Based On The PLC Frequency Conversion Velocity Modulation Constant Pressure Water Supply System Design And Implementation

Economic and social development, the results of the city is expanding. But alongwith the increase of urban resident population and the rising of our living standard,people to the urban water supply system of the quality, quantity and stabilityrequirements more and more is also high. In contrast, some of the small andmedium-sized cities in our country the waterworks, especially some old plant automaticcontrol system of the poor performance of the unit, the corresponding control also relymainly on the manual operation to complete. This makes the system control process iscomplicated, and at the same time, manual control is difficult to water supply pipenetwork pressure and water level changes to make timely corresponding. So, in order toensure that the urban water supply, the water supply system is usually overpressurecondition operation, not only low efficiency, but also make the urban pipeline exposuredamage is more serious. In this situation, this paper consider our country small andmedium-sized city water supply system condition, based on PLC frequency control ofmotor speed constant pressure water supply control system design.In all of the frequency control of motor speed constant pressure water supplysystem, for single pump performance control, mainly through the converter to supplyfrequency change to realize the control of motor speed, and then realize the pumpperformance curve changes. Based on energy consumption level work condition of thechart analysis, can be found, we must use frequency control of motor speed to realizethe constant pressure water supply system, reduce the speed, flow rate and water pumpspeed is proportional to the power system, and the speed of the three power down, withthe traditional water supply way through the valve to realize throttle way, comparedwith frequency control of motor speed constant pressure system of energy loss less, soas to realize the energy saving.In the control system, the main programming software for the German Simenscompany STEP Micro Win platform, the water supply system is used in the pressurecontrol PID control on the detailed design, the PID controller design on the placedinside the PLC. Through the controller, can realize the pressure set value and measured value deviation for processing, the inverter output voltage and frequency real-timecontrol, through to the water pump motor speed change to the outlet of the water pumpflow control, so as to realize the automatic adjustment of the pipe network pressure, willeventually pipe network pressure stable in the preset value nearby. In addition,according to the theory of software engineering design code for PLC platform forsystem analysis and design, make the software of the specific functional requirements,and based on this, the whole system framework and the interface design.Based on the actual operation of the whole system and debugging, can realize theautomatic control process of water supply, and based on this, also can effectively reducethe energy consumption and to ensure the water supply system in the optimumoperation state operation. System has the easy installation and maintenance, operation isstable, reliable, complete functions, friendly man-machine interface and easy to usecharacteristics.