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first-order-plus-dead-time
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Proportional stabilization and closed-loop identification of an unstable fractional order process
, Article Journal of Process Control ; Vol. 24, Issue. 5 , 2014 , pp. 542-549 ; ISSN: 09591524 ; Tavazoei, M. S ; Sharif University of Technology
Abstract
This paper deals with proportional stabilization and closed-loop step response identification of the fractional order counterparts of the unstable first order plus dead time (FOPDT) processes. At first, the necessary and sufficient condition for stabilizability of such processes by proportional controllers is found. Then, by assuming that a process of this kind has been stabilized by a proportional controller and the step response data of the closed-loop system is available, an algorithm is proposed for estimating the order and the parameters of an unstable fractional order model by using the mentioned data
Fractional PI Tuning for the First Order Plus Dead Time Processes
, M.Sc. Thesis Sharif University of Technology ; Tavazoei, Mohammad Saleh (Supervisor)
Abstract
In this thesis, a new method has been developed for tuning of fractional PI ( ) and fractional [PI] ( ) controllers for the first order plus dead-time ( ) systems. By using the performance-map method ( ) and based on phase and gain margins' criteria, a formula which is function of fractional order ( ) and normalized dead-time ( ) has been proposed for the proportional and integral coefficients. In addition, an equation has been given for the fractional order of controller to minimize the integrated absolute error ( ) index. Moreover, overshoot and settling-time of the step response of the system have been improved by dynamic setpoint weighting. Simulation results have shown that proposed...
A new view to Ziegler-Nichols step response tuning method: Analytic non-fragility justification
, Article Journal of Process Control ; Volume 23, Issue 1 , 2013 , Pages 23-33 ; 09591524 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
2013
Abstract
Recently, exploiting the centroids of stability regions (admissible regions) to be used in tuning two-parameter controllers has been considered as an approach to obtain non-fragile two-parameter controllers. Such an approach can be extended for three-dimensional stability spaces (admissible spaces) by considering the center of mass of these spaces in tuning three-parameter controllers. In this paper, the mentioned approach is used to tune PID controllers for controlling integrator plus dead-time (IPDT) and first order plus dead-time (FOPDT) processes. It is shown that the tuning method resulted from this approach is very similar to the Ziegler-Nichols step response tuning method....
A non-linear controller design for the evaporator of a heat recovery steam generator
, Article Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy ; Volume 223, Issue 5 , 2009 , Pages 535-541 ; 09576509 (ISSN) ; Nademi, H ; Sharif University of Technology
2009
Abstract
This article addresses a combined approach of sliding mode control (SMC) with generalized predictive control (GPC) to achieve fluid temperature control in the evaporator of a heat recovery steam generator. The evaporator is modelled as a first-order plus dead time process. The model is developed using the experimental data obtained at an actual power plant. An output error identification algorithm is used to minimize the error between the model and the experiments in different operating conditions. A GPC method is exploited to optimize the sliding surface and the coefficients of the switching functions used in SMC. The proposed control schemes are evaluated by thorough simulation for...