自動(dòng)化專(zhuān)業(yè)畢業(yè)設(shè)計(jì)英文翻譯--供水專(zhuān)用變頻器的設(shè)計(jì)和應(yīng)用

1、DESIGN AND IMPLEME.NTATION OF A VARIABLE FREQUENCY REGULATORY SYSTEM FOR WATER SUPPLYABSTRACTThe designs of the variable frequency constant pressure water supply for a single hydraulic pump and high power multiple h

2、ydraulic motors systems are presented in this paper. This system can save energy by controlling the speed of the pipe motors which depend upon the number of consumers in use. This system was also uccessfully implemented

3、 in most of the modern buildings in. Shanghai, China. Finally, the choice criteria for variable frequency regulators for water supply system will be discussed.INTRODUCTIONIt is inevitable to install high level water sto

4、rage systems or reservoirs for a multiple story building or residential areas. This kind of system results in increasing construction cost and cleaning problems. Nevertheless, hydraulic pumps are used toraise the energy

5、level of the water. The conventional high level reservoir system is in fact a pressure regulatory system. This pressure (head) is proportional to the height of the reservoir. Resistance of pipes is varying from time to t

6、ime. When number of users increases, that means number of relief valves to be open is increased. It in turn reduces the resistance of the pipes. In order to reduce the construction cost, eliminate the cleansing problem

7、of the high level reservoirs, and make the system simple, a variable frequency constant pressure closed loop system is presented to control the speeds of the hydraulic pumps.In this paper, the designs of the variable fre

8、quency constant pressure water supply for a single hydraulic pump and high power multiple hydraulic motors systems are presented. From static characteristics of water flow system, the critical point can be obtained to ac

9、hieve the minimization of energy consumed. The implementation of this system is also discussed. The choice of variable frequency regulators for water supply system is finally presented. ADVANTAGESOFTHEPROPOSEDSYSTEMIn sh

10、ort, the advantages of this proposed variable frequency constant pressure system for water supply are 1. In a 3 hydraulic motors system, the capacity of the variable frequency regulator is just one-third of the capacit

11、y of the overall system. The cost is much reduced. 2. Since the system consists of multiple pumping motors, they can be controlled by PLC such that the system is more reliable.3. Energy saving can be achieved by control

12、ling the speed of pump motors, pressure can be kept constant no matter what water flow is (from zero to its maximum capacity)4. Each pumping imotor can be started smoothly by using this variable frequency regulator, it

13、 reduces pulse current. This kind of water supply system could become a new trend in modern multiple-story building design.PRINCIPLE OF OPERATIONThe principle of operation was initially illustrated by a single pump syst

14、em. Fig. 1 shows a block diagram of a variable frequency constant pressure system which is suitable for single pump or small scale water flow system. The model type is JS.5-P1. The pressure sensor (PS) transducers the

15、water pressure in pipes to e1ectrical signals. This signal will go to pressure regulator (PR) through an amplifier (A) and a comparator compared with the set value of water When the flow rate is continuously increased a

16、nd beyond 66.6%, and the frequency regulator reaches its rated frequency 50 Hz, PLC will command the second motor to connect to the mains again and the third one at stand-by mode. The operating region of the third one f

17、alls within curves 3 and 6 in the Fig. 4. If the flow rate is reduced from 66.6% to 33.3%, PIX will command to one of the pump motors cut off from the mains. When the flowrate further reduces, and less than 33.3%, there

18、will be only one motor connected to the mains. From the working principle, the three pump motors are operated in turn to meet the requirement of energy saving. CRITERIA FOR FREQUENCY, REGULATORFor the load of the hydrau

19、lic pump, the torque is proportional to the square of the motor speed, it is also proportional to the square of the supply frequency, f2. To a electric motor, the torque is equal to Cm *Φm*I2*cosα, where Cm, is a consta

20、nt, Φm, is the magnetic flux of rotating field, I2 is the rotor current, and cosα is the power factor of rotor circuit. I2 normally cannot exceed its rated value.If the voltage drop in the stator is negligible, $, will b

21、e proportional to supply voltage V. In order to maintain, the supply voltage V should be required to be proportional to the square of the frequency. Therefore, the characteristic of V versus f should be set to be a quad

22、ratic relationship.CONCLUSION This type of variable frequency constant pressure closed loop system for water supply was designed and implemented in Shanghai, China. The performance was proven satisfactory. A copy of a ph