Design of boiler drum temperature control system (process control course design matlab/simulink)

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send out ： Boiler drum
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One 、 Description of team members' task division
xxx Students are responsible for drawing the process flow chart with control points , And construct the principle block diagram of the control scheme .xxx Students have finished in MATLAB Construction of simulation model in , Parameter debugging and analysis and sorting of simulation results .xxz Students are responsible for integrating the content of the above two students , Write a complete design report .

Two 、 Task analysis
Boiler is an important power equipment of the whole plant , Its task is to supply qualified and stable steam , To meet the needs of production . So , All main parameters of the boiler production process must be strictly controlled . Boiler equipment is a complex control object , The main input variables include load 、 Boiler feed water 、 Amount of fuel 、 Desuperheating water 、 Air supply and induced air volume , The main output variables include drum water level 、 Superheated steam temperature and pressure 、 Oxygen content of flue gas and negative pressure of furnace . Therefore, the boiler is a multi input 、 Complex control objects with multiple outputs and mutual coupling .
For boiler drum temperature control system , The controlled variable is drum temperature , The main control variable is water supply . The purpose of control is that the temperature in the drum fluctuates within the allowable range .
3、 ... and 、 Object property analysis
Object characteristic refers to the interaction law between the output parameters and input parameters of the control object .
This course is in progress , It is assumed that the main factors affecting the drum temperature only consider the production load and fuel quantity , And suppose ：
The characteristics of the drum temperature object are ：

The characteristic of fuel flow is ：
The disturbance characteristics of production load on drum temperature are ：

Four 、 Control scheme design
4.1 Single closed loop design

4.2 Cascade loop design
4.3 Feedforward feedback loop design
Feedforward control is the control variable （ It refers to a process variable controlled by the actuator , In this simulation , That is, the amount of fuel ）, Controlled variables are not included （ That is, drum temperature ）.

5、 ... and 、 Simulation results and analysis
5.1 Single closed loop design simulation
The closed-loop system is independent of the given signal and the disturbance in the detection device , Because it has strong anti-interference performance , But for the system with pure delay, the single closed-loop system , Rely solely on proportional control , Here's the picture ：

The system will produce large overshoot , And the reaction time will be longer , Finally, it is stable above the given value , There is static error .
So add PID The control is shown in the figure below ：
PID Parameter positive definite , utilize simulink The module has its own setting , The results of （ See the report for parameters ）.

The integration link will eliminate the static error , Differential link can eliminate lag , Speed up system response .
As shown in the figure ： The system overshoot is reduced , Reaction speed up , The adjustment process becomes stable .

5.2 Cascade control design simulation
The simulation model is as follows ：

The simulation waveform is as follows ：
Compare the cascade with the original single closed loop ： The overshoot is reduced , The reaction time is nearly consistent due to the lag , That is, the reaction time is faster . Conduct internal pid When setting parameters, disconnect the main circuit first , Carry out... Of the secondary circuit pid Parameter setting . As shown in the figure below .

PID Parameters ：
（1） External PID Parameters （ See the report for parameters ）.
（2） Inside PID Parameters （ See the report for parameters ）.

The response curve of cascade control after parameter setting is shown in the figure 5.11 Shown .
5.3 Feedforward control system design simulation
The simulation diagram is as follows ：

The simulation waveform is as follows ：
PID Parameters （ See report for details ）

Compare with the original closed-loop ：

The conclusion is that the overshoot is greatly reduced , Faster reaction time .

6、 ... and 、 Design summary and experience
6.1 Conclusion
（1） Whether it's a single closed loop 、 Cascade or feedforward control , Can achieve system stability .
（2） A single closed loop has PID The control system of can be adjusted quickly , But the cascade control system can greatly reduce overshoot , Speed up system adjustment , The feedforward control system eliminates the influence of disturbance in advance , It ensures the stability and rapidity of the system .

6.2 Experience
Simulink It has a wide range of adaptability 、 The structure and process are clear and the simulation is fine 、 Close to reality 、 Efficient 、 Flexibility and so on , And based on the above advantages Simulink It has been widely used in complex simulation and design of control theory and digital signal processing . So learn to skillfully use simulink It is of great help to our future study .
Through single closed loop 、 Design of cascade and feedforward control system , Let's see PID The role of each link and the characteristics of the three methods , Let's have a better understanding of process control . This course has enhanced our team members' sense of teamwork and ability of division of labor and cooperation . We had a productive session ！