Delay Multivariable Decoupling Pid Control Of Satisfaction Research

Multivariable processes with time delays are often encountered in chemical and industrial practice. Researches to these systems are the hot spots and difficult points of process control, and have important theoretical research meaning and application value. Static decouplers are used in classic control methods, then the decoupled systems are described as first order plus dead time (FOPDT) or second order plus dead time (SOPDT) models. At last generic PID turning methods are used. As the development of control theory,computer technique and optimize methods, better performances are required to the control systems with the advancement of quality-control. The classic methods can not satisfy the desired performances.A design method of decoupling controller with better dynamic characters is proposed in this paper. They have more simple structures than the existing dynamic decouplers. Decoupler tuning methods for two-input two-output systems and three-input three-output systems are presented considering the effects of model-mismatch. At the same time, two approximate methods are proposed for the purposes of simplifying the structures of the decoupler under different decouple requires:a. FOPDT approximate method based on low frequency of Nyquist can be used for low decouple demand;b. Improved Pade approximate can be used when high decouple demand is required.The models of decoupled systems are neither accurate nor FOPDT systems, thereforeall the classic PID controller design methods are not suitable anymore. The satisfied PID controllers are used. After decoupling, satisfactory design of performance criterions and optimization of controller parameters are considered together, by designing satisfactory-rate functions of performance criterions and comprehensive satisfactory-rate function of the decoupled systems. And satisfactory optimization model of multivariable control system is constructed. Then the satisfactory parameters of PID controller are given using Genetic Algorithms.The theoretical analysis and simulation results show that better performances can be obtained than papers existed, and indicating that the method introduced is effective and practical.