Research On The Optimal Control Strategy For Energy Efficiency Of Constant Pressure Water Supply System

Constant Pressure Water Supply System(CPWSS)is widely used in secondary Water Supply System with reliable Water Supply,strong real-time and unattended characteristics by maintaining pressure as the control goal and dispatching pump unit with intelligent frequency conversion speed regulation technology.However,the operation characteristics of Water Supply System(WSS)are not considered by the conventional dispatching strategy of pump set,which lead to low efficiency and excessive energy consumption of the WSS.To solve this problem,this paper proposes a pump scheduling strategy based on energy optimization,which has simple control logic and good energy saving effect.This article focuses on the following:First of all,the operation of pump and parallel pump unit are studied,the energy-conserving and operating principle of the CPWSS are analyzed,and the viability of efficiency optimization of the CPWSS is discussed.It is proved that the water supply pump group is composed of many pumps,and there are many pump dispatching schemes in the same water supply condition to meet the water supply demand of the system.The conventional pump group dispatching control strategy is not the most energy saving.Secondly,the working characteristics of single pump water supply,parallel water supply of multiple pumps of the same model and parallel water supply of many pumps of different types are analyzed.Taking the minimum energy consumption as the objective function,the energy efficiency mathematical models of these three water supply systems are established.The mathematical model of the CPWSS composed by single pump is analyzed by the graphic method.The conclusion is drawn that the selection of pumps should cover the high efficiency area of pumps as much as possible.Based on the Lagrange multiplier method,the mathematical model of the WSS with multiple pumps of the same type in parallel and constant pressure is analyzed.It is proved that the energy consumption of the WSS is minimum when the speed is adjusted at the same speed.Combined with the practical engineering experience,the energy efficiency optimization control strategy based on the critical frequency is proposed.An improved Differential Evolution(DE)algorithm is proposed to optimize the mathematical model of the WSS with multiple pumps of the different model in parallel and constant pressure.The simulation results show that the improved DE algorithm has strong applicability and good optimization performance.Based on the optimization results of the improved DE algorithm,the energy efficiency optimization control strategy of the system is proposed.Finally,the prototype of CPWSS is designed and built,and the rationality of the mathematical model of the WSS is proved by the experimental research.Based on the experimental verification,a flow estimation algorithm without flowmeter is proposed,which can accurately calculate the outflow flow of water supply system and save the cost of system composition.By comparing the energy efficiency optimization control strategy proposed in this paper with the conventional pump scheduling strategy,the results show that the energy efficiency optimization control strategy is feasible and the energy saving effect is remarkable.