【正文】 ........................................................................12 控制系統(tǒng)的硬件設(shè)計與選型 ...........................................................................13 主電路設(shè)計 ....................................................................................................13 電氣控制電路設(shè)計 ........................................................................................14 系統(tǒng)主要配置的選型 ....................................................................................16 PLC 的選型 .......................................................................................................19 系統(tǒng)可靠性措施 ..............................................................................................204 PLC 控制系統(tǒng)的設(shè)計 .......................................................................................22 水泵工頻/變頻運(yùn)行狀態(tài)及轉(zhuǎn)換過程分析 .....................................................22 供水狀態(tài)及其轉(zhuǎn)換 ........................................................................................22 狀態(tài)轉(zhuǎn)換關(guān)系 ...............................................................................................22 狀態(tài)轉(zhuǎn)換條件 ...............................................................................................24 PLC 程序設(shè)計 .................................................................................................25 PLC 編程語言 .............................................................................................25 梯形圖語言編程的一般規(guī)則 .....................................................................25 供水系統(tǒng)控制模塊的設(shè)計 ..............................................................................26 系統(tǒng)初始化模塊 ............................................................................................26 水泵運(yùn)行與狀態(tài)轉(zhuǎn)換模塊 ............................................................................265 恒壓供水系統(tǒng)的 PID 調(diào)節(jié) .................................................................................28 PID 控制及其控制算法 ....................................................................................28 恒壓供水 PID 調(diào)節(jié)過程分析 ..........................................................................29結(jié) 論 .......................................................................................................................31附 錄 .......................................................................................................................32致謝 .........................................................................................................................34參考文獻(xiàn) .................................................................................................................3511 緒 論 課題背景及意義隨著社會經(jīng)濟(jì)的迅速發(fā)展，水對人民生活與工業(yè)生產(chǎn)的影響日益加強(qiáng)，人民對供水的質(zhì)量和供水系統(tǒng)可靠性的要求不斷提高。 論文論述了采用多泵并聯(lián)供水方案的合理性，分析了多泵供水方式的各種供水狀態(tài)及轉(zhuǎn)換條件，分析了電機(jī)由變頻轉(zhuǎn)工頻運(yùn)行方式的切換過程及存在的問題。本文根據(jù)城區(qū)供水管網(wǎng)改造工程設(shè)計了一套由 PLC、變頻器、遠(yuǎn)傳壓力表、多臺水泵機(jī)組、計算機(jī)等主要設(shè)備構(gòu)成的全自動變頻恒壓供水及其遠(yuǎn)程監(jiān)控系統(tǒng)，具有自動工頻/變頻恒壓運(yùn)行、可實現(xiàn)遠(yuǎn)程自動控制和現(xiàn)場手動控制等功能。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 autom atic conversion and voltage constant Water Supply and remote monitoring system, which consist of the PLC, the converter, the remote transition pressure gauges, the multipumps unit, the puter and so on. It is of automatic linefrequency /conversion function, remote and local automatic control. In this paper, the mechanism of energy saving, which uses speed governing with invertor to design voltage constant water supply system, peting with traditional valve controlled pressure constant system. Closed loop system is built by presetting the parameter of the PID inside of convertor, and feedback of remote 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 conversion 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. In addition，the bination of the system and the puter is achieved，which improved the overall function of the system．Key words：PLC。實現(xiàn)恒壓供水的自動控制，不需要操作人員頻繁的操作，大大降低了人員的勞動強(qiáng)度，節(jié)省了人力和能源的消耗。變頻調(diào)速以其優(yōu)異的調(diào)速和起、制動性能，高效率、高功率因數(shù)和節(jié)電效果，得到了廣2泛的應(yīng)用。如利德福華的一些高壓供水變頻器。同時用于水泵轉(zhuǎn)速控制的變頻器也存在一定的滯后效應(yīng)。由圖 21可以看出，流量 Q 越大，揚(yáng)程 H 越小。揚(yáng)程cQ特性曲線和管阻特性曲線的交點，稱為供水系統(tǒng)的工作點，如圖 21 中 A 點。由公式(23)可以看出，功率與轉(zhuǎn)速的立方成正比 [2]，流量與轉(zhuǎn)速成正比，損耗功率與流量成正比，所以調(diào)速控制方式要比閥門控制方式供水功率要小得多，節(jié)能效果顯著，所以本文供水系統(tǒng)采用變頻調(diào)速恒壓供水方式。 供水系統(tǒng)中的水錘效應(yīng)及消除方法水錘效應(yīng)在極短時間內(nèi)，因水流量的急劇變化，引起在管道的壓強(qiáng)過高或過低的沖擊，并產(chǎn)生空化現(xiàn)象，使管道受壓產(chǎn)生噪聲，猶如錘子敲擊管子一樣，稱為水錘效應(yīng)。83 供水系統(tǒng)恒壓控制與硬件設(shè)計 異步電動機(jī)調(diào)速方法及選型轉(zhuǎn)速控制法實現(xiàn)恒壓供水，供水質(zhì)量好、能耗低、效率高，并可延長設(shè)備的使用壽命，提高系統(tǒng)的安全性。通過改變電動機(jī)的轉(zhuǎn)差率實現(xiàn)電機(jī)轉(zhuǎn)速的改變。 變頻調(diào)速變頻調(diào)速機(jī)械特性最常用的變頻器采取的是變壓變頻方式的。(4)減少了起動電流，也就減少了系統(tǒng)對電網(wǎng)的沖擊，提高了自身系統(tǒng)的可靠性。處于供水低谷小流量或夜間小流量時，為進(jìn)一步減少功耗，采用一臺小流量泵來維持正常的泄漏和水壓。（4）PLC 控制系統(tǒng)：包括硬件線路和軟件控制程序，完成對恒壓供水系統(tǒng)壓力