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1外文文献原稿和译文原稿Thewatersupplysystemisthenationalproductionandlifeindispensableimportantoneannulus.Thetraditionalmethodofwatersupplyarea,waterpollution,infrastructureinvestment,butthemaindrawbackisthatwatercannotbekeptconstant,causingpartoftheequipmentcannotworknormally.VariablefrequencyspeedcontroltechnologyisanewmatureACmotorsteplessspeedregulatingtechnology,itsuniqueexcellentcontrolperformanceiswidelyappliedtothespeedcontrolfield,especiallyinwatersupplyindustry.Duetothesafetyinproductionandthewaterqualityofspecialneeds,forconstantpressurewatersupplywiththestringentrequirements,sothefrequencycontroltechnologyhasbeenmorein-depthapplication.Constantpressurewatersupplywaystoadvancedtechnology,constantpressure,convenientoperation,reliableoperation,energysaving,highdegreeofautomation,inpumpstationwatersupplycanperformthefollowingfunctions:(1)tomaintainconstantpressure;(2)thecontrolsystemcanbemanualorautomaticoperation;(3)apluralityofpumpautomaticswitchoperation;(4)systemofsleepandwake,whenpeoplestopwhenwater,thesystemisinasleepstate,untilthewaterdemandautomaticallywake;(5)adjuststhePIDparametersonline;(6)pumpunitandcircuitprotectiondetectionalarm,signaldisplay.Theactualpressureofthepipenetworkfeedbackandagivenpressurewerecompared,whenthepressureofapipenetworkislow,increasetheoutputoffrequencyconverter,pumpspeedfaster,watersupplyquantityincreases,forcingthepipenetworkpressurerise.Vicepumpspeedslowdown,reducethewatersupplypipenetworkpressuredrop,,tokeeptheconstantpressurewatersupply.SystemhardwarestructureSystemusesapressuresensor,PLCandinverterasacentralcontroldevice,toachieveadesiredfunction.Source:networktransmissionanddistributionequipment2installationinpipelinepressuresensor,fordetectingthewaterpressureofthepipenetwork,convertingpressureis4~20mAcurrentorvoltagesignalis0~10V,suppliedtotheinverter.Converterpumpmotorcontroldevice,inaccordancewiththeconstantwaterpressureneedstobe0~50Hzfrequencysignalsupplypumpmotor,adjustitsspeedSAJconverterispowerful,i.e.pre-programmedsetparameterset,willusetherequiredintheprocessofsettingthenumberofparametersisreducedtoaminimum,defaultvalueaccordingtotheapplicationparameterofthemacrochoiceanddifferent.ThesystemadoptsthePIDcontrolapplicationmacro,closedloopcontrol.Inverterbasedonaconstantpressurecorrespondingtothevoltagesettingvalueandfromthepressuresensortoobtainthefeedbackcurrentsignal,theuseofPIDcontrolmacroautomaticallyadjust,changethefrequencyoutputvaluetoadjustthecontrolthespeedofthepumpmotor,toensurethatthepipenetworkpressureconstantrequirements.Theapplicationofinverterintheconstantpressurewatersupply一．ThecharacteristicandanalysisofvariablefrequencyspeedregulationThewaterusersingeneralisdynamic,sothewatersupplyisinsufficientorexcesswatersupplysituationhasoccurred.Thewatersupplyandtheimbalancebetweentheconcentratedreflectioninwatersupplypressure,namelywaterandwatersupplyisless,thelowpressure;lesswaterconsumptionandwatersupply,thepressure.Keepthewaterpressureconstant,canmakethewatersupplyandwaterbalancebetweenwatersupplyandwaterforalongtime,thatis,lesswaterwhenthewaterisless,soastoimprovethequalityofwatersupply.Constantpressurewatersupplysystemfortheuserisveryimportant.Inproductionandlivingwater,ifwatersupplyduetoinsufficientpressureorshortofwater,mayaffectthequalityoflife,seriouswhencaninfluencethesurvivalsafety,suchaswhenafireoccurs,ifthewaterpressureisinsufficientorwatersupply,canquicklyfire,maycausesignificanteconomiclossesandcasualties.Therefore,waterareabymeansofArtsistheconstantpressurewatersupplysystem,canproducegreateconomicbenefitandsocialbenefit.Withthedevelopmentofelectricpowertechnology,frequencyconversiontechnologyperfected,withvariablefrequencyspeedcontrolasthecoreofthe3intelligentwatercontrolsystemreplacedtheprevioushighlevelwatertankandapressuretankandwatersupplyequipment,stablestarting,thestartingcurrentcanbelimitedwithinspecifiedcurrent,therebyavoidingthestartingtimeoftheimpactofpowergrid;becausetheaveragerotationalspeedofpumpisreduced,whichcanextendthepumpsandvalvesandotherthingsoflife;toeliminatethestartandstopofthewaterhammereffect.Thestableandsafeperformance,simpleandconvenientoperation,andcompleteandthoughtfulfunction,willmakethewatersupplyandwaterconservation,energysaving,laborsaving,ultimatelyachieveefficientoperation.二．TheapplicationofvariablefrequencycontrolconstantpressurewatersupplymodeUsuallyinthesamewayinthewatersupplysystem,settingmultiplecommonpump,watersupplywhenthequantityofmultipumpfullopen,watersupplyononeortwohours.Inthevariablefrequencyspeedcontrolforconstantpressurewatersupply,intwoways,oneisallpumpswithafrequencyconverter;andeachwaterpumpwithafrequencyconverter.Afteramethodbasedonpressurefeedbacksignal,operatedbyPIDautomaticallyadjuststheoutputfrequencyoftheinverter,changethespeedofthemotor,eventuallyreachingthepurposeofnetworkvoltage,aclosedloop,isrelativelysimple,butthecostishigh.Thepreviousmethodoflowcost,lessthankindofpoorperformance,butthecontrolprogramiscomplex,isthefuturedirectionofdevelopment,suchastheShanghaiartsandscienceand