PLC boiler water level controller based on fuzzy theory

PLC controller boiler water level controller based on fuzzy theory, wuhan university zhen-ya li welcome to e exhibition hall hall 7 hot water/steam boiler hot water boiler, steam boiler, muffler, softened water equipment, boilers. 。 。 1 introduction steam drum water level system is a larger disturbance and nonlinear characteristics of lag system. At present, most of the steam drum water level control of the conventional PID control method, but due to the conventional PID control parameters are fixed, almost can't find can adapt to the disturbance of various control parameters, which is often difficult to meet the requirements of its control effect, cause the system unstable or even out of control. Here we develop a set of control system of PLC and single-chip microcomputer. 2 the system hardware configuration the small and medium-sized industrial boiler controller is mainly composed of single chip microcomputer and PLC of two parts, the control system as shown in chart 1. Figure 1 industrial boiler system diagram for steam drum water level measurement of the fuzzy controller, the range is adopted for [ - 100毫米,100毫米) With a resolution of 5 mm reed cylinder type water level gauge. Magnetic drum magnetic field effect on dry reed pipe, corresponding to generate the corresponding water level signal, water level signal into the microcontroller output five binary level to the PLC, but also to send in single chip microcomputer. Single-chip microcomputer according to predefined process conditions, the water level of the value, the threshold value and the related alarm signal output display on the panel. On the steam drum water level gauge on both sides of high water level alarm, low alarm is not into the single chip microcomputer, and directly sent to the PLC. The six on the operation panel on the front panel 6 button switch state is connected to the input terminal of PLC controller. PLC controller based on all of the input signal, the implementation of the corresponding control algorithm, the calculation results by output to control the corresponding equipment. After the input signal is collected by single-chip microcomputer processing to the PLC, only important high/low water level protection signal by single-chip computer directly to the PLC. From a security consideration, first of all, there are two sets of liquid level measuring device, water level signal measurement accurate and reliable. And set the water level deviation deviation alarm function, when the water level on both sides of the measuring deviation exceeds a certain value, the controller panel displays. Secondly PLC anti-jamming capability is strong, not easy to fail. By single chip microcomputer, PLC input/output greatly reduced, and the input amount was reduced to 18 points, the output reduced to 10 points, and SCM cheap, make the system cost is low. The PLC software design of 3 3 based on fuzzy theory. 1 steps for fuzzy controller design under the condition of the input is e, and delta e control the size of the u, first of all, according to the actual fields and determined the quantitative level [ - 6 ~ +] Ke = 0, respectively, to get quantitative factors. 06年,K△e = 0。 5、Ku = 15。 3. Choose to describe various fuzzy subset of a fuzzy variable, to make them on the field distribution is reasonable, that they should be better to cover the entire universe. In defining the fuzzy subset theory of idea to make any of these fuzzy subsets of the domain of the maximum membership degree not too small, otherwise will appear near the point is not sensitive region, that is out of control, the fuzzy control system control performance deteriorate. Using fuzzy conditional statement for the if {: e = Ai和△e = Bi Ci u =我= 1,2。 。 。 } The Ai, Bi, Ci respectively each linguistic variable values on the theory of domain. So I can get such as schedule control status table. Finally using the weighted average method to get the final output quantitative results, accurate after the control quantity is 3. Part 2 PLC application program mainly includes security protection, automatic control and manual control of three parts, as shown in figure 2. Figure 2 parts automatic control program including manual operator can according to the water level, pressure change control. A, B, the switching time of the pump, and the state of the induced draft fan. Auto parts mainly according to the water level data from the microcontroller, determine the quantitative number, to A, B control of pump and fan, the basic procedure is shown in figure 3. First get sent the safety of the water level signal from the single chip microcomputer, according to the code for water level on which quantitative range, and then according to the history information of IR201 store for A, B pump switches and switch time time X, and the induced draft fan for automatic control. Figure 3 4 conclusion part of the automatic control program corresponding to the system speed, high control accuracy and reasonable structure, complete functions, high reliability, the hardware and software configuration has higher practical value and promotion prospects, able to adapt to the control of industrial boiler. Save money and personnel, and improve the level of the automatic control of industrial boiler, eliminate the hidden danger of the accident, in addition, the system also greatly reduces the maintenance workload of the control system and equipment spare parts, spare parts replacement and replacement cycle, considerable economic benefit. This article from 5, 2005 'industrial control technology'
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