Tank Level Control Research Articles

Tank-level robust control of LNG carrier based on hyperbolic tangent function nonlinear modification

Abstract The objective of this study was to achieve a better control effect of the controller on the liquid level of the liquefied natural gas (LNG) carrier and to achieve the goal of energy saving and carbon reduction. This paper took the loaded square tank of an S175 high-speed container ship as the research plant, combined with the closed-loop gain-shaping algorithm (CGSA) and nonlinear modification technology to further optimize the controller. We initially employed a third-order CGSA approach in formulating the foundation of our linear controller. Subsequently, we introduced a non-linear modification to this controller by harnessing the power of the hyperbolic tangent function, and the control effect is verified by the MATLAB simulation experiment. Based on the outcomes of MATLAB simulations, by integrating the third-order CGSA technique and introducing non-linear modification through the hyperbolic tangent function, we observed a significant enhancement in the controller's performance. Specifically, it outperformed the traditional PID controller by a substantial margin, demonstrating a remarkable 19% boost in control efficacy. Additionally, it provides better energy savings than the non-linear controller. The controller designed in this paper has a better control effect on the liquid tank-level control of LNG ships, the control process is more energy-saving and the purpose of carbon reduction is realized.

Fractional PID with Genetic Algorithm Approach for Industrial Tank Level Control Process

Process control is used in various types of industries to boost production while using current resources, product quality, and safety, with level control being one of the most important schemes. It is suggested that study be conducted on nonlinear continuous processes, particularly in process control applications such as conical tank level control. Initially, each process receives one set of Proportional-Integral (PI) controller settings and a First Order Plus Dead-Time (FOPDT) model using the Ziegler Nicholas (ZN) step response tuning method. The numerous FOPDT models and parameter sets are also obtained. Responses obtained with a single set of parameters and responses obtained with many sets of parameters are compared. By creating a Fractional PID Controller (FPID) with Genetic Algorithm (GA), a simulation-based tuning strategy is proposed. The step responses are acquired through experimental research using fine-tuned settings. At most operational points, the Fractional PID Controller with Genetic Algorithm-based tuning approach outperforms, with lowest oscillation, extremely tiny overshoot, minimum average ISE, and minimum average IAE. The proposed FPID with GA method provides better setpoint and regulatory tracking performance compared to ZN-PID.

Double feedforward compensation for cascade control schemes

This paper addresses the problem of dealing with measurable disturbances in cascade control schemes. The combination of cascade and feedforward control algorithms is analyzed. The design of a static feedforward compensators control scheme to assist the controller in the rejection of measurable disturbances is a widely accepted solution in the literature. This article proposes a new solution by implementing two static feedforward controllers, one in the outer and other in the inner loop, as part of the cascade control scheme. The tuning rules for the feedforward compensators are proposed to enhance the process performance for the load disturbances rejection problem. Simulation examples demonstrate the advantages of the proposed solution by improving the process output performance while reducing the control effort. Moreover, the new solution is evaluated in simulation on two non-linear typical processes in chemical industry, a tank level control and concentration control in a Continuous Stirred Tank Reactor (CSTR).

Simulation Design of Level Cascade Control System for Double-capacity Water Tanks

As a typical representative of process control, double-capacity water tank level control is a common automation control system used to control the level of two tanks to achieve level stabilisation and control, which is widely used in various fields of industrial production. Liquid level control is the key to the performance of the whole control system due to the existence of hysteresis and other problems in the control. Serial control of the sub-loop has a rapid control role, it can effectively overcome the impact of the disturbance into the sub-loop, improve the dynamic characteristics of the object, so in order to achieve better control performance, this design uses serial control to achieve the level of double-capacity water tank fixed value control. Double-capacity water tank level series control system to the tank level as the controlled quantity, first of all, the characteristics of the tank, the establishment of its mathematical modelling, and then the use of MATLAB on the simulation of the tank as well as PID parameter adjustment, and finally through the response curve to analyze the control performance of the system. The simulation results show that the double-capacity water tank level series control performance is good, the system can achieve the level of static-free regulation, and anti-interference ability is strong, with good dynamic and steady state performance.

Design and Realisation of Level Cascade Control System for Double-capacity Water Tanks

As a typical representative of process control, double-capacity water tank level control is a common automation control system used to control the level of two water tanks to achieve level stability and control, which is widely used in various fields of industrial production. In actual production, the accuracy and control effect of liquid level control directly affects the production cost of the factory, economic benefits and even the safety factor of the equipment. Therefore, in order to ensure safety and convenient operation, it is necessary to research and develop advanced level control methods and strategies. The sub-loop of serial stage control has a fast control effect, which can effectively overcome the influence of the perturbation into the sub-loop and improve the dynamic characteristics of the object, therefore, this paper adopts the serial stage control algorithm to achieve the constant value control of the liquid level of the double-capacity water tank and compare it with the conventional PID control algorithm, and the realisation results show that the serial stage control has a good ability to inhibit the secondary perturbation, and it can effectively improve the system's rapidity and accuracy.

A novel fault detection and diagnostic Petri net methodology for dynamic systems

Faults can have significant, negative impacts on the operation and performance of simple and complex dynamic systems. Based on the integration of Bayesian network diagnostic features with Petri net formalism, the existing Bayesian-supported Petri net tool has demonstrated the flexibility of using the Petri net approach for diagnosing failure scenario of a dynamic system. However, studies on using the proposed hybrid Petri net approach for condition monitoring and early detection and diagnosis of single and multiple failures in a dynamic system with feedback control loops are yet to be investigated. Thus, this paper presents a methodology to address this research gap using the operation of a water tank level control system as a case study. The method combines the constructed Generalised Stochastic Petri Net (GSPN) model of the system operation with its corresponding fault diagnostic Petri net model, created using the proposed modified Bayesian Stochastic Petri Net (mBSPN) formalism. The GSPN model establishes the causal relationships between the system’s components and/or subsystems. It further identifies deviations in the sensor measurements of the observable process variables characterising the system operation. The information provided by the sensors in the system model are then inputted into the mBSPN model to diagnose the root cause of the observed deviations. The obtained results demonstrated the capability of using the proposed integrated Petri net methodology for system condition monitoring, early fault detection and diagnosis of single and multiple failures in a dynamic system with feedback control loops.

Prototype Development of an SMS-Based Industrial Water Tank Level Monitoring and Control Parameters System

This study describes the creation of a prototype SMS-based fluid parameter monitoring system. Many water industry and oil servicing/plant maintenance companies use workers to measure and monitor fluid parameters such as flow rate, temperature, pressure, and level (taking periodic readings). The method is determined to be extremely difficult and severe, raising serious concerns. To address the aforementioned issue, it is proposed that a system be developed that would reduce the staff stress of manual monitoring of fluid parameters and notify the same to personnel for necessary action. The suggested system is made up of both hardware and software. The hardware section consists of four units: power supply, input, control, and output, all of which were created utilizing a top-down system design approach. The C programming language was used to write the software that controls the entire system. Following that, multiple units were constructed and tested. When the system is turned on, the sensors monitor various fluid (water) characteristics and provide signals to the microcontroller, which analyzes the parameters and sends them to a display unit and the employee's mobile phone for alert notification. The outcome is quite precise and accurate. A simulation of the system performance was also performed in PROTEUS. This proposed method is inexpensive and can be implemented in oil service organizations to provide faultless services in place of employees.

Analysis of the effects of recycling on process control

Abstract The union of different devices in order to obtain a specific response for a process is commonly called a control system. For a control system, it is necessary to have one or more controllers. Among the most used in the industrial sector are the PID and PI controllers. Next to these controllers is the control software. Scilab is a good example of control software. It is characterized as free code software, with no cost for its acquisition, in addition to having a large computational power and integrated tools, such as Xcos, intended for modeling and simulation. For the union with Scilab, there is Arduino. Such a mixture can be used, for example, to control liquid levels in tanks. In this context, the present work aims to study the tank-level control system based on PID and PI controllers through the union between Scilab and Arduino. Phenomenological models were developed based on closed-loop control (feedback control system) of the process with two tanks not coupled with recycle. Furthermore, for comparison purposes, two approaches were used for each process: one considering the saturation of the manipulated variable and the other without the presence of such saturation. At first, there was a need to implement an anti-windup system. For tuning the controller parameters, the ISE method was used, executed through a programming code developed in Scilab. The parameters found for the two systems were tested on a made-up experimental bench. Therefore, using the block diagrams and the method here called “ISE method”, satisfactory values were obtained for the control parameters. These were ratified in the tests carried out in the experimental module. Level control was achieved with greater prominence for the PI controller since there is one less parameter to be tuned and processed by the system. This controller provided results close to the PID controller for cycles up to 50%. In general, the PI controller showed maximum response deviations smaller than the PID, such as deviations of 1.55 cm and 2.40 cm, respectively, for the case with 75% recycle. It was also clear the influence of the saturation of the manipulated variable on the system response, but not on the tuning of the controller parameters.

A Water Tank Level Control System with Time Lag Using CGSA and Nonlinear Switch Decoration

Tank level control has some unavoidable factors such as disturbance, non-linearity, and time lag. This paper proposes a simple and robust control scheme with nice energy-saving effects and smooth output to improve the quality of the controller and meet real-world application requirements. A linear controller is first designed using a third-order closed-loop gain-shaping algorithm. We then use an arcsine function to modify the system with non-linear switching to reduce the effect of the non-linear modification on the dynamic performance of the control system. Furthermore, we use the Nyquist stability criterion to demonstrate the stability of the closed-loop system in the presence of time lag. The results of the final simulation experiment show that the controller not only has high control quality but also has the characteristics of energy saving and smooth output under the condition of lag and pump performance constraints. These features are necessary for extending the life of the pump and enhancing the applicability of the tank level controller.

Modified active disturbance rejection control with pre-compensation for a class of high-order system

With more and more sustainable energy integrated into the bulk power system, the coal-fired unit is obliged to speed up the response to the deep peek and frequency regulation command, and this results in great challenges for the control systems. To improve the control performance of the coal-fired unit, a modified active disturbance rejection control with pre-compensation (PMADRC) is proposed for high-order systems with the type of K/(Ts+1)n. The stability, sensitivity, and robustness of the proposed PMADRC are analyzed. An effective tuning procedure is also provided based on plenty of simulations. Besides, contrastive simulations and experiments based on the water tank level control platform validate the superiority of PMADRC in setpoint tracking and disturbance rejection. The advantages of the PMADRC guarantee high control performance and make it have the potential for applications in coal-fired units.

Research on the Control Methods Based on Liquid Level System

Liquid level control is a common process control in industry, and its impact on production cannot be ignored. Liquid level control systems are used in various aspects of life, such as reservoirs, cisterns, river levels, etc. Among the common liquid level control systems, the double-volume water tank is a typical controlled object, which is widely used in industrial production. The control difficulty of has also increased due to its nonlinearity and delay. PID control can achieve satisfactory results in the face of accurate mathematical models and is still widely used in society. However, PID control is less effective when dealing with nonlinear systems that are difficult to describe accurately with mathematical models. For better level control, this paper designs a double-volume tank level control system with single-loop PID control, Cascade PID Control and fuzzy PID control based on PID control theory, and compares their control effects. This paper therefore concludes that the control effect of fuzzy PID control is better than the other two controls, and through experiments, we also find that fuzzy PID has decent adaptivity. This paper provides a certain research basis for the subsequent research on PID control, which has important theoretical significance and engineering value.

Simultaneous tuning of cascade controllers based on nonlinear optimization

Cascade control is widely used in the process industry, especially to reject disturbances. Typically, the controller parameters in the inner and outer loops of the cascade controller structure are defined in a strict sequence. In this paper, simultaneous tuning of cascade controllers is proposed to improve the performance of the system under load disturbance. For this purpose, the cost function of a nonlinear optimization problem is formulated to minimize the effect of disturbances on the system output. In addition, robustness constraints are defined for the maximum sensitivity function to independently guarantee a robust system for inner and outer loops. In this sense, the designer can explicitly and independently address the trade-off between performance and robustness for both loops. Simulation studies illustrate the performance and effectiveness of the proposed controller design method compared to well-known methods in the literature. These results indicate that the proposed method reduces the integrated absolute error (IAE) under load disturbance by up to [Formula: see text]. In addition, experimental results from a tank-level control application in the mineral process industry illustrate the practical applicability of the proposed method. In this case, the proposed method reduces the IAE under load disturbance by [Formula: see text].

Adaptive Practical Nonlinear Model Predictive Control for Echo State Network Models.

This article proposes an adaptive practical nonlinear model predictive (NMPC) control algorithm which uses an echo state network (ESN) estimated online as a process model. In the proposed control algorithm, the ESN readout parameters are estimated online using a recursive least-squares method that considers an adaptive directional forgetting factor. The ESN model is used to obtain online a nonlinear prediction of the system free response, and a linearized version of the neural model is obtained at each sampling time to get a local approximation of the system step response, which is used to build the dynamic matrix of the system. The proposed controller was evaluated in a benchmark conical tank level control problem, and the results were compared with three baseline controllers. The proposed approach achieved similar results as the ones obtained by its nonadaptive baseline version in a scenario with the process operating with the nominal parameters, and outperformed all baseline algorithms in a scenario with process parameter changes. Additionally, the computational time required by the proposed algorithm was one-tenth of that required by the baseline NMPC, which shows that the proposed algorithm is suitable to implement state-of-the-art adaptive NMPC in a computationally affordable manner.

Securing Oil Tank Level Control System against Adversary Attacks using Fuzzy Logic Technique

Securing Oil Tank Level Control System against Adversary Attacks using Fuzzy Logic Technique

Gain-Scheduled Level Controller for FESTO MPS PA Station Tank

In this article, a Gain Scheduling (GS) approach is proposed to control the FESTO MPS PA Station Tank level by controlling the centrifugal pump. The open loop transfer function for each operating condition is experimentally obtained. The data from the open-loop system is imported to MATLAB in order to get the transfer function for each condition. The data shows that each operating point has a different transfer function in terms of gain and time constant. Based on this, a gain-scheduling controller is proposed to handle the variations of process model parameters. The proposed controller parameters are adapted based on the operating conditions of the system. These parameters include the tank capacitance and the flow pipe resistance and/or the valve resistance to the flow. Two different controller techniques for FESTO MPS PA Station Tank level control are applied, verified and compared. The first controller is based on classical Proportional Integral (PI) controller, while the second one is based on the proposed gain scheduling controller. Experimental results show that the proposed gain-scheduling controller can manipulate the process at different operating conditions with parameters variations in order to give uniform performance. The classical PI controller has failed to achieve this requirement at different operation conditions.

Particle swarm algorithm and OLE for process control based PID design for dual capacity water tank

Typical dual capacity tank level control systems suffer from long control regulation times, large nonlinear output deviations and hysteresis. Facing with this situation, an optimization of multi-parameter control of PID controller using particle swarm algorithm (PSO) is proposed to reduce the overshoot phenomenon. By analyzing the mathematical model of the dual capacity water tank, the PSO intelligent algorithm is combined with the PID controller to obtain the optimal control parameters and performance indicators in MATLAB, through the OPC communication protocol, the water level of the tank is transmitted to the Kingview monitoring system to display the change curve in real time. The results showed that the PSO algorithm and OPC protocol can combine the complex algorithm function of MATLAB with the excellent plotting of Kingview, play a key role in the dual capacity tank level systems.

Robust Controller Decorated by Nonlinear S Function and Its Application to Water Tank

In this manuscript, a concept of modifying the results of the existing robust controller decorated by a nonlinear S function is presented to improve the system performance. A case-based study of level control of water tanks illustrates the effectiveness of nonlinear decoration in improving robustness and controlling energy-saving performance with an S-function-decorated robust controller. The performance of the controlled system was analyzed through Lyapunov stability theorem and robust control theory, and was evaluated with a performance index. By demonstrating three comparing simulations of different scenes, it testifies to the fact that the nonlinear decorated robust controller meets the requirement of improving the system performance index. Compared with the nonlinear feedback and the fuzzy control, the performance index of the system using a nonlinear decorated controller is reduced by more than 10% with satisfactory robustness. This nonlinear decorated robust controller is proven to be energy efficient, simple and clear and easy to use, valuable for extensive application.

Predictive extended state observer-based robust control for uncertain linear systems with experimental validation

This paper describes a predictive extended state observer-based robust control for uncertain process control applications. The technique discussed in the article uses the extended state observer (ESO) that can estimate the dynamics of the system as well as total disturbance encountered in the system. The disturbances, parametric uncertainties associated with the processes are treated as an extended state variable to be estimated in real-time using ESO. With the implementation of a predictive algorithm with an ESO, the proposed control structure extends its applicability to time-delayed higher-order processes. The proposed control technique utilizes the simple first-order modified predictive ESO even in the case of higher-order processes. The novel predictive ESO is able to obtain a delay less estimation of total disturbance as compared with existing normal ESO. Also, novel predictive ESO maintains its stability margin in presence of time delay as well provides better response as compared with normal ESO. Numerical simulations show that the proposed scheme provides a significant improvement in transient response as compared with internal model control-based proportional-integral-derivative (IMC-PID) control. The proposed scheme requires less knowledge of the process as compared with the IMC-PID structure. The implementation of the proposed control is tested on a real-life single tank level control system. Because of its merit, the suggested technique can be used as automatic for online tuning, as it is less reliant on the process model.

Type-2 fuzzy controller’s performance index. Case study: tank level control

This paper deals with the design and implementation of type-2 fuzzy controller, through a tank level control plant as a pilot system to analyze the response using performance indexes. The controller was developed using type-2 fuzzy logic from a mathematical approach and utilizing the identification of the process through a parametric method. Additionally, a classical proportional, integral, and derivative controller was used to generate the bases for the linguistic variables required by the fuzzy controller implementation. Finally, a statistical analysis of the transient and steady-state response margins is performed, which aims to provide a numerical index of the system response performance.

Tank-Level Control of Liquefied Natural Gas Carrier Based on Gaussian Function Nonlinear Decoration

This paper introduces a novel controller into the tank level control of liquefied natural gas (LNG) carrier. The proposed controller can simplify the design process and save energy output of the controller under the premise of achieving a good control effect of the liquid level of a liquefied natural gas (LNG) carrier tank. Moreover, Gaussian function is adopted to decorate nonlinearly the output of the linear controller designed by using the second-order closed loop gain-shaping algorithm, and then the final controller is obtained. The effectiveness of the controller is verified by simulation experiments on the LNG carrier ‘‘Da-Peng Sun’’ No.2 liquid tank. The simulation results show that the comprehensive control performance index J of the second-order closed loop gain-shaping controller decorated by Gaussian function reduces by 11.8% and 95.3%, respectively, compared with the controller without nonlinear decoration and the linear proportional–integral–differential (PID) controller, meeting the requirement of energy saving and realizing a good control result of the tank level of the LNG carrier.