Hasil untuk "Applications of electric power"

Ge Wang, Zhilun Lu, Yong Li et al.

Materials exhibiting high energy/power density are currently needed to meet the growing demand of portable electronics, electric vehicles and large-scale energy storage devices. The highest energy densities are achieved for fuel cells, batteries, and supercapacitors, but conventional dielectric capacitors are receiving increased attention for pulsed power applications due to their high power density and their fast charge–discharge speed. The key to high energy density in dielectric capacitors is a large maximum but small remanent (zero in the case of linear dielectrics) polarization and a high electric breakdown strength. Polymer dielectric capacitors offer high power/energy density for applications at room temperature, but above 100 °C they are unreliable and suffer from dielectric breakdown. For high-temperature applications, therefore, dielectric ceramics are the only feasible alternative. Lead-based ceramics such as La-doped lead zirconate titanate exhibit good energy storage properties, but their toxicity raises concern over their use in consumer applications, where capacitors are exclusively lead free. Lead-free compositions with superior power density are thus required. In this paper, we introduce the fundamental principles of energy storage in dielectrics. We discuss key factors to improve energy storage properties such as the control of local structure, phase assemblage, dielectric layer thickness, microstructure, conductivity, and electrical homogeneity through the choice of base systems, dopants, and alloying additions, followed by a comprehensive review of the state-of-the-art. Finally, we comment on the future requirements for new materials in high power/energy density capacitor applications.

Wangda Li, Evan M. Erickson, A. Manthiram

Jun Liu, Zhenan Bao, Yi Cui et al.

Zhong Lin Wang

Self-powered system is a system that can sustainably operate without an external power supply for sensing, detection, data processing and data transmission. Nanogenerators were first developed for self-powered systems based on piezoelectric effect and triboelectrification effect for converting tiny mechanical energy into electricity, which have applications in internet of things, environmental/infrastructural monitoring, medical science and security. In this paper, we present the fundamental theory of the nanogenerators starting from the Maxwell equations. In the Maxwell's displacement current, the first term e 0 ∂ E ∂ t gives the birth of electromagnetic wave, which is the foundation of wireless communication, radar and later the information technology. Our study indicates that the second term ∂ P ∂ t in the Maxwell's displacement current is directly related to the output electric current of the nanogenerator, meaning that our nanogenerators are the applications of Maxwell's displacement current in energy and sensors. By contrast, electromagnetic generators are built based on Lorentz force driven flow of free electrons in a conductor. This study presents the similarity and differences between pieozoelectric nanogenerator and triboelectric nanogenerator, as well as the classical electromagnetic generator, so that the impact and uniqueness of the nanogenerators can be clearly understood. We also present the three major applications of nanogenerators as micro/nano-power source, self-powered sensors and blue energy.

Yuan Yang, G. Zheng, Yi Cui

Tinghai Cheng, Jiajia Shao, Zhongqiu Wang

P. Pandey, Vikas Shinde, R. Deopurkar et al.

Dong Liu, Jingnan Zhao, Mingli Lu et al.

Snow accumulation and ice formation can significantly reduce pavement friction, posing a serious threat to traffic safety during winter. Traditional snow-removal methods, including mechanical removal, chemical de-icing agents, and heated pavement systems, suffer from several limitations such as low efficiency, environmental impacts, and high operational costs. Electrically conductive asphalt concrete (ECAC) has therefore emerged as a promising active snow-melting technology. When an electric current passes through the conductive network formed within the asphalt mixture, heat is generated through the Joule heating effect. After incorporating conductive fillers, the electrical resistivity of ECAC mixtures can be reduced from approximately 10⁶–10⁸ Ω·cm for conventional asphalt mixtures to about 10⁻¹–10² Ω·cm. Under an applied voltage typically ranging from 30 to 60 V, ECAC pavements can increase the surface temperature by 10–30 °C within 10–30 min, thereby enabling rapid snow melting and ice removal. Meanwhile, an optimized conductive network can maintain sufficient mechanical performance, with dynamic stability generally exceeding 3000 cycles/mm. When the conductive filler content is reasonably controlled, only a limited reduction in fatigue resistance is observed. This paper presents a comprehensive review of electrically conductive asphalt concrete technologies for snow-melting pavements. The background, underlying mechanisms, material development, system configuration, and field applications of ECAC are systematically summarized. Finally, the current challenges are discussed, including the stability of conductive networks, the trade-off between electrical conductivity and pavement performance, and electrical safety. Future research directions focusing on material optimization, intelligent power control, and long-term field performance evaluation are proposed to support the practical application of ECAC pavements in sustainable winter road maintenance.

S. Faraji, F. N. Ani

Jiseong Kim, Jonghoon J. Kim, Sunkyu Kong et al.

A. E. Shamrai, I.V. Isaiev

Purpose Development of a model for a compensated 6–10 kV network and a methodology for selecting its element parameters based on estimating the minimum level of higher harmonics in the single-phase-to-ground fault current. Methodology. To estimate the minimum level of higher harmonics in single-phase-to-ground fault current currents, a generalized model of a compensated 6–10 kV cable network and its constituent elements, implemented in the Matlab system with the Simulink extension package, was used. The generalized model of the compensated 6–10 kV cable network and its element parameters were obtained based on a statistical analysis of data from the power supply systems of cities and industrial enterprises. Findings. The main requirements for the equivalent calculation scheme of a 6–10 kV cable network for estimating the minimum level of higher harmonics in the single-phase-to-ground fault current were formulated, and the ranges of variation and average values of its parameters were determined. The developed mathematical model of the 6–10 kV cable network accounts for the main factors determining the minimum level of higher harmonics in the single-phase-to-ground fault current. Based on the results of computational experiments performed on the mathematical models of 6–10 kV cable networks, it was established that to ensure the required sensitivity, single-phase-to-ground fault protection devices based on the use of higher harmonics must have a primary pickup current of no more than 0.1A. Originality.  A model of a compensated 6–10 kV network was developed, which allows clarifying the sensitivity requirements for single-phase-to-ground fault protection systems based on the use of higher harmonics, thereby enhancing their operational efficiency. Practical value. Based on the mathematical model, a methodology for selecting its element parameters is proposed, which utilizes the estimation of the minimum level of higher harmonics in the single-phase-to-ground fault currents.

Ammar Armghan, Khaled Aliqab, Meshari Alsharari

Metamaterials designed with nanostructures can effectively convert solar energy into thermal energy, facilitating various applications such as photovoltaic systems, energy harvesting, and thermal applications. This study investigates a periodic array of square-shaped nickel nanostructures metasurface aimed at optimizing solar radiation capture, resulting in an aggregate absorption rate of 98 % within 400–8000 nm range. This broadband absorption results from the localized surface plasmon resonance phenomenon. The proposed device shows a near perfect matching with the solar power radiation AM 1.5 model curve, achieving a solar absorption rate of above 98 %. Moreover, the proposed device shows excellent performance under the blackbody thermal radiation curve with a high thermal radiation efficiency of 95 % at 873 K. Further attributes of the proposed device include hardiness to different light wave polarization conditions and incident angles. Additionally, we have verified the broadband high absorption characteristics through an examination of impedance matching theory, in sighting the distribution of electric field within its structure and impact on the absorption rate with the variation in the different parameters of the unit cell. The findings indicate that the proposed structure exhibits potential for industrial and commercial applications including photovoltaic system, energy harvesting and thermal applications.

Tomasz Serafin, Weronika Nitka

Calibration sample selection and forecast combination are two simple yet powerful tools used in forecasting. They can be combined with a variety of models to significantly improve prediction accuracy, at the same time offering easy implementation and low computational complexity. While their effectiveness has been repeatedly confirmed in prior scientific literature, the topic is still underexplored in the field of electricity price forecasting. In this research article we apply the Autoregressive Hybrid Nearest Neighbors (ARHNN) method to three long-term time series describing the German, Spanish and New England electricity markets. We show that it outperforms popular literature benchmarks in terms of forecast accuracy by up to 10%. We also propose two simplified variants of the method, granting a vast decrease in computation time with only minor loss of prediction accuracy. Finally, we compare the forecasts' performance in a battery storage system trading case study. We find that using a forecast-driven strategy can achieve up to 80% of theoretical maximum profits while trading, demonstrating business value in practical applications.

Kai Kang, Feng Liu, Yifan Su et al.

Power systems with high renewable energy penetration are highly influenced by weather conditions, often facing significant challenges such as persistent power shortages and severe power fluctuations over long time scales. This paper addresses the critical need for effective characterization of extreme scenarios under these situations. First, novel risk indices are proposed to quantify the severity of continuous power shortages and substantial power fluctuations over long-term operations. These indices are independent of specific scheduling strategies and incorporate the system's resource regulation capabilities. By employing a filtering-based approach, the proposed indices focus on retaining key characteristics of continuous power shortages and fluctuation events, enabling the identification of extreme scenarios on long time scales. Secondly, an extreme scenario generation method is developed using Gaussian mixture models and sequential Monte Carlo simulation. Especially, this method periodically evaluates the severity of generated scenarios based on the defined risk indices, retaining extreme scenarios while discarding less critical ones. Finally, case studies based on real-world data demonstrate the efficacy of the proposed method. The results confirm that integrating the identified extreme scenarios significantly enhances the system's ability to ensure long-term security and reliability under high renewable energy penetration.

Andrew Sullivan, Ross J. Turner, Stanislav S. Shabala et al.

We predict the non-thermal pressure (NTP) induced in the cores of galaxy clusters by kinetic jet feedback from an active galactic nucleus (AGN). We model a population of Fanaroff-Riley type I jets when sampling power-law distributions in jet power and age, which we evolve in time with a two-phase jet-lobe model. We couple the energy of each jet outburst to the surrounding gas inside spherical shells, allowing us to estimate the fraction of NTP to total pressure induced in the cluster. We predict the mean profile for this NTP fraction over the source population in a variety of cluster environments and for different AGN jet duty cycles. For typical gas and dark matter profiles, the mean NTP fraction peaks at ~4-6% when the AGN jets are active for 10-30% of the total AGN lifecycle. These predictions are in good agreement with observational constraints, suggesting that AGN feedback imparts only small non-thermal contributions to the cluster's core. Furthermore, we find a relationship between the peak in the mean NTP fraction and the AGN jet duty cycle in a given cluster environment. Applying this to Hitomi measurements of the NTP in the Perseus cluster, we infer an AGN jet duty cycle that is consistent with independent evidence of Perseus' AGN jet activity. We propose this as a novel approach for observationally inferring the past AGN activity of real clusters from their observed NTP fraction and environmental profiles.

Beatriz Lopes da Costa, Matías R. Bolaños, Ricardo Chaves et al.

Over the last decades, Quantum Key Distribution (QKD) has risen as a promising solution for secure communications. However, like all cryptographic protocols, QKD implementations can open security vulnerabilities. Until now, the study of physical vulnerabilities in QKD setups has primarily focused on the optical channel. In classical cryptoanalysis, power and electromagnetic side-channel analysis are powerful techniques used to access unwanted information about the encryption key in symmetric-key algorithms. In QKD they have rarely been used, since they require an eavesdropper to have access to Alice or Bob's setups. However, security proofs of QKD protocols generally assume that these setups are secure, making it crucial to understand the necessary security measures to ensure this protection. In this work, we propose and implement a power side-channel analysis to a QKD system, by exploiting the power consumption of the electronic driver controlling the electro-optical components of the QKD transmitter. QKD modules typically require very precise electronic drivers, such as Field Programmable Gate Arrays (FPGAs). Here, we show that the FPGA's power consumption can leak information about the QKD operation, and consequently the transmitted key. The analysis was performed on the QKD transmitter at the University of Padua. Our results are consistent and show critical information leakage, having reached a maximum accuracy of 73.35% in predicting transmitted qubits at a 100 MHz repetition frequency.

Mojtaba Babaei, Mojtaba Feyzi, Abbas Nazari Marashi

Abstract A new analytic model for calculating of the air‐gap flux density (AGFD) of surface‐mounted permanent magnet synchronous machines (SMPMSMs) is presented. This proposed model is capable to taking into account the effects of magnetic saturation, armature reaction and stator slots opening. Furthermore, the real form of air‐gap distribution and spatial distribution of flux density of the PM poles are considered. The armature reaction effect is modeled using phasor diagram analysis of the motor as a function of the load torque, the armature current amplitude, power factor and the inverse air gap length. Also, saturation phenomenon predicted using the new non‐linear proposed function in connection with the armature reaction effects and the properties of the lamination material. It is shown that the proposed model capable to predicting acceptably the air gap flux density waveform of the SMPMSMs at lagging and leading power factors and with the load torque variation. The presented analytical approach is verified by the two‐dimensional finite‐element analysis (FEA) results.

Goran Rozing, Dina Jukić, Hrvoje Glavaš et al.

Batteries as a power source are the basis for all major hand tool manufacturers as vide variety of portable products became battery powered for more convenient usage. Manufacturers disable unapproved battery applications in their products by designing batteries specific for these products. In practice, the life of power tool batteries depends on two parameters: natural aging and the type of use. In a case study of a Battery Powered Grass Trimmer which battery broke after four years, the repair procedure for the package is shown. However, shortly after the repair, the Battery Powered Grass Trimmer suffered a bearing deformation that rendered it unusable. Due to its age and the unavailability of replacing electric engine, the Trimmer was scrapped and a detailed Life Cycle Analysis (LCA) applying SimaPro methodology is provided. Since the product under study is no longer on the market, a properly functioning, refurbished battery with significantly increased capacity is used in a new battery-powered grass trimmer from another manufacturer. The paper's final consideration underscores the need for an international standard that regulates battery compatibility and reduces waste, especially electronic waste.

Haoran Ju, Yongxue Wang, Yiwu Feng et al.

Thermal energy storage in long-distance heating supply pipelines can improve the peak shaving and frequency regulation capabilities of combined heat and power (CHP) units participating in the power grid. In this study, a one-dimensional numerical model was established to predict the thermal lag in long-distance pipelines at different scale levels. The dynamic response of the temperature at the end of the heating pipeline was considered. For the one-way pipe lengths of 10 km, 15 km and 20 km, the response times of the temperature at the distal end were 2.33 h, 2.94 h and 3.54 h, respectively. The longer the flow period, the further the warming-up time is delayed. An optimization scheduling approach was also created to illustrate the peak shaving capabilities of a CHP unit combined with a long-distance pipeline thermal energy storage component. It was demonstrated that the maximum heating load of the unit increased up to 503.08 MW, and the heating load could be expanded in the range of 17.88 MW to 203.76 MW at the minimum electric load of the unit of 104.08 MW. Finally, the particle swarm optimization method was adopted to guide the operating strategy through a whole day to meet both the electric power and heating power requirements. For the optimized case, the comprehensive energy utilization efficiency and the exergy efficiency increase to 64.4% and 56.73%. The thermal energy storage applications based on long-distance pipelines were simulated quantitively and proved to be effective in promoting the operational flexibility of the CHP unit.

Stuart Licht

The present invention relates to rechargeable electrochemical battery cells (molten air batteries). The cells use air and a molten electrolyte, are quasi-reversible (rechargeable) and have the capacity for multiple electrons stored per molecule, have high intrinsic electric energy storage capacities. The present disclosure also relates to the use of such in a range of electronic, transportation and power generation devices, including as greenhouse gas reduction applications, electric car batteries and increased capacity energy storage systems for the electric grid. US patent 10637115 is for the invention of air and carbon or CO2 Molten Air batteries, while US patent 11094980 is for the invention of air and metal, boron and a variety of salt/Molten Air batteries.