Research On Constant Pressure Water-supply System Based On Fuzzy-PID Controller

Along with the rapid development of social economy,water is very important to people’s life and industrial production,so people are continuously improving the requirements to the quality of water supplying,reliability of water supply system and energy saving.But most of the secondary pressurized waterworks which were built in the 1960s and 1970s and whose technology is backward,the equipments are old fashion and energy wastes seriously.Therefore,renovating the technology in order to improve the utilization ratio of the old sets of water pumps,applying the advanced automation technology,intelligent control technology and network communication technology to the water supply field,saving the energy is proposed as new requirements to the water supply system.This paper expounds the basic characteristics of the water supply system and the principle of Variable Frequency Speed-control,analyzes the structure and the energy saving principle of the Variable Frequency Speed-control constant pressure water supply system.According to the practical control requirements,design the automatic constant pressure water supply monitor and control system which is constituted by Siemens S7-300 PLC,WinCC,MM430 frequency converter and pump motors etc.It solves the following questions:1.Owing to the original works using manual operated the buttons to control the motor’s switch and to open or close valves,the automation level is quite low,so the system uses PLC as controller,makes the system to run automatically,can realize the unattended.2.According to the current situation that the original water plants only can use manual monitor equipment and read the meters on a regular time,the system uses WinCC as the monitor interface.It not only can realize the monitoring fuction,but also can achieve fast archiving,query,modify parameters,and so on.3.According to the current situation that the original water plants relies on pitch/cut a whole pump,adjusts the water pressure by controlling the valve opening,efficiency of the pump is low,energy wasting is serious,the system uses the frequency converter to go stepless speed regulation,reduces the influence of water hammer effect,improves the control precision.and reaches the aim of saving energy.4.The principle,structure and characteristics of PID control,Fuzzy control and Fuzzy-PID control are analyzed,and the simulation and the anti-interruption experiment are done with Matlab.The results show that the Fuzzy-PID control system includes he advantages of PID control and Fuzzy control system.So the system’s rising time is short, the over-shooting is small,the performance of anti-interruption is strong,and the robustness is good.5.Fuzzy-PID parameter self-setting algorithm in PLC is designed through research of PID and Fuzzy control.Researching the Fuzzy-PID parameter self-setting control system,except with the theoretical value,it has important practical guiding meaning to improve the running status of water supply system,improve the stability and reliability of the system,and realize of energy saving and cut-down consumption.