چكيده به لاتين
Abstract
This study tries to propose a method for controlling the process of distributed parameter (shell and tube heat exchanger) which includes time delay in its model. By using the dominant gain concept, the behavior of such functions (distributed parameter) is easily specified in the frequency domain, without using complex theories and calculating function zeros, also the location of the function zeros could be predicted. This study minimizes the system phase angle value based on dominant gain concept and by using the genetic algorithm in the frequency domain, the time delay reaches the minimum in control loop system. By comparing the dominant gain concept and zeros asymptotic location theory, it could be concluded that in fact, the presence of time delay causes infinite zeroes in the characteristic equation and based on the location of these zeros, the control system could be minimum phase or non-minimum phase. In this research, four states of the zeros locations in the coordinate axis and the effect of these zeros location on the performance of the control system are studied. Finally, by using the genetic algorithm, the optimal controller parameters where derived. The optimal phase tuning method step responses were compared with other methods such as Ziegler Nichols method, Smith compensator method, Kaya method and least squares integral error method. Also, the effect of long time delay on the optimal phase tuning method and other methods was studied.
Keywords: Time delay compensator, Optimal phase tuning method, Heat exchange control in frequency domain, Controller design by using genetic algorithm.
