Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 423
Author(s):  
Gun-Baek So

Although a controller is well-tuned for set-point tracking, it shows poor control results for load disturbance rejection and vice versa. In this paper, a modified two-degree-of-freedom (2-DOF) control framework to solve this problem is proposed, and an optimal tuning method for the pa-rameters of each proportional integral derivative (PID) controller is discussed. The unique feature of the proposed scheme is that a feedforward controller is embedded in the parallel control structure to improve set-point tracking performance. This feedforward controller and the standard PID con-troller are combined to create a new set-point weighted PID controller with a set-point weighting function. Therefore, in this study, two controllers are used: a set-point weighted PID controller for set-point tracking and a conventional PID controller for load disturbance rejection. The parameters included in the two controllers are tuned separately to improve set-point tracking and load dis-turbance rejection performances, respectively. Each controller is optimally tuned by genetic algo-rithm (GA) in terms of minimizing the IAE performance index, and what is special at this time is that it also tunes the set-point weighting parameter simultaneously. The simulation results performed on four virtual processes verify that the proposed method shows better performance in set-point tracking and load disturbance rejection than those of the other methods.


Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 262
Author(s):  
Pengchong Chen ◽  
Ying Luo ◽  
Yibing Peng ◽  
Yangquan Chen

In this paper, a fractional-order active disturbance rejection controller (FOADRC), combining a fractional-order proportional derivative (FOPD) controller and an extended state observer (ESO), is proposed for a permanent magnet synchronous motor (PMSM) speed servo system. The global stable region in the parameter (Kp, Kd, μ)-space corresponding to the observer bandwidth ωo can be obtained by D-decomposition method. To achieve a satisfied tracking and anti-load disturbance performance, an optimal ADRC tuning strategy is proposed. This tuning strategy is applicable to both FOADRC and integer-order active disturbance rejection controller (IOADRC). The tuning method not only meets user-specified frequency-domain indicators but also achieves a time-domain performance index. Simulation and experimental results demonstrate that the proposed FOADRC achieves better speed tracking, and more robustness to external disturbance performances than traditional IOADRC and typical Proportional-Integral-Derivative (PID) controller. For example, the JITAE for speed tracking of the designed FOADRC are less than 52.59% and 55.36% of the JITAE of IOADRC and PID controller, respectively. Besides, the JITAE for anti-load disturbance of the designed FOADRC are less than 17.11% and 52.50% of the JITAE of IOADRC and PID controller, respectively.


2020 ◽  
Vol 42 (12) ◽  
pp. 2221-2233 ◽  
Author(s):  
Yun Cheng ◽  
Zengqiang Chen ◽  
Mingwei Sun ◽  
Qinglin Sun

Although the heat integrated distillation is an energy-efficient and environment-friendly separation technology, it has not been commercialized. One of the reasons is that the nonlinear dynamics and the interactions between various control loops have limited the performance of the traditional control strategy. To achieve a high-purity product concentration, a dynamic decoupling control strategy based on active disturbance rejection control (ADRC) is proposed. The effects of interactions, uncertainties and external disturbances can be estimated and rejected by using extended state observer. Considering the constraints on manipulated variables, an optimized ADRC is designed for the first-order system. Moreover, a concentration observer based on a nonlinear wave model is formulated to reduce the number of sensors. In the simulation research, the related internal model control (IMC), multi-loop ADRC and model predictive control (MPC) are compared with the proposed control scheme. The simulation results demonstrate the advantages of the proposed control scheme on tight control, decoupling performance and disturbance rejection for the high-purity heat integrated distillation column.


1982 ◽  
Vol 104 (3) ◽  
pp. 270-274 ◽  
Author(s):  
S. Thompson

A procedure is presented for designing multivariable controllers for unidentified plant. It is assumed that the open-loop plant is stable and its response to step inputs are basically nonoscillatory. For such plant, no mathematical model is required in order to generate multivariable I, PI, or PID controllers. Method of tuning the controllers are also presented and demonstrated, first on a low order linear distillation column model, and finally on a high order, nonlinear, once-through boiler model typical of the type used in nuclear power plant simulation studies.


Author(s):  
Oladimeji Ibrahim ◽  
Nor Zaihar B Yahaya ◽  
Nordin Saad

Power converter operations and efficiency is affected by variation in supply voltage, loads current, circuit elements, ageing and temperature.  To meet the objective of tight voltage regulation, power converters circuit module and the control unit must be robust to reject disturbances arising from supply, load variation and changes in circuit elements. PID controller has been the most widely used in power converter control. This paper presents studies of robustness of PID controller tuning methods to step changes in the set point and disturbance rejection in power converter control. A DC-DC boost converter was modelled using averaged state-space mothod and PID controllers were designed with five different tuning methods. The study reveals the transient response and disturbance rejection capability of each tuning methods for their suitability in power supply design applications.


2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Nixuan Liu ◽  
Siqi Cao ◽  
Juntao Fei

This paper proposed a fractional-order PID controller and active disturbance rejection control (ADRC) method for the current compensation of active power filter (APF). The control method consists of two closed loops. One is a reference current tracking loop based on the ADRC controller, which can treat the internal and external uncertainties of the system as a whole. The other is the voltage control loop with the fractional-order PID controller for more flexibility. Simulation results demonstrate that the proposed control method has a stronger robustness and higher compensating precision comparing with the double-loop PID control method.


2018 ◽  
Vol 7 (2.31) ◽  
pp. 41
Author(s):  
J Ramyashree ◽  
M R. Roja ◽  
G Sivagurunathan ◽  
R Kotteeswaran

Distillation is the process of separating the components or substances from a liquid mixture by selective boiling and condensation. It is one of the most underestimated fields of chemical engineering and has been around for well over hundred years. This paper deals with the tuning of centralized and decentralized Multivariable PID controller for Wood and Berry distillation column using Firefly algorithm (FA). FA uses controller parameters as decision variables and minimization of IAE as objective function. At the end of the search, optimum solutions for controller parameters are obtained which upon implementation provides challenging results for both top and bottom products. Simulation has been carried out using Matlab/Simulink platform.


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