"PLC和变频器应用于恒压供水系统设计：高性能、节能、可靠性的实现"

The rapid socio-economic development and the expansion of cities, coupled with the increasing demand for water quality and reliability of water supply systems, have led to the inevitable trend of designing high-performance, energy-efficient, and adaptable constant pressure water supply systems using advanced automation, control, and communication technologies. This design is specifically targeted towards residential water usage and incorporates a control system composed of PLC, frequency converter, and PID controller to regulate the output flow of the water pump. The electric motor pump group consists of three parallel water pumps powered by the frequency converter or utility power grid, and the speed and switching between the frequency converter motor pump group are controlled based on the outlet water pressure and flow of the water supply system, ensuring the system operates in the most efficient state to guarantee on-demand water supply. This article introduces a PLC-controlled frequency-variable-speed water supply system that employs the PLC for logical control and the frequency converter for pressure regulation. Through PID calculations and PLC control of the frequency and utility power switching, the system achieves closed-loop automatic constant pressure water supply regulation. The operational results demonstrate that the system features stable pressure, simple structure, and reliable operation. Key words: constant pressure water supply; PLC; PID control; frequency-variable-speed.