【正文】 以上問題。采用該系統(tǒng)進行供水可以提高供水系統(tǒng)的穩(wěn)定性和可靠性，同時系統(tǒng)具有良好的節(jié)能性，這在能源日益緊缺的今天尤為重要，所以研究設(shè)計該系統(tǒng)，對于提高企業(yè)效率以及人民的生活水平、降低能耗等方面具有重要的現(xiàn)實意義，且 運用恒壓變頻供水系統(tǒng) 有如下特點 ： (a) 節(jié)電：優(yōu)化的節(jié)能控制軟件，使水泵實現(xiàn)最大限度地節(jié)能運行； (b) 節(jié)水：根據(jù)實際用 水況設(shè)定管網(wǎng)壓力，自動控制水泵出水量，減少了水的跑、漏現(xiàn)象； (c) 運行可靠：由專用變頻器實現(xiàn)泵的軟起動，使水泵實現(xiàn)由變頻到工頻的最小沖擊切換防止管網(wǎng)沖擊、避免管網(wǎng)壓力超限，管道破裂； (d) 控制靈活：分段供水，定時供水，手動選擇工作方式； (e) 自我保護功能完善：假如水泵出現(xiàn)故障，系統(tǒng)會顯示故障并同時啟動備用泵，以維持供水平衡； (f) 萬一自控系統(tǒng)出現(xiàn)故障，用戶可以直接操作手動系統(tǒng)，以保護供水； (g) 夜間泵識別功能，實現(xiàn)最大限度節(jié)能。 其穩(wěn)定安全的運 行性能、簡單方便的操作方式、以及齊全周到的功能，將使供水實現(xiàn)節(jié)水、節(jié)電、節(jié)省人力，最終達到高效率的運行目的。 隨著電力技術(shù)的發(fā)展，變頻調(diào)速技術(shù)的日趨完善，以變頻調(diào)速為核心的智能供水控制系統(tǒng)取代了以往高位水箱和壓力罐等供水設(shè)備，起動平穩(wěn)，起動電流可限制在額定電流以內(nèi)，從而避免了起動時對電網(wǎng)的沖擊。s requirements are getting higher and higher. Variable frequency constant pressure water supply system has bee an inevitable trend. This paper designs a set of PLC based variable frequency speed regulation constant pressure water supply system. The system consists of a programmable logic controller, 2 soft starters, 2 converters, 7 pump motors. One is the use of low voltage state at night, the rest of these are used to be cyclic operation mode. In the operation of the system by the pressure sensor measured the pipeline pressure, the pressure and expectation values are pared, after that by the PLC control converter output frequency of different power, and then change the speed of the pump motor to track the desired value of the water pressure. This paper introduces how to select the main ponents, connection mode, operation principle, and the software design of the system. The emphasis is on the analysis of the program design method, describes the overall design ideas. Key words: variable frequency speed regulation, constant pressure water supply, converter, PLC III 目 錄 摘要 .................................................................................................................................................................................. I ABSTRACT.................................................................................................................................................................. II 1 緒論 ............................................................................................................................................................................ 1 選題背景 ....................................................................................................................................................... 1 選題依據(jù) ....................................................................................................................................................... 1 國內(nèi)外發(fā)展概況 ......................................................................................................................................... 2 設(shè)計 內(nèi)容及要求 ......................................................................................................................................... 3 2 恒壓變頻供水系統(tǒng)的方案設(shè)計 ........................................................................................................................... 4 系統(tǒng)的基本工作原理 ................................................................................................................................ 4 本課題研究的對象 ..................................................................................................................................... 4 控制方式的選擇 ......................................................................................................................................... 5 系統(tǒng) 原理與 組成 ......................................................................................................................................... 6 系統(tǒng)的組成及原理圖 .................................................................................................................... 6 變頻控制 原理 .................................................................................................................................. 7 系統(tǒng)水泵切換控制分析 ................................................................................................................ 8 3 恒壓變頻供水系統(tǒng)的硬件設(shè)計 ........................................................................................................................... 9 系統(tǒng)主要設(shè)備電路的設(shè)計 ....................................................................................................................... 9 PLC的設(shè)計 ....................................................................................................................................... 9 變頻器的設(shè)計 ................................................................................................................................ 11 軟啟動器的設(shè)計 ........................................................................................................................... 16 系統(tǒng)控制電路的設(shè)計 .............................................................................................................................. 18 4 恒壓變 頻供水系統(tǒng)的軟件設(shè)計 ......................................................................................................................... 20 主程序循環(huán) 流程圖 ................................................................................................................................... 20 系統(tǒng)上電 步驟 ................................................................................................................................ 20 變頻器選擇 .................................................................................................................................... 20 軟啟動 器 選擇 ................................................................................................................................ 21 故障檢測 ......................................................................................................................................... 22 夜間工作模式 .........................................................................................................................