Control Structure Design Research Articles

Multi-objective optimization and dynamic characteristic analysis of solid oxide fuel cell - Supercritical carbon dioxide brayton cycle hybrid system

Solid oxide fuel cells (SOFCs) are widely used in distributed power generation systems due to their high energy conversion efficiency, low emissions. Therefore, investigating the dynamic characteristics of fuel cell integration systems is significant for ensuring the efficient and stable operation of SOFC integrated systems. In this study, an SOFC integrated system with a supercritical CO2 Brayton cycle as the bottoming cycle is proposed. A dynamic model is established to investigate the dynamic characteristics of this system under optimal operating conditions. This integrated system is optimized from the perspectives of two objectives: energy conversion efficiency and operational cost. Using the Pareto frontier, the optimal solutions are a system electrical efficiency of 61.21 % and a total cost rate of 4583.8 $/hour. These optimized results are used as steady-state design points for the integrated system. At the steady-state design point, flow and voltage perturbation simulation experiments are conducted on the integrated system to analyze the dynamic characteristics of key system parameters. This study provides a theoretical foundation for the control structure design of SOFC integrated systems.

An isogeometric approach to dynamic structures for integrating topology optimization and optimal control at macro and micro scales

In the context of active vibration suppression, an integrated topology optimization framework is proposed for the optimal control of dynamic structures. This article formulates a new composite objective function by considering the external harmonic excitations with different excitation frequencies and the complex-valued displacement field. Within the proposed optimal control performance function, the symmetric weighting matrix, the magnitudes of which are related to the importance of the control forces, is integrated into dynamic compliance to serve the state displacement. Utilizing the non-uniform rational B-splines (NURBS) basis functions, the material interpolation model defined at control points is described by the NURBS surface, which is incorporated into the optimization formulation for optimal structural and vibration control design. The sensitivity results are deduced in terms of the pseudo-densities and the corresponding weights at control points from both macro and micro perspectives of structural dynamics. To demonstrate the effectiveness of the integrated topology optimization of dynamic structures at macro and micro scales, several numerical examples, including the topology optimization of solid beams in plane stress and Mindlin plates with 3D microstructures, are provided and discussed in terms of structural shape and topology, frequency response curve, and modal displacement.

2DOF-PID-TD: A new hybrid control approach of load frequency control in an interconnected thermal-hydro power system

The Load Frequency Control (LFC) scheme, with its primary aim being the maintenance of uniform frequency, has been a heavily researched topic for decades. Achieving a consistent frequency necessitates a delicate balance between load demand and power generation. Researchers strive to find an optimal solution within the LFC domain—one that can effectively withstand drastic load fluctuations. Despite a plethora of efforts, the LFC dilemma remains unresolved, complicated by factors such as dwindling demand-supply and the rapid integration of renewables. Furthermore, the lack of innovation in controller structure design exacerbates the complexity of solving modern LFC problems. Consequently, a robust control approach capable of handling uncertainties while simultaneously regulating system frequency becomes crucial. In light of this, we propose a novel hybrid control architecture called 2DOF-PID-TD. This architecture combines Two Degrees Of Freedom Proportional-Integral-Derivative (2DOF-PID) and Tilt-Derivative (TD) controllers. To optimize the proposed controller, we employ a metaheuristic called the Artificial Gorilla Troops Optimizer (AGTO), which mimics the social behavior and intelligence of gorilla troops. The proposed approach is analyzed in a realistic multi-area multi-source hydro-thermal system, accounting for nonlinearities, random load perturbations, and system parametric uncertainties. Experimental results, when compared with current state-of-the-art optimization algorithms and traditional controller structures, demonstrate the prowess of our approach in terms of precision, robustness, and resilience.

Design and implementation of an improved adaptive embedded-factor current controller for three-phase grid-connected inverter

This paper presents an improved current controller based on a series proportional integral resonant structure in synchronous reference frame in order to address low-order harmonics issue of the injected-grid current for three-phase grid-connected inverter. Additionally, to improve dynamic performance, an adapted factor is embedded into the proposed controller structure. Moreover, to design the parameters of the proposed controller, different constraint conditions are investigated. Based on the proposed controller structure and parameters design method, satisfactory steady-state and faster dynamic performances are both obtained in comparison to those of the conventional parallel proportional integral resonant controller. What's more, the proposed controller is easy to implement in practice. Simulation and experimental results are finally given to verify the effectiveness and superiority of the proposed controller.

Leeds FAS2 FSR: environmental challenges for the design of an in-river control structure

As flood-risk authorities look to counter increasing peak river flows due to a changing climate, traditional linear flood defences are in many cases proving to be an unsustainable method of managing flood risk. Full containment of flows in the river channel will require ever-increasing defence heights, cutting off communities from their rivers and natural heritage. Upstream flood storage provides a potential alternative means of flood management, allowing the peak of the flood to attenuate and downstream river levels to be kept within a tolerable range. The Leeds Flood Alleviation Scheme Phase 2 uses a combined approach: linear defences are constructed in urban reaches and complemented by an online flood storage reservoir (FSR) upstream of the city. The FSR halves the annual probability of defences overtopping within the city centre from 1 to 0.5%, achieved through active variable flow control at the FSR. This paper explores some of the challenges faced in the design and construction of the in-river flow control structure which is integral to the operation of the FSR. In particular this paper will consider some of the key environmental objectives for the scheme and offer considerations for working in a dynamic and environmentally sensitive fluvial environment.

Efficient river hydrodynamics modelling in realistic river systems using a Fourier neural operator-based network

Effective river management relies heavily on the accurate simulation of river flow dynamics to develop scenario-based strategies and inform decision making. Deep learning (DL) models, as alternatives to conventional simulation techniques, offer a compelling blend of precision and efficiency. This study introduces FNOCL (Fourier Neural Operator with ConvLSTM units), a novel DL neural network for modelling unsteady natural river flows. The network is adept at handling the complexities of spatial and temporal variations. FNOCL builds upon the Fourier neural operator (FNO) by incorporating convolutional long short-term memory (ConvLSTM) layers, combining robust performance with high proficiency in terms of capturing spatiotemporal patterns. Notably, FNOCL accommodates complex river cross-section profiles, thus enabling the accurate modelling of flow dynamics within intricate river morphologies. Our study applies FNOCL to two distinct river networks with varying morphology complexity levels. With reference to the HEC-RAS model, FNOCL showcases its ability to attain high accuracy in model prediction tasks and superior generalization with regard to addressing the uncertainty associated with inflow variations and cross-sectional changes. In comparative analyses with benchmark models (i.e., FNO and ConvLSTM), FNOCL performs most efficiently during the training process and obtains the most accurate water level and river flow predictions in the spatiotemporal domain. Furthermore, FNOCL exhibits a substantial speedup over HEC-RAS, notably reaching up to 50 times in a complex river network. These results highlight FNOCL as an efficient surrogate for conventional simulators, facilitating precise analyses across various scenarios. It provides efficient computations for system responses within complex river flow networks, thereby enhancing applications in river management, such as flood risk assessment, flood control, and the planning and design of hydraulic control structures.

Low-Temperature Nanosecond Laser Process of HZO-IGZO FeFETs toward Monolithic 3D System on Chip Integration.

Ferroelectric field-effect transistors (FeFETs) are increasingly important for in-memory computing and monolithic 3D (M3D) integration in system-on-chip (SoC) applications. However, the high-temperature processing required by most ferroelectric memories can lead to thermal damage to the underlying device layers, which poses significant physical limitations for 3D integration processes. To solve this problem, the study proposes using a nanosecond pulsed laser for selective annealing of hafnia-based FeFETs, enabling precise control of heat penetration depth within thin films. Sufficient thermal energy is delivered to the IGZO oxide channel and HZO ferroelectric gate oxide without causing thermal damage to the bottom layer, which has a low transition temperature (<250 °C). Using optimized laser conditions, a fast response time (<1 µs) and excellent stability (cycle >106, retention >106 s) are achieved in the ferroelectric HZO film. The resulting FeFET exhibited a wide memory window (>1.7V) with a high on/off ratio (>105). In addition, moderate ferroelectric properties (2·Pr of 14.7 µCcm-2) and pattern recognition rate-based linearity (potentiation: 1.13, depression: 1.6) are obtained. These results demonstrate compatibility in HZO FeFETs by specific laser annealing control and thin-film layer design for various structures (3D integrated, flexible) with neuromorphic applications.

Effect of Change in Plant Capacity towards Controllability of Biohydrogen Production Plant from Biomass

This paper discusses the plant-wide control system of a biohydrogen plant from biomass. The plant’s control structure is designed by assessing the use of model predictive control (MPC) and proportional-integral (PI) controllers for each controlled variable. Then, the control structure design is tested by set point and disturbance change tests, and its performance is evaluated by integral square error (ISE). This plant is simulated in two different capacities to understand the effect of change in plant capacity on the plant’s controllability. Results show that the plant with capacity A has controllability of +25% and −5%, while the plant with capacity B has controllability of +100% and −5% for the dry biomass molar flow rate change test. Both plants have the same controllability of +100% and −100% for the dry biomass temperature test. Both plants result in a dry biomass conversion rate of 16.52%, where the amount of H2 produced is 382 kg/h and 2,291 kg/h, respectively.

Advanced plant-wide control design tools applied to the fluid catalytic cracker-fractionator benchmark

In this work two advanced multivariable control structure design tools are applied on the recently appeared fluid catalytic cracking (FCC)-fractionator benchmark process. Indeed, the partial least squares-based sum of squared deviations (PLS-based SSD) approach and the control allocation (CA) with measurement combination procedure are proposed here to develop new control policies. The minimally invasive feature of PLS-based SSD, allows to obtain an open-loop steady-state model of the process by using closed-loop normal data and to perform a performance/feasibility assessment of the already installed control structure. In this regard, the procedure identified some global integrity problems of the industrial-based control structure proposed in previous works and, therefore, new plant-wide control structures (with different sizing and input/output pairings) were proposed, where the SSD indexes have improved in the range of 50% to 90% and the matrix conditioning guaranteed. The proposed control structures were dynamically tested under typical set point and disturbance variations.

A controller design method based on the integration of structure search and parameter optimization

For the controller structure design problem, a controller design method based on the integration of structure search and parameter optimization is proposed with the idea of ENAS, which automates the controller structure design work, and searches for the most suitable controller structure and completes the parameter optimization in a relatively short time. The simulation study with the galvano scanner as the controlled plant shows that the number of iterations and the consumption time of the method are only 15% of the traditional method in achieving the same performance compared with the traditional design method.

Frequency data driven optimal design of different PI control structures for a multivariable process

Multivariable process are commonly found in industry. The coupling between the different loops makes the control design difficult. In this article, an optimization problem based on the frequency response of the process is used to designed three different multivariable PI control structures. These structures are: centralized control, decentralized control and decentralized controller plus simplified decoupler. To facilitate the centralized control implementation, it is implemented as a decentralized controller plus simplified decoupler. The decoupler is designed using an approximate first-order plus time delay process model. These structures are applied to control a continuous stirred tank reactor with a Van de Vusse chemical reaction, and performance indices are used to compare the obtained results.

Towards Using Behavior Trees in Industrial Automation Controllers.

The Industry 4.0 paradigm manifests the shift towards mass customization and cyber-physical production systems (CPPS) and sets new requirements for industrial automation software in terms of modularity, flexibility, and short development cycles of control programs. Though programmable logical controllers (PLCs) have been evolving into versatile and powerful edge devices, there is a lack of PLC software flexibility and integration between low-level programs and task-oriented control frameworks. Behavior trees (BTs) are a novel framework that enables the rapid design of modular hierarchical control structures. It combines improved modularity with a simple and intuitive design of control logic. This paper proposes an approach for improving the control software design by integrating BTs into PLC programs and separating hardware-related functionalities from the coordination logic. Several integration strategies are shown. The first two integrate BTs with the IEC 61131 PLCs and are based on the use of the PLCopen Common Behavior Model. The last one shows an event-based BTs version for the IEC 61499 controllers. An application example demonstrates the approach. A new PLC software design improves modularity, supports better separation of concerns, and enables rapid development and reconfiguration of the control software. It also provides better integration of low-level PLC code and AI-based task-oriented frameworks.

Design and multilevel regulation of transition metal phosphides for efficient and industrial water electrolysis.

Renewable energy electrolysis of water to produce hydrogen is an effective measure to break the energy dilemma. However, achieving activity and stability at a high current density is still a key problem in water electrolyzers. Transition metal phosphides (TMPs), with high activity and relative inexpensiveness, have become excellent candidates for the production of highly pure green hydrogen for industrial applications. In this mini-review, multilevel regulation strategies including nanoscale control, surface composition and interface structure design of high-performance TMPs for hydrogen evolution are systematically summarized. On this basis, in order to achieve large-scale hydrogen production in industry, the hydrogen evolution performance and stability of TMPs at a high current density are also discussed. Peculiarly, the practical application and requirements in proton exchange membrane (PEM) or anion exchange membrane (AEM) electrolyzers can guide the advanced design of regulatory strategies of TMPs for green hydrogen production from renewable energy. Finally, the challenges and prospects in the future development trend of TMPs for efficient and industrial water electrolysis are given.

Development of Synthetic Unit Hydrographs Using Spatial Proximity Regionalization for the Makiling Forest Reserve, Philippines

There is a dearth of streamflow data in the Philippines to generate hydrographs needed for flood forecasting and water resources assessment. A method of generating and calibrating synthetic hydrographs using model simulations and spatial proximity regionalization is presented. Synthetic unit hydrographs of four storm events in the gauged watershed of Makiling Forest Reserve were generated using Soil Conservation Service Unit Hydrograph, Clark Unit Hydrograph, and Snyder’s Unit Hydrograph methods. The generated synthetic hydrographs for each runoff modeling technique were calibrated with the actual hydrographs of the watershed. Snyder’s Unit Hydrograph model results were the most acceptable based on the Nash-Sutcliffe Efficiency, Index of Volumetric Fit, and Relative Error of Peak Flow. The weighted values of the calibrated watershed parameters computed using spatial proximity regionalization technique and the hyetographs derived from the Rainfall Intensity Duration Frequency Curve of the University of the Philippines Los Baños-National Agrometeorological Station were used to generate the synthetic unit hydrographs for three neighboring ungauged watersheds at 2-, 5-, 10-, 15-, 20-, 25-, 50, 100-year return periods. Total runoff volume, the magnitude of peak flows, and time to peak derived from the generated hydrographs can be used in watershed planning, water resources management, flood forecasting and the design of various water control structures.

Research on the modeling and control mechanism of three-phase cascade rectification stage of non-power frequency transformer

Non-power frequency transformers are essential and important devices for new energy generation and smart grid construction. This article analyzes the working principle of voltage cascade rectifier stage, constructs a mathematical model of three-phase cascade rectifier stage system, and simplifies its model. Finally, the idea of overall control of the voltage loop in the rectifier stage system was derived, and the traditional control method of rectification was directly transplanted into the overall control system of the cascade rectifier stage. At the same time, the characteristics of voltage loop and current loop of cascade rectifier stage system are analyzed, and the relevant control structure block diagram and controller design idea are given, which lays an important theoretical foundation for in-depth study of non-power frequency transformer.

Adaptive Variable Structure Controller Design for Uncertain Switched Systems With Unknown Time-varying Delay

Adaptive Variable Structure Controller Design for Uncertain Switched Systems With Unknown Time-varying Delay

Freshwater turtle climbing abilities: Implications for the design and use of shoreline erosion control structures

Freshwater shoreline modifications can reduce connectivity between aquatic and terrestrial environments, contributing to the decline of freshwater biodiversity. Freshwater turtles may be particularly vulnerable to shoreline modifications because they must access land for essential activities such as nesting, basking, and dispersal. Here, we tested the clinging abilities of three freshwater turtle species (i.e., painted turtles, Chrysemys picta; eastern musk turtles, Sternotherus odoratus; and northern map turtles, Graptemys geographica) to inform design criteria for mitigating the impacts of shoreline modifications on the ability of turtles to perform these behaviours. We tested clinging behavior using a ramp and pulley system with smooth and rough concrete ramps to find the maximum clinging angle for all three species. We found that painted turtles were the weakest at clinging, averaging a maximum clinging angle of 37° on a smooth ramp and 73° on a rough ramp. Eastern musk turtles had an average maximum clinging angle of 45° on a smooth ramp and 87° on a rough ramp. Northern map turtles had an average maximum clinging angle of 41° on a smooth ramp and 87° on a rough ramp. For all three species, surface type had significant effects upon maximum clinging angles, and mass was also statistically significant in affecting the clinging of eastern musk and northern map turtles. As the painted turtles were the weakest clingers and the most ubiquitous species (Van Dijk, 2016), we used this species to validate the clinging trials through volitional climbing tests. Successful climbs peaked at 35° on the smooth ramps and 40° on the rough ramps. To maintain turtle accessibility in areas with these species, future shoreline modifications should be textured and not have slopes that exceed 40°.

Research on identification of the hydraulic and structural vibration sources in a tubular pumping station

The hydraulic and structural vibration sources of pumping station are investigated in current research. Based on a vertical shaft tubular pumping station project in an eastern province of China, a three-dimensional fluid-solid coupling model of the pumping station is established, including the fluid in the flow channel, concrete structure, and hydraulic machinery. Two-way fluid-structure interaction (FSI) method is used to calculate the coupled vibration responses of the pumping station. Based on the FSI simulation results, the hydraulic and structural vibration sources of the pumping station are explored from the frequency perspective based on the Fourier transform theory and the vibration energy transmission perspective based on the time-delayed transfer entropy method. Research results show that the fluid pulsation generated by the rotation of the impeller is the main hydraulic vibration source, and the rotating impeller is the main structural vibration source that causes the vibration of the unit and the concrete structure. This research could provide a scientific basis for structural vibration control, vibration reduction, and isolation design of the pumping station.

Comprehensive Evaluation of Hydrodynamic Retarders with Fuzzy Analytic Hierarchy Process and Improved Radar Chart

The braking performance of hydrodynamic retarders is critical for the safety and economy of heavy-duty vehicles. In order to effectively improve the braking system to meet the needs of the market, an evaluation method for quantifying the performance of hydrodynamic retarders is imperative. In this paper, ten evaluation criteria are put forward according to relevant national standards and market requirements, then the scores corresponding to these criteria are obtained by performance bench test. A fuzzy modification of the analytic hierarchy process (AHP) method is applied to determine the relative weights of the chosen evaluation criteria, where uncertain and imprecise judgments of decision-makers are translated into fuzzy numbers. Furthermore, the improved radar chart method is used to comprehensively evaluate and rank the braking performance of three types of hydrodynamic retarders as an empirical example. In addition, the weight sensitivity analysis is conducted to examine the robustness of the ranking results. The results show that the proposed method is effective and feasible. It provides a reference for multi-objective optimization control strategies and structure designs of hydrodynamic retarders.

Control structure design with constraints for a slung load quadrotor system

We propose a control structure for a quadrotor carrying a slung load with swing-angle constraints. This quadrotor is supposed to pass through the waypoints at specified speeds. First, a cascaded PID autopilot is designed, which adaptively gives attention to position and speed requirements as a function of their errors. Its parameters are found from an optimization problem solved using the PSO algorithm. Second, this controller’s performance is improved by adding the Complementary Controller employing an ANN. 5. Training data for the ANN is created by solving optimal control problems. The ANN is activated when the swing angle constraint is about to be violated. It is trained using optimal control values corresponding to the cases where the swing angle falls in a particular band about the upper swing angle constraint. Simulations are performed in a MATLAB environment. Finally, some of the simulation results are validated on a physical system.