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Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

SCADA systems play an important role in tracking the behaviour of critical process variables and connecting geographically dispersed subsystems at the industrial plant level. This article presents a PLC and SCADA-based control framework to automate and supervise the temperature control processes in the heat exchanger plant. The OMRON (NX1P2-9024DT1) PLC is interfaced with the Wonderware InTouch SCADA system to gather data, create a simulated temperature control prototype and carry out the necessary control operations within the heat exchanger plant. The PLC controls the entire process and programming of PLC is done using Sysmac studio automation software using the ladder programming language. The proposed system controls the temperature of the heat exchanger system through PID and Fractional Order PID (P I λ D μ ) controllers with Integral Anti-windup technique. Various control strategies like Cascade Control, Feedforward Control and Smith Predictor for time delayed process are discussed for controlling the temperature of the process. The performance of both PID and fractional order PID controllers is optimized using adaptive heuristic optimization techniques like Genetic Algorithm (GA), Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO). In control system design and analysis, the calculated performance indices are used as quantitative measures for evaluating the performance of a system. The combined form of temperature controller with Cascade control, Feedforward control and dead-time compensator is modelled and examined for simulation using MATLAB. Simulation and real-time experimentation analysis of the developed controllers are executed with metaheuristic optimization techniques based on different performance indices like ISE, IAE and ITAE. [ABSTRACT FROM AUTHOR]

This paper deals with the design problem of networked cascade control systems (NCCSs) with two different event‐triggered mechanisms (ETMs) for the feedback loops. A combination of stochastic denial‐of‐service (DoS) attack and deception attack has been considered for the communication network. To comply with the practical point of view, the primary and the secondary systems have been considered with distinct disturbances. First, the closed‐loop system with state feedback controllers is provided in a unified stochastic delayed system. Then, the Lyapunov–Krasovskii stability theory and stochastic analysis techniques are employed to derive and formulate H∞$$ {\mathcal{H}}_{\infty } $$ control design conditions in terms of linear matrix inequalities (LMIs). Finally, a superheater steam temperature control is utilized to assess the applicability of the proposed method. [ABSTRACT FROM AUTHOR]

This article presents a proposal for the automation of a batch reactor for the production of addition polymers, in which an exothermic chemical reaction, generated in the polymerization process, takes place. We propose to control the temperature of the product through a split range control strategy with cascade controllers considering the product temperature loop as the primary loop and the jacket temperature loop as the secondary loop. The phenomenological modeling of the reactor was carried out from material and energy balances to obtain the transfer function of the system and estimate the parameters of the controllers. The results obtained in the simulation and control of the process show the good performance of the system working with the process temperature set-point between 92 °C and 96 °C. In addition, a significant improvement in the monomer-polymer conversion of the product is observed in this range. [ABSTRACT FROM AUTHOR]

Aiming at the problems of large delay and poor anti-disturbance ability in the outlet temperature control system of the heat exchanger to optimize the control accuracy of the system and improve the control performance, this paper proposes a control scheme combining predictive functional control with proportional-integral-derivative control. Using the incremental proportional-integral-derivative control algorithm to improve the optimization objective function of the predictive functional control algorithm, a predictive functional control optimization model with a proportional-integral-derivative structure is established. The feedforward compensation control is adopted to eliminate the influence of external disturbances on the heat exchanger temperature control system. Through simulation, the proposed control scheme is compared with the feedforward cascade compound control scheme based on a proportional-integral-derivative main controller. The results show that the scheme has a small over harmonic and strong anti-interference ability. The adaptability and stability of the system are significantly improved, and the exit temperature of the heat exchanger can be effectively controlled. [ABSTRACT FROM AUTHOR]

To solve the problem that the conventional PID with unsatisfactory control effect when the structure and parameters of the boiler superheated temperature model changed greatly, an adaptive PI controller was proposed based on actor-critical (AC) reinforcement learning (RL). A radial basis function neural network (RBF-NN) was used to realize AC-RL structure. The PI controller parameter was used as output of actor network and evaluated by the critical network to generate temporal difference (TD) error signal. The weights of RBF-NN were constantly updated by the TD error signal online. The structural characteristics of boiler super-heated steam temperature control system were introduced, and the RL-PI controller design and algorithm implementation steps were given to complete the design of boiler super-heated steam temperature control system. The simulations of the typical nonlinear time-varying super-heated steam temperature system were carried out with the proposed adaptive RL-PI controller under six working conditions of normal working conditions, gain increase, inertia increase, gain mutation, inertia mutation and disturbance. The results show that compared with model predictive control, fuzzy control and conventional PI cascade control methods, the proposed RL-PI controller has stronger self-learning ability, faster convergence speed and stronger robustness. [ABSTRACT FROM AUTHOR]

Dividing wall column (DWC) is an advanced technology which could decrease energy consumption. As the vertical wall inserted in DWC increases the degree of freedom of systems, the control becomes more difficult than the conventional columns. In this study, the mixture glycols (1, 2-propanediol+ 1, 3-butanediol+ 1, 4-butanediol) were taken as feed, an optimized DWC structure was proposed, and three control structures for DWC were tested by ± 10% feed disturbances. The temperature control structure (CS1) was hard to control the system while composition control structure (CS2) and flow rate-composition cascade control structure (CS3) had good performance on controlling the DWC. It showed that CS3 was superior to CS2, as CS3 could stabilize the DWC within 4 hours, and the maximum deviations of the three products, namely 1, 2-propanediol, 1, 3-butanediol and 1, 4-butanediol, were 0.07%, 1.44%, and 0.46% respectively, while CS2 could realize the stability within 7 hours, and the corresponding numbers were 0.35%, 2.78%, and 0.41%, respectively. [ABSTRACT FROM AUTHOR]

BACKGROUND: The triple‐column extractive distillation (TCED) process for the ternary multi‐azeotropic mixture of N‐hexane/acetone/chloroform is a significant step in waste recovery and purification. Given the common occurrence of feed disturbances in practical industrial production, a feasible dynamic control scheme should effectively resist feed disturbances and ensure product quality, enabling the process to run steadily and safely with a high efficiency. However, it is challenging to design a robust control scheme for separation processes accompanied by side‐stream capability. In this work, dynamic control schemes were designed for four separation processes: conventional and double side‐stream TCED processes with single and double entrainers. A multipoint temperature control scheme, composition‐temperature cascade control scheme and variable ratio control were combined to improve the dynamic performance of the control schemes. RESULTS: The results showed that the control schemes designed for the four extractive distillation processes are highly robust, resisting ±20% feed flow and composition disturbances. A variable ratio control combined with composition‐temperature cascade was found to be vital for double side‐stream TCED schemes. CONCLUSION: The conventional TCED with a single entrainer (CS‐TCED) is an optimal process for N‐hexane/acetone/chloroform separation both from control and economic perspectives. The designed control scheme is simple, low‐cost and easy‐to‐implement with a superior dynamic performance over other separation schemes. This study has a certain theoretical guidance for N‐hexane/acetone/chloroform separation in terms of economic benefits and practical production. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The heat dissipation capacity of the radiator of vehicle fuel cell thermal management system is easily affected by the ambient, so the system needs to have a high ability to suppress disturbance. Based on cascade internal model control with nonlinear feedforward compensate (CIFC), a temperature tracking control scheme is designed for a real vehicle fuel cell system. By defining the heat dissipation coefficient, CIFC can compensate the heat dissipation capacity of the radiator in different environment and driving condition for real vehicle so that reduce the impact of environmental factors on the fuel cell temperature management system. The control scheme is applied on a real fuel cell passenger car. Simulation and real vehicle experiments show that the scheme has good accuracy, stability, rapidity and robustness. The simulation results show that the algorithm can track the set temperature under each load current without steady-state error, the step response adjustment time is 54s and there is no overshoot both under normal atmospheric temperature and higher atmospheric temperature. The real vehicle experiment results show that the overshoot is less than 2°C, the temperature tracking speed can reach 1.1°C, and the system can stay stable with the change of vehicle speed and load without steady-state error. • Model based controller is proposed for fuel cell temperature control. • Experiments on a real fuel cell vehicle are implemented. • There is no steady-state error in the experiment. • Overshooting can be limited to less than 2 °C in the experiments. [ABSTRACT FROM AUTHOR]

In order to accurately control the gas temperature of a supersonic heat-airflow simulated test system, this paper introduces the working principle of the system, including the fuel supply subsystem and the air supply subsystem, establishes the mathematical model of the system, including the fuel supply subsystem, the air supply subsystem and the gas temperature, and analyses the characteristics of the system. Based on characteristics such as non-linearity, parameter time variations, disturbance and pure time delay exist in the system; a new cascade control scheme that can control both the fuel supply subsystem and the air supply subsystem is proposed to achieve an accurate control of the gas temperature. On this basis, the simulation and experimental studies are carried out by the proposed control algorithm. The results show that the proposed gas temperature cascade control algorithm can achieve a fast, stable and no overshoot control of the gas temperature in a wide operating range, and the control accuracy can reach at ±5°C.

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Today, the use of proportional-integral-derivative (PID) control units continues in many control applications due to their simple structure. In areas such as pressure, temperature, flow control, PID control element is used and many new methods are applied in adjusting control parameters. In this study, the LTR 701 Controlled Airflow and Temperature Experimental System was used to study the temperature and pressure control at different flow rates in the pipelines. In this control system, temperature was controlled with PID control element, pressure was controlled with PI control element, and reaction of control parameters at different temperatures and pressures were investigated. Also, temperature was controlled as cascade with PI element in elementary controller and P element in secondary controller. The manual adjustment method has been applied to adjust the control parameters. In addition, the experimental system is modelled in MATLAB-SIMULINK. On this model, simulation results showed that it is matching the experimental results. [ABSTRACT FROM AUTHOR]

• A temperature cascade control scheme integrating DRL and PID is developed. • A strategy is proposed for training robust controllers without overfitting. • The PID-DRL cascade control shows better performances in a gas-phase PE process. This study investigates using deep reinforcement learning (DRL) with proportional-integral-derivative (PID) control for temperature cascade control in a fluidized bed reactor within a commercial gas-phase polyethylene process. The heat exchange system's nonlinearity and frequent disturbances pose challenges for PID controllers, particularly under varying conditions. To address this, a PID-DRL cascade control scheme is developed, where a DRL controller is used in the secondary loop. The DRL controller, designed using the actor-critic framework, is trained using the Deep Deterministic Policy Gradient algorithm. The DRL controller is evaluated in three stand-alone secondary loop experiments, as well as three cascade control experiments. Results reveal the DRL controller surpass the traditional PID controller in both scenarios. The DRL controller shows better set point tracking and interference suppression, indicated by lower integral absolute error (IAE) values. The proposed cascade control structure can be used to enhance reactor stability and product quality in gas-phase polyethylene processes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Feasible composition/temperature cascade control for a Kaibel column is studied. • The PI-MPC scheme uses PI controllers in the lower layer and MPC in the upper layer. • A composition estimation soft sensor is introduced to improve the PI-MPC performance. Kaibel dividing-wall distillation column (KDWDC) is a very effective distillation process intensification technology. However, the misgivings of controllability problems impede its industrialization. Therefore, three feasible control schemes are studied in this paper, including the composition/temperature cascade control scheme with PI controllers in the lower layer and MPC in the upper layer (PI-MPC), the PI-MPC scheme with a composition estimator (PI-MPC-CE), and the PI scheme with pure temperature controllers. In the PI-MPC scheme, the MPC can deal with the complicated dynamics of the KDWDC, while the PI controller can quickly stabilize the KDWDC. The PI-MPC-CE scheme can continuously predict the primary controlled variables from the easy-to-access auxiliary variables. Dynamic performances prove that the PI-MPC-CE scheme are better than the PI and PI-MPC scheme with lesser number of oscillations, shorter settling times, and reduced maximum and steady-state deviations. Besides, it is very promising because it disposes of the continuous real-time composition detection. [ABSTRACT FROM AUTHOR]

A conventional reactive distillation column will not be able to produce high purity isopropyl acetate (IPAc) due to the existence of a minimum boiling azeotrope in the system. In this work, a novel reactive and extractive distillation (RED) process was proposed and used for the synthesis of IPAc. Results showed that the purity of IPAc reached 99.5%. Then, the RED flowsheet was optimized with minimum total annual cost (TAC), and a number of key variables were determined with the assistance of program written in Visual Basic 6.0 (VB). After that, two control structures of the RED process were developed: a basic control structure with temperature/proportional cascade control and an improved control structure with composition/temperature cascade control. The integral of squared error (ISE) was introduced to evaluate the performance of control systems, it revealed that the improved control structure had better controllability. [ABSTRACT FROM AUTHOR]

• A control strategy of a space thermionic nuclear reactor is proposed. • The cascade control system is designed for electric power and coolant temperature. • The frequency domain analysis method is used to tune the control parameters. • The bumpless switching of control system is studied to realize the wide rang power regulation. Nuclear reactors are gaining increasing attention for use in spacecraft owing to their long life and high power-density. Because the dynamic characteristics and operation strategy of a space nuclear reactor (SNR) are different from those of a traditional reactor, its control strategy must be investigated to design an appropriate control system. In this study, the dynamic characteristics of the time and frequency domains are analyzed. Based on this analysis, a control strategy is proposed. The cascade control method is applied to the design of control systems, including electric power and coolant temperature control systems. The controller parameters are tuned using the frequency-domain analysis method. To verify the control performance, step and ramp disturbances of the electric power and coolant temperature setpoints are introduced, and comprehensive comparisons are made. Additionally, the startup process is simulated; it reveals that the cascade control systems perform better compared with the traditional proportional-integral-derivative (PID) control. Moreover, the control performance of the wide-range power regulation is smooth and steady. Thus, the control strategy and cascade control system designed in this study can be applied to the thermionic nuclear reactors in space. [ABSTRACT FROM AUTHOR]

This paper deals with the H ∞ control design for the networked cascade control systems (NCCSs) subject to periodic denial-of-service (DoS) attack. The controller structure is based on the state-feedback controller for the both control loops. The communication network of the primary loop is equipped with an event-triggered mechanism while the network is under periodic DoS attack. For stability analysis and controller design, the mathematical model of the closed-loop system is formulated based on the switching systems approach. By using the piecewise Lyapunov-functional-based approach and average dwell time techniques, some stability and stabilization criteria are derived and presented in the form of linear matrix inequalities (LMIs). Finally, an steam temperature cascade control system is utilized as a practical example to demonstrate the effectiveness of the proposed method. • The mathematical model of the proposed NCCS under DoS attack is formulated as a switching system. • Stability and stabilization of the closed-loop system is analysed by using the piecewise Lyapunov-functional-based approach. • A MDADT technique is employed to derive some new stability criteria for the proposed NCCS. • The proposed method have been applied for an steam temperature cascade control system as a practical example. [ABSTRACT FROM AUTHOR]

Due to its nonlinear feature, supply air temperature control systems at air handling units using single-loop fixed gain control frequently suffer unstable response under dynamic conditions. This paper is aimed at identifying a more effective control strategy to stabilize the valve control and achieve desirable supply air temperature response under various operation conditions by evaluating three control strategies, cascade, gain scheduling and cascade plus gain scheduling controls. Firstly, a control-oriented model is developed and calibrated through open-loop tests. Then, the control issues with single-loop fixed gain control are evaluated through simulations and field tests, which indicates that the system has more aggressive response or becomes unstable under lower load conditions when the chilled-water flow rate is less than 0.1 L/s. Finally, three control strategies are proposed and evaluated. The results reveal that all three proposed controls can achieve better robustness with the integral square error of supply air temperature decreased to 16%, 47% and 5%, respectively, under lower load condition. However, since high-frequency oscillation of the control valve occurs with cascade and cascade plus gain scheduling control, the gain scheduling control is recommended considering a trade-off among the supply air temperature response, valve lifetime and implementation complexity. • Supply air temperature control is unstable at lower chilled-water flow rate. • Cascade and gain scheduling controls are applied to solve this issue. • Cascade control has better robustness but with high-frequency valve oscillation. • Gain scheduling control cuts integral square error of supply air temperature to 47%. • Gain scheduling control improves performance with simpler and more generic design. [ABSTRACT FROM AUTHOR]

These days, in times of recession, we are forced by competitiveness and the optimization of production to lower the costs of the temperature control in pharmaceutical batch reactors and increase the quantity and quality of the produced pharmaceutical product (active pharmaceutical substances). Therefore, a control algorithm is needed which provides us rapid and precise temperature control. This paper deals with the development of a control algorithm, where two predictive functional controllers are connected in a cascade for heating and cooling the content of the hybrid batch reactor. The algorithm has to be designed to cope with the constraints and the mixed discrete and continuous nature of the process of heating and cooling. The main goal of the control law is to achieve rapid and exact tracking of the reference temperature, good disturbance rejection and, in particular, a small number of heating and cooling medium switchings. The simulation results of the proposed algorithm give us much better performance compared to a conventional cascade PI algorithm.

In this article, a practical temperature control issue of gas for a high-speed heat-airflow wind tunnel (HSHAWT) is solved. Based on the principal analysis and the system configuration description, the mathematical models to describe the dynamic characteristics of the fuel delivery system and the fuel combustion system are established. Two control frameworks of gas temperature for HSHAWTare proposed. One is to realize the gas temperature control by using the method that regulates the fuel flow rate on the basis of the air flow rate being a constant; the other is the two-loop cascade control framework that takes gas temperature as a controlled objective, fuel flow rate as a controlled object in the secondary control loop, and gas temperature as the controlled object in the main control loop. Furthermore, experimental comparative studies on the flow rate of fuel and temperature of gas are carried out by using a variety of control algorithms, and a satisfactory control effect on the gas temperature is achieved. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A neural network (NN)‐based cascade control system is developed, in which the primary proportional–integral–derivative (PID) controller is constructed by NN. A new entropy‐based measure, named the centred error entropy (CEE) index, which is a weighted combination of the error cross‐correntropy (ECC) criterion and the error entropy criterion (EEC), is proposed to tune the NN‐PID controller. The purpose of introducing CEE in controller design is to ensure that the uncertainty in the tracking error is minimised and also the peak value of the error probability density function being controlled toward zero. The NN‐controller design based on this new performance function is developed and the convergent conditions are investigated using a linearisation technique. During the control process, the CEE index is estimated by a Gaussian kernel function. Adaptive rules are developed to update the kernel size in order to achieve more accurate estimation of the CEE index. This NN cascade control approach is applied to superheated steam temperature control of a simulated power plant system, from which the effectiveness and strength of the proposed strategy are discussed by comparison with NN‐PID controllers tuned with EEC and ECC criterions. [ABSTRACT FROM AUTHOR]

• An intelligent control strategy without the composition analyzer is proposed. • Variable selection based on correlation improves BPNN prediction accuracy. • The universality of the intelligent control strategy is proved by two PSD cases. In this paper, an intelligent control strategy based on back propagation neural network (BPNN) is proposed for product composition control in pressure-swing distillation (PSD) processes. A data-driven intelligent controller based on BPNN was combined with PID control instead of traditional composition controllers to avoid the problem that composition is difficult to measure online in real-time. The intelligent controllers are used to predict temperature set point in composition- temperature cascade control by using the process variables easy to measure, e.g., reboiler duty, thus avoiding composition measurement. The critical variables for output prediction are analyzed by correlation analysis to present the relationship between the output variables and input variables, then to train highly correlated variables by BPNN. Two typical triple-columns PSD processes, i.e., Ethanol/THF/Water and ACN/IPA/Water, were used to verify the reliability and accuracy of the intelligent controllers under ±20% of feed flow and composition disturbances. Results demonstrated that the proposed intelligent control strategy presents good dynamic performance without the composition analyzer. This study is significant in improving dynamic performance and solving practical application problems by combining the traditional PID control and data-driven intelligent control. [Display omitted] [ABSTRACT FROM AUTHOR]

Peritoneal Carcinomatosis (PC) is one of the final stages of abdominal cancers. Nowadays Cytoreductive Surgery followed by Hyperthermic Intraperitoneal Chemotherapy (HIPEC) proves to be a promising therapeutic solution. The authors are developing an HIPE Cequipment and this paper presentsan advanced cytostatic solution temperature control structure. A cascade plus feed-forward control structure is proposed in order to compensate the major temperature disturbances: the temperature loss due to the heat exchange between the solution and the environment, and the heat exchange between the cytostatic solution circulated inside the abdominal cavity and the human body. The assessment of the results is made via computer simulation. [ABSTRACT FROM AUTHOR]

In this paper, one-variable linear regression mathematical model of top of regenerator temperature and ue temperature in machine side is built using the linear regress theory. The parameters of ARX model is determined by identification method of least square method and the mathematical model of flue temperature control is established. Applying the basis cascade control theory, system adopts flue temperature and coal flue gas ow as controlled parameters of host circuit and subsidiary circuit respectively. The compound Fuzzy-PID control strategy is presented combined with the characteristics of temperature system after analyzing the conventional PID control algorithm and fuzzy control algorithm. Using step signal and periodic signal to simulate the conventional PID and compound Fuzzy-PID algorithm, the result has indicated: Compound Fuzzy PID control algorithm combines with the advantages of fuzzy control and PID control algorithm, including fast response speed and strong anti-interference ability. When external conditions change, the fuzzy PID compound control can show the strong adaptability and robustness which e ectively improve the stability of the control system. [ABSTRACT FROM AUTHOR]

This paper presents the application of a Multivariable Generalized Predictive Controller (MGPC) for simultaneous temperature and humidity control in a Heating, Ventilating and Air- Conditioning (HVAC) system. The multivariable controlled process dynamics is modeled using a set of MISO models on-line identified from measured input-output process data. The controller synthesis is based on direct optimization of selected quadratic cost function with respect to amplitude and rate input constraints. Efficacy of the proposed adaptive MGPC algorithm is experimentally demonstrated on a laboratory-scale model of HVAC system. To control the airconditioning part of system the designed multivariable predictive controller is considered in a cascade dual-rate control scheme with PID auxiliary controllers. [ABSTRACT FROM AUTHOR]

• Reinforcement learning can explore operating strategies of semi-batch reactors. • Operation phase-based control can be achieved by multi-agent reinforcement learning. • Reinforcement learning-based controllers can be designed for cascade control. The operation of semi-batch reactors requires caution because the feeding reagents can accumulate, leading to hazardous situations due to the loss of control ability. This work aims to develop a method that explores the optimal operational strategy of semi-batch reactors. Since reinforcement learning (RL) is an efficient tool to find optimal strategies, we tested the applicability of this concept. We developed a problem-specific RL-based solution for the optimal control of semi-batch reactors in different operation phases. The RL-controller varies the feeding rate in the feeding phase directly, while in the mixing phase, it works as a master in a cascade control structure. The RL-controllers were trained with different neural network architectures to define the most suitable one. The developed RL-based controllers worked very well and were able to keep the temperature at the desired setpoint in the investigated system. The results confirm the benefit of the proposed problem-specific RL-controller. [ABSTRACT FROM AUTHOR]

In order to meet stringent temperature-control requirements in a high-speed airflow wind tunnel (HAWT) for thermal simulation under complicated work conditions such as thermal strength experiment of aero engine blade and dynamic calibration of high temperature thermal coupler, this paper proposes a novel cascade fuzzy-PID (C-Fuzzy-PID) compound control method for regulating the fuel-oil flow rate in the inner loop and temperature in the outer loop. The mathematical models that characterize the dynamics of the heat airflow temperature in the combustor and the fuel-oil flow rate for combustion are derived, upon which the improved PID control laws for the inner and outer loops are described. The former employs a fuzzy-PID controller with a predictor for controlling flow rate in the inner loop, which effectively overcomes influences according to its characteristics of large inertia and transport lag in fuel-oil supply system on the temperature responses. The latter combines disturbance compensation and a fuzzy-PID feedback law to suppress influences due to factors such as change in work conditions, disturbances, and time-varying parameter variations. The C-Fuzzy-PID method has been numerically investigated by comparing simulation results against two traditional PID-based methods, as well as experimentally validated confirming that the proposed control algorithm has strong robustness and excellent adaptability for temperature control of an HAWT. [ABSTRACT FROM PUBLISHER]

This paper introduces a new class of advanced control algorithms for batch-reactor temperature control where a nonlinear PI controller with a feed-forward part in a cascade combination with a P controller is used. The main goal of the algorithm is to optimize production by lowering the costs of the temperature control and increasing the quantity and quality of the chemical, biological, pharmaceutical, food and beverage products produced in these reactors. The algorithm is designed to cope with the constraints and the mixed discrete and continuous nature of the process by manipulating variables for heating and cooling. The stability and robustness of the control algorithm is proven through the Popov Stability Criterion. The simulation results of the proposed algorithm show much better performance compared to a conventional cascade PI control structure, which is most commonly used in industry. Furthermore, the study also shows real-time implementation on a bioreactor using the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper investigates the temperature control of the heat air-flow wind tunnel for sensor temperature-calibration and heat strength experiment. Firstly, a mathematical model was established to describe the dynamic characteristics of the fuel sup-plying system based on a variable frequency driving pump. Then, based on the classical cascade control, an improved control law with the Smith predictive estimate and the fuzzy proportional-integral-derivative was proposed. The simulation result shows that the control effect of the proposed control strategy is better than the ordinary proportional-integral-derivative cascade control strategy. [ABSTRACT FROM AUTHOR]

Abstract: The polymerize process is the first stage in PAN-based carbon fiber production, and its temperature control affects directly the quality and yield of the last products. It has the serious time delay character if polymerizer temperature is controlled by the mixture of the hot water and the cold one, and the polymerization process will release a lot of heat. All these make it is very complex to control the polymerizer temperature. The paper analyzes polymerizing technology firstly, then provides design and realization methods of polymerizer temperature cascade control based on generalized predictive control (GPC), and the system is realized through the control layer and the monitoring layer. The former realizes the model identification and the recursive computation in the generalized predictive control, and sends the results to the latter, and the latter realizes PID with dead-zone control of the mixed water temperature control using the results of the main regulator. The practice shows that the polymerize temperature cascade system runs well and has evident effect with effective control. [Copyright &y& Elsevier]

Abstract: This article presents the development to reliably seal copper canisters containing the Swedish nuclear waste, using friction stir welding. To avoid defects and welding tool fractures, it is important to control the welding temperature within a span of 790–910°C. A cascade controller is used to efficiently suppress fast power input disturbances reducing their impact on the temperature. The controller is tuned using a recently presented method for robust PID control. Results show that the controller keeps the temperature within during the 40min long joint line sequences. Apart from the cascaded control structure, good process knowledge and control strategies adapted to different weld sequences have contributed to the successful results. [Copyright &y& Elsevier]

Abstract: The divided wall column system is a promising energy-saving alternative for separating multi-component mixtures. However, high energy efficiency and stable operations can only be achieved with careful design of steady state operation and control scheme. In this study, the effects of liquid split and vapor split ratios on the energy efficiency and controllability of a divided wall column system for separating ethanol, n-propanol, and n-butanol were investigated. A region with high energy efficiency was identified. However, relative gain analysis found that the performance of multi-loops composition control would be very poor. Dynamic tests showed that multi-loop temperature control cannot return the product compositions to the desired values in case of feed composition disturbances. Outside this region, composition control can compensate for external disturbances such as feed flow rate and feed composition changes but not changes in operating region caused by internal variations such as liquid and vapor splits. Offsets in the product purities were found if temperature controls were used and there are disturbances in feed composition or changes in operating region caused by upsets in liquid and vapor splits. There is a trade-off between energy efficiency and controllability. A composition + temperature cascade scheme was proposed to stabilize the operation with high energy efficiency. The proposed scheme was able to maintain high product purity and reject external disturbances in feed flow and composition changes as well as internal disturbances such as changes in liquid and vapor splits. [Copyright &y& Elsevier]

Abstract: The object of the paper is to develop a simple and practical control strategy for a molten carbonate fuel cell (MCFC) system. Based on a dynamic model and the control demand, a cascade control strategy is designed. The master controller imposes a change of cell current representing a change in power demand and sets the amount of fuel gas, the steam-to-carbon ratio, the air number and the cathode gas recycle ratio to their corresponding conditions for optimal steady state electric efficiency. Two feedback PID controllers are in the inner loop, one guarantees the solid temperature not to exceed a maximum temperature by changing the air number around the default set by the master controller; the other controls the maximum temperature difference by adjusting the steam-to-carbon ratio. Step response tests show that this control strategy works well when the cell current changes. [Copyright &y& Elsevier]

Abstract: A predictive functional control (PFC) technique is applied to the temperature control of a pilot-plant batch reactor equipped with a mono-fluid heating/cooling system. A cascade control structure has been implemented according to the process sub-units reactor and heating/cooling system. Hereby differences in the sub-units dynamics are taken into consideration. PFC technique is described and its main differences with a standard model predictive control (MPC) technique are discussed. To evaluate its robustness, PFC has been applied to the temperature control of an exothermic chemical reaction. Experimental results show that PFC enables a precise tracking of the set-point temperature and that the PFC performances are mainly determined by its internal dynamic process model. Finally, results show the performance of the cascade control structure to handle different dynamics of the heating/cooling system. [Copyright &y& Elsevier]

• A novel dual compression middle vessel batch distillation column (DC MVBDC) is designed as evaluated. • Cascade control structures for effective composition control are investigated. • Performance between MVBDC and DC MVBDC with temperature control structure are compared for the same separation task. • Energy consumption per operational cycle of DC MVBDC is minimized using dynamic optimization. [Display omitted] Multivessel batch distillation has been found to be an effective method for the separation of multi-component mixtures. In this article, an effort has been made to devise a fast middle vessel batch distillation column (MVBDC) for the ternary separation of an Ethanol/Propanol/Butanol mixture by the means of inducing vapor compression in the system. ASPEN PLUS V12 has been used to generate the initial steady-state flowsheet of the process for equipment sizing. In contrast, ASPEN Dynamics was used to evaluate the performance of the batch distillation with various control structures and to perform a dynamic optimization on the proposed batch distillation column. MATLAB was used to identify single-input single-output transfer functions for more effective PID controller tuning. The proposed Middle vessel batch distillation was found to separate each component of the mixture to a purity of 99 mol% in 22 h (for the cascade control structures) and 21.73 h (for the temperature control structure). This was found to be significantly lesser than the batch time of a conventional batch distillation column (28.12 h), while the energy consumed by the proposed column was 3.4 MMkcal lesser than the energy consumed by the conventional column. Dynamic optimization further reduced the batch time by 14.4% while simultaneously reducing the energy consumed by 20.3%. [ABSTRACT FROM AUTHOR]

Biodiesel is a promising renewable energy option that significantly reduces the emission of greenhouse gases and other toxic byproducts. However, a major challenge in the industrial scale production of biodiesel is the desired product purity. To this end, reactive distillation (RD) processes, which involve simultaneous removal of the byproduct during the transesterification reaction, can drive the equilibrium towards high product yield. In the present study, we first optimized the heat exchange network (HEN) for a high purity RD process leading to a 34% reduction in the overall energy consumption. Further, a robust control scheme is proposed to mitigate any feed disturbance in the process that may compromise the product purity. Three rigorous case studies are performed to investigate the effect of composition control in the cascade with the temperature control of the product composition. The cascade control scheme effectively countered the disturbances and maintained the fatty acid mono-alkyl ester (FAME) purity. [ABSTRACT FROM AUTHOR]

• Dynamic control analysis of eco-efficient double side-stream ternary extractive distillation process is studied. • A newly robust control scheme is developed that handles the large step disturbances. • Dynamic control performance is improved by using the composition control loops. • Good product compositions controls are achieved without any product offsets. The novel contribution of this paper is to implement the dynamic control investigation for the energy-saving double side-stream ternary extractive distillation configuration with constructing the practical and workable plumbing arrangement taking the representative example of separating a ternary benzene/isopropanol/water mixture. The new proposed control scheme achieves the stable regulatory control at rejecting the large disturbances of throughput and feed composition, wherein the particularly key control loops are controlling the product isopropanol composition by adjusting the extractant flow rate into extractive column C 2 with simultaneously regulating the reflux ratio in extractive column C 1 to abate the solvent dilution effect through composition cascade temperature control loops. Image, graphical abstract [ABSTRACT FROM AUTHOR]

For the sour water strippers in petroleum refinery plants, three prediction models were developed first, including the estimators of sour water feed concentrations using convenient online measurements, the minimum reboiler duty and the corresponding internal temperature at a specific location (Tstage,29). Feedforward control schemes were developed based on these prediction models. Four categories of control schemes, including feedforward, feedback, feedback with external reset, and feedforward-feedback, were proposed and evaluated by the rigorous dynamic simulation model of the sour water stripper for their dynamic responses to the sour water feed stream disturbances. The comparison of control performance, in terms of the settling time, integrated absolute error (IAE) of the NH3 concentration of the stripped sour water and IAE of the specific reboiler duty, reveals that FFT (feedforward control of Tstage,29) and FBA-DT3 (feedback control with 3 min concentration measurement delay) are the best control schemes. The second-best control scheme is FBAT (cascade feedback control of concentration with temperature). [ABSTRACT FROM AUTHOR]

• A hybrid feedback and feedforward control strategy is proposed. • The cascade control consists a temperature controller and a feedwater flow controller. • Feedforward controller is applied to reduce the effects on temperature from the sodium flow. • The controller parameters are tuned based on trial and error method. • Control performance is evaluated by simulation under symmetrical and unsymmetrical conditions. The sodium-heated steam generator plays a crucial role in the operation and safety of sodium-cooled fast reactor. The configuration with multiple steam generators poses challenges to the feedwater control system design. It is necessary to adopt an appropriate control strategy. Based on the dynamic analysis, hybrid feedback and feedforward control theory is applied in the loop feedwater control. The feedback control consists of a temperature controller and a feedwater flow controller. The feedforward controller is applied to reduce the effects on the sodium temperature from the sodium flow. To eliminate the unbalance among different branches, branch temperature controller is applied. The controller parameters are tuned using trial and error method. The control performance is evaluated through simulation under symmetrical and unsymmetrical conditions. The simulation results are analyzed. It can be found the changes in the setpoint can be quickly traced and disturbances are rejected efficiently with the designed control system. [ABSTRACT FROM AUTHOR]

To optimize fuel cell system efficiency, compared with the regulation control of temperature, the latest engineering practice is more inclined to perform tracking control. The fuel cell temperature subsystem has the characteristics of slow response and strong nonlinearity, which poses challenges to tracking control. This paper proposes a cascade internal model control (CIMC) to make the stack outlet temperature track the target value when fuel cell load currents changes. Both simulation and experiment show that the control method has good rapidity, accuracy and robustness. The Simulation results based on AMESIM® shows that the step response static errors of static points test and step signal test are all 0 °C. The response time of step signal test is around 47s. Both of the step response and dynamic response the overshooting are 0 °C without divergence. The experiment results on a real 120 kW commercial fuel cell system test bench are similar with the simulation results with 0 °C static error at different working conditions, 44s response time for step response and overshooting around 1 °C at the dynamic working condition, which is acceptable for the tested PEMFC stack. • Fuel cell temperature tracking control problem is formulated. • Cascade internal model controller is proposed for fuel cell temperature control. • Rigorous proof is given for the controller design. • Experiments on a real 120 kW fuel cell system are implemented. • Overshooting can be limited to less than 1 °C in the experiments. [ABSTRACT FROM AUTHOR]

Superheated steam temperature (SST) is a significant index for a coal-fired power plant. Its control is becoming more and more challenging for the reason that the control requirements are stricter and the load command changes extensively and frequently. To deal with the aforementioned challenges, previously the cascade control strategy was usually applied to the control of SST. However, its structure and tuning procedure are complex. To solve this problem, this paper proposes a single-loop control strategy for SST based on a hybrid active disturbance rejection control (ADRC). The stability and ability to reject the secondary disturbance are analyzed theoretically in order to perfect the theory of the hybrid ADRC. Then a tuning procedure is summarized for the hybrid ADRC by analyzing the influences of all parameters on control performance. Using the proposed tuning method, a simulation is carried out illustrating that the hybrid ADRC is able to improve the dynamic performance of SST with good robustness. Eventually, the hybrid ADRC is applied to the SST system of a power plant simulator. Experimental results indicate that the single-loop control strategy based on the hybrid ADRC has better control performance and simpler structure than cascade control strategies. The successful application of the proposed hybrid ADRC shows its promising prospect of field tests in future power industry with the increasing demand on integrating more renewables into the grid. [ABSTRACT FROM AUTHOR]