System Voltage Research Articles

Simulation of Voltage and Frequency Stabilization in PV-Based Microgrids Using Virtual Synchronous Generator Control

In recent years, distributed generation technologies and micro-grids have garnered increasing attention, particularly with the rapid growth of renewable energy sources (RESs) integrated via power electronic converters. As the penetration of RESs in modern power systems rises, voltage and frequency support, traditionally provided by synchronous generators, can be effectively managed by Virtual Synchronous Generator (VSG) control. This paper presents the modeling and analysis of voltage and frequency stability enhancement in a PV-based micro-grid system using VSG control. The micro-grid system under study operates at 400V, 50Hz, and is integrated with a 0.4kV power distribution line. Mathematical models of the VSG control strategy are developed in MATLAB/Simulink. Simulation results demonstrate that VSG control significantly improves the voltage and frequency stability of the PV-based micro-grid system.

Entropy-driven self-assembled enzyme-DNA nanomatrix cascade DNAzyme-CRISPR/cas system for multiplexed enhancement of self-powered sensing platform for protein detection

Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated Proteins (CRISPR/Cas) system can accurately identify and cleave target DNA sequences, while the effective combination of DNA nanomatrix and entropy-driven self-assembled enzymes can significantly enhance the sensitivity, stability, and diversified functionality of sensors through highly ordered molecular arrangement and spontaneous efficient assembly processes. Herein, a carbon-encapsulated MoS2 hollow nanorod (C-MoS2) with excellent conductivity and multiple active sites is used to construct bioanode of biofuel cell by integrating it with an entropy-driven self-assembled enzyme-DNA nanomatrix cascade DNAzyme-CRISPR/Cas system. When thrombin binds aptamer, it exposes the trigger strand on the anode, initiating chain displacement. This activates DNAzyme, triggering a cascade reaction that cleaves and releases the probe strand. The probe then binds CrRNA, forming a multimeric complex with Cas protein.When non-specific cleavage of the single strand occurs, it leads to the release of glucose oxidase (GOD) from the DNA matrix and causes a significant decrease in the value of the system's open-circuit voltage (EOCV). The EOCV values show a good negative correlation with the concentration of thrombin (TB) in the range of 0.00001–100 nM, achieving a limit of detection of 3.55 fM (S/N = 3).

Techno-economic performance of different DC power distribution networks in official buildings based on a real-time analysis method

The integration of photovoltaic (PV) and energy storage systems into official buildings has garnered considerable attention, which are recognized as DC power sources. Notably, DC power can satisfy the majority of electrical demands in official buildings. The primary objective of this research is to enhance overall system efficiency by efficiently utilizing renewable energy through direct current (DC) power distribution compared to alternating current (AC) systems. This study proposes a techno-economic analysis framework to guide designers in selecting system configuration and voltage levels. The analysis covers various PV capacities, load compositions, and battery capacities, with the aim of optimizing power distribution efficiency and achieving a more competitive levelized cost of energy (LCOE). The proposed model integrates the dynamic efficiency of actual converters and wire gauges, enabling real-time computation of the energy supply–demand balance within the power distribution system, including associated conversion and transmission losses. The results indicate that conversion loss accounts for approximately 80% of the overall energy loss within power distribution networks. The implementation of DC power distribution significantly improves system efficiency and economic viability. Specifically, the DC375 system exhibits superior techno-economic performance in scenarios involving high PV and battery capacities. In scenarios with limited PV and battery capacity, the building power distribution system should employ a hybrid AC-DC topology to efficiently distribute the available PV output to building loads powered by DC

Short Communication: Ultralow Voltage Electrokinetic Particle Trapping in DC-iEK Devices Using 9V Alkaline Batteries as Power Supply.

This contribution describes direct current insulator-based electrokinetic (DC-iEK) microfluidic devices stimulated by 9V alkaline batteries for the trapping of 2-µm diameter fluorescent polystyrene particles. These devices featured two triangular insulating posts within the fluidic channel. Particle trapping was clearly observed at 18V (two 9V batteries connected in series), but only intermittent particle trapping was observed with a single 9V battery. Particle trapping was determined by measuring the increase in relative fluorescence intensity at the gap region between the single pair of triangular posts. Results demonstrate that the use of low stimulating voltages (deemed as ultralow) in DC-iEK systems may be more suitable for accurate and precise electrokinetic characterization of particles-by exhibiting a very well-localized trapping region with negligible particle oscillations therein, respectively-than for high-performance and high-throughput particle manipulation (i.e., concentration, separation, filtering, or isolation).

The formative time delay and electron avalanche number distributions for multielectron initiation of streamer breakdown

Electron avalanche statistics were mainly studied with a single electron initiation and there was no mathematical transition reported to the formative time delay distribution. This paper deals with the transition from the electron avalanche number distribution to the formative time delay distribution for multielectron initiation and streamer breakdown mechanism. The goal of the research is a detailed analysis of the formative time delay of electrical breakdown for different applications, such as spark counters, resistive plate chambers, gas-discharge switches, and high voltage systems with gas as an insulator. The electron avalanche number distribution for multielectron initiation is described by negative binomial distribution (NBD). Regarding the newly derived formative time delay distribution, when the number of initiating electrons k is small, the formative time delay distributions are asymmetric with the pronounced right tail. With increasing k, the formative time distributions shift to the shorter formative times and become narrower and higher, more symmetric and Gauss-like. As statistical tests show, for k≳20 the hypothesis that the formative time delay distributions are Gaussians cannot be rejected. As illustrations, the formative time delay distributions in neon and air at low reduced electric field are shown and briefly discussed. The distributions for methylal, ether and methane are presented in order to compare the estimated distribution parameters with available experimental data and to model the measured distributions.

Static Voltage Stability Analysis with the Integration of Distributed Generation: An Albanian Case Study

Modern power networks face significant operational uncertainties that can threaten the stability of the power grid, due to the rising integration of distributed generation (DG), particularly from renewable energy sources, such as photovoltaic plants. The integration of distributed generation (DG) into power systems has become a pivotal factor in enhancing the efficiency and sustainability of electricity supply. This paper presents a detailed static voltage stability analysis of the Albanian power grid, focused on the effects of the Karavasta Photovoltaic Park, one of Albania’s largest renewable energy projects. Using a combination of P-V and Q-V curves, V-Q sensitivity analysis, and modal analysis, the study reveals significant improvements in the system’s voltage stability following the integration of the PV plant. The NEPLAN software is used for voltage stability analysis. Particularly, the reactive power margin at the critical node Nst. Babice increased considerably from -82.009 MVAr to -1061.2 MVAr, while the system’s loading margin improved from 99.08% to 101.97%, demonstrating that the integration of large-scale PV generation enhances voltage stability by providing additional reactive power support and improving the grid’s resilience to voltage collapse. Furthermore, the modal analysis identified the Bistrice-Delvine-Sarande buses as the system’s weakest points, highlighting areas where additional reinforcement is required. As more renewable energy has to be integrated into the grid, the study also emphasizes the importance of making targeted interventions at critical buses and branches to ensure long-term stability. The results of this research are essential for Albania’s energy transition as the country seeks to diversify its energy sources, especially solar power. More generally, the methodologies and results in this paper provide a suggestion for maintaining power system voltage stability with increased renewable energy penetration.

Design of a Univariate Dual‐Loop Voltage System Based on the Multisampling Method

ABSTRACTThis study presents an innovative control framework designed for voltage source inverters (VSIs) equipped with LC output filters. The objective of this control framework is to reduce delay and suppress aliasing effects by employing multisampling techniques and implementing repetitive filtering methods. The multisampling approach can significantly reduce control delays, thereby enhancing both the bandwidth and stability margins of the system. The implementation of multisampling techniques for inverter voltage can enhance dynamic performance. However, it may introduce high‐frequency ripples in the control loop, resulting in low‐order aliasing harmonics and ultimately leading to output voltage distortion. To address this issue, a multiple notch filter with minimal phase delay is employed suppress aliasing. The optimal parameters of the system are determined by evaluating the filter specifications, filtering effectiveness, output voltage ripple, and overall system performance, while also considering the actual filtering requirements and circuit size. Its effectiveness and performance are carefully verified by experimental results.

Hierarchical Optimization Configuration Strategy of Synchronous Condenser in High Penetration Wind Power Sending Systems

The increasing deployment of large-scale wind turbines in place of conventional generators is expected to lead to the dominance of asynchronous power sources in future power systems, further accelerating the trend toward grid electrification. As a result, the ability of power sources to support system voltage and frequency is gradually diminishing. Synchronous condensers (SCs), which are synchronous machines operating without prime movers, serve as effective devices for providing both dynamic voltage support and inertia. They can significantly enhance the system’s capacity to maintain voltage and frequency stability. However, most existing studies on the optimization of synchronous condenser configurations tend to focus on only one aspect at a time rather than addressing both simultaneously, limiting the full potential of these devices. Optimizing either the voltage or frequency in isolation often results in suboptimal improvements in the other. Moreover, the simultaneous optimization of both voltage and frequency can lead to non-convergent outcomes, complicating the search for an optimal solution. To address this, the paper proposes a hierarchical optimization strategy for synchronous condenser configuration aimed at enhancing both voltage and frequency stability. First, the connection sites for the synchronous condensers are determined based on short-circuit ratio (SCR) constraints. Next, an outer layer optimization model is developed to minimize the total installed capacity of the condensers while taking into account the SCR and transient overvoltage levels as constraints. Following this, an inner layer optimization model is introduced, incorporating a rate of change in the frequency and maximum frequency deviation as constraints. The model is solved using the bacterial foraging optimization algorithm (BFOA). Finally, a case study of a power grid with a high proportion of wind power validates the effectiveness of the proposed synchronous condenser configuration strategy. Compared to traditional methods, the total required capacity of synchronous condensers was significantly reduced.

A comprehensive simultaneous allocation algorithm of charging stations and vehicle to grid operation in radial networks

The widespread adoption of electric vehicles (EVs) helps improve air quality by minimizing pollutants and promoting sustainable transportation practices. The integration of a substantial fleet of EVs leads to an increase in the installation of charging stations. The unplanned allocation of these loads impacts the distribution systems, such as increasing power loss. This paper introduces an algorithm that proposes an optimal allocation strategy for charging stations (CSs) in a distribution system. The allocation process aims to minimize the total apparent energy losses and ensure that the system voltage profile remains within limits. Load profile, charging and discharging profiles of CSs are considered. Vehicle-to-Grid (V2G) mode is one of the merits of integrating EVs in the grid, so this feature has been used to maintain system voltage stability and minimize energy loss. Power rating and locations of V2G mode are optimally determined to guarantee power quality indices. A hybrid algorithm of genetic algorithm (GA) and Self-Adaptive Multi-Population Elitist JAYA (SAMPE-JAYA) is developed to simultaneously allocate CSs and V2G in the systems. The proposed algorithm is verified on standard systems, IEEE 33, and 69-bus systems. The proposed algorithm is verified on standard IEEE 33-bus and 69-bus systems. V2G integration with CSs results in a reduction of energy losses by 6.33% and 22.25%, respectively, and voltage deviation improvements to 7.61% and 7.88% for the two systems.

Solar Panel Light Intensity and Voltage Measurement System Using Atmega 328

This research explores the development of a real-time measurement system for light intensity and voltage in solar panels. It utilizes the ATmega328 microcontroller with an INA219 sensor for voltage measurement, a BH1750 sensor for light intensity measurement, and a logger module. The objective of this research is to assist and reduce losses in the use of solar panels. The research method is a simplified version of the 4D model, reduced to 3D: define, design, and develop. This system is designed to accurately collect data directly from solar panels, with a recorded data error rate of 23%. The gathered data is stored via an SD card on the logger module and converted into CSV text format. Test results indicate that this system can measure accurately and store data in a readily accessible and processable format. ATmega328, as the system's core, allows accurate real-time monitoring of solar panel conditions while storing data in CSV format, facilitating further analysis. Therefore, this system can be a valuable tool for monitoring and enhancing the energy efficiency produced by solar panels.

Stochastic optimal PV placement and command based power control for voltage and power factor correction using MOPSO algorithm

This paper addresses a multi-objective particle swarm optimization (MOPSO) algorithm to locate the best position at which a single distributed generator (DG) with optimum voltage amplitude and phase can be installed. The objective is to maximize the power factor and voltage in IEEE 9-Bus system and voltage in IEEE 15-Bus system using MATLAB/SIMULINK software. Systematic simulations revealed that a single DG at Bus-5 with voltage amplitude/phase of 230 kV/-13∘ caused highest objective function value of 1.9919 with an improvement in power factor and voltage of 1.39% and 1.15% respectively. In IEEE 15-Bus system, DG at Bus-3 caused the highest objective function (0.8828) with DG voltage amplitude/phase of 10.735 kV/23.12∘ and 11.89% voltage improvement. Finally, a robust control program in dq0 domain is developed to achieve calculated powers from photovoltaic generator at DG bus whose effect is validated to be the same at all buses as given by the MOPSO algorithm.

Optimizing Voltage for Effective X-ray Computed Tomography Scan: A Study on Varied Soil Bulk Densities and Container Sizes

Numerous studies have highlighted the role of X-ray computed tomography (X-ray CT) in understanding root architecture. Nevertheless, setting definitive scanning parameters for diverse soils in varied container sizes remains challenging. This study investigates the influence of X-ray CT system voltage on the penetration capability in diverse soils and container sizes, focusing on two key parameters: (1) gray values, which indicate X-ray attenuation and contribute to image contrast, and (2) signal-to-noise ratio, a measure of image clarity. Five soil samples were collected from various depths within a soil profile to encompass bulk density values ranging from 1.34 to 1.84 g·cm−3 to conduct the experiment. Containers with dimensions of 6 × 6 × 6 cm³, 8 × 8 × 6 cm³, 10 × 10 × 6 cm³, 12 × 12 × 6 cm³, 14 × 14 × 6 cm³, and 16 × 16 × 6 cm³ were used. Voltage levels spanning 75 to 225 kV, in 25-kV increments, were applied to each sample. The observed gray values of the X-ray images were fitted using a logistic model of three parameters. Results showed that increasing voltage leads to enhanced penetration up to a plateau point, irrespective of soil density or container size. This plateau could potentially yield higher quality scans, given that lower voltages result in subdued gray values and reduced image contrast. Notably, it was observed that soil properties, including mineral composition, directly affect image gray values. This study established optimal voltage settings for specific soil types at fixed densities, offering valuable insights for researchers investigating soil–root interactions. Although the current findings are based on five soils, a more extensive sampling encompassing diverse soil textures and densities is necessary for a comprehensive understanding of X-ray penetration behavior across various soil types.

Comparison of Advanced Flexible Alternating Current Transmission System (FACTS) Devices with Conventional Technologies for Power System Stability Enhancement: An Updated Review

The continuously growing penetration of renewable energy sources (RESs) in electrical networks provides increasing challenges and critical situations to be managed by worldwide system operators. Due to their features and variability, non-programmable RES power plants, whose increasing penetration reduces the inertia level of the power system, may determine the instability effects on the grids, especially from the frequency and voltage regulation standpoints. The present study focuses on the support that advanced FACTS (Flexible Alternating Current Transmission System) devices, such as STATCOMs (Static Synchronous Compensators), can provide to the power system operation in terms of system inertia improvement, frequency stability, and voltage stability. In particular, a review of the scientific literature and practice is performed, with the aim of benchmarking the ongoing evolution of these technologies, also comparing them with different options based on synchronous condensers, synchronous condensers integrated with flywheels, and STATCOMs with supercapacitors. The outcome of the analysis consists of an updated evaluation of the state-of-the-art technological development in the field and of a comparison between different FACTSs with the purpose of identifying the most suitable solutions for different practical situations, also taking account of synergies across various options. This study includes an updated overview regarding the status of STATCOM installation in the Italian power grid.

Implementasi Metode Artificial Bee Colony Untuk Penempatan Distributed Generator Pada Penyulang Rayon Tanjung

Distributed Generation (DG) is a power plant that is spread over the power distribution network. In principle, electrical power output is generated by power plants located far from the load center and electrical power is transmitted to the load center through transmission and distribution networks. The longer the cable from the power plant or substation, the lower the voltage at the end load. Sub-optimal DG placement and size can result in increased power losses and affect the system voltage profile. In addition, suboptimal generation capacity can lead to voltage instability, reduced system security, and potential impacts on system frequency and emissions. Therefore, this study will use the Artificial Bee Colony (ABC) method to determine the optimal DG capacity and location. In the base case condition, the power losses in the system are 118 KW and 99 Kvar. Power losses after the installation of 1 DG active power loss becomes 37.4 KW and reactive power loss becomes 31.65 Kvar. Placement of 2 DGs reduces active power loss to 17 KW and reactive power loss to 15 Kvar. While the placement of 3 DG reduces active power loss to 33 KW and reactive power loss to 28 KVar.

Protecting Electrical Workers in Conducting Locations with Restricted Movements

Conducting Locations with Restricted Movements (CLRs) pose unique electrical hazards due to the extensive presence of grounded conductive materials with which a person is likely to come into contact and the restricted freedom of movement of workers within these spaces. Extended physical contact is not solely a result of spatial constraints. It could also be associated with the specific tasks that workers need to execute. An example of this is work conducted on a transmission tower. This paper investigates the electrical safety measures necessary to protect operators in such environments. By examining the role of body resistance and the impact of different current pathways, this author highlights the inadequacy of the conventional disconnection of supply fault protection measure in CLRs. The paper discusses protective strategies, including supplementary equipotential bonding, use of double or reinforced insulation, electrical separation, and extra-low voltage systems. These measures are critical in mitigating the risk of electric shock and ensuring safety of workers in CLRs.

Voltage and Fuel Utilization Control Strategy for Solid Oxide Fuel Cell Based on Active Disturbance Rejection Control

ABSTRACTSolid oxide fuel cell (SOFC) systems have become a research focus because of their clean and high‐efficiency properties. Control of output voltage and fuel utilization is critical to the energy management for multi‐energy systems incorporating SOFC energy supply. However, maintaining precise control of the system's voltage in the presence of perturbations can be challenging. Moreover, the system's voltage control process can lead to fuel utilization fluctuations, which may affect the economy and safety. The design of the controller must meet both of these requirements. The stringent control requirements lead to poor parameter adaptability of existing controllers. This paper designs a nonlinear function and adopts a nonlinear/linear active disturbance rejection controller (ADRC) based on state switching to solve the output voltage tracking control problem of SOFC and maintain the fuel utilization rate in the ideal range. The simulation experimental results show that the proposed method has the advantages of strong and superior parameter adaptability with less control effort, which provides theoretical guidance for the design of the output voltage controller of the actual SOFC system.

Grey wolf optimization for enhanced performance in wind power system with dual-star induction generators

This study investigates strategies for enhancing the performance of dual-star induction generators in wind power systems by optimizing the full control algorithm. The control mechanisms involved include the PID (Proportional-Integral-Derivative) controller for speed regulation and the PI (Proportional-Integral) controller for flux, DC-link voltage, and grid connection control. The primary objective is to optimize the entire system by fine-tuning PID and PI controllers through the application of meta-heuristic algorithms, specifically Grey Wolf Optimization (GWO) and Particle Swarm Optimization (PSO). These algorithms play a crucial role in estimating the optimal values of Kp, Ki, and Kd for the PID speed controller, as well as Kp and Ki for the PI controller used in the flux, DC-link voltage, and grid connection for wind energy conversion system based dual-star induction generator. This comprehensive optimization ensures accurate parameter tuning for optimal system performance. A comparative analysis of the optimization results has been conducted, focusing on the outcomes obtained with the GWO algorithm. The findings reveal a notable reduction in steady-state error, signifying improved stability, and an overall enhancement in the wind power system’s performance. This study contributes valuable insights into the effective application of meta-heuristic algorithms for optimizing dual-star induction generators in wind power systems.

A New Magnetic Coupler with High Misalignment Tolerance and Inherent Constant Current–Constant Voltage for Underground Wireless Charging

In an underground inductive power transfer (IPT), it is inevitable to produce the phenomenon of misalignment between the transmitter and the receiver, which will reduce the output current, voltage and output efficiency of the whole IPT system. Aiming to solve this problem, a universal hybrid coupler is proposed, which can still stabilize the output in the expected range and has the ability of anti-misalignment when the X and Z directions are misaligned. The coupler is composed of a BP coupler and Γ type network. The secondary edge of the coupler introduces a Γ network, which decouples the two main coils on the same side of the receiver from the auxiliary coil and reduces the complexity of the system. The coupler can effectively reduce the coupling fluctuation caused by physical movement between the downhole transmitting end and the receiving end, thereby ensuring the stable output of the coupler. As a widely used IPT system, it can access the rest of the circuit topology whose output is independent of the load and achieve misalignment-tolerant output. Finally, based on the proposed hybrid IPT coupler theory, a 500 W misalignment-tolerant coupler prototype was built, and the compensation topologies were configured as series–series (SS) and series/inductance/capacitance/capacitor (S/LCC) structures. When the X and Z direction is misaligned, the constant current and voltage independent of the load can be output by switching the compensation topology. The experimental results are the same as the theoretical analysis.

Semiconducting minerals participated extracellular electron transfer in red soil of Ningxia Plain, China

In recent years, exploring interactions between sunlight, semiconducting minerals and microorganisms in nature has attracted great attention. However, relatively little research has been conducted on the interaction between minerals and microorganisms in the plain areas of the Yellow River Basin under sunlight. In this study, the mineral composition and microbial community of red soil from the Ningxia Plain, China were analyzed. X–ray diffraction (XRD) results showed that red soil contained semiconducting minerals such as birnessite, hematite and goethite. 16S rRNA analysis found that electroactive microorganisms such as Proteobacteria, Firmicutes and Actinobacteriota were enriched in in–situ microbial community of red soil. Afterwards, electrochemical tests such as linear sweep voltammetry (LSV) and I–t curves, indicated that red soil exhibited good semiconducting properties under light irradiation. Finally, a dual chamber system and electrochemical techniques were used to explore the electron transfer relationship between red soil and microorganisms. The open circuit voltage (350 mV) and maximum power density (1242.72 mW/m2) of red soil cathode system were significantly improved compared to blank graphite electrode, indicating that red soil could serve as electron acceptors for microbial extracellular respiration. Red soil electrode in live bacteria exhibited the highest photocurrent density (0.29 μA/cm2) and the lowest charge transfer resistance (Rct) (223 Ω) under light conditions, indicating that red soil accelerated the rapid transfer of electrons, reduced polarization loss, and enhanced extracellular electron transfer (EET) process under light conditions. This study demonstrated that the participation of semiconducting minerals in microbial EET processes under sunlight in the Ningxia Plain, China.

The Biomimetic Electrical Stimulation System Inducing Osteogenic Differentiations of BMSCs.

Electrical stimulation has been used clinically as an adjunct therapy to accelerate the healing of bone defects, and its mechanism requires further investigations. The complexity of the physiological microenvironment makes it challenging to study the effect of electrical signal on cells alone. Therefore, an artificial system mimicking cell microenvironment in vitro was developed to address this issue. In this work, a novel electrical stimulation system was constructed based on polypyrrole nanowires (ppyNWs) with a high aspect ratio. Synthesized ppyNWs formed a conductive network in the composited hydrogel which contained modified gelatin with methacrylate, providing a conductive cell culture matrix for bone marrow mesenchymal stem cells. The dual-network conductive hydrogel had improved mechanical, electrical, and hydrophilic properties. It was able to imitate the three-dimensional structure of the cell microenvironment and allowed adjustable electrical stimulations in the following system. This hydrogel was integrated with cell culture plates, platinum electrodes, copper wires, and external power sources to construct the artificial electrical stimulation system. The optimum voltage of the electrical stimulation system was determined to be 2 V, which exhibited remarkable biocompatibility. Moreover, this system had significant promotion in cell spreading, osteogenic makers, and bone-related gene expression of stem cells. RNA-seq analysis revealed that osteogenesis was correlated to Notch, BMP/Smad, and calcium signal pathways. It was proven that this biomimetic system could regulate the osteogenesis procedure, and it provided further information about how the electrical signal regulates osteogenic differentiations.