【正文】 兩個(gè)接觸器與工頻電源和變頻器輸出電源相聯(lián)，變頻器輸入電源前面接入一個(gè)空氣開(kāi)關(guān)，來(lái)實(shí)現(xiàn)電機(jī)、變頻器的接通，空氣開(kāi)關(guān)的容量依據(jù)電機(jī)的額定電流來(lái)確定。為了保護(hù)PLC設(shè)備，PLC輸出端口并不是直接和交流接觸器連接，而是通過(guò)中間繼電器去控制電機(jī)或者閥門(mén)的動(dòng)作。圖52 電流互感器的接線圖補(bǔ)水泵有三臺(tái)，3。圖53 補(bǔ)水泵系統(tǒng)電氣控制圖變頻器主電路電源輸入端子(R, S, T)經(jīng)過(guò)空氣開(kāi)關(guān)與三相電源連接，變頻器主電路輸出端子(U, V, W)經(jīng)接觸器接至三相電動(dòng)機(jī)上，當(dāng)旋轉(zhuǎn)方向預(yù)設(shè)定不一致時(shí)，需要調(diào)換輸出端子(U, V, W)的任意兩相。在實(shí)現(xiàn)組內(nèi)互鎖的時(shí)候，嚴(yán)禁出現(xiàn)一臺(tái)電動(dòng)機(jī)同時(shí)接在工頻電源和變頻電源的情況，同時(shí)要求變頻器始終只與一臺(tái)電動(dòng)機(jī)相連，而且當(dāng)大容量電動(dòng)機(jī)變頻工作的時(shí)候，小容量電動(dòng)機(jī)要么是工頻工作運(yùn)行，要么是停止工作。 循環(huán)泵控制系統(tǒng)循環(huán)泵控制系統(tǒng)有4臺(tái)循環(huán)泵，本系統(tǒng)配置兩臺(tái)變頻器，另外一臺(tái)作為備用。其電氣控制原理相對(duì)簡(jiǎn)單。即： （3）以上各量都是連續(xù)量，第一項(xiàng)為比例項(xiàng)，最后一項(xiàng)為微分項(xiàng)，中間兩項(xiàng)為積分項(xiàng)。表61 PID回路表參數(shù)偏移地址數(shù)據(jù)格式I／0類型中斷描述過(guò)程變量(PVn)0雙字，實(shí)數(shù)I過(guò)程變量，～設(shè)定值（SPn）4雙字，實(shí)數(shù)I給定值，～輸出值（Mn）8雙字，實(shí)數(shù)I／0輸出值，～增益（Kc）12雙字，實(shí)數(shù)I比例常數(shù)，正、負(fù)采樣時(shí)間（Ts）16雙字，實(shí)數(shù)I單位為秒．正數(shù)積分時(shí)間（Ti）20雙字，實(shí)數(shù)I單位為分鐘，正數(shù)微分時(shí)間（Td）24雙字，實(shí)數(shù)I單位為分鐘，正數(shù)積分項(xiàng)前值（Mx）28雙字，實(shí)數(shù)I／0積分項(xiàng)前值，～過(guò)程變量前值PVn132雙字，實(shí)數(shù)I／0最近一次PID變量值(2)PID指令使能輸入有效時(shí)，該指令利用回路表中的輸入信息和組態(tài)信息，進(jìn)行PID運(yùn)算。標(biāo)準(zhǔn)化實(shí)數(shù)又分為雙極性()和單極性()兩種。例如只需要比例回路或只需要比例積分回路，通過(guò)對(duì)常量參數(shù)的設(shè)置，可以關(guān)閉不需要的控制類型。（6）應(yīng)用實(shí)例系統(tǒng)使用比例積分微分控制。輸出值是進(jìn)水泵的速度，可以從允許最大值的0％變到100％。其增益和時(shí)間常數(shù)可以通過(guò)工程計(jì)算初步確定。圖13 PID程序當(dāng)工作在手動(dòng)方式下，可以把水泵的速度(～)直接寫(xiě)入回路表中的輸出寄存器(VD108)。本例中的程序僅有自動(dòng)控制方式的設(shè)計(jì)。=1時(shí)進(jìn)行PID“自動(dòng)”控制，把PID運(yùn)算的輸出值送到AQWO中，從而控制進(jìn)水泵的速度，以保持水箱的水面高度。這個(gè)條件無(wú)論是自動(dòng)控制還是手動(dòng)控制都需要給到鍋爐燃燒機(jī)才能啟動(dòng)鍋爐。待鍋爐碟閥打開(kāi)后啟動(dòng)條件滿足，啟動(dòng)程序輸出啟動(dòng)信號(hào)；需要注意的一點(diǎn)是自動(dòng)啟動(dòng)和手動(dòng)啟動(dòng)信號(hào)的互鎖，即選擇自動(dòng)控制時(shí)復(fù)位手動(dòng)啟動(dòng)信號(hào)，選擇手動(dòng)控制時(shí)，復(fù)位自動(dòng)啟動(dòng)信號(hào)。(4) 鍋爐的閥門(mén)控制模擬量控制的閥門(mén)一般是用4－20毫安電流信號(hào)控制閥門(mén)開(kāi)度，對(duì)應(yīng)的閥門(mén)開(kāi)度從0%100%，對(duì)應(yīng)PLC內(nèi)存的數(shù)據(jù)大小從6400－32000。變頻控制需要給定變頻器一個(gè)頻率給定值，一種方式是通信傳輸，另一種方式給定模擬量值。然后通過(guò)壓力PID控制調(diào)節(jié)變頻器頻率，以穩(wěn)定出水壓力。運(yùn)行時(shí)，系統(tǒng)根據(jù)回水壓力的設(shè)定值初步確定啟動(dòng)幾臺(tái)補(bǔ)水泵，若兩臺(tái)泵或者只用一臺(tái)即可滿足回水壓力，則只啟動(dòng)1泵系統(tǒng)或34泵系統(tǒng)(包括2變頻器)，若需要兩臺(tái)以上泵才能達(dá)到回水壓力的設(shè)定值，則先用1變頻器(或2變頻器)啟動(dòng)12泵(或34泵)，切換到工頻運(yùn)行，然后再用2變頻器(或1變頻器)拖動(dòng)34泵(或12泵)，進(jìn)入變頻器運(yùn)行。LDW= LW16, LW6 //比較當(dāng)前采樣次數(shù)是否等于預(yù)制采樣次數(shù)ITD LW6, LD42DTR LD42, LD46 //將采樣次數(shù)有16位整數(shù)轉(zhuǎn)換位32位實(shí)數(shù)MOVR LD12, LD18/R LD46, LD18 //求出采樣平均值MOVR , LD12 //清空累加器MOVW +0, LW16 //清空計(jì)數(shù)器R , LD18*R LD8, LD18 //轉(zhuǎn)換為十進(jìn)制數(shù)值+R LD2, LD18 //修正Network 3 LD MOVR LD18, LD22 //輸出Network 4 LD //返回主程序求比例值的子程序Network 1 // 根據(jù)實(shí)際值的上下限和 PLC采集值的上下限，計(jì)算出實(shí)際值與采集值的比例LD MOVR LD0, LD20R LD4, LD20 //實(shí)際值上限減去實(shí)際值下限，求出差值1MOVR LD8, LD24R LD12, LD24 //采集值上限減去采集值下限，求出差值2MOVR LD20, LD16/R LD24, LD16 //差值1除以差值2求出比例值Network 2 LD CRET //返回主程序數(shù)據(jù)轉(zhuǎn)換子程序Network 1 LD MOVW LW0, LW12 //輸入值I LW2, LW12 //模塊采集值下限ITD LW12, LD14DTR LD14, LD18MOVR LD18, LD8 //dived是模塊采集值上下限差值/R LD4, LD8 //輸出結(jié)果Network 2 // 返回主程序LD CRET // 返回主程序圖19 補(bǔ)水泵控制流程圖結(jié)論 在理論上將以上設(shè)計(jì)應(yīng)用到供暖鍋爐系統(tǒng)后，連接好輸入輸出分配和主電路，按照步驟進(jìn)行調(diào)試，調(diào)試過(guò)程會(huì)全部通過(guò)，完全滿足供暖鍋爐的控制要求。當(dāng)然本次畢業(yè)設(shè)計(jì)雖然功能單一，但由于是時(shí)間原因，未能做出實(shí)物進(jìn)行論題的論證，多少會(huì)有遺憾。特別是在課題的設(shè)計(jì)過(guò)程中，對(duì)論文的技術(shù)問(wèn)題，朱老師都花費(fèi)了大量的心血，付出了大量的勞動(dòng)，并一直給予我無(wú)微不至的指導(dǎo)與多方面的幫助，使我的知識(shí)、能力等各方面都有了很大的進(jìn)步，在此，謹(jǐn)向朱老師表示最衷心的感謝！在課題進(jìn)行期間，學(xué)院為我們提供了良好的學(xué)習(xí)和設(shè)計(jì)環(huán)境。由于時(shí)間和知識(shí)水平所限，論文中還可能會(huì)有許多紕漏或錯(cuò)誤之處，懇請(qǐng)各位老師和同學(xué)批評(píng)指正。t guarantee the request of the higher quantity and high new the image of the technique business enterprise.The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel39。 And the PLC emergence also became the epochmaking topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people39。 But lead even is a fatal error greatly is what we can39。t guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, being a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick.The PLC correspondence has already e more body now its value, at the PLC and correspondence between PLC, can pass the munication of the information and the share of the data to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to e to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data。t send out and accept at the same time, for example when you make a phone call is to c