The Application Of PLC And Fuzzy PID Technology In Constant Pressure Water Supply

With the rapid development of urbanization and the increasing demand for housing, the demand of high-rise buildings will be consistent growth, this condition also brings more and more problems and the prominent problem is water supply of high-rise buildings. There are existing a lot of problems in traditional water supply mode, for example, inefficiency, lack of stability, waste of resources. However, the high-rise buildings require the system has good stability and energy saving. In order to solve the above problem faultlessly, in this paper, the constant pressure water supply system take full advantage of PLC technique and fuzzy PID control technique. The system has used many advanced techniques, such as fuzzy control technique, frequency control technique, and electric control technique. These advanced techniques make the system owning the ability of intelligence and high efficiency, completing the task easily.The constant pressure water supply system includes several features, for example,hysteresis, large inertia and so on. The traditional way can not fit the whole working situation,so the system must use the algorithm which possesses the ability of self-adaptation. Because of fuzzy PID algorithm own the merit of traditional PID algorithm and fuzzy control algorithm at the same time, the system use fuzzy PID control algorithm. Then, the system can solve all the problems that the high-rise buildings appeared. This system adopts the software MATLAB and Simulink for the aided design of fuzzy PID controller. First of all, the system should determine its input and output variables and blurred the variables. Secondly, by using the designer’s knowledge and experience, the constant pressure water supply system ensure its fuzzy logic controller rules. At last, the constant pressure water supply system accomplish the output variables’ s clearness. After using the MATLAB software to complete the fuzzy PID controller,by selecting the constant pressure water supply system’s model, the system can accomplish its simulation. By comparing simulation waves of fuzzy PID algorithm and traditional PID algorithm, it is obvious that fuzzy PID algorithm’s function is much better than traditional PID algorithm in dynamic characteristics, static-state characteristics and robustness.The design of system’s hardware is consisted by S7-200 PLC, MM430 inverter, water pump motor and sensor. The work flow of the system is as follow: In the first place, the pressure sensor gather water gage and send it to PLC system. Secondly, after the processing of water gage, the PLC system output analog signal into frequency converter. Finally, according to the analog signal that the PLC system has sent, the frequency converter change its frequency and then change the speed of electric motor. The design of program is consisted by automatic and manual operation mode, according to the system’s working circumstances in practice, theprogram adopt automatic or manual operation mode. The application of fuzzy PID controller strengthen the self-adaptation ability of the constant pressure water supply system and enhance work efficiency of frequency converter and water pump motor. The system own lots of merit,such as the small fluctuation of the water gage, reducing waste of electricity, reducing failure rate of the equipment. The constant pressure water supply system can reach the requirement of the high-rise buildings and meet the needs of daily water consumption for the residents.