1、 毕业设计 (论文 )翻译资料 课题名称： S7-200 PLC 控制的变频 调速恒压供水系统设计 毕业设计 (论文 )起止时间： 2007 年 3 月 1 日 6 月 10 日 (共 17 周 ) 学生姓名： 学号： 指导教师： 报告日期： - 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
2、discusses the principe and systems structure of automatic water supply system by using frequency conversion speed regulation in detail. Then the systems advantages are discussed and some key problems that should be pay attention to designing are presented. Keyword: Frequency conversion speed regulat
3、ion； 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
4、 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 p
5、erfect, 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 de
6、sign 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-
7、 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 t
8、he 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 chan
9、ging 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 pr
10、inciple 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
11、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 pressur
12、e 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 - 2 - machinery axle power and its the third power of in direct radio rotational speed of electrical machinery mixed, that i
13、s 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% oclock of specified rotational speed, the power consumption of the governor is 0.73 =0.343, account for specified 35%. That is to sa
14、y , 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 k
15、now, 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 con
16、trols 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 est
17、ablishing 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
18、 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 co
19、ntrolling 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 an
20、d 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 mak
21、e 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
22、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 situatio
23、n 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
