CN103105862A - Double-tank cascade liquid level system based on piping and instrument diagram (PID) controller - Google Patents
Double-tank cascade liquid level system based on piping and instrument diagram (PID) controller Download PDFInfo
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- CN103105862A CN103105862A CN 201110375275 CN201110375275A CN103105862A CN 103105862 A CN103105862 A CN 103105862A CN 201110375275 CN201110375275 CN 201110375275 CN 201110375275 A CN201110375275 A CN 201110375275A CN 103105862 A CN103105862 A CN 103105862A
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Abstract
The invention discloses a double-tank cascade liquid level system based on a piping and instrument diagram (PID) controller. The double-tank cascade liquid level system based on the PID controller mainly is mainly composed of a water storage tank (1), a lower water tank (2) which is arranged above the water storage tank (1) and an upper water tank (3) which is arranged above the lower water tank (2). The water storage tank (1), the lower water tank (2) and the upper water tank (3) are communicated with one another. The double-tank cascade liquid level system based on the PID controller further comprises a motor-driven control valve (4). The water storage tank (1) and the upper water tank (3) are both connected with the motor-driven control valve (4) through water pipes. Control devices are arranged on motor-driven control valve (4) and the water pipes between the lower water tank (2) and the upper water tank (3). The double-tank cascade liquid level system based on the PID controller not only achieves a good control effect, but also is lower in control cost, good in control effect and high in practical value. And when a perturbance occurs, a minor loop where a middle water tank is located can response quickly to eliminate effect of the perturbance. Ideal control effect is achieved.
Description
Technical field
The present invention relates to a kind of double volume tandem liquid level control system based on the PID controller.
Background technology
Liquid level is one of control parameter that often runs in industrial process production, required control object is carried out accurate liquid level control, and is related to the quality of product, is the major issue that ensures production effect and safety.Thereby the control of liquid level has important practical significance and application prospect widely.
Control theory has experienced classical control theory, two developing stage of modern control theory, has entered now Nonlinear Intelligent control theory developing period.The problem that solves from control theory and opinion, a lot of great, basic problems as controllability, observability, stability etc., have all been set up fairly perfect theoretical system in tradition control.Use traditional control theory and substantially can satisfy the needs in engineering and various other fields.But along with the development of industry and modern science and technology, in every field, automatic control system is also more and more higher to the requirement of control accuracy, response speed, system stability and adaptive faculty.Since the eighties in last century, the quick update of robot calculator and the high-speed development of computing technique have promoted carrying out in a deep going way of control theory research, and have entered one section new course.Along with developing rapidly of control theory, many advanced persons' control algolithm has appearred.But the various controllers take PID as principle are still basic control unit indispensable in process control.So far, pid control algorithm worldwide is used in the industrial process more than 80%, and the PID control technology has obtained good development, and the researcher has proposed many Control System Design methods and parameter adjustment is theoretical.This is because PID control has simple in structure, easy realization, controls the characteristics such as effective, and the pid algorithm principle is simple and clear, the parameter explicit physical meaning, and the theoretical analysis system is complete, by vast control engineering teacher is familiar with.
Tank level control system is the system take liquid level as controlled parameter, and its every field in industry is related to widely.In industrial processes, having a lot of places to carry out liquid level to control object controls, make liquid level remain on accurately given numerical value, as in building material industry, glass furnace liquid level stable to the serviceable life of kiln and the quality of product playing vital effect.Also have in commercial production, especially also can often run into liquid level control problem in oil, chemical industry and metallurgical production.Therefore, required control object being carried out accurate liquid level control, be related to the realization of controlling target, is the major issue that ensures production effect and safety.
Nineteen thirty-nine, Taylor Instrument Company and Foxboro Instrument Company produce the pneumatic controller that has pid control function fully.People generally believe that PID should be referred to as Based Intelligent Control, because it is based on production operation personnel's control experience.The inventor thinks by observation, and controller should resemble and go to control a skilled operator, reduces until the error that occurs in the elimination system.Control three subject matters that have that face at PID at that time: (1) seeks a kind of straightforward procedure, regulates parameters for three that can calculate the PID controller.(2) judge whether production run is controlled.(3) operation of PID controller does not rely on the mechanical organ of complicated rapid wear.Theoretical research mainly concentrates on the first two problem, nineteen forty-two, gives part and solves.Second Problem is the controllability of system.The 3rd problem is due to the develop rapidly of the industrial revolution, and the PID controller of today uses electronic component and microprocessor substantially, has given the solution of almost Perfect.
The PID controller remains most widely used industrial control unit (ICU) now as the practical the earliest controller history of existing nearly 70 years.Trace it to its cause, be because the PID controller has following principal feature: (1) PID controller is easily understood, and does not need accurate especially system model in use.(2) usability is flexible, only needs to set three parameters and gets final product.Under many circumstances, whole three unit might not be needed, one to two unit wherein can be got.(3) pid parameter is more easily adjusted, and namely pid parameter can in time be adjusted according to the dynamic perfromance of process.If the dynamic perfromance of process changes, for example may be caused by the variation of load that system dynamic characteristic changes, pid parameter just can be adjusted again.And the step input response curve is the PID control most important foundation of effect and standard.It is generally acknowledged that it is the most serious interference that step is disturbed, as long as feedback control system can return to set-point in setting time under this type of disturbs, system meets the demands substantially.
Summary of the invention
The object of the invention is to overcome the shortcoming and defect of above-mentioned prior art, a kind of double volume tandem liquid level control system based on the PID controller is provided, should not only have good control effect based on the double volume tandem liquid level control system of PID controller, and it is low to control cost, the control effect is fine, has higher practical value; And if thanks for your hospitality movable property and give birth to, the subloop at middle water tank place can react fast, eliminates the effect of disturbance, reaches desirable control effect.
Purpose of the present invention is achieved through the following technical solutions: based on the double volume tandem liquid level control system of PID controller, mainly be made of middle water tank, lower header, the sub-control device that is connected with middle water tank and the main control unit that is connected with lower header, described sub-control device all is connected with same actuator with main control unit.
Described sub-control device mainly is made of the secondary stress transmitter that is connected with middle water tank and the secondary controller that is connected with the secondary stress transmitter, and described secondary controller is connected with actuator.
Described main control unit mainly is made of the principal pressure transmitter that is connected with lower header and the master selector that is connected with the principal pressure transmitter, and described master selector is connected with actuator.
In sum, the invention has the beneficial effects as follows: not only have good control effect, and it is low to control cost, controls effect fine, have higher practical value; And if thanks for your hospitality movable property and give birth to, the subloop at middle water tank place can react fast, eliminates the effect of disturbance, reaches desirable control effect.
Description of drawings
Fig. 1 is structural representation of the present invention.
Embodiment
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited only to this.
Embodiment:
As shown in Figure 1, the double volume tandem liquid level control system based on the PID controller that the present invention relates to, mainly be made of middle water tank, lower header, the sub-control device that is connected with middle water tank and the main control unit that is connected with lower header, described sub-control device all is connected with same actuator with main control unit.
Described sub-control device mainly is made of the secondary stress transmitter that is connected with middle water tank and the secondary controller that is connected with the secondary stress transmitter, and described secondary controller is connected with actuator.
Described main control unit mainly is made of the principal pressure transmitter that is connected with lower header and the master selector that is connected with the principal pressure transmitter, and described master selector is connected with actuator.
The course of work of the present invention is: at first, regulate the secondary controller parameter; Then, the liquid level of principal pressure transmitters sense in the lower header, the signal that detects is sent to master selector; The liquid level of secondary stress transmitters sense in the middle water tank, the signal that detects is sent to secondary controller; Master selector and secondary controller are according to detection signal and the actual demand sent into, and the output regulating command is to actuator; Actuator is regulated the current size that enters lower header and middle water tank according to instruction, and then regulates the water level of lower header and middle water tank.
The above is only preferred embodiment of the present invention, is not the present invention is done any pro forma restriction, and every foundation technical spirit of the present invention, any simple modification, equivalent variations that above embodiment is done are within all falling into protection scope of the present invention.
Claims (3)
1. based on the double volume tandem liquid level control system of PID controller, it is characterized in that, mainly be made of middle water tank, lower header, the sub-control device that is connected with middle water tank and the main control unit that is connected with lower header, described sub-control device all is connected with same actuator with main control unit.
2. the double volume tandem liquid level control system based on the PID controller according to claim 1, it is characterized in that, described sub-control device mainly is made of the secondary stress transmitter that is connected with middle water tank and the secondary controller that is connected with the secondary stress transmitter, and described secondary controller is connected with actuator.
3. the double volume tandem liquid level control system based on the PID controller according to claim 1, it is characterized in that, described main control unit mainly is made of the principal pressure transmitter that is connected with lower header and the master selector that is connected with the principal pressure transmitter, and described master selector is connected with actuator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110375275 CN103105862A (en) | 2011-11-14 | 2011-11-14 | Double-tank cascade liquid level system based on piping and instrument diagram (PID) controller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110375275 CN103105862A (en) | 2011-11-14 | 2011-11-14 | Double-tank cascade liquid level system based on piping and instrument diagram (PID) controller |
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| CN103105862A true CN103105862A (en) | 2013-05-15 |
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| CN 201110375275 Pending CN103105862A (en) | 2011-11-14 | 2011-11-14 | Double-tank cascade liquid level system based on piping and instrument diagram (PID) controller |
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Application publication date: 20130515 |