plc供水外文文献.doc

Transducer and PLC in the water control system applicationsM. Bani Younis and G. FreyJuniorprofessorship Agentenbased AutomationUniversity of KaiserslautemP. 0. Box 3049, D-67653 Kaiserslautem, Germany1. IntroductionCurrently, the water level control in a large part of the electrical pumps are not towing gear shift system, no gear shift most of the electrical energy consumed in the water supply to the frequent changes in the pumps stopped. This not only makes the electrical work in inefficient zones, cut short the useful life of electrical and electrical equipment for the frequent failure to stop the high rate, leading to serious waste of water resources, system maintenance, repairs larger workload.With high living water and industrial water gradually increased, the traditional control methods that are outdated. Originally used for artificial water level control, water level due to the lack of accurate positioning hour monitoring, it is difficult to accurately control the pumps have stopped; Using buoys or mechanical control devices such as water supply situation has made some changes, but because of mechanical failure more devices, poor reliability to maintenance will face great trouble.Frequency conversion technology, with its superiority in the area of energy efficiency and Hengya pressure control system can be solved by the existence of the above problems. Consider selecting Chanpianji or Plc and transducer combination at the core of the system can achieve a better control results. But in software design, Plc programming of more than Shanpianji concise, and visual; From the hardware interface considerations, Shanpianji circuit slightly complex; From the economic considerations, the Plc processes are mature, cost and small Plc Shanpianji a little, because the system parameters to be adjusted in accordance with the situation on the ground, Plc software, the time parameters adjustments simpler, so more conducive to after-sale personnel.Programmable Logic Controllers (PLCs) are a special type of computers that are used in industrial and safety critical applications. The purpose of a PLC is to control a particular process, or a collection of processes, by producing electrical control signals in response to electrical process- related inputs signals. The systems controlled by PLCs vary tremendously, with applications in manufacturing, chemical process control, machining, transportation, power distribution, and many other fields. Automation applications can range in complexity from a simple panel to operate the lights and motorized window shades in a conference room to completely automated manufacturing lines.With the widening of their application horizon， PLC programs are being subject to increased complexity and high quality demands especially for safety-critical applications. The growing complexity of the applications within the compliance of limited development time as well as the reusability of existing software or PLC modules requires a formal approach to be developed I. Ensuring the high quality demands requires verification and validation procedures as well as analysis and simulation of existing systems to be carried out 2. One of the important fields for the formalization of PLC programs that have been growing up in recent time is Reverse-engineering 3. Reverse Engineering is a process of evaluating something to understand how it works in order to duplicate or enhance it. While the reuse of PLC codes is being established as a tool for combating the complexity of PLC programs, Reverse Engineering is supposed to receive increased importance in the coming years especially if exiting hardware has to be replaced by new hardware with different programming environmentsTransducer in the water system in conjunction with the introduction of small Plc technology not only change the traditional use of water control valves, and in energy conservation, Hengya control, are very good results, the paper introduced a transducer -PLC control technology in the pump control applications.2. System control theory and composition1.constant pressure water system basic working principleSystem uses Automatic Frequency Control regulation or pump motor speed. Plus or minus pump.It is primarily by the Frequency Control System.PID regulator,pressure sensors,liquid level sensor power control circuits and other conponents.Host users control system or control board light over-the-counter transactions,buttons,switchto understand and control systen operation,Based on the PID control mode,the operator interface settings in water pressure,PLC to pressure settings and measured valucs for the deviation PID operation and regulation of distribution through inverter pump speed,so that water pressure was maintained at the set value.2.Systen hanlware configurationThe system uses Siernens S7-200 PLC and its configuration software constitute a constant WinCC V6.0 Water pressure control system,water pressure monitoring process.Industroal Ethernct controller for PLC and the operator station computer communication betwween the Remote I/O network for the PLC and the operator station compuler communication betwween the Remote I/O network for the PLC controller and inverter,the soft starter of communication betwween equipment.PLC controller mainly used to monitor and control water and electricity systems.For1#-4#pressurized pump converter using the ABB Acs510-01-031A4 inverter,HMI operatostation selection DELL conputers,conputer,Industrial Ethernet server card Siemens conmmunications company CP1612.3.Software design of SystenThe control system software company Siemens PCS7V5.2 package.STEPV5.2 PLC controller.HMImonitoring system used WinCCV6.0 version.HMI server and operating station are using the Windows2000 operating system to have an open programming environment.Heating Sation Wincc configuration control software maior constant pressure water system and coal Gallery in two parts.Implemention of the system of automatic detection and automatic control.Detection constant pressure water and coal Gallcry equipment operation parameters.the real-time data acquisition.uploads.real-time data acquisition.uploads,real-time display and recording.Ciontrol unit operation.fault alarm and automatic parking operation .Theconstant pressureof water supply pressure system configuration parameters.real-time monitoring regulatory pressure pumps water pressure and so valued.CoalHanding Gallery in to control the volume.of coal to speed,to monitor the quality of coal (coal crushing degree of quality and impurity)4. PLC-Based Fuzzy Constant water supply system design constant pressure water system components1 Constant Pressure Water FormFrom the water supply system programmable controller,inverter,pressure transmiter,and the constact group on the pump unit and other components.Programmable controller selection of AB ControlLogix system.It includes Logix5550 controller,analog input modules,digital input and output modules and communication modutes.Which analog input modute used to test the water pressure on the export signal,digital input module and valves Kai stopped.Inverselection of AB 1336 Plus Inverter.Inverter and Devi2 cenet controller thtough the network for communication.2.Constant Pressure Water PrincipleThe outlet channel of pressure sensor installation will export water pressure signals are converted to electrical signals, send PLC fuzzy inference operation, the output control signals to the converter, regulating the operation of pump motor speed, until the actual elimination of hydraulic pressure and set the deviation, constant voltage supply. Programmable controller can control pumps Kai stopped. When the system started working, inverter control from start on 1st pump frequency operation. If users increased consumption of the converter output frequency up to 50 Hz, the pressure will still be less than the set value, then after some time delay, on the 1st of the pump switching frequency operation; Inverter start again on the 2nd pump operation. If pressure is less than the set value, they will be on the 2nd to pump switching frequency operation; Inverter start again on the 3rd pump operation until the output pressure settings to achieve so far. However, if users to reduce water consumption, in accordance with the “Kai-stop” principle will be followed with pumps. This cycle repeatedly to achieve constant pressure water system.3.Fuzzy2PI control algorithmAs the water supply system in many areas (such as the pipe network and pumps) nonlinear, time-varying, and the variables still exist between the cross-coupling, so it is difficult to establish a precise mathematical system model. For such a complicated process that merely using the conventional PID control is difficult to achieve the desired control. Fuzzy control is not dependent on the mathematical model and the right parameters sensitive to the merits, Fuzzy used to control the water supply system, we can improve the control system dynamic performance. But Fuzzy Control System steady-state performance is poor, this design of a dual-mode Fuzzy2PI control, As shown in figure 2, and its design thinking is; when the pressure is greater error when using fuzzy control, to obtain good transient; When the pressure on the stead-state error into smaller, switched to process from PI control, to obtain good steady precision. PI control algorithms and fuzzy control algorithms are PLC, switching time by a computer program based on prior to the error autormatically.The system uses two-input single-output fuzzy controller. to pressure the desired value and the measurement of e error and the error as a fuzzy controller input linguistic variables, transducer frequency variation u language as output variables. To e error, the error rate ec and control volume u fuzzy subset of ( NB,NS,ZE,PS,PB) and they quantified the domain of seven grades, (-3,-2,-1,0,1,2,3). Fuzzy subset of the membership function used triangle. Initial experience of fuzzy control rules, as shown in table 1. Under these rules calculation of the total fuzzy relation R:Where x, U fuzzy relationship matrix on behalf of the “Cartesian” and the “and” operator. According minimax inference rules synthesis of output variables language domain of fuzzy sets U:U Finally, the weighted average method used for solutions vague and fuzzy volume U converted into precise amount u. The process is carried out offline, eventually Fuzzy Control Table, as shown in table 2. This form of the PLC memory storage, real-time control, fuzzy control would streamline the process for finding inquiries on the questionnaire process.4.Parametric Selection of Frequency-water systemA reasonable selection pressure control parameters constant pressure to achieve energy-supply system. The realization of is this objective the key is pressure control parameter selection, usually pipe network pressure control point two choice: a pipe network is the most negative pressure on constant pressure control and the other is the constant pressure pump outlet.Pressure control. How will the two choices, we have to analyze simple Network pressure on the most disadvantaged constant, the water pipe network by QMAX reduced to Q1, pumps reduce speed, and water characteristic curve of A (unchanged) at the intersection point C, pump characteristic curve downward, network pressure on the most disadvantaged H0. And the pump outlet pressure constant pressure control, Ha unchanged, reduce water consumption by QMAX QI and Ha to pay to point B, water characteristic curve upward A through B, the network most disadvantaged Hb pressure into points. Hb-H0 lift the poor namely, energy waste, so I chose the most disadvantaged network points for the smallest head pressure control parameters. Formation pressure on the closed-loop control system, making the pump speed and PID regulator set pressure match, achieve maximum energy-saving effect, but the constant pressure to achieve the purpose of water supply.The converter and put into operation after the commissioning of the system to ensure optimum operation of the state means necessary. According to the inverter load inertia size of the start and stop the motor when the time is not the same, Set time is too short to be accelerated when the inverter overcurrent, overvoltage decelerating protection; Set time will lead to excessive speed converter running in the system become regulate slow, delayed response, contingency ability is poor. Yi system at the state short-term instability. To protect the converter is not tripping, the scene of many of them using converter increases deceleration time setting too long, the problems they bring very easily be the appearance of the normal equipment and hide, but the converter operating in less-than-optimal state. So the scene when used according to the load driven by a different nature, testing out the permission of the shortest load increases deceleration time, setting. For the pump motor, plus deceleration time in the choice between 0.2-20 seconds.3.CONCLUSIONS AND OUTLOOK1.Uses the frequency changer - PLC constant pressure water supply installment to have following several merits: A:The electricity saving benefit is high. The traditional water pump electrical machinery uses the large capacity electrical machinery, is constant with the valve control water volume, creates the electrical energy waste.Frequency conversion system, regardless of the operational parameter how, the electrical machinery efficiency cant reduce, the electrical machinery power factor can obtain the enhancement.B:Moves is reliable, is stable. In the system core part - frequency conversion velometer itself reliability is very high, in the ordinary circumstances may the long-term usage 100,000/Above h. The system also selects the soft start method, does not have the electrical impact, does not pollute the electrical network, moreover frequency changer bringing owes presses, the pressure, the overflow, the overload, superheat as well as loses speed and so on each kind of protection function. The system adopts damping filter processing to the pipe network fluctuation of pressure, the water supply constant pressure precision is high, usually can control in the 0.002Mpa scope. C:The structure is simple, the operation is simple. The installment control system uses the integration rate to be high, necessary plan nimble diverse, obtains water pump movement each kind of combination by the programmable controller. The velocity modulation scope is broad, to water volume change adaptiveness.D:The service life is long, the automaticity is high, does not need the human to safeguard, maintains the quantity to be few.Above system the effect is remarkable in the actual application, if brings in PLC and the frequency changer the programmer the function integration, potential becomes some special-purpose frequency changers, such system reliability and the toughness big enhancement, the application is simpler, the system total cost also can drop.2.May foresee: The future frequency conversion technology will be able to develop to the below direction:(1) high performanceThus including internal leveling circuit, the contravariant electric circuit all use the high frequency PWM electric circuit to cause the input, the output all are sine waves; Uses the multi-densification regarding the large capacity frequency changer and many machine is parallel; Reduces frequency changer own loss, the realization high efficiency; Realizes autotune or from the optimization, the remote control and controls far; Even more faces the user, further enhances the workability and Maintainability: Turns towards, the featherweight development small, as well as reduces the cost and so on.(2) intellectualization Including two aspects: Reduces the hardware as far as possible, realizes the hardware software; Uses the intelligent electric power electronic device and other intellectualized part. The integration is the intellectualized foundation.(3) entire digitization In recent years, each kind of modern control theory, the expert system, the fuzzy control and the neuron control and so on all were the development hot spots, will cause the electric power electronic control technological development to a brand-new stage. Estimated the 21st century entire numerical control the application will be more widespread thoroughly, even will substitute for the simulation control.(4) systematizationFrequency conversion technology development is inseparable from the development of related technologies, frequency conversion technology development in the 21st century is to grid, regulators, rely machine, electric motors, production machinery and control systems as a whole, from the system for consideration.3. The features of PLC3.1 FeaturesThe main difference from other computers is that PLCs are armored for severeconditions such as dust moisture heat cold and have the facility for extensiveinput/output I/O arrangements. These connect the PLC to sensors and actuators.PLCs read limit switches analog process variables such as temperature and pressureand the positions of complex positioning systems. Some use machine vision. On theactuator side PLCs operate electric motors pneumatic or hydraulic cylindersmagnetic relays solenoids or analog outputs. The input/output arrangements may bebuilt into a simple PLC or the PLC may have external I