Current Components Research Articles

A fast, simple and local protection scheme for fault detection and classification during power swings based on differential current component

Among the various challenges of transmission line distance protection, it has become increasingly difficult to deal with the symmetrical phenomenon of power swing (PS) and it can lead to maloperation of distance relays and power system blackout. Distance relays have challenges in distinguishing the symmetrical fault during power swing and would send a wrong trip command to the circuit breakers, leading to major blackouts. To solve this issue, the main objective of this study is to provide a fast, simple, and local protection scheme based on differential current component (DCC), which is extracted by the difference in predicted and actual samples of local current component. Autoregression technique is used to predict the future cycle current samples using available samples. Based on the DCC, a novel index named differential current component ratio (DCCR) is introduced to effectively detect the internal symmetrical faults from fast/slow power swing conditions. Several tests are run for different fault types, different power swing frequencies, different fault locations, different fault resistances and different fault inception instants. Finally, the results are compared with the available methods. Results demonstrate the high accuracy of the proposed method in fast and accurate detection of internal symmetrical faults during power swing in different frequency rates in less than one cycle.

A synchronization method based on current orthogonal decomposition considering harmonic components for wireless power transfer system

AbstractIn order to improve the wireless power transfer (WPT) system, an active rectifier is commonly used. Synchronization technology is critical for active rectifier. The traditional synchronization method based on zero‐crossing detection (ZCD) is unstable and not suitable for the case with lots of harmonic component in the resonant current. Here, a new synchronization method with harmonic compensation is proposed for the WPT system without the ZCD of the resonant current. A mathematical model is built to analyse and compensate the impact caused by the harmonic on phase angle. Therefore, the proposed method can be applied to the high‐order resonant network like LCC compensated topology where the harmonic component is rich in the resonant current. For verifying the proposed synchronization method, a laboratory prototype is built. The experimental results prove that the system can operate stably with parameter perturbation and different load. The peak transfer efficiency of the system can achieve the 94.5%.

Advances in mRNA LNP-Based Cancer Vaccines: Mechanisms, Formulation Aspects, Challenges, and Future Directions

After the COVID-19 pandemic, mRNA-based vaccines have emerged as a revolutionary technology in immunization and vaccination. These vaccines have shown remarkable efficacy against the virus and opened up avenues for their possible application in other diseases. This has renewed interest and investment in mRNA vaccine research and development, attracting the scientific community to explore all its other applications beyond infectious diseases. Recently, researchers have focused on the possibility of adapting this vaccination approach to cancer immunotherapy. While there is a huge potential, challenges still remain in the design and optimization of the synthetic mRNA molecules and the lipid nanoparticle delivery system required to ensure the adequate elicitation of the immune response and the successful eradication of tumors. This review points out the basic mechanisms of mRNA-LNP vaccines in cancer immunotherapy and recent approaches in mRNA vaccine design. This review displays the current mRNA modifications and lipid nanoparticle components and how these factors affect vaccine efficacy. Furthermore, this review discusses the future directions and clinical applications of mRNA-LNP vaccines in cancer treatment.

A low-cost strategy for systematically removing DC short-circuit currents in AC/DC-HDN

For any practically applied AC/DC hybrid distribution network (AC/DC-HDN), the hard issue of removing DC short-circuit currents must be solved by a cost-effective scheme. However, up to now, in the most published achievements of AC/DC-HDN, the systematic scheme to address the above issue is rarely found. This paper proposes a novel strategy with a low cost for solving this problem. The proposed strategy can: (i) greatly decrease the DC short-circuit current components flowing from the AC/DC converters to the fault point, (ii) fast switch off the paths of DC short-circuit current components from DG branches to the fault point, (iii) completely block the DC short-circuit current components that feed into the fault point from the capacitors paralleled on the DC ports of load branches. Also, in this paper, a new topology of DC/DC converter with a controlled zero-current output function is proposed for fast switching off the paths of DC short-circuit current components from DG branches to the fault point. The scheme of relay protection and automatic control matching with the proposed strategy is designed. The principles of the scheme and design are explained in detail. The simulation results verified the effectiveness of the proposed strategy are given.

Solid and hollow plasmonic nanoresonators for carrier envelope phase read-out

The geometry of gold plasmonic nanoantennae was numerically optimized to maximize their sensitivity to the carrier envelope phase (CEP) of the exciting ultra-short laser pulses. Three structure types, triangular, teardrop-shaped and plasmonic lens, were optimized in solid and hollow compositions as well. Hollow / solid singlets results in the largest/intermediate CEP dependent (Q1) – to – CEP independent (Q0) integrated current components’ ratio, while their Q1 was the smallest / intermediate. The largest / intermediate Q12/Q0 CEP sensitivity was achieved via solid / hollow plasmonic lenses due to their large near-field enhancement and Q1, while the Q1/Q0 ratio was smaller than for counterpart singlets.

Power Quality Improvement Using a Novel Simplified Adaptive Control of Solar PV Integrated Shunt Active Power Filter

ABSTRACTPower quality improvement in grid‐tied solar photovoltaic (PV) system is one of the emergent current research trends. To address the power quality concern, shunt active power filters (SAPF) are widely deployed and researched in grid‐tied PV systems. This paper presents a simplified adaptive transversal (SAT)‐filter control scheme for the two‐stage PV‐SAPF system. The proposed control has the ability to improve different power quality indices. Also, it features faster operation under steady‐state and under dynamic conditions, better dc‐offset rejection ability due to estimation of the accurate fundamental component of the load current. To justify the effectiveness of the proposed control scheme, a thorough comparison is carried out with different conventional and adaptive control schemes. Simulations and extensive experimental analysis are carried out under severe transient conditions such as balanced‐unbalanced supply, sudden load, and irradiation change scenario.

Short‐circuit current of a hydropower plant with consideration of constant switching and fault arc voltages

AbstractThe correct generator circuit breaker (GCB) dimensioning is essential for the safe and reliable operation of a power plant or generation system. The dimensioning is usually based on standardized calculation methods according to standards (IEC standard 60909‐0, IEC/IEEE standard 62271‐37‐013, IEEE Std C37), often supplemented by selected transient calculations. A non‐systematic approach can often be observed here, which does not adequately take into account significant influencing variables or operating states of the generator. This article therefore systematically examines various parameters that influence the short‐circuit current components of the generator and are relevant for the dimensioning of the generator circuit‐breaker: short‐circuit angle, operating point, impedance ratios, phase clearing, switching arc, and fault arc. The results of the current parameters most relevant to the dimensioning of the GCB were then compared for different calculation methods. Special attention was paid to the effect of the switching and fault arc, which were modelled as a constant arc voltage, and its effect on the short‐circuit currents is systematically recorded. This work aims to summarize all relevant variables that influence the generator short‐circuit current and are relevant for the dimensioning of the GCB and to present the different results based on a short‐circuit calculation according to the standard and transient calculation to create a basis for a proper dimensioning of the generator circuit breaker.

Acceptance as a possible link between past psychedelic experiences and psychological flexibility

Increased psychological flexibility (PF) may underlie the lasting positive effects of psychedelic experiences on mental well-being. The associations between different components of PF, psychological inflexibility (PI), and well-being with psychedelic use are not well understood. We conducted a cross-sectional internet survey of participants (N = 629) with experience of classical psychedelics. Using network analysis, we examined how aspects of a single psychedelic experience (mystical-type features and psychological insights) and the frequency of past psychedelic use, were associated with current PF and PI components, as well as with mental well-being and ill-being. Mediation analyses explored whether PF mediated the relationship between past psychedelic use and well-being or ill-being. The network analysis linked psychological insight to the PF component Acceptance, with no association found between the frequency of past use and PF. Mediation analyses showed PF mediates the association between past psychedelic use and well-being and ill-being. These results suggest that the quality and depth of the psychedelic experience, rather than the frequency of use, are primarily linked to psychological flexibility, particularly Acceptance, and overall well-being. This underscores the importance of treating PF as a multidimensional construct to better understand the long-term mental health benefits of psychedelics.

Understanding Environmental Barrier Coating Lifetimes and Performance for Industrial Gas Turbines

Abstract Hydrogen or hydrogen blend fuels are expected to replace natural gas in land-based industrial gas turbines (IGTs) to support a greener power economy. Silicon carbide (SiC) base ceramic matrix composites (CMCs) are considered for replacement of Ni-based superalloys to facilitate future efficiency improvements. SiC CMCs require environmental barrier coatings (EBCs) to mitigate volatilization from high-temperature steam, thus making the EBC lifetime critical information for identifying CMC component lifetimes. The goal of this project is to determine the maximum bond coating temperature underneath the EBC for achieving an IGT component lifetime goal of 25,000 h, which is far greater than current CMC component lifetime requirements for aeroturbine applications. To provide data for the lifetime model, laboratory testing used atmospheric plasma-sprayed rare-earth silicate EBCs on monolithic SiC substrates with an intermediate Si bond coating. Specimens exposed to 1-h thermal cycles in flowing air–steam environments and reaction kinetics were assessed from 700 °C to 1350 °C by measuring the thickness of the thermally grown silica scales. The silica growth and phase transformation appear critical in predicting EBC lifetime and several strategies have been explored to reduce the oxide growth rate and improve EBC durability at elevated temperatures. Advanced characterization using Raman spectroscopy has helped clarify this system.

Quo Vadis, Elimination Voltammetry?

The article presents an open personal approach to the future of elimination voltammetry with linear scan (EVLS) in the context of the expected development and research of new materials and new technologies. With this development, the application capability of EVLS will be expanded, the basis of which is a mathematical apparatus that allows some current components to be eliminated from the overall voltammetric record, while others to be preserved. Although EVLS played a provisional and unquestionable role in electroanalytical applications, where it helped to obtain lower limits of detection (LOD) values of various organic and inorganic substances and to reveal electrode processes hidden in voltammetric signals, its further development indicates promising use in other research areas as well. The aim of the communication is a more precise but also more general definition of the elimination method, its specific paradigms, prospects and goals for the future.

Harmonics Measurement Errors in Grids with High Presence of Power Electronics Converters

The article presents field results and discusses the harmonic measurement errors of power quality analyzers (PQA) due to sampling aliasing of currents and voltages in grids with the presence of power electronics converters (PEC). The PQA may imply non-existing harmonic components incorrectly depending on the sampling rate of the PQA and the switching frequency of the PEC. Such phenomenon is prone to become more common and unpredictable due to the amplification of high-frequency components in voltages and currents due to interactions between PEC, loads, and grid elements. The conclusion is that PQAs, as required by standards in use currently, are not prepared to identify and quantify, when necessary and correctly, the high-frequency components that are present in modern electric networks with multiple PECs.

Transport of non-equilibrium quasiparticle excitations in superconducting aluminum

The electron transport of non-equilibrium quasiparticles injected into superconducting aluminum from a normal metal has been experimentally studied at ultralow temperatures. We studied hybrid nanostructures in the form of a T-shaped normal metal electrode (copper) – a dielectric tunnel layer (aluminum oxide) – a superconducting fork (aluminum), which can be considered as a solid-state analogues of a two-beam optical interferometer. At fixed bias voltages larger than the superconducting gap, a non-monotonic dependence of the tunnel current on perpendicular magnetic field is observed. The effect is interpreted as the presence of a coherent component of the quasiparticle current.

Direct Current Ripple Component Detection Algorithm Based on Improved Variational Mode Decomposition

Background: The development of smart grids requires energy meters that enable accurate measurements. Objective: In response to the current issue where Direct Current (DC) energy meters only measure DC components and not ripple components, we propose to design a novel algorithm to achieve accurate separation of DC components and ripple components in DC signals. Methodology: This patent proposes a precise detection algorithm for ripple components. The algorithm is based on the Wavelet Decomposition combined with Flamingo Search Algorithm-Variational Mode Decomposition (WD-FSA-VMD). Firstly, we analyze the ripple characteristics in the DC signal and use the Wavelet Decomposition (WD) algorithm to separate the ripple components in the DC signal accurately. Secondly, we utilize the Flamingo Search Algorithm (FSA) to optimize the number of modal decompositions and the penalty factor in the Variational Mode Decomposition (VMD). This allows us to accurately extract the ripple components. Finally, we conducted simulation experiments comparing the improved algorithm with the original algorithm. Results: The experimental results indicate that the signal correlation coefficient obtained by the WDFSA- VMD algorithm increases by 82.64% compared to traditional VMD, and it increases by 16.72% compared to the combined Wavelet Decomposition with Whale Optimization Algorithm-Variational Mode De-composition (WD-WOA-VMD). Conclusion: The improved algorithm we proposed has good adaptability and separation performance. It is prospective for the new algorithm to provide a valuable reference to ripple detection technology.

Improvement of the Source Current Quality for a Shunt Active Power Filter Operating Using Hysteresis Technique with Stabilized Switching Frequency

Determining the current reference for a shunt active power filter (SAPF) can be carried out in many ways. Once the reference is determined, it can be shaped by SAPF switches with the use of pulse width modulation (PWM)/hysteresis control techniques. There are many variants of shaping the compensation waveform using these techniques. Nevertheless, regardless of the PWM/hysteresis technique adopted, a switching frequency current component appears in the system. It acts as a carrier used to inject a compensating current into the grid. Once the compensating current has been entered into the grid, the switching component should be reduced in it. This can be performed using RLC passive filters in various variants. The article discusses a variable/stabilized frequency hysteresis current control technique adapted for SAPF regulation with the use of current closed-loop control (source current direct control). For this technique, the passive filter should be placed outside the current control loop. The article focuses on examining the effectiveness of the interaction of the RLC filter with SAPF acting with such a control technique.

High performance Calcium Copper Titanate/Polyimide dielectrics composites enabled through colloidal stabilization

AbstractTransition to electrified transportation demands advanced power electronic components with the capability to improve range, reliability, and cost of ownership to accelerate mass market adoption. Thus, improvement in the current designs, manufacturing processes, materials, and components capable of providing reliable and efficient operation at higher temperatures play important roles in meeting future needs. To address these challenges, this article focuses on novel dielectric materials designed to reduce the volume of the most important and bulky component of a power electronic system, a capacitor. A new composite dielectric material was developed by integrating the positive attributes of both polymer and ceramic capacitors to overcome the challenges of state‐of‐the‐art dielectric materials. The developed composite properties have been evaluated and showed promising results, achieving a dielectric constant of 250 at 100 Hz, 25°C, unseen in current literature. Additionally, these materials can function at high temperatures (>150°C) with good breakdown strength, providing promising working conditions for capacitors, especially in electric vehicle applications.Highlights Dielectric composites were synthesized from calcium copper titanate and polyimide. A dispersive agent showed promise in achieving a homogenous, stable mixture. Composites were prepared using tape casting. A dielectric constant of 250 was achieved at 100 Hz, 25°C. At elevated temperature, the dielectric constant increased to over 700%.

The Impact of Flow-Thermal Characteristics in Ship-Board Solid Oxide Fuel Cells

Hydrogen is increasingly recognized as a clean and reliable energy vector for decarbonization in the future. In the marine sector, marine solid oxide fuel cells (SOFCs) that employ hydrogen as an energy source have already been developed. In this study, a multi-channel plate-anode-loaded SOFC was taken as the research object. A three-dimensional steady-state computational fluid dynamics (CFD) model for anode-supported SOFC was established, which is based on the mass conservation, energy conservation, momentum conservation, electrochemical reactions, and charge transport equations, including detailed geometric shapes, model boundary condition settings, and the numerical methods employed. The polarization curves calculated from the numerical simulation were compared with experimental results from the literature to verify the model’s accuracy. The curved model was applied by enlarging the flow channels or adding blocks. Numerical calculations were employed to obtain the current density, temperature distribution, and component concentration distribution under the operating conditions of the SOFC. Subsequently, the distribution patterns of various physical parameters during the SOFC operation were analyzed. Compared to the classical model, the temperature of the curved model was reduced by 1.3%, and the velocities of the cathode and anode were increased by 4.9% and 5.0%, respectively, with a 2.42% enhancement in performance. The findings of this study provide robust support for research into and the application of marine SOFCs, and offer they insights into how we may achieving “dual carbon” goals.

Influence of Tibial Component Design Features and Interference Fit on Implant-Bone Micromotion in Total Ankle Replacement: A Finite Element Study.

Implant survivorship in uncemented total ankle replacement (TAR) is dependent on achieving initial stability. This is because early micromotion between the implant and bone can disrupt the process of osseointegration, leading to poor long-term outcomes. Tibial implant fixation features are designed to resist micromotion, aided by bony sidewall retention and interference fit. The goal of this study was to investigate design-specific factors influencing implant-bone micromotion in TAR tibial components with interference fit. Three implant designs with fixation features representative of current TAR tibial components (ARC, SPIKES, KEEL) were virtually inserted into models of the distal tibias of 2 patients with end-stage ankle arthritis. Tibia models were generated from deidentified patient computed tomography scans, with material properties for modeling bone behavior and compaction during press-fit. Finite element analysis (FEA) was used to simulate 2 fixation configurations: (1) no sidewalls or interference fit, and (2) sidewalls with interference fit. Load profiles representing the stance phase of gait were applied to the models, and implant-bone micromotions were computed from FEA output. Sidewalls and interference fit substantially influenced implant-bone micromotions across all designs studied. When sidewalls and interference fit were modeled, average micromotions were less than 11 µm, consistent across the stance phase of gait. Without sidewalls or interference fit, micromotions were largest near either heel strike or toe-off. In the absence of sidewalls and interference fit, the amount of micromotion generally aligned inversely with the size of implant fixation features; the ARC design had the largest micromotion (~540 µm average), whereas the KEEL design had the smallest micromotion (~15 µm). This study presents new insights into the effect of TAR fixation features on implant-bone micromotion. With sidewalls and interference fit, micromotion is predicted to be minimal for implants, whereas with no sidewalls and no interference fit, micromotion depended primarily on the implant design. This study presents new insights into the effect of TAR primary fixation features on implant-bone micromotion. Although design features heavily influenced implant stability in the model, their influence was greatly diminished when interference fit was introduced. The results of this study show the relative importance of design features and interference fit in the predicted initial stability of uncemented TAR, potentially a key factor in implant survivorship.

Transport through a monolayer-tube junction: Sheet-to-tube spin current

We develop a method to calculate the electron flow between an arbitrary atomic monolayer sheet and an arbitrary tube by expressing the corresponding sheet-tube tunneling matrix elements with those between sheets. We use this method to calculate the spin current from a monolayer silicene sheet with sublattice-staggered current-induced spin polarization to a silicene tube. The calculated sheet-to-tube spin current exhibits an oscillation as a function of the tube circumferential length because the Fermi points in the tube cross the Fermi circle in the sheet. Furthermore, the spin current with spin in the out-of-plane direction, which is absent in the sheet-sheet junction (including twisted sheets) with C3 rotational symmetry, appears in an oscillating form in the tube-sheet junction due to the broken C3 rotational symmetry. This is an example of the symmetry manipulation which realizes switching a particular component of the spin current.

Automatic modeling of the current state components of ancient buildings based on 3D deformation algorithm

AbstractAncient buildings possess significant artistic and cultural value. The digitization of these structures is a crucial aspect of their restoration, providing foundational data for subsequent stress and health analyses. However, creating accurate models of ancient buildings is a challenging endeavor, even for experienced researchers, especially when dealing with a large number of structures. A pressing issue that needs addressing is how to quickly obtain accurate models of ancient buildings while ensuring both precision and efficiency. Currently, one of the more precise methods for reconstructing models of ancient buildings involves the use of scanned point clouds and manual reconstruction through modeling software. However, this method suffers from poor accuracy and low efficiency, making the modeling process complex and time-consuming. In this article, we will refer to the model generated from the point cloud of real components as the "current state model", and the unforced mesh model of the ancient building as the "standard model". An algorithm is proposed to construct the current state model of ancient buildings by guiding the deformation of the unforced standard model using the scanned point cloud model. First, this paper designs an automatic modeling method for ancient building components as the foundational data before deformation, addressing the issue of low modeling efficiency for ancient buildings. Second, it proposes a method for automatically calculating deformation control point pairs based on the characteristics of ancient buildings, solving the problem of manually locating control points. Finally, the proposed adaptive weight Laplacian deformation algorithm is applied to deform the standard model into the current state model.

An in-phase filter-based flux observation strategy for sensorless control of PMSMs

Due to the complexity of determining the initial rotor flux and detecting errors, conventional rotor flux observation methods are easily affected by direct current (DC) components and harmonics. To address this issue, this paper proposes an in-phase filter (IPF)-based rotor flux observation strategy for sensorless control of permanent magnet synchronous machines (PMSMs). The core components of the IPF consist of a double second-order generalized integrator (DSOGI) and a phase angle compensation transfer function (PACTF). The DSOGI provides a accurate electrical angular frequency, while the PACTF implements a phase correction to the vq′ signals. By employing IPF structure, accurate observations for rotor flux, electronic speed, and rotor position are achieved, which can be effectively used in the sensorless control of PMSMs, eliminating the need for magnitude and phase compensations. Finally, the proposed observation strategy is applied to an experimental bench of a PMSM, and its effectiveness is illustrated by experimental results. From experimental results, it can be concluded that the IPF is significantly better than the LPF, and 5% more accurate than the observer based on cascade second-order generalized integral(CSOGI) overall.