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1、SHANDONGUNIVERSITYOFTECHNOLOGY畢業(yè)設(shè)計(jì)說明書小型水廠恒壓供水控制系統(tǒng)設(shè)計(jì)學(xué)院:電氣與電子工程學(xué)院專業(yè):自動(dòng)化學(xué)生姓名:李曉粉學(xué)號(hào):0812205761指導(dǎo)教師:李素玲2012年6月中文摘要摘要隨著社會(huì)的飛快發(fā)展,城市建設(shè)規(guī)模的不斷擴(kuò)大,工業(yè)化化水平的不斷提高,人們生活水平的不斷提高,人們對(duì)城市供水的質(zhì)量、數(shù)量、穩(wěn)定性提出了更高的要求。本論文根據(jù)小型水廠的工藝特點(diǎn)與要求,設(shè)計(jì)了一套基于PLC的變頻恒壓供水控制系統(tǒng)。該系統(tǒng)主要由PLC、變頻器、水泵機(jī)組、壓力變送器、液位變送器等構(gòu)成。系統(tǒng)有六臺(tái)
2、水泵電機(jī),一臺(tái)大功率水泵電機(jī)用變頻器啟動(dòng),變頻調(diào)速運(yùn)行,另一臺(tái)大功率水泵電機(jī)備用,另外四臺(tái)電機(jī)順序工頻運(yùn)行。壓力變送器檢測當(dāng)前水壓信號(hào),送入PLC與設(shè)定值比較后進(jìn)行PID運(yùn)算,從而控制變頻器的輸出電壓和頻率,進(jìn)而改變水泵電機(jī)的轉(zhuǎn)速來改變供水量。當(dāng)變頻器的頻率輸出升到48Hz時(shí),管網(wǎng)壓力還是過低,這時(shí)要開啟工頻泵;當(dāng)變頻器的頻率輸出降到20Hz時(shí),管網(wǎng)壓力還是過高,這時(shí)需要停止工頻泵。最終保持管網(wǎng)壓力穩(wěn)定在設(shè)定值附近。關(guān)鍵詞:變頻調(diào)速,PLC,恒壓供水IAbstractAbstractWiththerapiddevelo
3、pmentofthesociety,thescaleofcityconstructionisexpanding,andtheindustrializationlevelincreases,people’sstandardoflivingisrisingconstantly,sopeoplearecontinuouslyimprovingtherequirementstothequalityofwatersupplying,reliabilityofwatersupplysystemandenergysaving.Acc
4、ordingtotherequirementofwatersupply,thispaperdesignsasetofwatersupplysystemoffrequencycontrolofconstantvoltagebasedonPLC..ThesystemconsistsofPLC,frequencyregulator,unitsofpumps,waterleveltransducer,pressuretransducerandsoon.Therearesixpumpsmotorsinthissystem.One
5、ofthebiggestmotorsisstartedwiththefrequencyregulator,theotherbiggestisalternate,anotherarestartedinsequence.PressureregulatordetectsthewaterpressuresignalandthenputsitintothePLCtocomparewiththesetvalue,thenthePIDoperatessoastocontroltheoutputvoltageandfrequencyo
6、ffrequencyregulator,andchangethespeedofthepumpmotortochangethesupplyquantity.Whentheoutputofthefrequencyregulatorisupto48Hz,butthepipepressureistoolow,theindustrialfrequencypumpwillbestartedatthistime;Whentheoutputofthefrequencyregulatorisdownto20Hz,butthepipepr
7、essureistoohigh,theindustrialfrequencypumpwillbestoppedatthistime.Ultimatelythepressureofthepipenetworkremainsconstantaroundthesetting.Keywords:variablefrequencyspeed-regulating,PLC,constant-pressurewatersupplyII目錄目錄摘要............................................
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