Constant pressure water-supply system based on Fuzzy and PID switching control 

LI Yi， LIU Fei
（Key Laboratory of Advanced Process Control for Light Industry Ministry of Education，
Jiangnan University， Wuxi 214122， China）

Abstract： Aiming at the problems that traditional water supply system is not stable and energy is wasted seriously，a switching  control method based on Fuzzy and PID，as well as its hardware circuit and software system，were presented to design the variable frequency and constant pressure water-supply system based on PLC. System was composed by PLC，inverter，pressure transmitter，flow meter，electric valve，PC and so on. By analyzing the simulation results obtained using Simulink，the differences of control performance between Fuzzy-PID and traditional PID were illustrated. The picture of monitor system was realized by WINCC，which has realized remote monitor and raised the management level. Through the WINCC configuration software，the operational states of pumps were monitored and the associated parameters were recorded，the way that how to realize the communication between PC and PLC was covered in more detail. The results indicate that the constant pressure water supply system based on the Fuzzy-PID control strategy is more cost-efficient，compared with the traditional water supply method，and it has much faster and more accurate compared with the traditional PID control system.
Key words： PLC； frequency conversion； water-supply system； Fuzzy； PID； monitor system