楼宇恒压供水控制系统设计

摘要

变频调速恒压供水系统具有运行稳定可靠，占地面积小，节电节水，自动化程度高，操作控制方便等特点，这对于企业节能降耗、提高经济效益和保障设备安全、稳定运行具有现实意义。

系统由四台主水泵，一台 MM430型变频器，一台S7-200系列中的CPU224型PLC和EM235型扩展模快、一个YTZ一150型电位器式远传压力表及若干辅助部件组成。

各部分功能如下：安装于供水管道上的远传压力表将管网水压力转换成4--20mA的电信号；变频器用于调节水泵转速以调节流量；PLC用于逻辑切换。当用水量变化时，通过调节各水泵在工频与变频运行，以此进行合理调配电机，调速供水。这样避免水泵频繁起动，同时减少系统能量消耗。此外，系统还配备了外围辅助电路，以保障自动控制系统出现故障时可通过人工调节方式维持系统运行，保证连续生产。控制电路具有完善的保护和报警功能，如短路、过载、水池缺水保护和报警等。远传压力表将采集到的用户管网压力信号传送到PLC中，PLC经PID运算再将信号传送给变频器，以控制水泵的转速和管网水压，以维持管网压力恒定。系统采用一台变频器控制4台电动机的起动、运行与调速，自动完成泵组软启动及无冲击切换，使水压平稳过渡。系统采用循环控制功能，可使各泵进行轮流工作，延长了设备的使用寿命。

该系统能够对供水过程进行自动控制，能够有效地降低能耗，保证了供水系统维持在最佳运行状况，提高了生产管理水平。系统可靠性高、经济性强

关键词PLC；PID；变频调速；恒压供水

Abstract

The constant pressure water supply system with frequency-speed control has the features of high stability，less floor space，electricity and water-saving,high automatization and easy operation,which provides a practical platform to

reduce enterprises'consumption of energy，and which also provides a significant method to increase the economic benefit and a way to ensure the safe operation and stability of the equipments．

The system consists of 3 major feed pumps，one set of auxiliary feed pump，one set of type MICROMASlER430 transducer,one set of type S7-200 CUP224 PLC and type EM235 extensive module,one set of YTZ-150 potentiometric long-distance pressure sensor．The function of respective component is as follows：the long—distance pressure gauge installed on

the water supply pipeline converts the pressure on the pipeline into 4-20mA electrical signals,the transducer is in charge of regulating the revs of the water pump to control the water flux，the PLC unit is responsible for the logical switches of the pumps．The whole pipeline network is equipped with all air pressure tank to ensure that the water supply pressurization system has certain capacity to store energy．when the flux increases，the timing pump will regulate the pump's rotate speed. The long-distance pressure sensor collects the pressure signals from the pipeline network,and transfers the signal to PLC．PLC transmits the signals to the transducer via the PID operation to control the pump’S rotate speed and water pressure,thus keeping the pressure of the pipeline in balance．The transducer of the system is responsible for the start-up，operation and timing of the 4 engines，which automatically completes the pump unit soft start and an impact-free switch is achieved to ensure the smooth transition of the water pressure．The system also introduces a cyclic control function to stop and rest the pumps engines by turns；

the transducer in real-time．The changes ofthe voltage and frequency cause the changes of the rotate speed of the Pump engines to control the water output．By this way,the automatic regulation of pressure on the pipeline network Can be achieved to keep pipeline pressure stable and dose to the given value．

Key Words：PLC：variable frequency speed control PID control；constant pressure water

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