Control Technique Research Articles

Performance Enhancement of Microgrid Systems Using Backstepping Control for Grid Side Converter and MPPT Optimization

Microgrid networks represent a crucial model in the field of power transmission and distribution, integrating renewable energy sources with modern control technologies. This research focuses on enhancing the performance of a microgrid system connected to the main grid through a three-phase converter controlled using Voltage Oriented Control (VOC). The microgrid comprises a storage element and a photovoltaic (PV) generation system. To improve system efficiency and power quality, backstepping (BS) controllers are implemented and compared with traditional control methods. Three control systems are evaluated: a conventional system using Perturb and Observe (P&O) algorithm for Maximum Power Point Tracking (MPPT) and Proportional-Integral (PI) controllers for grid-side converter (GSC) control, a hybrid system with BS-modified P&O (BS-P&O) for MPPT and PI controllers for GSC, and an advanced system employing BS-P&O for MPPT and BS controllers for GSC. The research demonstrates that BS controllers exhibit superior dynamic performance, contributing to improved regulation of DC-link voltage, active and reactive powers. Additionally, they achieve lower Total Harmonic Distortion (THD) values and increase the overall efficiency of the PV system. The proposed advanced control strategy shows particular effectiveness in tracking speed, disturbance rejection, and power quality enhancement. This study underscores the potential of nonlinear control techniques in optimizing microgrid operations and facilitating the integration of renewable energy sources into the main grid.

A new genome sequence resource for five invasive fruit flies of agricultural concern: Ceratitis capitata, C. quilicii, C. rosa, Zeugodacus cucurbitae and Bactrocera zonata (Diptera, Tephritidae)

Here, we present novel high quality genome assemblies for five invasive tephritid species of agricultural concern: Ceratitis capitata, C. quilicii, C. rosa, Zeugodacus cucurbitae and Bactrocera zonata (read depths between 65 and 78x). Three assemblies (C. capitata, C. quilicii and Z. cucurbitae) were scaffolded with chromosome conformation data and annotated using RNAseq reads. For some species this is the first reference genome available (B. zonata, C. quilicii and C. rosa), for others we have published improved annotated genomes (C. capitata and Z. cucurbitae). Together, the new references provide an important resource to advance research on genetic techniques for population control, develop rapid species identification methods, and explore eco-evolutionary studies.

Prescribed Performance-Based Formation Control for Multiple Autonomous Underwater Helicopters with Complex Dynamic Characteristics

This research addresses the challenge of formation control among multiple homogeneous autonomous underwater helicopters (AUHs) in the presence of external disturbances and complex dynamic characteristics. The study introduces a novel approach by integrating both disturbance and state observers within the control law framework to manage external disturbances and the immeasurability of velocity, respectively. Concurrently, localized radial basis function neural networks (RBFNNs) of identical configurations are incorporated into the formation control law to assimilate model uncertainties. Building upon this integration, an experience-based formation control strategy is developed, leveraging accumulated knowledge to diminish computational demands while maintaining stipulated performance criteria. Furthermore, the incorporation of a finite-time prescribed performance control (FTPPC) technique enhances the learning process’s efficiency by expediting convergence. Numerical simulations are presented to validate the efficacy of the proposed methodology.

Advanced Control Strategies for Cleaner Energy Conversion in Biomass Gasification

The escalating climate crisis necessitates urgent and decisive action to mitigate greenhouse gas emissions. Gasification stands out as a highly adaptable process for energy conversion, capable of handling a wide range of feedstocks, from coal to biomass. The process plays a significant role in improving sustainability by converting these feedstocks into synthesic gas (syngas), which can be used as a cleaner energy source or as a building block for producing various chemicals. The utilization of syngas obtained through gasification not only reduces the reliance on fossil fuels but also helps in reducing greenhouse gases (GHGs), thereby contributing to a more sustainable energy landscape. To maintain optimal operational conditions and ensure the quality and safety of the product, an effective control system is crucial in the gasification process. This paper presents a comparative analysis of three control strategies applied to a numerical model of rice husk gasification: classical control, fuzzy logic control, and dynamic matrix control. The analysis is based on a comprehensive model that includes the equations necessary to capture the dynamic behavior of the gasification process across its various stages. The goal is to identify the most effective control strategy, and the performance of each control strategy is evaluated based on the integral of the absolute value of the error (IAE). The results indicatethat fuzzy logic control consistently outperforms classical control techniques, demonstrating superior disturbance rejection, enhanced stability, and overall improved control accuracy. These findings highlight the importance of selecting an appropriate advanced control strategy to optimize sustainable gasification processes.

A 10 V-to-1 V Double Step-Down Buck Converter Using Time-Based Current Mode Control with Minimum Delay Frequency Difference Phase Adder for 1 MHz Operation

An extreme step-down ratio buck converter is proposed using a double step-down (DSD) buck converter architecture and a single time-based current mode PWM controller able to generate two non-overlapping control signal phases. Current sampling for two inductors is implemented with a multiplexer and a pair of VCOs only, which treats the two inductors as one inductor operating at double the frequency. This is achieved without the use of any large external passive components in the controller while remaining stable. The type-II time-based controller uses a VCO, a frequency difference phase adder (FDPA), and a phase detector, generating a control signal with fully integrated components with minimum area. FDPA for proportional control also significantly limits the signal delay of the high gain controller, allowing the use of time-based control technique at <10 MHz, which improves converter efficiency. The proposed time-based current mode controller DSD buck converter is simulated in 130 nm BCD technology operating at 1 MHz for 10 V to 1 V conversion. The simulated peak efficiency is 82.2% at 0.4 A, and recovers from a 1.8 A loading and unloading current step in 5.75 μs and 9.9 μs, respectively.

Vibration control of a base-excited rotor supported by active magnetic bearings using the linear active disturbance rejection controller

Rotor systems supported on a moving base, such as turbines on a ship, by active magnetic bearings are commonly subjected to additional excitations, namely base excitations. As a result, rotor vibration could be increased dramatically and even endanger the normal operation of the rotating machinery. This paper extends the linear active disturbance rejection control (LADRC) technique to the field of suppressing the base-excited effect. According to the characteristics of the LADRC, the decentralized control structure is adopted, and the control principle of employing the LADRC is illustrated. To improve the performance of the LADRC, using assisted parameters to facilitate its designation is a common method. Based on the control principle, the method for acquiring the assisted parameters is designed. Afterward, the effect of the controller parameters, including bandwidth parameters and assisted parameters, on the LADRC performance is analyzed systematically in terms of stability, noise rejection, and base excitation rejection. Based on the analyzed results, the steps for the controller tuning are suggested. On the designed test rig of an AMBs-rotor system with base excitations, the vibration suppression tests are performed to demonstrate the effectiveness of the LADRC technique and validate the conclusions of theoretical analysis.

Output feedback control for non-strict feedback nonlinear systems: an adaptive fuzzy backstepping scheme

The adaptive fuzzy tracking control design issue is considered in this paper for a class of non-strict feedback nonlinear systems subject to external disturbances. A fuzzy high-gain state observer is constructed to reconstruct the unmeasurable states of the system by leveraging the universal approximation property of fuzzy logic systems for arbitrary unknown nonlinear functions. Within the framework of backstepping control design and in conjunction with adaptive techniques, an adaptive fuzzy control approach is presented. Subsequently, to work out the inherent ‘complexity explosion’ problem of the proposed control approach, dynamic surface control technique is introduced, leading to a simplified adaptive fuzzy output feedback control scheme. Stability analysis shows that the two proposed control schemes can ensure that all signals of the closed-loop system are semi-globally uniformly ultimately bounded, meanwhile the system tracking error can converge to a small neighborhood around the origin. Ultimately, a numerical simulation example is provided to validate the feasibility of the proposed control scheme.

Theory and experiment for autonomous quadrotor flight via bounded robust finite-time homogeneous sliding mode control: A roadmap to search and rescue

This paper introduces a new saturated robust control technique for quadrotor aircraft modeled by second-order Ordinary Differential Equations (ODEs), considering disturbances in the control channel (matched disturbances). The control design employs a Sliding Mode Control (SMC) approach, featuring in: (i) a novel saturated homogeneous sliding manifold, (ii) a novel tracking controller, namely, Bounded Robust Finite-Time Homogeneous Sliding Mode Control (BRFTHSMC). An Improved Fixed-time Convergent Extended State Observer (IFCESO) is incorporated into the control scheme to handle disturbances. Together the BRFTHSMC and the IFCESO establish a reliable Active Disturbance Rejection Control (ADRC) framework. The latter ensures finite-time convergence of the errors quantities to the origin along with effective disturbance rejection. Rigorous stability analysis is conducted based on Lyapunov theory. Beside control design, another distinguishing theoretical outcome of this paper in the form of Corollary is the extension of the present results to integrator-type systems (higher-order systems). The study is substantiated through MATLAB®/Simulink simulations and Robot Operating System (ROS)/Gazebo implementation, validating the theoretical foundation. Extensive experimental tests on real hardware, including attitude and Cartesian trajectory tracking under various disturbances, further affirm the theoretical findings. The synthesized control system surpasses alternative methods in terms of control signal’s boundedness, finite-time tracking stability, transient response performance, and steady-state precision. Notably, the control input circumvents singularity challenges observed in conventional SMC approaches. In addition to trajectory tracking experiments, the controller’s effectiveness is demonstrated in real-world search and rescue scenarios. Therefore, a Deep Neural Network (DNN) algorithm, based on a MS COCO-pretrained Single Shot Detector (SSD-Mobilenet-v2), is employed for a person detection mission in an unknown search area.

Research on ride control strategy of electromagnetic suspension based on sliding mode algorithm

This study proposes a main inner loop control technique to address the dynamic response of the electromagnetic suspension during vehicle driving. The genetic algorithm is employed to optimize the control parameters of the linear quadratic adjustment controller in the control main loop, with the aim of achieving the desired control force. In the control inner loop, a closed-loop sliding mode controller is designed based on the exponential approximation law to regulate the current. The Lyapunov function was utilized to assess the stability of the controller in terms of its theoretical feasibility. The simulation results of Matlab/Simulink show that under the given working conditions, compared with the passive suspension, sliding mode control and fuzzy sliding mode control for references, the root mean square value and peak value of the vertical acceleration of the body and the dynamic load of the tire with the improved sliding mode control are significantly reduced, the root mean square value of the dynamic deflection of the suspension was not improved. However, on the whole, the ride comfort of the vehicle has been improved.

Enhancing Elevator Ride Quality through Vector Control Techniques and S-Curve Profiles

This study examines motor drive techniques, including Field-Oriented Control (FOC), sensorless FOC, and Direct Torque Control (DTC), to improve elevator ride quality by reducing jerk-sudden changes in acceleration that cause discomfort. A 200 cm tall prototype elevator system was developed, using S-curve velocity profiles alongside the considered control strategies. The system includes a TMS320F28379D DSP-controlled induction motor, sensors, and an encoder to assess performance. Results show that FOC with S-curve profiles reduces jerk by 72–73%, significantly improving comfort compared to the standard trapezoidal profile. Sensorless FOC reduces jerk by 68–71%, providing a cost-effective option, though it faces challenges during downward motion under load. DTC, reduces jerk by 65–68% and results in less smooth travel, especially during downward movement. In comparison, the trapezoidal velocity profile produced higher jerk levels and less ride comfort. This study emphasizes the critical role of control technique selection in enhancing elevator comfort and efficiency.

Evaluating Adaptive Droop Control for Steady-State Power Balancing in DC Microgrids Using Controller Hardware-in-the-Loop

DC microgrids (DCMGs) have been gaining attention due to their advantages over AC microgrids. The most commonly used control technique for DCMGs is droop control. Despite its benefits, droop control has drawbacks, such as power mismatch and deviations in DC bus voltage, often caused by differences in line resistance among grid-forming power electronics converters. To address these issues, the article proposes an adaptive droop control technique to correct steady-state power imbalances between grid-forming units in the DCMG. Additionally, a hierarchical voltage level is introduced to regulate the DC bus voltage. The analyzed DCMG includes two energy storage units, electronic loads, and a renewable energy source, each with its respective power electronic converter. The proposed technique uses real-time output power measurements from the energy storage system to calculate line resistance differences, incorporating these into the adaptive droop calculation. Several operating conditions are tested using a controller hardware-in-the-loop. The results validate the proposed technique and design guidelines.

Implementation and Performance Evaluation of Intelligent Techniques for Controlling a Pressurized Water Reactor

Pressurized water reactors (PWRs) are the most common and widely used type of reactor, and ensuring the stability of the reactor is of utmost importance. The challenges lie in effectively managing power fluctuations and sudden changes in reactivity that could result in unsafe situations. Reactor power fluctuations can cause changes in behavior. At the same time, the transfer of heat from the fuel to the coolant and reactivity changes resulting from differences in fuel and coolant temperatures can also make the systemunpredictable. The primary goal of a power controller used in a nuclear reactor is to sustain the specified power level, which guarantees the security of the power plant. To address these challenges, this paper presents a dynamic model of a PWR and applies several control techniques to the system for power level control. Specifically, a traditional PID controller, a Neural Network controller, a Fuzzy self-tuned PID controller, and a Neuro-Fuzzy self-tuned PID controller were individually designed and evaluated to enhance the performance of the reactor power control system under constant and variable reference power. In addition, the robustness of each controller was appraised against time delays and external disturbances. The system was tested with various initial power values to evaluate its performance under different conditions. The results demonstrate that the Neuro-Fuzzy self-tuned PID controller has the best performance, as well as the fastest response time compared to the other controllers.Furthermore, the intelligent controllers were found to exhibit good robustness against time delays and external disturbances. The system's stability was not significantly affected by changes in the initial power value, although it had a minor effect on the transient response. Overall,the findings of this study can inform the design and optimization of control systems for PWRs, with the ultimate goal of improving their safety, reliability, and performance.

A Robust Control Strategy for Effective Field-Oriented Control of PMSMs

Field-Oriented Control (FOC) is widely recognized as a standard framework for Permanent Magnet Synchronous Motor (PMSM) drives. Linear control techniques are commonly employed in designing controllers for this strategy. However, traditional control methods often exhibit performance limitations and reduced robustness, particularly under harsh operating conditions, which makes the FOC structure less appealing and less effective. To address and overcome these challenges, this study proposes a Second-order Non-singular Terminal Sliding (SNTS) mode approach to achieve fast, accurate, and robust tracking for the FOC control structure applied to PMSM drives. The SNTS method combines the benefits of non-singular terminal sliding mode and second-order control laws. This approach ensures rapid and precise tracking while minimizing steady-state errors by using a nonlinear terminal sliding mode surface instead of a linear one. Furthermore, the system state transitions smoothly along the sliding mode surface with continuous functions, which reduces chattering around the sliding surface. The second-order control law incorporated into this method helps mitigate chattering and achieve fast convergence. The Lyapunov stability theory is employed to verify the stability of the SNTS technique designed for the PMSM system. Simulation and experimental validation on a hardware platform confirm the effectiveness and superiority of the proposed SNTS method, demonstrating its capability to enhance the performance of speed controllers for PMSM drives.

Environmental drivers of spatial variation in myrtle rust development on a critically endangered tree species

The spread of invasive plant pathogens is on the rise globally, introducing additional threats to forest ecosystems and their constituent species above those already caused by climate change and other anthropogenic stressors. Austropuccinia psidii is a widespread invasive fungus that infects hundreds of species in the Myrtaceae plant family, causing myrtle rust. It was first detected in New Zealand in 2017, where the threatened endemic tree Lophomyrtus bullata is one of the worst affected hosts. Recent studies have described heavy disease severity on this species but environmental drivers of spatial variation in disease severity have not been explored, including the possible role of edge effects which are prevalent across much of this species' highly fragmented natural range. In this study, we tracked changes in disease incidence and severity across a forest edge gradient over three years. Individuals further from the forest edge, where forest canopies were more intact, forest structure more complex, and with greater understorey humidity, had greater disease severity in the first year of infection. In subsequent years, the influence of edge was no longer evident as myrtle rust severity became more even across the site, but disease was more prevalent in denser L. bullata populations. Only small individuals were asymptomatic across all three years. Since all available myrtle rust control techniques are currently feasible only at small scales, our research implies that their application needs to be as early as possible before infection spreads and across all suitable microclimates, and without bias toward easily accessible forest edges.

Stochastic assessment of voltage sags and techno-economic optimization

Power quality has become an essential concern for industries and domestic energy consumption with the development of sophisticated equipment like micro-electronic devices. When a power quality event happens, such as voltage sag, financial losses for industries increase tremendously. Therefore, voltage sag evaluation becomes crucial for predicting the number of events and severity of voltage sag events of the electrical network. Industries can determine the mitigation investment needed for optimal operation using the knowledge obtained through voltage sag analysis method. Thus, the first part of the study addressed the development of a stochastic assessment method for voltage sag at an interested bus in the power system network, which was an initial objective of the study. The second part of the research investigates dynamic voltage restorer (DVR) control techniques, as well as the necessary capacitance and energy storage dimensions. The studies also recommend a technique for economic evaluation that emphasizes the expense of voltage sag events as well as the cost of investment in DVR with and without voltage sag events. The size of DVR and economic assessment model established in these studies enables industries to rate the cost of voltage sag and the total investment in mitigation devices.

A comprehensive review on power quality issues and disturbances mitigation through shunt active power filters

In contemporary power systems, power quality (PQ) has become a matter of paramount concern. The challenges associated with PQ extend beyond conventional three-phase systems, encompassing the integration of various distributed generation (DG) sources like renewable energy installations, storage systems, and diverse power generation technologies such as diesel generators and fuel cells. The prevalent adoption of rapid-switching devices within the utility infrastructure has resulted in a surge of harmonics and reactive power disturbances. The increased use of harmonics-producing loads has led to several power quality issues, particularly harmonics. The distortions caused by these power quality issues must adhere to the limits established by international standards. Mitigation of these concerns is critical, and active power filters are a realistic option. However, passive filters have problems such as bulkiness, and resonance with either/both load and utility impedance, and the source impedance affects filtering properties. As a result, active power filters (APF) are designed to address the shortcomings of passive filters. Active power filters (APF) offer several advantages over passive filters, including compact size, enhanced filtering characteristics, dynamic performance, and flexible operation. The control strategy of APF strongly influences the APF performance, efficiency, and reliability. This paper presents a detailed assessment of current active filter control systems, highlighting their key features. The characteristics, performance, applicability, and implementation of various control techniques are explored and investigated.

Performance analysis of interlinking converter exchanging power between AC/DC renewable microgrids with advanced control technique

In a distribution system there are many types of AC/DC microgrids integrated at different locations. These microgrids may contain conventional or renewable sources which generate power using natural resources. The power generated by these microgrid sources is uncertain as the natural resources are unpredictable. Therefore, powers from these AC/DC micro grids need to be shared so as to compensate the load demand throughout the distribution system. An interlinking converter (ILC) is connected between the AC/DC microgrids operated by a novel advanced PQ control technique. Both the DC and AC microgrids are interconnected through ILC achieving power exchange between them as per the power demand and generation on both microgrids. Different operating conditions are considered for the analysis and the simulation of these modules are done using MALTAB/Simulink software. Several parameters like DC link voltage, ILC currents, point of common coupling (PCC) frequency, total harmonic distortions (THDs) and active power values are considered for validating the stability of the considered system.

Dietary feeding techniques for body weight control in horses with equine metabolic syndrome

Dietary feeding techniques for body weight control in horses with equine metabolic syndrome

Advanced control and optimization strategies for a 2-phase interleaved boost converter

Renowned for their adeptness in smoothing current flow and maintaining balanced operation, 2-phase interleaved boost converters (IBC) demonstrate remarkable efficiency, especially when confronted with demanding loads. This makes them a preferred choice for high-power applications such as renewable energy systems, high-power supplies, and electric vehicle power trains. In contrast, standard boost converters are typically favored in low-power, low-demand scenarios. The control of a 2-phase IBC involves running two boost converters in parallel but with a phase shift to reduce ripple currents, improve efficiency, and increase power handling capabilities. To ensure stability and optimal performance, the control strategies for these converters focus on achieving balanced operation between the phases. Hence, the control of 2-phase IBC presents a significant challenge due to their non-minimum phase behavior. The core focus of this article is the implementation of a composite model predictive control (MPC) technique to regulate a 2-phase interleaved boost converter. It introduces a novel approach, model predictive sliding mode control (MPSMC), which leverages the strengths of both MPC and sliding mode control (SMC). The benefits of this hybrid method, termed MPSMC, are thoroughly developed and simulated using MATLAB/Simulink. The results, as discussed in the respective section, provide an in-depth understanding of its effectiveness in practical applications.

Osteogenic tailoring of oriented bone matrix organization using on/off micropatterning for osteoblast adhesion on titanium surfaces.

Titanium (Ti) implants are well known for their mechanical reliability and chemical stability, crucial for successful bone regeneration. Various shape control and surface modification techniques to enhance biological activity have been developed. Despite the crucial importance of the collagen/apatite bone microstructure for mechanical function, antimicrobial properties, and biocompatibility, precise and versatile pattern control for regenerating the microstructure remains challenging. Here, we developed a novel osteogenic tailoring stripe-micropatterned MPC-Ti substrate that induces genetic-level control of oriented bone matrix organization. This biomaterial was created by micropatterning 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer onto a titanium (Ti) surface through a selective photoreaction. The stripe-micropatterned MPC-Ti substrate establishes a distinct interface for cell adhesion, robustly inducing osteoblast cytoskeleton alignment through actin cytoskeletal alignment, and facilitating the formation of a bone-mimicking-oriented collagen/apatite tissue. Moreover, our study revealed that this bone alignment process is promoted through the activation of the Wnt/β-catenin signaling pathway, which is triggered by nuclear deformation induced by strong cellular alignment guidance. This innovative material is essential for personalized next-generation medical devices, offering high customizability and active restoration of the bone microstructure. STATEMENT OF SIGNIFICANCE: This study demonstrates a novel osteogenic tailoring stripe-micropatterned MPC-Ti substrate that induces osteoblast alignment and bone matrix orientation based on genetic mechanism. By employing a light-reactive MPC polymer, we successfully micropatterned the titanium surface, creating a biomaterial that stimulates unidirectional osteoblast alignment and enhances the formation of natural bone-mimetic anisotropic microstructures. The innovative approach of regulating cell adhesion and cytoskeletal alignment activates the Wnt/β-catenin signaling pathway, crucial for both bone differentiation and orientation. This study presents the first biomaterial that artificially induces the construction of mechanically superior anisotropic bone tissue, and it is expected to promote functional bone regeneration by enhancing bone differentiation and orientation-targeting both the quantity and quality of bone tissue.