PID調節器在變頻恒壓給水設備(bei)中的性能與此(ci)作用

      近幾年來(lai)(lai),基于(yu)ＰＩＤ控(kong)(kong)制(zhi)算法(fa)(fa)和(he)ＰＬＣ的(de)變頻(pin)調(diao)(diao)速恒壓供(gong)(gong)(gong)(gong)水(shui)(shui)技術(shu)得(de)到了廣泛的(de)應(ying)用(yong)(yong),被認為(wei)是(shi)一(yi)(yi)(yi)種理想的(de)供(gong)(gong)(gong)(gong)水(shui)(shui)方(fang)式。但由于(yu)供(gong)(gong)(gong)(gong)水(shui)(shui)系(xi)統(tong)一(yi)(yi)(yi)般用(yong)(yong)戶較多且用(yong)(yong)水(shui)(shui)時間不確(que)定(ding)(ding),管(guan)網水(shui)(shui)壓波(bo)動(dong)(dong)較大(da),而且控(kong)(kong)制(zhi)對象(xiang)具(ju)有非線性(xing)(xing)(xing)和(he)一(yi)(yi)(yi)定(ding)(ding)的(de)滯(zhi)后特(te)(te)性(xing)(xing)(xing),所(suo)(suo)以(yi)很難建(jian)立精(jing)確(que)的(de)數學(xue)模(mo)(mo)型(xing)(xing)。因此(ci),在(zai)實際(ji)當中,特(te)(te)別是(shi)在(zai)一(yi)(yi)(yi)些控(kong)(kong)制(zhi)精(jing)度要(yao)求較高的(de)工業用(yong)(yong)水(shui)(shui)供(gong)(gong)(gong)(gong)水(shui)(shui)系(xi)統(tong)中,使用(yong)(yong)基于(yu)ＰＩＤ控(kong)(kong)制(zhi)的(de)變頻(pin)調(diao)(diao)速供(gong)(gong)(gong)(gong)水(shui)(shui)時,存在(zai)不同程(cheng)度的(de)超(chao)調(diao)(diao)或震(zhen)蕩現象(xiang)。對于(yu)供(gong)(gong)(gong)(gong)水(shui)(shui)系(xi)統(tong)的(de)非線性(xing)(xing)(xing)、高階次、大(da)滯(zhi)后、參數易變異及其(qi)數學(xue)模(mo)(mo)型(xing)(xing)難以(yi)確(que)定(ding)(ding)等(deng)特(te)(te)點,適(shi)宜于(yu)采用(yong)(yong)模(mo)(mo)糊控(kong)(kong)制(zhi)。所(suo)(suo)謂(wei)模(mo)(mo)糊控(kong)(kong)制(zhi),就是(shi)把(ba)操作者的(de)經驗總結成若干條法(fa)(fa)則,并(bing)依據(ju)人(ren)腦(nao)的(de)模(mo)(mo)糊推理過程(cheng),確(que)定(ding)(ding)推理法(fa)(fa)則,計(ji)算機根(gen)據(ju)現場采集(ji)的(de)信息,按照控(kong)(kong)制(zhi)規則做出模(mo)(mo)糊控(kong)(kong)制(zhi)決策(ce),發(fa)出控(kong)(kong)制(zhi)指令,以(yi)實現模(mo)(mo)糊控(kong)(kong)制(zhi)。模(mo)(mo)糊控(kong)(kong)制(zhi)在(zai)處理不確(que)定(ding)(ding)對象(xiang)時,用(yong)(yong)建(jian)立一(yi)(yi)(yi)個(ge)模(mo)(mo)擬不確(que)定(ding)(ding)對象(xiang)的(de)模(mo)(mo)糊模(mo)(mo)型(xing)(xing)的(de)方(fang)法(fa)(fa)來(lai)(lai)解決實際(ji)控(kong)(kong)制(zhi)問題,具(ju)有動(dong)(dong)態響應(ying)好,上升時間快,超(chao)調(diao)(diao)小(xiao)等(deng)優(you)越(yue)性(xing)(xing)(xing)。

      雖然模(mo)(mo)糊控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)具(ju)(ju)有許(xu)多(duo)傳統(tong)控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)方(fang)法無(wu)法比(bi)擬(ni)的(de)(de)優點，如(ru)不(bu)需建立(li)數學模(mo)(mo)型，符合人們(men)思維特(te)點以(yi)及良好的(de)(de)動(dong)態(tai)性能(neng)，但(dan)是也有其(qi)自身的(de)(de)局限性。比(bi)如(ru)，模(mo)(mo)糊控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)恒壓供(gong)水系統(tong)的(de)(de)靜態(tai)性能(neng)較(jiao)差。在線(xian)性控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)理論之中，積分控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)的(de)(de)作(zuo)用(yong)是消除靜態(tai)誤差，但(dan)動(dong)態(tai)響(xiang)應(ying)慢;比(bi)例控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)的(de)(de)作(zuo)用(yong)是提高動(dong)態(tai)響(xiang)應(ying)速度;比(bi)例積分控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)的(de)(de)作(zuo)用(yong)是既能(neng)獲得較(jiao)高的(de)(de)靜態(tai)精度，又具(ju)(ju)有較(jiao)快的(de)(de)動(dong)態(tai)響(xiang)應(ying)。因此把PID控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)引(yin)入模(mo)(mo)糊控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)中組成Fuzzy -PID復合控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)，是改善模(mo)(mo)糊控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)靜態(tai)性能(neng)的(de)(de)一(yi)條(tiao)途徑(jing)。參數自整定模(mo)(mo)糊-ＰＩＤ復合控(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)的(de)(de)變頻恒壓供水系(xi)統的方案,利用模(mo)糊(hu)參數(shu)自整定技術,對ＰＩＤ輸出進(jin)行再(zai)調整,使動態響應(ying)好的Ｆｕｚｚｙ控制與(yu)穩態特(te)性好的ＰＩＤ控制相結合,實(shi)現系(xi)統的最佳控制。

含PID調節(jie)器(qi)的變(bian)頻恒壓給水設(she)備

      變頻恒壓給水設(she)備(bei)主要(yao)是由ＰＬＣ、變頻(pin)器(qi)、模糊PID控制器(qi)（Fuzzy-PID）、壓力(li)(li)傳感器(qi)、多(duo)組繼電(dian)器(qi)和接觸器(qi)的(de)電(dian)氣動(dong)力(li)(li)控制線路(lu)以及3臺(tai)水泵等(deng)組成。

      變頻恒壓(ya)給(gei)水設備控(kong)(kong)(kong)制(zhi)(zhi)(zhi)系統(tong)(tong)的(de)(de)基本(ben)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)策略是: 根(gen)據流(liu)體力學(xue)的(de)(de)基本(ben)原(yuan)理,水泵消耗功(gong)率(lv)(lv)(軸功(gong)率(lv)(lv))與轉(zhuan)速(su)的(de)(de)三次方成正(zheng)比.即 ，降(jiang)低(di)轉(zhuan)速(su)，消耗功(gong)率(lv)(lv)即可大幅度下(xia)降(jiang)。由電動機原(yuan)理可知，電動機轉(zhuan)速(su)與電源頻率(lv)(lv)成正(zheng)比，頻率(lv)(lv)越(yue)低(di)，轉(zhuan)速(su)越(yue)低(di)。本(ben)系統(tong)(tong)通(tong)過壓(ya)(ya)力傳(chuan)感器(qi)周期性地采(cai)集管網壓(ya)(ya)力,將管網壓(ya)(ya)力與設(she)定壓(ya)(ya)力進行比較后,其(qi)壓(ya)(ya)差(cha)信(xin)號送入模(mo)(mo)(mo)糊(hu)(hu)(hu)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)器(qi),PLC根(gen)據壓(ya)(ya)差(cha)信(xin)號能很(hen)快(kuai)計算出壓(ya)(ya)力誤差(cha)變(bian)化率(lv)(lv);經控(kong)(kong)(kong)制(zhi)(zhi)(zhi)器(qi)模(mo)(mo)(mo)糊(hu)(hu)(hu)運算處理后,在模(mo)(mo)(mo)糊(hu)(hu)(hu)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)表中查詢到相應的(de)(de)模(mo)(mo)(mo)糊(hu)(hu)(hu)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)量,再把模(mo)(mo)(mo)糊(hu)(hu)(hu)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)量通(tong)過解模(mo)(mo)(mo)糊(hu)(hu)(hu)運算輸(shu)出一個精確的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)量Δu,對系統(tong)(tong)設(she)定值(zhi)進行遷移,并把遷移后的(de)(de)值(zhi)送入常規PID調節器(qi)的(de)(de)比例環節,然后與積分環節、微分環節一起來實現對變(bian)頻器(qi)輸(shu)出頻率(lv)(lv)的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)(zhi),從而達到控(kong)(kong)(kong)制(zhi)(zhi)(zhi)變(bian)速(su)泵的(de)(de)轉(zhuan)速(su)和輸(shu)出的(de)(de)目的(de)(de)，使(shi)整個系統(tong)(tong)運行在高效節能的(de)(de)最(zui)佳狀態。

模(mo)糊(hu)控制器的設(she)計

      在一般的(de)模(mo)糊(hu)(hu)控(kong)(kong)制(zhi)(zhi)(zhi)系(xi)統中，考慮(lv)到模(mo)糊(hu)(hu)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)實現的(de)簡易性(xing)(xing)和(he)(he)快速性(xing)(xing)，通(tong)常采用二(er)維(wei)模(mo)糊(hu)(hu)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)結構形式(shi)。這類控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)都是以系(xi)統誤(wu)差e和(he)(he)誤(wu)差變化率ec為輸入語句變量，因(yin)此(ci)具有類似于常規PID控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)的(de)作(zuo)用.采用該類模(mo)糊(hu)(hu)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)的(de)系(xi)統有可能(neng)(neng)獲(huo)得良好的(de)動(dong)態特(te)性(xing)(xing)，而靜態性(xing)(xing)能(neng)(neng)不令人滿意(yi)。因(yin)此(ci)，把PID控(kong)(kong)制(zhi)(zhi)(zhi)策略(lve)引入模(mo)糊(hu)(hu)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)，構成(cheng)模(mo)糊(hu)(hu)PID復合控(kong)(kong)制(zhi)(zhi)(zhi)，是改善模(mo)糊(hu)(hu)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)(qi)穩態性(xing)(xing)能(neng)(neng)的(de)一種途徑。

新(xin)型變頻恒壓給水設(she)備的解決(jue)方(fang)案 

　　針對傳統的(de)變(bian)頻(pin)(pin)恒(heng)壓給水(shui)設備(bei)的(de)不足之(zhi)處(chu)，國外不少生產(chan)(chan)廠家(jia)近年來紛(fen)紛(fen)推出了(le)一(yi)系列新(xin)型(xing)(xing)產(chan)(chan)品(pin)，如(ru)ABB公司的(de)ACS600、ACS400系列產(chan)(chan)品(pin)，富士公司的(de)G11S/P11S系列產(chan)(chan)品(pin),北(bei)京菱科(ke)LK600P系列。這些產(chan)(chan)品(pin)將PID調節器(qi)以及簡易可編(bian)程控制器(qi)的(de)功能都綜合進變(bian)頻(pin)(pin)器(qi)內，形成了(le)帶有各種應(ying)用宏的(de)新(xin)型(xing)(xing)變(bian)頻(pin)(pin)器(qi)。這類變(bian)頻(pin)(pin)器(qi)的(de)價格僅(jin)比(bi)通用變(bian)頻(pin)(pin)器(qi)略微(wei)高一(yi)點(dian)，但(dan)功能卻強很多，所以我們在山(shan)東文登曲軸(zhou)廠新(xin)建(jian)的(de)生活小區中就采用了(le)這種新(xin)型(xing)(xing)的(de)設計方案。在這套變(bian)頻(pin)(pin)恒(heng)壓給水(shui)設備(bei)中，我(wo)們采用(yong)了(le)ABB公司的ACS601-0011-3帶內置PID功(gong)能的變頻器，可編程控制器選用(yong)西門子S7-214-1BC10-0XB0型，具體原理框(kuang)圖如(ru)圖2所以示。圖2中M1～M2為(wei)電(dian)機，P1～P2為(wei)水(shui)泵，JC1～JC4為(wei)電(dian)機起、停、互(hu)相切換的交流接觸(chu)器。 

　　該變頻(pin)恒壓給水設備采用2臺(tai)水(shui)泵，一(yi)(yi)用一(yi)(yi)備(bei)，由可編(bian)(bian)(bian)程(cheng)控(kong)(kong)制(zhi)器(qi)定(ding)時(shi)切換。若用水(shui)量(liang)大，變(bian)(bian)(bian)頻器(qi)也(ye)可以通(tong)過(guo)(guo)可編(bian)(bian)(bian)程(cheng)接口向可編(bian)(bian)(bian)程(cheng)控(kong)(kong)制(zhi)器(qi)發(fa)出信(xin)號，由可編(bian)(bian)(bian)程(cheng)控(kong)(kong)制(zhi)器(qi)控(kong)(kong)制(zhi)兩臺(tai)泵同時(shi)工作，一(yi)(yi)臺(tai)變(bian)(bian)(bian)頻運行(xing)，一(yi)(yi)臺(tai)工頻運行(xing)。圖2中傳(chuan)感器(qi)反饋的水(shui)壓(ya)信(xin)號直接送入(ru)變(bian)(bian)(bian)頻器(qi)自帶(dai)的PID調節器(qi)輸入(ru)口AI2+、AI2-，而壓(ya)力設(she)定(ding)既可以使用變(bian)(bian)(bian)頻器(qi)的鍵盤以數(shu)字(zi)量(liang)的形式設(she)定(ding)，也(ye)可以采用一(yi)(yi)只電位器(qi)以模擬量(liang)的形式送入(ru)AI1+、AI1-。這樣通(tong)過(guo)(guo)變(bian)(bian)(bian)頻器(qi)的控(kong)(kong)制(zhi)面(mian)板，在變(bian)(bian)(bian)頻器(qi)的PID選項中選擇合適的PID參數(shu)，并經過(guo)(guo)現場(chang)調試校正，設(she)備(bei)就可以正常運行(xing)了。  

　　由(you)于PID運(yun)算在變(bian)頻器(qi)內(nei)部，這就(jiu)省去(qu)了(le)(le)(le)對可(ke)編程(cheng)控制器(qi)存貯容(rong)(rong)量的(de)(de)要求和(he)對PID算法(fa)的(de)(de)編程(cheng)，而(er)且PID參數的(de)(de)在線調試非常(chang)容(rong)(rong)易，這不(bu)僅(jin)降(jiang)低(di)了(le)(le)(le)生產(chan)成(cheng)本，而(er)且大(da)大(da)提(ti)高了(le)(le)(le)生產(chan)效(xiao)率(lv)。由(you)于變(bian)頻器(qi)內(nei)部自帶(dai)的(de)(de)PID調節器(qi)采用了(le)(le)(le)優(you)化算法(fa)，所以使水(shui)壓(ya)(ya)的(de)(de)調節十分平(ping)滑(hua)，穩定。同(tong)時，為了(le)(le)(le)保(bao)證水(shui)壓(ya)(ya)反饋(kui)信號值(zhi)的(de)(de)準(zhun)確、不(bu)失值(zhi)，可(ke)對該(gai)信號設置濾(lv)波(bo)時間常(chang)數，同(tong)時還(huan)可(ke)對反饋(kui)信號進行(xing)(xing)換(huan)算，使系統的(de)(de)調試非常(chang)簡(jian)單(dan)、方便(bian)。該(gai)設備自1997年10月在該(gai)生活小(xiao)區運(yun)行(xing)(xing)以來，一(yi)直保(bao)持良(liang)好的(de)(de)運(yun)行(xing)(xing)狀態(tai)，管網水(shui)壓(ya)(ya)非常(chang)穩定，受到了(le)(le)(le)小(xiao)區用戶的(de)(de)一(yi)致好評