ABSTRACＴ
Ａccordｉng to tｈe rｅqｕiｒｅｍent oｆ Ｃｈina'ｓ urbａn wａter ｓup
ｐly， this papｅｒ ｄesigns ａ sｅｔ of wａter suｐply system of frequecey ｃ
onｔｒol of ｃoｎｓtaｎｔ vｏltaｇe baseｄ oｎ PLＣ， and ｈave ｄeveｌoｐeｄ
ｇooｄ operation managemenｔ intｅｒfacｅ usｉng Sｕpervｉsｉon Controｌ aｎ
d Data Ａcquisition.The sｙsｔem ｉs made up of PLC， traｎsdｕceｒ，ｕｎits
of puｍｐs，pressｕre seｎsor aｎd coｎｔrol mａｃhine ａｎd ｓｏ ｏｎ.
Tｈiｓ system is formed by three pｕmｐ gｅｎeraｔors，and thｅy forｍ the
circulaｔｉｎg rｕn mode ｏｆ frequenｃｙ convｅrsiｏn. Witｈ general freｑueｎ
cy converter ｒealize fｏr three pｈaｓe puｍp generator soft ｓｔaｒt wiｔh fｒeq
ｕency ｃoｎtrol，opeｒaｔion sｗiｔｃh ａdｏｐts the prｉnciｐlｅ of”staｒt
ｆｉｒsｔ stop fｉrst”. Thｅ detection sｉgnaｌ of pressure sensor oｆ ｈｙdｒau
ｌic pｒeｓｓure，viａ PＬＣ with sｅｔ value by ｃarｒy ｏut PID ｃompaｒison
opｅｒation,sｏ,cｏｎtｒol freｑuency ａnｄ the exｐoｒt voｌtage of frequeｎｃy
conveｒtｅｒ，aｎd then the rotatｉonal spｅed thａt chaｎges puｍp ｇeｎeraｔ
oｒ ｃome to chaｎge waｔer suｐｐlｙ quａntｉty，eventually,ｉｔ ｉs ｎearby to
maiｎtain ｐipｅ net pressuｒe tｏ sｔabilｉze when set ｖａlue. Ｔhrougｈ
work contｒol ｍａcｈiｎe ｔhe ｃｏnｎeｃtiｏn with PLC,with groｕp form ｓo
ｆtｗａｒe ｃonsｕmmatｅly systematic monitoｒiｎg,haｖe reａlizeｄ oｐeｒａｔ
ioｎ state deｖeｌopmenｔ to shoｗ and daｔa，report to tｈe poｌice iｎquiry.
Kｅywords：Variaｂｌe fｒｅquｅｎcy speeｄ－regｕlａtingConstant－ｐreｓsuｒe
waｔer suppｌyPLC
