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浙江工業(yè)大學浙西分校信息與電子工程系畢業(yè)（翻譯資料）
中文部分
恒壓供水的控制與節(jié)能的探索
摘要:在簡要分析國內外給水系統(tǒng)現(xiàn)狀的基礎上,介紹了系統(tǒng)的組成,提出了以變頻調速為核心所構成的全自動給水系統(tǒng)控制方式,并以實例詳細分析了該系統(tǒng)的組成、工作原理以及在控制與節(jié)能方面所表現(xiàn)出的優(yōu)越性.文中根據作者的實際使用經驗,簡要闡述了該系統(tǒng)在應用中應注意的一些問題。
關鍵詞: 變頻調速;恒壓供水。PID調節(jié)器中圖法? ?
一、引 言
目前,我國居民小區(qū)與高層建筑的生活供水,普遍采用工頻方式.它存在著能耗大,噪音高,水源存在二次污染等諸多問題.而用變頻調速控制的給水裝置是一種較為理想的模式.進入90年代中后期,隨著變頻調速技術的不斷發(fā)展與完善,基于該項技術的全自動恒壓給水方式已在發(fā)達國家得到廣泛的應用,且日趨成熟.近幾年來,作者在變頻調速給水控制系統(tǒng)的設計與施工方面做了些實際工作,積累了一些經驗,并形成了對于一些問題的看法.水泵節(jié)能原理變頻調速系統(tǒng)之所以得到推廣,一個很重要的原因就是它有較好的節(jié)能效果.
一臺水泵的實際揚程與電源頻率的平方成正比.因而通過變頻器改變水泵電機的供電頻率,就可控制水泵的供水壓力.恒壓供水自動控制變頻恒壓供水原理框圖如圖1所示. 為給定的壓力值, 為壓力傳感器從管道上所測得的實際壓力值,PID調節(jié)器通過對兩者的誤差運算,并經過控制變頻器的頻率輸出,從而使管道的壓力始終保持在設定值上。
該系統(tǒng)能自動檢測用戶的瞬時水壓,據此調節(jié)給水量的多少及電機的運行狀況.還可根據所需的給水壓力設定控制壓力值,讓設備始終處于恒壓狀態(tài),從負載電機的特性可知,所配電機的軸功率與其轉速的三次方成正比,即 .例如,當變頻器輸出頻率為35Hz(最高設定為50Hz),也就是實際轉速為額定轉速的70%時,調速器的用電量為0.343,約占額定的35%.也就是說,水泵總處于恒壓變流量匹配方式的工作狀態(tài),從而消除了超壓和回流的無功損耗.恒速與變頻調速軸功率變化曲線如圖2所示,比較可知,變頻調速方式節(jié)能效果最為明顯。
二、實例分析：
恒壓供水是通過變頻調速來調節(jié)水的流量從而達到恒壓的目的,它最終控制的目標是水壓.控制對象具有非線性、滯后特性.PID調節(jié)器性能的好壞,在很大程度上決定了恒壓供水的質量.當系統(tǒng)在啟動與停止階段,或壓力設定值大幅度變化時,由于在短時間內存在很大的偏差,因而無論PID調節(jié)器的控制算法采用增量式還是位置式,其積分項將取蓄水池、水泵組(1M,2M)及相關輔配件構成.本系統(tǒng)的核心是變頻調速控制柜,它通過壓力傳感器對管網壓力進行實時監(jiān)測,并轉換為電信號提供給變頻器進行運算,通過變頻器、可編程控制器PLC與繼電器陣列的共同控制,構成了完善的全自動變頻調速給水系統(tǒng)。
變頻器的品種繁多,如三菱、富士、三肯及ABB等型號.一般常選用泵類、風機專用系列.以三菱FR-A140E為例,它除了一般品牌所具有的功能外,還有如下特點:內部采用IPM智能功率模塊,使電機的噪音減至最低;變頻器與工頻電源之間可進行切換,用戶只需通過PLC輸入啟動、停止及自動切換指令,就可方便地通過接觸器的互鎖動作來切換不同的水泵,而不需要像以往那樣自行設計繁瑣的控制程序,這是該變頻器所特有的功能之一;內置的瞬時停電再啟動與再試啟動功能,在無人看管的情況下,即使變頻器停機后也可自行啟動,完全實現(xiàn)了以自動化方式的運行.本系統(tǒng)中的PID調節(jié)器可用變頻器內置式值很大,這就會存在偏差調節(jié).在消除偏差調節(jié)的過程中,必然導致系統(tǒng)出現(xiàn)較大的超調和長時間的振蕩,同時還會產生嚴重的積分飽和現(xiàn)象,從而影響了設備的正常運行.要把這種影響降至最低,就應在控制算法中采用積分分離的PID控制方式,以達到預期效果.經這樣處理后,可大大縮短系統(tǒng)達到穩(wěn)定的過渡過程時間.系統(tǒng)中配備兩臺11kW水泵(1M為主泵,2M為備用泵)供600余戶居民用水.兩臺泵同時工作時提供最大高峰流量,單臺則滿足小流量和夜間供水.另外,所有水泵均能以變頻方式運行,即可以循環(huán)方式軟啟動,這樣能減小對電網和管網的沖擊.值得注意的是,兩泵在變頻與工頻之間切換時,僅有程序互鎖是不夠的,輸出必須采用機械聯(lián)鎖接觸器,這樣可避免兩個接觸器瞬間同時閉合的情況,以免造成電源的瞬間短路。
變頻調速系統(tǒng)的主回路原理圖,壓力傳感器P實時監(jiān)測水壓信號的大小,信號經PID處理,輸入至變頻器.小流量時,水泵電機1M運轉(1KM1吸合),并通過反饋通道不斷調整其轉速,以保持壓力的恒定;在大流量的情況下,經壓力比較電路通過PLC發(fā)出“變頻/工頻切換”與“運行聯(lián)鎖”指令,機械聯(lián)鎖接觸器(2KM(2KM1+2KM2)中的2KM2、接觸器3KM得電.這時,電機2M以變頻方式啟動,1M則切換至工頻全速運行.這樣,本系統(tǒng)能始終將用水量維持在一個恒定的壓力上.前述小區(qū)建成初期,供水采用工頻方式,因能耗大,可靠性差,住戶反映強烈.改用變頻供水后,裝機總容量較原設備減小25%,實際綜合節(jié)電指標接近30%,效果顯著。
三、應用中的幾個問題
在大多數(shù)情況下,現(xiàn)場的使用環(huán)境較為惡劣.變頻器雖然本身具有很強的保護功能,如欠壓、過壓、過流、電流限幅選擇整定、過載、過熱、缺相、短路及斷水保護功能等,但仍應做到防患于未然.經使用發(fā)現(xiàn),三菱、富士兩種品牌,由于在設計和制造中充分考慮了各種惡劣的運行環(huán)境.在同樣條件下的可靠性和使用壽命較某些品牌高.湖北鄂西山區(qū)某小城市,平均海拔1200m,常年大部分時間濕度偏高(80%左右),二氧化硫污染嚴重,某廠生產的一套變頻供水設備,因未考慮上述因素,以至于不到一年的時間,設備的有關部件嚴重腐蝕.而我們在同一地區(qū)設計、安裝的同類產品,因充分考慮了各種不同的情況,在設備與元件的選型上,采用了船用標準.經兩年多的使用,運行良好,經受了各種嚴峻的考驗.在實際使用中發(fā)現(xiàn),變頻器本身就是一個強大的干擾發(fā)生源,往往會影響設備的正常運行.特別是水泵低轉速運轉時,變頻器上顯示的頻率與實際運行頻率不符.干擾的傳播途徑一般有兩種:線路串擾和空間輻射干擾.根據現(xiàn)場的實際情況可采取相應的措施予以解決.例如,對可編程控制器的電源端增加濾波與吸收回路,PID調節(jié)器單元的輸入輸出一定要有可靠屏蔽,將變頻器、電機上的接地端子牢固地與接地樁子相連,控制線與動力線要留有一定的距離,以增強抗電磁干擾的能力.只有這樣,才能使系統(tǒng)在高溫、潮濕、霉菌、強干擾等嚴酷的條件下保持長期穩(wěn)定的工作狀態(tài)。
四、結束語
以變頻調速為核心的供水方式,節(jié)水、節(jié)電效果明顯,可廣泛適用于20～10000戶居民生活區(qū)、高層建筑、賓館、飯店、消防或小區(qū)加壓供水,也是中小型自來水廠給水的理想設施.其供水質量高,經濟效益明顯,社會效益巨大,隨著國民經濟的發(fā)展和人民生活水平的不斷提高,它一定會在我國逐步得到應用與推廣。
五、參考文獻
張萬忠,王民權.《一種新型變頻恒壓供水泵站的設計方案》.電氣時代,1999(10):22～232
劉迎春.《傳感器原理設計與應用.》北京:國防科技大學出版社,1989.59～623
呂光大.《建筑電氣安裝工程手冊》.北京:水利電力出版社,1995.222～2244
給排水自動化工程編寫組.給排水自動化工程.北京:水利電力出版社,1997.301～312
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浙江工業(yè)大學浙西分校信息與電子工程系畢業(yè)設計（翻譯資料）
English Part
畢業(yè)設計(論文)翻譯資料
信息與電子工程 系 工業(yè)電氣自動化 專業(yè) 04 級 1 班
課題名稱：S7-200 PLC控制的變頻
調速恒壓供水系統(tǒng)設計
畢業(yè)設計(論文)起止時間：
2007 年 3 月 1 日～ 6 月 10 日(共 17 周)
學生姓名： 學號：
指導教師：
報告日期： 2007-3-１
The control and Energy-saving of automatic Water Supply System
?Abstract: Based one simple analysis of the methods for water supply used domestically and abroad, this paper discusses the principe and system’s structure of automatic water supply system by using frequency conversion speed regulation in detail. Then the system’s advantages are discussed and some key problems that should be pay attention to designing are presented.
Keyword: Frequency conversion speed regulation; water supply with stable pressure: PID regulator.
1、 Foreword
At present , supply water in residential area and life of the skyscraper of our country generally adopt the way common frequently . It has heavy energy consumption, high noise ,and there has a great deal of questions in the source of water, such as secondary pollution etc. And it is a kind of comparatively ideal mode to adjust the watersupply device controlled rapidly with frequency conversion .Entering the middle and later periods of the 1990s, as the speed technology of frequency conversion achieves more development becomes perfect, the way of the full-automatic constant pressure that based on this technology supplied water has already been widely used in the developed country , and is becoming riper.
In recent years, author has made some real work on rapidly to the transformation in frequency conversion supply water design and construction of control system , have accumulated some experience, and has formed the view on some questions. The reason why the energy-conserving principle frequency conversion of the water pump system of speed adjustment??becomes popularized , is mainly because that it has a better energy- conserving result. To pump system of frequency conversion, the water pump after adjusting the speed has functional relation of the following:
Q1/Q2 =n1/n2??(1)? ?H1/H2 = (n1/n2)2??(2)??of the type. Q1, Q2 represents the flow before and after the speed for the water pump respectively; N1, n2 represents the rotational speed before and after the speed for the water pump respectively; H1, H2 represents the lift before and after the speed for the water pump respectively .
According the above:H1/H2=(f1/f2)2??Namely real lift of a water pump is power the square of??frequency in direct radio. Therefore changing the power supply frequency of the electrical machinery of water pump through the frequency converter , can control supporting water pressure strength of the water pump . 2 constant pressure as Fig. 1 shows supply water of the automatically controlled frequency conversion water -supply system principle block diagram. P1??is the give pressure value, p2 for the actual pressure value had examined from the pipeline of the pressure sensor, PID regulator passes the error operation of the two value, and through controlling the frequency output of the frequency converter, thus make the pressure of the pipeline remain throughout on establishing value p1.
This system can measure users' instantaneous water pressure adjust automatically??, regulate the amount of quantity of supplying water and operation conditions of the electrical machinery in view of the above. Can according to give water pressure strength to set for and control pressure value which needed , make the equipment in the constant pressure state all the time, can know from load characteristic of electrical machinery axle power and its the third power of in direct radio rotational speed of electrical machinery mixed, that is p1/p2=(n1/n2)3. For example, as the frequency converter output frequency for 35Hz (establish as 50Hz at most), that is to say that the actual rotational speed is 70% o'clock of specified rotational speed, the power consumption of the governor is 0.73 =0.343, account for specified 35%. That is to say , the water pump is always in constant pressure and turn the working state of matching the way into the flow , is it is it keep to exceed to dispel and backset current have work loss. Constant speed transfer with frequency conversion speed axle power change curve as Fig. 2 shows , relatively can know, it is the most obvious that frequency conversion adjusts the energy-conserving result of speed way.
2、 Case??analyse
Constant pressure is it regulate flow of water to the purpose to up to constant pressure through suiting well rapidly in frequency conversion to supply water, the goal that it controls finally is the water pressure. Controlling the target has non-linear , lagging characteristics. The quality of PID regulator performance , has determined the quality of the water -supply system to a great extent When the system is during the course of starting and stopping, or the pressure establishing value changes by a large margin , because there is a very great deviation within short time, no matter the controll algorithm of PID regulator adopts the increment type or the position type, its total mark one will fetch the cistern , water pump group (1M , 2M ) and complement the fittings to form relevantly. The core of this system is that frequency conversion adjusts the speed switch board, it monitors the pressure of the pipe network in real time through the pressure sensor , and change into the electric signal and offer the frequency converter to to make operation, through the controlling commonly of frequency converter , programmable controller PLC and relay array, adjust the system of supplying water rapidly after forming perfect full-automatic frequency conversion.
Frequency converter is various in kind, for instance the types , such as Mitsubishi , Fuji , three Kenya and ABB ,etc.. Generally often select the pumps , special-purpose series of air blower for use. Whether take Mitsubishi FR-A140E as an example, it except general function had of brand , there are the following characteristics : The inside adopts the intellectual power module of IPM, it is lowest to make the noise of the electrical machinery to reduce??; Frequency converter, and work-frequency power can is it switch over to go on frequently, user is it is it start , stop through PLC and switch over the order automatically to input to need only, can conveniently through to lock movement switch over different water pump each other contactor, and does not need to design the tedious control procedure by oneself like the thing that in the past , this is one of this peculiar functions of frequency converter; Built-in instantaneous power cut starts and retries and starts the function , in a situation that nobody guarded, even if can be started by oneself after the frequency converter shuts down, totally realize with the operation of the automatic way. PID regulator available frequency converter of system this built-in value very heavy, this will store deviation in regulate. During the process of dispelling the deviation to regulate , must lead to the fact the system and present greater ultra mediation long-time vibration , can produce the serious integration saturation phenomenon also at the same time , thus influence the normal running of the equipment. Is it drop the influence to most low to want , should adopt PID control method that integration separate among controlling algorithm, in order to reach the anticipated result. After dealing with like this , can shorten the system and reach steady transition course time greatly System allocate two 11kW water pump support 600 over resident water. Two pump offer large peak flow most when working at the same time, single platform meet the small flow and supply water at night. In addition all water pump can run by way of frequency conversion , can circulate way soft to start, in this way , can reduce the impact to the electric wire netting and pipe network . What merits attention is two pump when frequency conversion and worker are switched over frequently , have procedure it locks to be enough each other only, outputting must adopt machinery to interlock the contactor , can avoid the situation that two contactors close at the same time in the twinkling of an eye in this way, so as not to short out in twinkling of an eye causing power .
pressure sensor P monitors the size of the water pressure signal in real time, the signal is dealt with by PID, input it to the frequency converter. At the small flow, water pump electrical machinery 1M turn round (whether 1KM1 is it shut to suck), and through feedback password change his rotational speed constantly, it is invariable in order to keep the pressure; In case of large flow , compare frequency conversion by pressure circuit send out through PLC " constant/changed switch over frequently" " operate and interlock " the order, machinery interlocks the contactor ( 2KM2 in 2KM (2KM1 +2KM2 ), contactor 3KM have the electricity. At this moment, electrical machinery 2M is started by way of frequency conversion, 1M is switched over and run at full speed frequently to run . In this way, this system can maintain water consumption on a invariable pressure all the time . Built up in the aforesaid district initial stage , supply water and adopt the way frequently of workers, because of energy consumption being heavy dependability is bad, the household reflects strongly. Use instead after frequency conversion supply water, installation total capacity reduce 25% than original equipment , economize on electricity the index is close 30% synthetically actually, the result is remarkable.
3、 Several questions while apply are in case of great majority
The environment for use of the scene is comparatively abominable . Though frequency converter has very strong protection functions itself, such as owe keep , excessive pressure , is it flow to pass, electric current amplitude limiting is it make exactly to choose, overload, overheated lacking looking , shorting out and disconnected ink protect the function But must prevent trouble before it happens . Through using finding , two kinds of brands of Mitsubishi , Fuji, because has fully considered various kinds of abominable running environment in design and manufacture. The dependability and service life under the same condition are higher than some brands. One small city of mountain area of west place in Hubei in Hubei, average 1200m above sea level, the humidity on the high side of long-term most of the time (about 80%), the sulfur dioxide is seriously polluted, a set of frequency conversion that one factory produces supplies water of the equipment, because has not considered above-mentioned factors , less than one year, the relevant parts of the equipment are corroded seriously. And the like product which we designed , installed in the same area, because has fully considered the situations of different difference, on the selecting types of the equipment and component , have adopted the ship standard. Through the use of more than two years , ran well , stood the tests of different sternness. Find in using actually , the frequency converter itself is that a strong interference takes place in the source , will often influence the normal running of the equipment. Especially when the low rotational speed of the water pump operates, the frequency shown on the frequency converter does not correspond to actual operation frequency. Generally there are two kinds of spread ways to interfere: The circuit bunch is disturbed and space radiation is interfered. Can take the corresponding measure to solve according to the actual conditions of the scene. For example is it strain wave and absorb the return circuit to increase to programmable power end of controller, PID regulator introduction of unit output sure to have reliable shielding , link frequency converter , ground terminal of electrical machinery with earth stake firmly, control the line and motive force line leave certain distance , in order to strengthen and resist the electromagnetic ability to interfere. Only in this way ,can make system keep the long and steady working state in high temperature , humidity , mould , strong harsh terms of interfering etc..
4、 Conclusions
Are by way of adjusting the speed as the central water supply in frequency conversion, the result is obvious to economize on water , economize on electricity, can be extensively suitable for 20-10000 residents the biotope , skyscraper , hotels and retaurants , fire control or district pressurize and supply water, it is ideal facilities that the medium and small- scale waterworks supplied water too. Its amount of water quality supported is high, the economic benefits are obvious, the social benefit is enormous, with the development of national economy and constant improvement of the living standards of the people, it is sure to be used and popularized progressively in our country
5、 List of references
Zhang Wanzhong, Zhu Jie, Wang Mingquan. A kind of new-type frequency conversion constant pressure supplies water of the plan of design of the pump station. Electrical age, 1999 (10): 22-232 Liu YingChun. Principle design of the sensor and application. Beijing: University of Science and Technology of the national defence publishing Presss, 1989.59-623??
Lu Guangda. Electric installation project manual of the building . Beijing: The electric publishing house of water conservancy, write the group in 1995.222- 2244 "
The automatic projecting ". Give and drain off water the automatic project. Beijing: The electric publishing house of water conservancy, 1997.301-312
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