulation and control chart is used to detect that the water flow in the water supply pipe network starts to increase abnormally,it is considered that there is a leakage in the pipe network at this time.By calculating the flow difference before and after the leakage,the estimated value of the leakage in the pipe network can be obtained.3)Based on the monitoring value of pressure changes of water supply network leakage optimization location.When the water supply pipe network leakage occurs,the pressure of each node of the pipe network will have different changes.The leakage location can be realized by analyzing the relationship between the pressure change of each monitoring point and the simulation results.This method has the advantages of simple structure,high accuracy and low false alarm rate.Firstly,the data changes of each pressure monitoring point during the leakage of water supply pipe network are calculated and the leakage flow is estimated.Then,assuming that all nodes may be the actual location of leakage,the estimated leakage amount is superimposed on each node and the simulation operation is carried out to record the pressure change of each node at the monitoring point when the flow anomaly increases.Finally,the difference between the monitored value and the simulated value is analyzed by the objective function,and the node with the smallest difference is considered as the actual leakage point.In this method,it is impossible to locate the leakage in the water supply pipe network in two cases,one is in the branch node and the other is in the pipe segment.Through the analysis of the leakage location results in the above cases,it is found that the positioning method proposed in this paper can effectively narrow the search scope of leakage location in these two cases.4)The hydraulic model of the water supply pipe network in Y county wasestablished,in which a flow monitoring point and six pressure monitoring points were set up.Four different leakage points are assumed in the pipe network and simulated by the leakage model.The method proposed in this paper is used to locate the simulated data and verify the feasibility and accuracy of this method in practical large-scale pipe network.The results show that this method can be used to locate the leakage accurately in the pipe network.If the leakage occurs in the unformed branch node,the scope of the leakage can be determined in the whole branch.If the leakage occurs in the pipe section,it can be located at the connected node of the pipe network.