MIMO Intelligent Decoupling Control Algorithm And Its Application In The Distillation Column

Industrial production process coupling is a kind of common phenomenon,especially in recent years, with the rapid development of science and technology,industrial system is more and more large, and the control method of this system is alsomore and more complex. An industrial process has many variables to be control, andbetween variables often have complex relationships, change of one process variablescan lead to other process variables change, this kind of phenomenon is called coupling.If the control object exist coupling phenomenon, it will cause the reduction of controlquality of control system, especially with serious coupled phenomenon it will leadsystem to run abnormally. The energy consumption of distillation process accounts forabout1/3of the total energy consumption in industry. So the improved controlmethod of column system is very necessary.On the base of reviewing current situationof decoupling control method of the column, the main research contents of this paperare as follows:(1)According to the traditional fuzzy control method of decoupling which can’tavoid the synthesis of the shortcomings of the operation rules, this paper broughtforward a variable self-adaptive fuzzy control method. And this method constructedtwo self-adaptive fuzzy PI controllers, and the control structure make the couplinginfluence between the output branches abate, and meanwhile each controller isindependent from each other. The simulation results show that this method has goodcontrol effect and adaptability.(2) If the system with large inertia time, the effect of above method will be worse.So this topic bringes forward a parameter self-tuning fuzzy PID controller and joins itto the decoupling link based on reference model decoupling control method, whichusing decoupling controller to achieve the purpose of independent channel control.The simulation experiment contrastes that this method had better decoupling controleffect than traditional reference model decoupling method. (3) When the system has pure delay and large inertia links, the above twomethods will be unable to meet the control requirements. According to theshortcomings of the above methods, this paper combins with biological immunology,the fuzzy theory and PID control methods and designed a self-adaptive fuzzy immunePI controller to solve the coupling problem. The control system structure of themethod can make each channel controller independent, furthermore the controlstructure is similar, which make this method easy to implement. After this method isapplied in pure delay and large inertia control system, the simulation results show itsbetter decoupling effect.Finally, the above methods are used in the column system. The system includescolumn device and control system of hardware and software. The control system iscomposed by the international famous Siemens PLC S7200and S7300; PLCprogramming software (STEP7) and KINGVIEW6.5monitoring software constitutethe software control system. The operation results prove that this column decouplingcontrol method is simple, feasible, and achieve good decoupling control purpose.