Reactive Energy Research Articles

Energy Storage‐Reactive Power Optimal Configuration for High Proportion New Energy Distribution Network Considering Voltage Quality and Flexibility

The increasing penetration rate of distributed energy brings more complex problems of voltage quality, safety and stability to the distribution network. A single optimal configuration of reactive power or energy storage is difficult to meet the increasingly diversified needs of modern power grids. This paper proposes a configuration strategy combining energy storage and reactive power to meet the needs of new energy distribution networks in terms of active power regulation and reactive power compensation, and to achieve tradeoff optimization in flexibility, voltage quality and economy, so as to adapt to the influence of new energy with different permeability. Firstly, the safety and stability evaluation system of distribution network is established with the target of flexibility demand and reactive power demand. Secondly, considering the coupling of planning layer and operation layer, a two‐layer model of energy‐reactive power optimization is established. After that, the gray wolf algorithm is used to solve the model, which enhances the global space exploration ability and reduces the possibility of falling into the local optimal. Finally, the improved IEEE33 node power distribution system is used for simulation test to verify the rationality and effectiveness of this scheme. The simulation results show that the scheme proposed in this paper can effectively improve the economy, security and stability of the distribution network, and can obtain an optimal configuration scheme with multi‐objective considerations under different new energy penetration rates. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Explicit Definitions for the Electromagnetic Energies in Electromagnetic Radiation and Mutual Coupling

It is still difficult to accurately evaluate the reactive electromagnetic energy and the radiative electromagnetic energy of a radiator, because there are no explicit expressions for them. This paper proposes to borrow the energy concept in the charged particle theory and separate the total electromagnetic energy of a radiator into three parts: a Coulomb–velocity energy, a radiative energy and a macroscopic Schott energy. Consequently, the Poynting vector is considered to include a real radiative power flow by the radiative energy and a pseudo power flow caused by the fluctuation of the reactive energy. The energies involved in the electromagnetic mutual coupling are separated in a similar way. All energies are defined with explicit expressions in which the vector potential plays an important role. The time domain formulation and the frequency domain formulation of the theory are consistent with each other. The theory is verified with the Hertzian dipole. Numerical examples demonstrate that this theory may provide proper interpretations for electromagnetic radiation and mutual coupling problems.

Management of electric vehicle charging stations in low-voltage distribution networks integrated with wind turbine–battery energy storage systems using metaheuristic optimization

This study investigates the IEEE 69-bus distribution network with three wind turbines (WTs) connected at the same buses of three battery energy storage systems (BESSs), with three 20- or 30-outlet electric vehicle charging stations (EVCSs) for charging electric vehicles (EVs). The honey badger algorithm (HBA) is adopted to minimize daily energy loss. The HBA determines the best size and position for three WT-BESS buses and three EVCS buses. The HBA calculates BESS size and operation mode to minimize daily energy loss. The demand of EVCSs varies throughout the day depending on the random choice of the number and state of charge of EVs entering the station. This results in the active and reactive energy losses and utility input energy decreasing by 63.5%, 60.6% and 59.6%, respectively, and the minimum voltage increasing from 0.9256 to 0.9839 pu. The network voltage profile and stability are also improved.

The evaluation of main results of the RMO Key and Supplementary comparisons for electrical power and energy

To overcome technical barriers in trade between countries, special international agreements on mutual recognition (MRA) of measurement results play an important role. National Metrology Institutes (NMIs) and Designated Institutes (DIs) play a major role in the implementation of these agreements. NMI and DI standards periodically participate in international comparisons to establish their equivalence to other similar standards. A comparative analysis of the results of NMI/DI participants of COOMET.EM-K5 of alternating current active power and GULFMET.EM-S5 of alternating current active and reactive energy comparisons, both in terms of regional and metrological traceability for Regional Metrology Organizations, was carried out. This analysis is related to the need to minimize the cost of NMIs/DIs in order to achieve the required metrological traceability, taking into account the geographical location of the leading NMIs. For checking consistency of these comparisons data ware used En number and z scores. The results for all participants of the comparisons are satisfactory both for En number and z scores.

Melatonin retards leaf senescence by modulating phytohormones metabolism in stored Chinese flowering cabbage

Abstract This paper was conducted to explore the effects of melatonin (MT) on the senescence of stored Chinese flowering cabbage and the potential modulatory mechanisms involved. The physiological findings demonstrated that MT successfully reduced chlorophyll loss and improved the photochemical effectiveness of cabbage leaves. In addition, MT decreased the transcription of senescence-associated genes (BrSAG12) and genes responsible for chlorophyll breakdown. Transcriptome analysis showed that MT-regulated genes were enriched in oxidative phosphorylation, hormone metabolism and signal transduction, and MT treatment reduced the high expression of genes linked to reactive oxygen species generation, energy metabolism, phytohormone (abscisic acid (ABA), ethylene (ET) and Jasmonic acid (JA)) biological synthesis and signal transduction, whilst promoting the activation of genes related to ROS scavenging, energy biosynthesis and plant-pathogen interactions. We emphasized the examination of the potential interaction between phytohormones metabolism and MT. Results showed that the application of MT decreased ABA, ET and JA levels as well as the expression of their biosynthesis genes, concurrently maintaining higher expression of cytokinin (CTK), auxin (IAA) and gibberellin (GA) biosynthetic genes and lower expression of degradation genes. Regulatory networks of transcription factors (TFs) and genes related to ABA, ET and JA metabolism showed that TFs such as DNA-binding One Zinc Finger 5.7 (DOF5.7), WRKY40 and homeobox-leucine zipper protein-16 (ATHB-16) might play important transcriptional regulatory roles in mediating MT postponed leaf senescence. Taken together, these findings suggested that the postponed senescence of cabbage treated with MT might be ascribed to the regulated oxidative phosphorylation, energy, phytohormone metabolism and transcription factors.

Mechanistic investigation of hydrogen generation from water and magnesium catalyst reaction: Advanced reactive molecular dynamics simulation

Magnesium is an effective catalyst for producing hydrogen through thermochemical water splitting. However, the slow reaction between Mg and water prevents this catalyst from being commercially useful. In this study, reactive MD simulations with accurate force fields and reactive potential energy surfaces are used to comprehend the slow-kinetics of the Mg-water reaction. At room temperature, water is split when it interacts with Mg nanoparticles and forms a Mg–H bond. Furthermore, at temperatures above 1200 K, Mg–H bonds begin to dissociate, resulting in the generation of hydrogen radicals from the Mg–H bond. The percentage of H–H bonds is almost zero until the reaction pathway reaches temperature 2000K, after which H radicals combine to form hydrogen gas. The analysis of temperature dependent data reveals that oxygen and hydrogen atoms combine with Mg elements to form massive stable linear and branched chains, resulting in slow Mg-water reaction kinetics for hydrogen production. Therefore, current studies utilizing reactive molecular dynamics can provide a means of improving the kinetics of the Mg-water reaction.

Enhanced cytotoxicity to lung cancer cells by mitochondrial delivery of camptothecin

Delivering traditional DNA-damaging anticancer drugs into mitochondria to damage mitochondria is a promising chemotherapy strategy. The impermeability of this mitochondrial inner membrane, however, impedes the delivery of drug molecules that could impact other important biological roles of mitochondria. Herein, the prodrug camptothecin (CPT)-triphenylphosphine (TPP) modified with hyaluronic acid (HA) via electrostatic adsorption (HA/CPT-TPP, HCT) was used to mediate the mitochondrial accumulation of CPT. These nanoparticles (NPs) showed enhanced drug accumulation in cancer cells through tumor targeting. HCT entered acidic lysosomes through endosomal transport, HA was degraded by hyaluronidase (HAase) in acidic lysosomes, and the positively charged CPT-TPP was exposed and accumulated fully in the mitochondria. Subsequently, CPT-TPP significantly disrupted the mitochondrial structure and damaged mitochondrial function, leading to increased reactive oxygen species (ROS) levels and energy depletion. Finally, HCT enhanced lung cancer cell apoptosis via the activation of caspase-3 and caspase-9. Furthermore, greatly increased tumor growth inhibition was observed in nude mice bearing A549 xenograft tumors after the administration of HCT via tail injection. This study demonstrated that the mitochondria-targeted delivery of CPT may be a promising antitumor therapeutic strategy.

Role of bioconvection and activation energy on MHD flow of Maxwell’s nanofluid with gyrotactic microorganisms in porous media: The Cattaneo–Christov model

This study examines and analyzes the impact of MHD and bioconvection on Maxwell’s nanofluid flow in a porous medium that contains gyrotactic microorganisms. In addition, more study on chemically reactive activation energy and Cattaneo–Christov heat flux is conducted, and the conclusions from this research are presented. The bioconvection flow of Maxwell nanofluids over a stretched sheet is presented by highly nonlinear partial differential equations, which are reduced to ordinary differential equations using suitable similarity transformations. A shooting method based on the Runge–Kutta technique is used to overcome the issue. The outcomes are graphically represented and explored numerically in detail for the relevant parameters’ impact on the velocity, temperature, concentration, and motile microorganisms profiles. Results reveal that the velocity profile is decreased by increasing the magnetic parameter, while those enhanced by the mixed convection parameters. The thermal boundary thickness and temperature profile negatively correlate with the thermal relaxation time and Prandtl number and are proportional to the magnetic parameter. Boosting the Brownian motion parameter, Deborah number, and thermophoresis parameter improves heat transport. The activation energy and Prandtl parameters show an upward trend in concentration profiles. The density of the motile microorganisms is a decreasing function of Lewis and Peclet numbers.

Confirmation of n‐Hexane as an Inert Co‐Solvent in the Production of Functionalized Silicon Nanoparticles from Reactive High‐Energy Ball Milling

AbstractAlkanes such as n‐hexane have been used as co‐solvents in the production of functionalized semiconductor nanoparticles from alkenes and alkynes using Reactive High Energy Ball Milling (RHEBM) under the assumption that they are non‐reactive under typical milling conditions. In this paper, a comparative study with two hydrocarbon solvents of comparable chain length, 1‐hexyne, and n‐hexane, and their milling products using three different commercially available silicon precursors, namely single crystal silicon wafers and polycrystalline particles having a nominal size of 4 µm and 1 mm, is reported. It is found that nanoparticle formation and surface functionalization in all the three silicon systems occurs only with 1‐hexyne; n‐hexane is non‐reactive and does not lead to appreciable functionalized nanoparticle formation under the conditions studied. Nanoparticles (where formed) and microparticle byproducts of appropriate samples are characterized by Transmission electronic microscope (TEM), Fourier transform infrared (FTIR), Photoluminiscence spectroscopy (PL), Nuclear magnetic resonance 1H/13C NMR, and thermogravimetry TGA to separately confirm nanoparticle formation and surface functionalization.

Impacts of Exponentially Growing/Decaying Pressure Gradient on Mixed Convection Flow of Viscous Reactive Fluid in a Vertical Tube: A Numerical Approach

This study examined the effects of a pressure gradient that was exponentially increasing or decreasing on the mixed convection flow of viscous reactive fluids in a vertical tube between two concentric tubes with r = 0 and r = b. The nonlinear partial differential equation governing the flow formation are solved using the implicit finite difference form where all time differentials were calculated using the forward difference formula, and second order central differences were utilized to approximate the first and second derivatives. The impacts of several physical parameters, including shear stress, the rate of heat transfer, mixed convection, viscous reactive fluid parameter, activation energy, Prandtl number, and exponential decaying/growing pressure gradient on skin friction and Nusselt number were investigated. It's intriguing to see that raising the values of Frank–Kamenetskii (λ), mixed convection (Gre) as well as exponential growing pressure term increases the velocity fluid, However, in the case of exponential decay, the parameter drop also causes the fluid's velocity to diminish. The results also showed that a small bump in the viscous reactive fluid parameter considerably improves the energy profile.

Molecular structure, electronic, topology and non-covalent interaction of 4-(Bis(2-chloroethyl)amino)-L-phenylalanine- Anti-blood cancer activity

In this study, it is attempted to scrutinize the global minimum energy structure of anti-blood cancer drug 4-(Bis(2-chloroethyl)amino)-L-phenylalanine (4B2CA-LPA) and functionalized density functional theory (DFT) calculations regarding their geometries, topological features of covalent, non-covalent interactions with employing Atoms in molecule (AIM) and Reduced density gradient (RDG) studies. As per the topological results, a new type of non-covalent attraction forces of hydrogen-hydrogen interaction was found in this molecule. Electrostatic potential variation as well as global reactive descriptor energy variations in the solvation phases was carried out by molecular electrostatic potential (MEP) and frontier molecular orbitals (FMOs) analysis. Moreover, the electronic excitations in liquids of 4B2CA-LPA were evaluated in UV-Vis absorptions. The local bonding electron transitions and optical properties of the compound were examined with natural bond orbital (NBO) studies. The 4B2CA-LPA molecule can serve as lead molecules for the growth of anti-blood cancer drugs. Molecular docking investigation has also been carried out to determine the ability of target molecules to bind with Hematopoietic inhibitors in blood cells.

A stratified flow of a non-Newtonian Casson fluid comprising microorganisms on a stretching sheet with activation energy

A stratified flow may be seen regularly in a number of significant industrial operations. For instance, the stratified flow regime is typically used by gas-condensate pipelines. Clearly, only a limited set of working situations for which this flow arrangement is stable allow for the achievement of the stratified two-phase flow zone. In this paper, the authors are considered the laminar, steady and incompressible magnetohydrodynamic flow of a non-Newtonian Casson fluid flow past a stratified extending sheet. The features of bio-convection, Brownian motion, thermal radiation thermophoresis, heat source, and chemically reactive activation energy have been employed. The set of equations administered flow of fluid is converted into ordinary differential equation by suitable variables. A semi-analytical investigation of the present analysis is performed with homotopy analysis method. Endorsement of the current results with previous results is also investigated. The outcomes showed that the velocity distribution of the fluid flow lessens with higher Casson and magnetic factors. The temperature profiles of fluid flow shrinkage as the Prandtl number and Casson factor increase and enlarges with higher values of thermal radiation, magnetic, and Brownian motion factors. It is found that the growing thermophoretic and Brownian motion factors reduce the rate of thermal flow of the Casson fluid flow. In contrast, the increasing thermal stratification parameter increases the thermal flow rate of fluid.

Contribution of STATCOM To Improving The Behavior Of High Voltage AC Networks

This work proposes the application of a STATCOM for reactive energy compensation; its dynamic behavior will be verified by simulations under the MATLAB/SIMULINK environment. The circulation of reactive energy in an electrical network causes voltage drops between two ends, therefore the active power transported decreases, and to deal with this problem several classic solutions have beenadopted. The STATCOM "static synchronous compensator" is a type of FACTS placed as a shunt, which can remedy the problem of the circulation of reactive energy, and the regulation of the voltage.

Cell-Free Mitochondrial DNA as a Novel biomarker for stress-related conditions - Meta-Analysis

Mitochondria is a central organelle that regulates various physiological functions of the cell, like Reactive oxygen species (ROS) generation, apoptosis, and energy metabolism; its dysfunction due to various stress factors will result in compromised O2 regulation, mitochondrial-related diseases and other conditions. Few studies have shown that Circulating cell-free mitochondrial DNA(CFmt-DNA) content in body fluids will change many stress, environmental and exercise needs. In this study, we aim to understand the relationship between CFmt-DNA and various stress conditions like Alzheimer's disease, Acute Appendicitis, strenuous exercise, major depressive disorder etc. This meta-analysis is done by PRISMA standards, and a specified methodology was used to conduct the study. We looked for relevant studies up to August 2022 in PubMed, Web of Science, and Science direct ELSEVIER. Meta Mar web tool was used to analyse the data. Additionally, research on publication bias was also done. After the initial search, a total of 832 articles were identified. Six articles were chosen for our meta-analysis after filtering out meta-analyses or reviews (165 publications), erroneous data (591 publications) and studies that lacked access to raw data (73 publications). Data from six studies were combined to compare the normalised CFmt-DNA copy numbers between the experimental group under various stress conditions and the control group. The copy number of CFmt-DNA did not differ significantly in comparison between the control and the experimental; the Standardized Mean Difference (SMD) was −1.38 (95% CI, −3.56 to 0.79), P = 0.1699 (P > 0.05) in the random effect model. The results of the random effects analysis showed that the study has heterogeneity in the research (I2 = 96%, P < 0.01). In the subgroup analysis, the sample collected from Cerebrospinal fluid (CSF), Tissue and Ex vivo lung perfusion (EVLPP) were statistically significant (P < 0.05). In conclusion, CFmt-DNA can be used as a potential biomarker even if there are variations in copy number. The copy number of CFmt-DNA is influenced by the stress situation and the biological source of the sample.

ЕЛЕКТРОМАГНІТНІ ПРОЦЕСИ У ТРИФАЗНОМУ МОСТОВОМУ КОМПЕНСАЦІЙНОМУ ПЕРЕТВОРЮВАЧІ

Electromagnetic processes are investigated in two versions of a three-phase bridge converter with improved energy characteristics, one of which contains one switching link, and the other two. The commutating link consists of a three-phase capacitor battery and a three-phase group of fully controlled devices. This technical solution makes it possible to ensure the recharging of the capacitors of the commutating link and the control of the energy process of the converter. The main content of the study is the analysis of electromagnetic processes in terms of the features of commutating processes and the proof of the energy capabilities of the options for implementing the converter. The amount of scientific research required for this is divided into three options. Each takes into account the peculiarities of electromagnetic processes associated with different modes of operation of converters, at different frequencies of control pulses of transistors of a commutating link and a shift in the moment of switching on transistors relative to the interval of operation of power electric diodes. As a result, a generalized mathematical model was created. She describes a variety of electromagnetic processes in converters, allows you to calculate the commutating and adjustment angles. They are the main characteristics of the energy process and prove that the developed versions of the converter are compensation. They are able not only to compensate for their own reactive energy, but also, if necessary, to generate reactive energy to the grid. References 12, figures 2, table 1.

RESEARCH OF VALVE MOTOR CONVERTER CONTROL METHODS

A technique for selecting the electrical equipment of a valve motor with machine commutation has been developed, which takes into account the ways of controlling the inverter. The installed capacity of the electrical equipment of the valve motor (VD) is determined by technological requirements and depends on the structure of the converter, the method of commutation of the converter keys and the methods of controlling the inverter. The use of autonomous inverters with artificial switching, the keys of which are switched due to the reactive energy accumulated in additional switching devices, increases the utilization factor of the synchronous machine. However, in this case, the circuit becomes more complicated and the installed power of the converter increases. The use of IGBT transistors and IGCT thyristors leads to a significant increase in the cost of the equipment.&#x0D; To reduce the influence of the rectifier VD on the network and match the drive voltage with the supply voltage, a matching transformer and reactive power compensation device may be needed. The amount of power of this equipment is affected by the method of controlling the rectifier, the nature of the engine load and the range of speed changes.&#x0D; Voltage regulation of the rectifier can be symmetrical or asymmetrical. Several methods of asymmetric regulation are known, among which one of the most expedient is alternating. In the case of alternating control in the three-phase bridge circuit, an artificial zero circuit is created, as a result of which the duration of the current flowing through the secondary windings of the transformer becomes less than 2/3 of the half-cycle of the supply voltage. In addition, the energy indicators also increase, in particular, the reactive power consumption decreases and the shift and power coefficients increase.

Robust cascade controller for the power factor of the three-phase supply and the induction motor velocity

It is well known that induction motors consume active and reactive energy from the utility grid to operate; additionally, when a power converter drives the motor, a high content of current harmonics is produced, and both circumstances decrease the utility grid power factor, which later requires to be improved. To this end, this paper presents a novel complete solution through a robust control system employed in a back-to-back topology power converter to deliver, instead of consuming, regulated reactive power toward the main grid, which comes from a capacitor bank in a DC-bus. This salient feature of delivering reactive power, and simultaneously, regulating the speed for an induction motor, becomes one of the contributions of this work to enhance the power factor. The robust converter controller is synthesized in a cascade form, by applying the linearization block control and state-feedback techniques. These techniques are combined with the super-twisting strategy for canceling the nonlinearities and the effect of the external disturbances. The complete system consists of a back-to-back converter, an LCL filter coupled to the main grid for mitigating the current harmonic content, and an induction motor under variable load conditions. Experimental tests expose the performance and robustness of the proposed controller, where a robust control for the reactive power acts under sudden changes in the active power produced through abrupt variations in the motor load.

Estimation of Stator and Magnet Temperatures of IPMSM From Active and Reactive Energies at Medium and High Speeds

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Interior Permanent magnet synchronous machines have a wide range of applications, such as in electric vehicles, home appliances, and robots, because of their high torque density and wide operating speed range. In the case of machines, the stator winding and magnet temperatures are generally crucial to guarantee the system’s safety and control accuracy. This study developed a method to estimate magnet and stator winding temperature by analyzing reactive and active energies. First, IPMSM Model involving stator winding and magnet temperatures was derived. In the derived IPMSM model with temperatures, a relationship between reactive energy and magnet temperature was found. Based on the relationship, magnet temperature can be estimated regardless of stator resistance information. Stator winding temperature is estimated based on the active energy by using the estimated magnet temperature. As a result, the proposed method can estimate magnet and stator temperatures simultaneously, considering the speed effect on motor parameters and inductance variation with the magnet temperature. Online estimation was performed to demonstrate the feasibility and validity of the proposed method. Through the online estimation, the maximum estimation errors in magnet and stator temperatures are less than 5 °C and 10 °C, respectively</i> .

Objective molecular dynamics investigation of dissociation and recombination kinetics in high-temperature nitrogen

In this study, we propose the use of the novel approach of objective molecular dynamics (OMD) simulating far-from-equilibrium gas dynamics problems with chemical reactions. The OMD method has an exact relation to models in continuum mechanics and can be used to improve those models. We provide a detailed molecular dynamics investigation of chemically reacting nitrogen gas in a space-homogeneous adiabatic reactor. The analysis is based on a first-principles derived reactive ReaxFF potential energy surface, which captures the relevant processes of rovibrational relaxation, dissociation, and exchange as well as recombination in a gas evolving under non-equilibrium conditions. We examine the evolution of the internal mode population distribution of all the molecules as well as the rovibrational probability distribution of the pre-collision dissociating and post-collision recombined N2 molecules to investigate the microscopic selectivity of various reactive processes. Subsequently, we make comparisons with results obtained by means of an alternative modeling approach called direct molecular simulation. The current work illustrates the application of the method of OMD to study the compression and expansion kinetics of dissociation-recombination nitrogen mixture relevant to normal shock wave and nozzle expansion.

Determination of a New Performance Indicator for the Assessment of Stand-Alone PV System

The use of stand-alone PV systems (SAPV) must be efficient and profitable for a better integration of solar energy in the global energy mix. However, the performance indicators that allow the evaluation of SAPV systems do not clearly inform us about the actual level of use of their sized and installed capacity. This article aims to determine a new performance indicator, called the theoretical power factor (TPF) by an original method based on the modelling of the SAPV system in the form of a matrix equation. The resolution of this matrix equation, makes it possible to bring out the reactive energy of the system during operation. A case study is presented and scenario I represents the case where the main elements are all assumed to operate at their rated capacity. scenario II represents the case were the rated capacity of storage system is reduced of 40%, scenario III represents the case were the rated current capacity of charge controller is reduced of 40%, and finally scenario IV represents the case were the rated power capacity of inverter is also reduced of 40%. The results obtained after implementation in the Spyder environment (python 5.1) show the effectiveness of TPF in the performance evaluation of SAPV systems. And also show how the TPF is substantially related to the capacity of each main element of the system. This being proved by the results obtained after the simulation of the four scenarios mentioned above. One can observe an increase in TPF of 0.1% in Scenario II during the period of low irradiance, and no change in TPF for the other scenarios in the same period. During the period of high irradiance, an increase in TPF of 17.9% is observed in scenario II and a decrease in TPF of 15.4% and 1.2% respectively in scenarios III and IV.