【正文】 as the control system of core, day after handling the sewage 10 104 t the processing of reach mark sewage can used for an agriculture irrigation. 1 Control system structure Control the way of concentration monitor management, scatter a control of the system emulation hold, place of honor machine, gather a line machine, printer to Be located on medium control room, two set PLCs are located on control the this kind of structure can make the information in the production line can centralized management with carry out whole operation, management with excellent make to control dangerous dispersion in the meantime, raise the system credibility. The upper puters Medium control two calculator adoption PII class works of room to control machine, circulate the operate system of Windows place of honor machine be responsible for on the scene establish each long range control(fullautomatic control, automatic control, order to move a control) with surveillance, make use of Intouch7. 0 engineering software packages provide a good person machine dialogue boundary but obtain concerning parameter and equipments appearance information from the PLC by searching a way, keep a view manifestation to e out on the CRT by good sketch type, print a necessary data in the meantime and be provided for lord to control and manager instruction and control boundary but include the system total diagram, system cent diagram, imitate the quantity general chart, parameter a constitution, report to the police a window, history trend and register a window etc. boundary the system total diagram, circulate the personnel can keep watch on signals, such as all movement appearances, equipments trouble and liquid which control an equipments and discharge...etc..Operate a personnel in the system the cent the diagram can carry on a single machine point to move to circulate an operation to all control equipmentses, bee the set automatically circulate operation or the whole factorieses fullautomatic operation bine the meantime place of honor machine 2 and do a plait distance a control room to establish another an inset type emulation to hold, is been one control by the place of honor machine, in order to keep the craft process of the view manifestation whole factory and main parameter value. 1. 2 The PLC stand According to wastewater treatment of two part, the spot the long range of the equipments the control output and the spot the signal collect to control a station pletion from two PLC wood native control station control the space grid, sewage promote a pump house, Pu spirit to sink sand pond39。 the long 一 distance control and monitoring of field equipment are uncharged of the upper puter。同時通過 Inter 將污水處理廠的污水?dāng)?shù)據(jù)輸送到國家環(huán)?？偩只蛘呤协h(huán)保局，以便卜級部門對污水處理廠的管理。在污水處理中，基于 PLC的控制系統(tǒng)在實時 性、可靠性、精確性等力一而滿足了設(shè)計要求，保證了污水處理的順利進(jìn)行。今后 SBR 法的自動控制的研究方向主要是尋找多個控制參數(shù)，既能反映進(jìn)水的水質(zhì)水量變化及反應(yīng)過程中的降解情況，又能作為計算機(jī)控制參數(shù)。目前以經(jīng)驗為主，以 DO、時間、流量作為工藝控制參數(shù)，來調(diào)整曝氣機(jī)的運行及排泥時間等，缺乏準(zhǔn)確的數(shù)學(xué)模型來實現(xiàn) SBR 法的更高層次的自動控制。如果風(fēng)機(jī)轉(zhuǎn)速降到允許的最低轉(zhuǎn)速時，輸出電流還超過額定值，則停風(fēng)機(jī)，同時發(fā)出報警信號。 在曝氣的整個周期內(nèi)，隨時監(jiān)控變頻器的輸出電流值，使其不超過變頻器的額定值。當(dāng)溶解氧值大于 2mg/L 時，風(fēng)機(jī)轉(zhuǎn)速下降 5 %；當(dāng)溶解氧值小于 2 mg/L 時，風(fēng)機(jī)轉(zhuǎn)速上升 5%.如果風(fēng)機(jī)轉(zhuǎn)速升到允許的最高轉(zhuǎn)速時，溶解氧值還小于 2mg/L，則維持最高轉(zhuǎn)速。 （ 5）溶解氧值自動調(diào)節(jié)模塊 —— 根據(jù)溶解氧值調(diào)節(jié)風(fēng)機(jī)轉(zhuǎn)速以及相關(guān)故障的報警。 （ 3）斷電保護(hù)模塊 —— 系統(tǒng)斷電后， PLC 將所有狀態(tài)鎖存，待加電后使 PLC恢復(fù)所保持的狀態(tài)繼續(xù)運行。 （ 2）開關(guān)量順序控制模塊 —— 協(xié)調(diào)控制各個閥、泵、風(fēng)機(jī)等設(shè)備的運行及相關(guān)故障的報警。 PLC3 站的控制程序分為五個程序模塊。 PLC 程序設(shè)計 采用的編程軟件是 Concept 2. 2XL。在每個曝氣池的不同地點設(shè) 4 塊溶解氧測試儀，測量池中污水的含氧量， PLC 每隔 5 min 檢測一次曝氣池內(nèi)的溶解氧值，根據(jù)溶解氧的平均值來控制風(fēng)機(jī)轉(zhuǎn)速。根據(jù) SBR工藝要求，曝氣池內(nèi)的溶解氧含量通 ?？刂圃?1～ 3 mg/L 范圍內(nèi)，在曝氣階段末溶解氧含量應(yīng)不超過 2 mg/，均會影響出水質(zhì)量。在這個過程中，包括控制各種閥、泵、風(fēng)機(jī)的順序及定時開關(guān)和風(fēng)機(jī)的轉(zhuǎn)速調(diào)節(jié)等。 PLC3 站控制的生物處理部分是整個污水處理的關(guān)鍵部分，限于篇幅，僅以PLC3 站的程序設(shè)計為例。前二種方式一般只在設(shè)各調(diào)試或維修時使用，系統(tǒng)主要以全自動控制方式運行。 PLC 的 CPU 模塊通過 MB+通信口與兩臺上位機(jī)進(jìn)行 數(shù)據(jù)交換，采集上位監(jiān)控系統(tǒng)的各種操作指令及現(xiàn)場檢測信號和數(shù)據(jù)，經(jīng)過分析處理，通過輸出模塊向控制對象輸出控制信號；同時，PLC 通過 MB+網(wǎng)向上位機(jī)返回各種數(shù)據(jù)，上位機(jī)對數(shù)據(jù)進(jìn)行運算處理，顯示各種信號和打印各種報表。 MB+網(wǎng)絡(luò)同其他網(wǎng)絡(luò)相比具有組網(wǎng)簡單、投資少、網(wǎng)絡(luò)速度快、通信穩(wěn)定性強(qiáng)等特點，它使計算機(jī)、控制器和其他數(shù)據(jù)源通過使用雙絞線或光纜在整個網(wǎng)絡(luò)上作為同位體進(jìn)行通信。因此，污水處理中用到的 PLC 選用施耐德的 Modicon Ouantum 系列。同樣，模擬量控制信號由 PLC 輸出后以 4～ 20mA 電流形式送到執(zhí)行機(jī)構(gòu)，控制執(zhí)行機(jī)構(gòu)的動作。 PLC3 本地控制站控制 SB