Pressure Constant City Water Supply System Based On PLC Control

With the continuous deepening of re forming and opening up, the construction and economy of s mall and m edium-sized cities in China have developed rapidly. People's living standards have improved constantly. The water supply system is demanded more as city water consum ption increasing. The urban construction and economic development and also people's daily work and life are impacted directly by the reliability, stability and the economical of energy conservation of the water supply system.An autom atic conversion and voltage constant W ater Supply and rem ote monitoring system, which consist of the PL C, the converter, the rem ote transition pressure gauges, the multi-pumps unit, the computer, the communication module and so on, is designed according to the W ater Supply Network Im provement Project of Zhangjiakou City - a west pum ping stati on secondary pressurized system of new water source. It is of autom atic line-frequency /conversion function, remote and local automatic control.In this paper, the m echanism of energy saving,which uses speed governing with invertor to design voltage constant water supply system, competing with traditional valve controlled pressure cons tant system. Closed loop syst em is built by presetting the param eter of the PID inside of conve rtor, and feedback of rem ote transiton hydraulic meter. Using the step regulation of convertor pump and frequency pump in full rang of flow to apply PID control on the change of water achieves energy saving of voltage constant water supply.This paper discusses the reasonability of water supply scheme with much pump parallel connection, and analyses the conve rsion condition and the various states of water supply of the much pump way of water supply as well as the switch process and the problem of a generator from variable frequency operation mode to work frequency operation mode. This paper has also give n the electrical design scheme and PLC controlling program schem e that realizes effectiv e state circulating convers ion control.The rationality of m ulti-pump parallel water su pply is d iscussed. The water supply state, transition condition of multi-pump supply and the transion of motor from convertion to line-frequency is anallized, and also the problems that exist.The problems, existing in tradition al water supply, are sovled which inhancing the reliablility of system. In addition, the combination of the system and the computer is achieved, whichi improved the overall function of the system..