Study Of Advanced Control Strategies In Temperature Control System

The temperature is a difficult industrial control object for its largeinertia,nonlinear and large time delay. Double heating tube decouplingexperimental device of the laboratory,the inner cylinder is small,the inertia isrelatively small,the outer cylinder is big,the inertia is relatively large.Conventional PID is difficult to have a better control result.First,using MATLAB Simulation to design the experiments of controlobject：1) Using the least squares method to identify the object mathematicalmodel.According to the response characteristics of the object,the recognitionmodel is a first order plus with lags.The experimental data collection method isto take open-loop step response of the object,When the barrel temperature isstability,to change one of the the control amount of the inside and outsidetube respectively,And every2min recorded temperature values,until threecollection that has the same temperature.2) Fuzzy PID Control Simulation of the outer tube. For the inertia of theouter cylinder temperature and the conventional PID can not achieve a very good control performance,this article design a fuzzy PID controller. TheMATLAB simulation verified the superiority of the fuzzy PID control to thelarge inertia control object. Compared with the conventional PID,the fuzzyPID control is not only faster adjustment speed,but also has a smallerovershoot and volatility And having a good anti-disturbance capacity to thecoupling effect of the external cylinder of the inner cylinder.3) Predictive PID cascade control Simulation of the outer tube. In order toreduce the impact change of the temperature of the outer tube to the internalcylinder temperature,firstly take the inner and outer tube as a time-varyingnonlinear control object and design a predictive PID cascade controller.Simulation results show that the prediction PID cascade control has a betterdisturbance rejection than the conventional PID, but the response speed issomewhat slower; Compare with the forecast control, the predictive PIDcascade control not only has a faster response,but also has good anti-disturbance ability,be able to better reduce the impact of the internal cylindertemperature due to the changes of the temperature of the outer tube.4) Fuzzy Decoupling Control Simulation of the outer tube. In order tobetter reduce the impact between the inside and outside tube while thetemperature changes,This article design a decoupled control link,to take a decoupling control to the coupling between the inside and outside the tube.MATLAB simulation verified the different control effect of the staticdecoupling and dynamic decoupling control system. Dynamic decouplingcompletely decoupled for the general control object on the basis of an accuratemodel of the object,the static decoupling is often able to achieve controlrequirements. To the non-linear characteristics of the control object,you candesign a fuzzy decoupling controller.Second,Physical implementation of control algorithm Based on Wincc andPLC300:For the experimental model can not accurately reflect the object factors ofthe process there will be interference and uncertain nonlinear in the actualoperation. In order to verify the reliability of the simulation design ofcontrol algorithms to the effect of the actual control object,This article useWinCC scripting to write the vague and prediction control program,Using thePLC300to the design the PID controller and to acquisition and output data,andachieving the predict the PID cascade control,fuzzy decoupling and Fuzzy PIDcontrol according to WinCC and PLC’s MPI communication. Through thephysical experiments,the result show the difference between the controlparameters of the simulation algorithm and the actual control parameters,but the simulation algorithm can basically reflect the actual control effect.