Energy Saving Optimal Control Of Urban Drainage System

In modern life,wastewater and rainfall runoff should be transported by urban drainage system to ensure drainage safety and avoid the pollution caused by flooding.Wastewater overflows are caused sometimes when rainstorm events occur due to some system restrictions such as drainage capacity of pumps,storage capacity of sewers and so on,which will cause water pollution and affect human health.Urban sewer network and pump stations is a complex system with flow uncertainty,nonlinearity,hysteresis characteristics.Due to the strong uncertainty of sewerage and rainfall runoff,the control strategies of pumps are always conservative,causing urban drainage system a high energy cost system.Therefore,the study of urban drainage system optimal control has the significance of both energy conservation and environment protection.Based on the above background,this dissertation will study in energy saving optimal control of urban drainage system,which includes the study of different control strategies based on the nonlinearity of pump performance and the selection rule of pump locations in urban drainage system,as well as the predictive control of the system simulated on MATLAB.The main work of this dissertation can be summarized as the following aspects:(1)Firstly,a mathematical model of urban drainage system is built.Then,to guarantee the energy saving effect,a nonlinear pump performance model is constructed.After that,energy saving optimization of urban drainage system based on pump performance is built.In this algorithm,centralized control is adopted,and energy consumption is calculated based on pump nonlinear characteristics.When comparing with traditional control methods,the simulation results demonstrate that the proposed optimization algorithm can reduce system energy consumption as well as avoid wastewater overflow.(2)Decentralized predictive control is used in energy saving optimization of urban drainage system to guarantee that no overflow occurs as well as algorithm complexity is reduced.The problem is compared with centralized control algorithm on MATLAB.The result shows that time spent on solving optimal problem is obviously reduced and the pump works more stably.(3)The problem of pump locations selection in urban drainage system is modeled using hybrid optimal strategy.The optimal pump locations can be obtained by solving the optimization problem,so as to achieve control goals by using less pumps.The algorithm is compared with algorithm not optimizing pump locations.From the experiment,the optimization algorithm can guarantee that overflow doesn't occur as well as saving more energy even the number of pumps reduced.