System Stabilizer Research Articles

Enhancing Magnetohydrodynamic Stability in Channel Flows through Porous Media Incorporating Darcy-Forchheimer Modifications into the Orr-Sommerfeld Analysis

This research paper investigates the stability characteristics of magnetohydrodynamic (MHD) flow within channels filled with porous media. Specifically, the study explores modifications to the classical Orr-Sommerfeld equation using the Darcy-Forchheimer model to account for the presence of porous media. The analysis aims to elucidate the combined influence of porous media and magnetic fields on flow stability in such systems. Numerical simulations and analytical techniques are employed to assess the impact of varying parameters on the stability behavior of the flow. The study revealed that the velocity profile increases with increase in Schmidt and Prandtl’s number and stabilizes with the increase in Grashof number and the buoyancy. The temperature profile increases with Reynold’s Number and Hartmann number. It stabilizes with Schmidt, Prandtl and Grashof number. The profile of species concentration stabilizes with thermo-phoretic parameter, Prandtl number and Darcy-Forchheimer’s parameter augumentation.

Biosorption as Technique for Remediation of Heavy Metals from Wastewater using Microbial Biosorbent

Biosorption, a sustainable technology, utilizes living or non-living organism and their derivative as sorbents for the removal of heavy metals from wastewater. This review explores the mechanisms and applications of biosorption in addressing environmental challenges posed by heavy metal contaminants. Pretreatment methods enhance biosorbent performance by modifying cell wall structures through physical and chemical alterations, increasing metal binding capacity. Immobilization techniques like cell entrapment and cross-linking improve biosorbent stability and reusability in continuous systems, offering controlled particle size and ease of biomass separation. Differential Scanning Calorimetry assesses biosorbent thermal stability, providing insights into performance under varying conditions. Non-living microorganisms present advantages for biosorption, including resilience to toxic wastes and extended storage capabilities. Economic considerations are crucial when evaluating biosorbent modifications for enhanced performance. The review show that biosorption using microbial biosorbents is a versatile and efficient method for heavy metal removal from wastewater, with applications in environmental remediation and sustainable water treatment practices. Future research should focus on novel biosorption strategies and optimization of existing techniques to effectively combat heavy metal pollution.

Investigating Integral Reinforcement Learning to Achieve Asymptotic Stability in Underactuated Mechanical Systems

Investigating Integral Reinforcement Learning to Achieve Asymptotic Stability in Underactuated Mechanical Systems

Design and experimental validation of a model-free controller for beam stabilization in adaptive optics systems

Design and experimental validation of a model-free controller for beam stabilization in adaptive optics systems

Coordinated Robust Damping Control for Hybrid SVC/SSSC to Enhance Power System Stability in Large-Scale Systems

Coordinated Robust Damping Control for Hybrid SVC/SSSC to Enhance Power System Stability in Large-Scale Systems

Fast Assessment Method for Transient Voltage Stability of Photovoltaic Receiving‐End Grid

The incorporation of renewable energy on a broad scale into power grids increases the complexity to the issue of transient voltage stability in power systems. This research presents a rapid evaluation technique for assessing the stability of voltage fluctuations in power grids that receive electricity from photovoltaic sources. At first, a receiving‐end system model was developed, which includes photovoltaics, and an alternative circuit of the virtual induction motor (IM) is obtained by utilizing the Thevenin equivalent. Second, the torque balance equation and the Kirchhoff voltage equation are interconnected to determine the unstable slip of the IM following a malfunction. Finally, by merging the unstable slip with the conventional transient stability discriminant index, the effects of different photovoltaic outputs, IM ratios, and system contact impedances on transient voltage stability are investigated. The proposed method avoids the computational burden of solving the differential‐algebraic equations describing the complex transient processes of the IM. It also obviates the necessity of iteratively modifying the receiving load or fault clearance time in the simulation platform to achieve the constrained stability condition of the system’s transient voltage. The transient stabilization of voltage results is efficiently obtained by directly solving algebraic equations.

Extremely Randomized Trees Approach to Voltage Stability Assessment of Power Distribution System

In modern power grids, ensuring operational stability necessitates real-time assessment of static voltage stability. This paper presents an advanced ensemble machine learning approach to estimate voltage stability in power distribution systems using data from phasor measurement units (PMUs). The methodology integrates multiple machine learning techniques into a unified predictive model to minimize bias and variance. A critical feature of this approach is the inclusion of a feature pre-processing step to eliminate redundant and irrelevant features, enhancing computational efficiency through dimensionality reduction. Additionally, a minority oversampling method for regression is utilized to address data disparity, ensuring robust model performance. Various ensemble models were evaluated using mean square error metrics, with the Bagging model ExtraTrees outperforming other algorithms. The proposed method's efficacy is validated on a 30-bus IEEE system, highlighting its potential for real-time applications. This research offers a robust solution for maintaining grid reliability and preventing power outages by providing accurate, real-time voltage stability assessments.

Power System Oscillation Monitoring and Damping Control Redesign under Ambient Conditions and Multiple Operating Points

Using prediction-error identification methods, this paper proposes a measurement data-driven approach to monitor power system oscillations at a power plant, identify a data-based model using an input signal and redesign the plant’s power system stabilizer damping controller to mitigate the observed oscillations under ambient conditions and multiple operating points. The advantage of the proposed methodology is that the damping performance can be monitored continuously and the redesign only requires measurements at the power plant along with the controllers structure, which are known by the power plant operator.

Optimum Coordination of Multi‐Band Power System Stabilizers and STATCOM Using the Modified Particle Swarm Algorithm

In this paper, to improve the small signal stability of the power system, the optimal coordination of multi‐band power system stabilizers (MB‐PSSs) and static synchronous compensator (STATCOM) has been done. The study is conducted on a standard four machines and two areas power system. To create coordination, a modified version of the particle swarm algorithm as well as the integral time absolute error (ITAE) criterion are proposed. To evaluate the proposed stability method in different operating conditions and in the form of two scenarios, a three‐phase fault with a duration of 200 ms has been applied in the communication line between the two areas. After the simulation, the values of overshoot, undershoot, settling time, and ITAE criteria for the proposed stability method have been calculated and their values have been compared with the results of power system stabilizer (PSS) and MB‐PSS stabilization methods. The results indicate that the proposed combined method of MB‐PSS and STATCOM performed better than the other two methods in improving the dynamic stability of the power system and has the lowest value of the criteria. The values of ITAE for the PSS, MB‐PSS stabilization methods and the proposed MB‐PSS and STATCOM combined method in the first scenario are equal to 0.002354, 0.0.001496, and 0.001242 p.u. and in the second scenario it is equal to 0.0.007418, 0.004015, and 0.003435 p.u., respectively.

Analysis of the progress of domestic post-occupancy evaluation (POE) research based on bibliometrics

This study aims to examine the status and developmental trends of Chinese Post-Occupancy Evaluation (POE) research literature from 2002 to 2022 using a bibliometric approach. Leveraging the CiteSpace software tool and utilizing the CNKI database as the exploration scope, we conducted visual analyses of publication volume, research institutions, highly cited papers, and keywords in Chinese POE research literature between 2002 and 2022. Through our analysis, we found that Chinese POE research has exhibited a shift from introducing macro-level theories and methods towards specific practical applications over the past 20 years. It also identified issues such as insufficient systemic stability and data granularity. This study, employing bibliometric methods and tools, makes a significant contribution to the field of POE research.

Polysaccharides as food system stabilizers

From the point of view of the modern healthy nutrition concept, dietary fiber (DF) occupies a leading position among functional ingredients. Expanding the range of food products with the help of DF can strengthen public health and human immune response. Insoluble natural polysaccharides (which make up the main group of polysaccharides) serve as an alternative to surfactants as stabilizers for food emulsions. The quality of ready-to-use food products such as ketchups and mayonnaises deteriorates during long-term refrigeration due to changes in physical and chemical properties. The present research aims to justify the use of disaggregated bacterial cellulose (BC) as a food system stabilizer for mayonnaise sauces and tomato ketchups. It is a unique structurizer of food systems due to its properties: high water-retaining and lipid-binding capacity, fibrillar structure, and lack of toxicity, hence the commercial interest in it as a food additive and functional ingredient. Using scanning probe microscopy, the sizes of BC fibrils were determined: length > 10 μm, width 100-150 nm. Physicochemical parameters of mayonnaise sauce and ketchup samples containing BC were analyzed and compared. The impact the amount of BC has on the organoleptic characteristics of ketchup and mayonnaise was determined.

PMU-Based Power System Stabilizer Design Using Coati Optimization Algorithm

Low-frequency oscillation modes can destabilize the power system if they do not have adequate damping rates. The interconnection of large power systems and the complexity of operation has caused the increase in these modes and conventional control techniques have difficulty guaranteeing adequate damping rates. This article proposes a design method for a Power System Stabilizer damping controller using data from Phasor Measurement Units (PMUs) to ensure adequate damping rates for the modes even in the event of PMU data failures. Case studies were simulated and analyzed using the IEEE 68-bus system.

Wide area damping of electromechanical oscillations based on implicit reference model adaptive control

Assessing the stability of low-frequency inter-area oscillations remains an important issue in modern electrical power systems. The paper proposes a novel method for optimal tuning of power system stabilizers for wide area damping of electromechanical oscillations based on implicit reference model adaptive control. An implicit reference model of the system is formed on the basis of choosing the desired values of the roots of the characteristic polynomial of the system by computing the determinant of its characteristic matrix. An adaptive tuning procedure seeks to preserve the “reference” values of the coefficients in the characteristic polynomial of the swing equation model of the system identified at the current operating point. The proposed approach can be also considered as an adaptive pole placement method applied to the linearized swing equation model. Numerical experiments with the IEEE 30 bus test model confirm that the proposed method can be effective in maintaining dynamic and transient stability.

Design of Power System Stabilizer for DFIG-based Wind Energy Integrated Power Systems Under Combined Influence of PLL and Virtual Inertia Controller

Design of Power System Stabilizer for DFIG-based Wind Energy Integrated Power Systems Under Combined Influence of PLL and Virtual Inertia Controller

A Hybrid Controlling Parameters of Power System Stabilizer and Virtual Inertia Using Harris Hawk Optimizer in Interconnected Renewable Power Systems

A Hybrid Controlling Parameters of Power System Stabilizer and Virtual Inertia Using Harris Hawk Optimizer in Interconnected Renewable Power Systems

A New Scheme of Harris Hawk Optimizer With Memory Saving Strategy (HHO-MSS) for Controlling Parameters of Power System Stabilizer and Virtual Inertia in Renewable Microgrid Power System

A New Scheme of Harris Hawk Optimizer With Memory Saving Strategy (HHO-MSS) for Controlling Parameters of Power System Stabilizer and Virtual Inertia in Renewable Microgrid Power System

Design and Analysis of a Step-Up Multi-Port Converter Applicable for Energy Conversion in Photovoltaic Battery Systems

Aiming at the problems of large power fluctuations and poor stability in photovoltaic and other new energy power generation systems, a step-up multiport converter (MPC) that can simultaneously connect low-voltage photovoltaic cells, batteries, and loads (independent loads or power grids) is proposed in this manuscript. According to the possible operating conditions of the system, the working principles are described in detail. Theoretical analysis based on different working modes is presented and a hybrid modulation control method including pulse width modulation (PWM) and phase shift modulation (PSM) are applied to realize energy transmission between photovoltaics, batteries, and power grids. A simulation model is built in the PSIM environment to validate each working state of the system and mode switching function. Experiments are carried out on an experimental platform using the dsPIC33FJ64GS606 digital microcontroller as the control center, and the experimental results successfully verify the system function and PWM + PSM control efficiency.

Competition, liquidity creation and bank stability

AbstractWe examine the conditioning role of competition in affecting the relationship between liquidity creation and bank risk in a sample of US banks from 2001 to 2016. We find aggregate evidence that competition is related to bank fragility as proxied by the Z‐score both directly and indirectly through its interaction with liquidity creation. However, when the ex‐ante level of liquidity creation is low and/or competition is low to moderate, competition is associated with an improvement in bank risk at a given level of liquidity creation. In addition, the joint fragility effect of competition and liquidity creation manifests more strongly, in an economic sense, in poorly capitalised banks and large banks with assets of more than $3 billion. Our findings emphasise the crucial role of targeted competition regulations in ensuring bank solvency and systemic stability while maintaining a robust level of competition.

Predefined‐time tracking control of a class of nonlinear systems via a novel C∞ performance function

AbstractIt is well‐known that the finite‐time and the fixed‐time control can ensure the finite‐time and the fixed‐time stabilities of systems, respectively. Therein the finite convergence time depends on both the initial conditions of systems and the controller design parameters, and the fixed convergence time only depends on the controller design parameters. The recently reported predefined‐time control removes the above limitations. Nevertheless, the existing predefined‐time control methods either require sliding modes, or suffer from the high‐gain control problem at the predefined time, or cannot be applied to high‐order systems. This article develops an alternative predefined‐time tracking control scheme of a class of nonlinear systems by introducing a novel performance function which reaches its terminal value at a predefined time. The developed predefined‐time tracking control scheme has higher compatibility, does not cause the high‐gain control problem at the predefined time and is applicable to arbitrary order systems. Theoretical analyses and simulations verify the effectiveness of our developed predefined‐time tracking control scheme.

A convolutional neural network framework to design power system stabilizer for damping oscillations in multi-machine power system

A convolutional neural network framework to design power system stabilizer for damping oscillations in multi-machine power system