【正文】
flux, the control system control the variable frequency and speed regulation, parallel pumps’ speed and cut over, cause the system move in the best rational situation, assure according to wants supply water. This design has many merits such as save energy.In this paper,the control principle of VVVF providingwater system is introduced,we use PLC to carry on logic control and use inverter to modulate pressure.Through PID control principle 南華學(xué)院畢業(yè)論文 ii .we realize Closedloop control in VVVF Providingwater System.The result indicates that the system has the stable pressure,simple structure,and reliable work.Keywords: Variable Frequency and Speed Regulation Water Supply of Constant Pressure PID Control System PLC 南華學(xué)院畢業(yè)論文 iii 目錄1 緒論 ..............................................................................................................................1 變頻恒壓供水產(chǎn)生的背景和意義 ...................................1 變頻恒壓供水系統(tǒng)的國(guó)內(nèi)研究現(xiàn)狀 .................................3 課題來(lái)源及本文的主要研究?jī)?nèi)容 ...................................32 恒壓供水系統(tǒng)的分析 ..................................................................................................4 恒壓供水系統(tǒng)的構(gòu)成 .............................................4 系統(tǒng)功能分析 ...................................................4 ..........................................................................................................6 變頻器的設(shè)計(jì) ...................................................6 PID 控制器的設(shè)計(jì) ...............................................7 PID 控制器的選擇 ...........................................7 PID 控制算法及特點(diǎn) .........................................7 PLC 的選擇及應(yīng)用 ...............................................9 在恒壓供水泵站中的主要任務(wù) ..............................9 控制系統(tǒng)的 I/O 分配 ........................................10 PLC 系統(tǒng)選型 ..............................................11 電氣控制系統(tǒng)原理圖 ............................................11 主電路圖 ..................................................11 控制電路圖 ................................................12 外圍接線圖 .............................................124 系統(tǒng)程序設(shè)計(jì) .............................................................................................................17 由“恒壓”要求出發(fā)的工作泵組數(shù)量管理 ..........................17 多泵組泵站泵組管理規(guī)范 .......................................17 程序的 結(jié)構(gòu)及程序功能的實(shí)現(xiàn) ....................................17 系統(tǒng)的梯形圖程序 ..............................................16 系統(tǒng)的運(yùn)行分析 ................................................26 南華學(xué)院畢業(yè)論文 iv 結(jié)束語(yǔ) ............................................................................................................................27謝 辭 ..............................................................................................................................28參考文獻(xiàn) ........................................................................................................................291 緒論隨著社會(huì)經(jīng)濟(jì)的迅速發(fā)展,水對(duì)人民生活與工業(yè)生產(chǎn)的影響日益加強(qiáng),人民對(duì)供水的質(zhì)量和供水系統(tǒng)可靠性的要求不斷提高。以下就逐一分析。這種供水方式,水泵工作在額定流量額定揚(yáng)程的條件下,水泵處于高效區(qū)。高層建筑還可分層設(shè)立水箱。氣壓罐方式依靠壓力罐中的壓縮空氣送水,氣壓罐配套水泵運(yùn)行時(shí),水泵在額定轉(zhuǎn)速、額定流量的條件下工作。在早期,由于國(guó)外生產(chǎn)的變頻器的功能主要限定在頻率控制、升降速控制、正反轉(zhuǎn)控制、起制動(dòng)控制、壓頻比控制及各種保護(hù)功能。本系統(tǒng)是三泵生活/消防雙恒壓供水系統(tǒng),變頻恒壓供水系統(tǒng)主要由變頻器、可編程控制器、壓力傳感器組成。當(dāng)有火災(zāi)發(fā)生時(shí),電磁閥YV2得電,關(guān)閉生活用水管網(wǎng),三臺(tái)泵供消防用水使用,并維持消防用水的高恒壓值。(4)三臺(tái)泵在啟動(dòng)時(shí)都要有軟啟動(dòng)功能。11/)(??均與送入電機(jī)的電流頻率/成正比例或接近于正比例。它的原理通