| The hydraulic model of water distribution system(WDS)is an important tool to realize the optimal dispatching,leakage monitoring,intelligent operation and maintenance of the network,and the nodal demand is the most uncertain factor affecting the accuracy of the model.With the extensive installation and application of remote smart demand meters based on Internet of things technology in some domestic cities,it is possible to build a high-precision or even real-time model to reduce errors;In addition,secondary water supply systems(SWSSs)have been widely used in the WDS,but there is less numerical simulation research on SWSSs.It is of great research value and significance to incorporate it into the WDS model and analyze its impact on the flow and pressure of municipal pipe network.Firstly,the hydraulic model of WDS in Binhu District,Hefei City,Anhui Province was constructed by using EPANET 2.0.Based on a large number of ten-minute remote smart demand meters installed in the area,the data processing analysis and construction of demand pattern were carried out,which was compared with the simulation results of the model constructed by traditional method.And then the construction method of real-time model is discussed;Secondly,the research on the construction of numerical model of two kinds of SWSSs,anti-negative pressure facility(ANPF)and peak shifting facility(PSF),was carried out,and the rationality and effectiveness of the numerical models were verified and analyzed through the experimental platform.Finally,by incorporating them into the constructed EPANET model of Binhu District,the influence of the layout mode(including location and quantity)of the two facilities on the flow and pressure was studied and analyzed.The results of hydraulic modeling show that the demand patterns of the same type of users are not exactly the same,the difference of SWSSs is the main factor leading to the different demand patterns of residential users;In the traditional modeling method,giving the same pattern to the same type of users is the main factor affecting the accuracy of the model.After using the numerical method to calibrate the nodal demand and pipe roughness coefficient based on MATLAB software,although the model accuracy meets the criteria(the absolute errors of all pressure monitoring points are within 2 m),there are still some errors between the simulated flow curve and the actual water consumption curve of the node,which is not conducive to practical application;The accuracy of the model inputting the demand patterns of all nodes meets the modeling criteria,and there is no need to calibrate the nodal demand.The roughness coefficient of the pipeline is calibrated by using Water GEMS software,and the accuracy of the model is further improved;By transmitting the remote data of demand meters to EPANET input file,real-time modeling can be realized,the absolute errors of all pressure monitoring points are within 1 m.The research results of two kinds of SWSSs show that the ANPF has little impact on the flow and pressure of the pipe network,but when the pressure is insufficient due to the expansion of the pipe network,the flow of the node without SWSSs will be significantly reduced;PSF has a significant impact on the municipal pipe network.An appropriate number of facilities can alleviate the flow and pressure fluctuation.After the expansion of the pipe network,it can also reduce the number of low-pressure nodes during the peak demand time.However,it should not be centrally installed at the end of the WDS.The research results have important reference value for the establishment of high-precision hydraulic model and alleviating the flow and pressure fluctuation of municipal pipe network. |
