1,649 results
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2. Charge migration of multilayer oil paper on the process of partial discharge under AC voltage.
- Author
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Gao, Bo, Li, Yixuan, Liu, Kai, Li, Xiaonan, Yang, Yan, and Wu, Guangning
- Subjects
PARTIAL discharges ,ELECTRIC discharges ,FOURIER integrals ,INFRARED spectroscopy ,ISOTHERMAL surfaces (Thermodynamics) - Abstract
As one of the main reasons for the deterioration of Nomex paper and charge migration, partial discharge (PD) plays a critical role during PD degradation. In this study, the PD characteristics of multilayer oil paper are focused on. In order to explore the characteristics of charge migration, the experiments of the relative permittivity, conductivity, isothermal surface potential decay, scanning electron microscopy and Fourier infrared spectroscopy have been carried out. The results show that the discharge branches of the second layer are two and three times longer than those in the first layer. In addition, the trap level of the first layer for PD degradation samples increases with the degree of PD degradation. The charges captured by deep traps provide seed charges for PD on the surface of the first layer. The charge transportation will accelerate the formation of shallow traps. The charge distribution and shallow traps contribute to the expansion of discharge branches. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Effects of TiO2 Nanoparticles on Streamer Propagation at the Surface of Oil-Impregnated Insulation Paper.
- Author
-
Ge, Yang, Lv, Yuzhen, Han, Qiubo, Sun, Qian, Huang, Meng, Li, Chengrong, Qi, Bo, and Yuan, Jinsha
- Subjects
TITANIUM dioxide nanoparticles ,ELECTRIC discharges ,SURFACE charges ,FLASHOVER ,NANOFLUIDS - Abstract
Recent studies have found that the surface flashover strength of oil-impregnated insulation paper can be improved by the modification of nanoparticles. To reveal the working mechanism, this paper presents an experimental study on the effects of TiO2 nanoparticles on streamer propagation process at the surface of oil-based nanofluid-impregnated insulation paper under lightning impulse voltage. The results show that the surface flashover voltage of nanofluid-impregnated insulation paper is significantly increased by 34.6%. Streamer characteristics including shape and length at the surface of oil-impregnated insulation paper were investigated using the schlieren technique. It is indicated that streamer characteristics are dramatically changed by the addition of TiO2 nanoparticles. For nanofluid-impregnated insulation paper, streamers with more but much shorter branches tend to develop into adjacent nanofluid rather than clinging to the paper compared to that for pure oil-impregnated paper. The reason responsible for the shape dissimilarity lies in the change of electrical force due to the permittivity difference between oil and paper. Furthermore, more shallow traps introduced by nanoparticles contribute to the faster surface charge dissipation of nanofluid-impregnated paper, reducing the charge accumulation at the streamer head and suppressing the electric field distortion. Thus, it is hard for streamers to develop at the surface of nanofluid-impregnated paper, resulting in an increase of surface flashover strength. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
4. Space charge dynamics in epoxy resin impregnated crepe paper multilayer under voltage polarity reversal.
- Author
-
Zhang, Hongliang, Liu, Peng, Feng, Hua, Zhang, Siyu, Li, Ding, and Peng, Zongren
- Subjects
- *
SPACE charge , *ELECTRIC discharges , *ELECTRIC fields , *EPOXY resins , *CHARGE transfer , *ELECTRIC potential - Abstract
In this paper, the temporal space charge dynamics under both temperature and voltage polarity reversal of an epoxy resin impregnated crepe paper are characterized by pulsed electroacoustic method. It is found that the space charge injection and the interfacial traps located between the epoxy and paper plays an important role in determining the space charge dynamics. The results reveal that below 353 K, the calculated interfacial charge density is consistent with the Maxwell-Wagner (MW) model, while above 353 K, it is smaller than the measured value. The time constant during charging is much smaller than that predicted by the MW model and the space charge injection showed polarity effect, which leads to the interfacial charge densities under polarity poling voltage not being equal. It is proposed that the interfacial traps and space charge injection should be responsible for the observed space charge dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
5. BREAKDOWN VOLTAGE OF MICRON RANGE AIR INCLUSIONS IN CAPACITOR PAPER.
- Author
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Palchykov, O. O.
- Subjects
BREAKDOWN voltage ,ELECTRIC discharges ,ELECTROSTATIC fields ,CAPACITORS ,ELECTRIC breakdown ,INSULATING materials ,ELECTRIC fields ,SHALLOW-water equations - Abstract
Copyright of Electrical Engineering & Electromechanics is the property of National Technical University, Kharkiv Polytechnic Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2020
- Full Text
- View/download PDF
6. Partial Discharge of Needle-Plane Defect in Oil-Paper Insulation under AC and DC Combined Voltages: Developing Processes and Characteristics.
- Author
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Jiantao Sun, Xining Li, Lingyu Zhu, Shengchang Ji, and Yanjie Cui
- Subjects
- *
PARTIAL discharges , *ELECTRIC discharges , *ELECTRIC insulators & insulation , *ALTERNATING currents , *DIRECT currents , *ELECTRIC fields - Abstract
Partial discharge (PD) behaviors of oil-paper insulation is distinctive in AC and DC combined electric fields in converter transformers from PD behaviors in pure AC or DC electric fields. The present study focuses on the PD developing processes and characteristics of oil-paper insulation systems with needle-plane defects under different AC/DC proportions. The degradation of oil-paper insulation can be accelerated by PD pulses incurred by needle-plane defects. AC-DC combined voltages are applied to the needle-plane defect model simultaneously in the established experimental platform, and the proportions of AC/DC voltages are decided according to the cases in actual converter transformers. The developing processes from the initiation of partial discharge until final breakdown were observed for each AC/DC proportion. PD parameters and patterns were acquired by a detector using the pulse current method. The test results indicate that the inception and breakdown voltages increase with the increase of the DC component in AC-DC combined voltages. However, pulse repetition rate and amplitude of PD shows a descending trend when AC/DC proportion decreases. Meanwhile, the PD recurrence rate in the phase between 180° and 360° becomes higher than that in the phase between 0° and 180° at the initial stage as the DC proportion increases; high-amplitude discharges mainly occur in the phase range between 180° and 360° when the pressboard is close to breakdown. The current study is useful in further research on fault diagnosis in converter transformers. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
7. Partition of the development stage of air-gap discharge in oil-paper insulation based on wavelet packet energy entropy.
- Author
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Xie, Bo, Chen, Weigen, Zhou, Qu, Du, Jinchao, and Cui, Lu
- Subjects
- *
ELECTRIC discharges , *ELECTRIC fault location , *ELECTRIC transformers , *ENERGY bands , *SIGNAL processing - Abstract
Air-gap discharge in oil-paper insulation is one of the main types of partial discharge (PD) in power transformer. The discharge development stage for monitoring and diagnosis of transformer potential faults is a significant area of study. The method of wavelet packet energy entropy, which is based on different frequency bands energy distribution of PD signals at different insulation states, is provided to explore the variation characteristics of the whole PD process. In this paper, air-gap discharge model is built in the simulative transformer tank that collects PD signals based on constant voltage method. This model also utilizes wavelet packet decomposition method to partition PD signal bands obtaining signal energy distribution in each frequency band, as well as total signal energy tendency along with PD development process. Wavelet packet energy entropy, which is the new PD feature parameter describing the development process, represents the order degree of PD signals which corresponds to dielectric strength. Finally, because of the cyclic change of this method, the step points of wavelet packet entropy are taken as the way to effectively divide the PD development stage. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
8. Experimental simulation of effects of copper sulphide on insulation system of transformers.
- Author
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Khan, Faheem and Rajan, J.
- Subjects
COPPER sulfide ,POWER transformer insulation ,ELECTRIC transformers ,CORROSION & anti-corrosives ,PHYSICS experiments ,ELECTRIC discharges - Abstract
The presence of Corrosive sulphur in mineral transformer oil affects the performance of insulation system of transformers. In this paper results of experimental investigations carried out on voltage current characteristics and insulation resistance of paper oil insulation in presence of copper sulphide are presented and discussed. A model for copper sulphide migration is proposed to explain the increase in leakage current and reduction in insulation resistance. Existence of two regions in voltagecurrent characteristics, one dependent on the insulation properties of paper oil insulation and other due to semi-conducting copper sulphide is discussed and explained. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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9. A Flexible Paper-Based Microdischarge Array Device: A Novel Route to Cost-Effective and Simple Setup Microplasma Generation Devices.
- Author
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Yang, Yao-Jhen and Hsu, Cheng-Che
- Subjects
- *
MICROPLASMAS , *ELECTRIC discharges , *PLASMA generators , *PLASMA production , *FABRICATION (Manufacturing) , *MICROARRAY technology - Abstract
A low-cost and simple-arranged paper-based microplasma array device made by tape and Xerox paper was presented. Uniform array of discharge can be sustained in Ar, He, and ambient air atmosphere. Stable discharge can be sustained for at least 55 min when plasma is ignited in Ar ambient, based on the examination of time-resolved optical emission spectra. Throughout the conditions investigated, the power consumed by the device was well below 0.3 W. We also demonstrated that stable and uniform discharge can be generated when the device was bent to a radius of curvature of 2.5 mm. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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10. Preferential orientation of I2-LiI(HPN)2 film for a flexible all-solid-state rechargeable lithium–iodine paper battery.
- Author
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Liu, Fang-Chao, Shadike, Zulipiya, Ding, Fei, Sang, Lin, and Fu, Zheng-Wen
- Subjects
- *
SOLID state batteries , *LITHIUM cells , *ELECTROCHEMICAL analysis , *TEMPERATURE effect , *ELECTRIC discharges - Abstract
A highly preferred orientation of I 2 -LiI(HPN) 2 film on the paper was found. The electrochemical property of a new flexible all-solid-state Li/I 2 -LiI(HPN) 2 film paper battery was examined at wide temperatures for the first time. This paper battery is capable of achieving a high discharge energy of 250 Wh/kg with a plateau potential region at 2.70 V versus Li/Li + at 70 °C. The interfacial layer of (LiI) (1+ x ) I (2− x ) (HPN) 2 instead of LiI between lithium and I 2 -LiI(HPN) 2 film should be responsible for the high electrochemical activity of the lithium–iodine paper battery. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
11. Creepage Discharge Characteristics of Solid Insulation Materials for Superconducting Power Cable.
- Author
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Onyou Lee, Minkyung Jeong, Sangsu Jeon, Hongseok Lee, Jonggi Hong, and Hyoungku Kang
- Subjects
ALTERNATING currents ,SUPERCONDUCTING cables ,ELECTRIC discharges ,EPOXY resins ,LAMINATED paper ,POLYPROPYLENE - Abstract
Solid insulation materials need to be robust in terms of both mechanical and electrical performance for application in a high-voltage superconducting apparatus. It is known that creepage discharge characteristics of solid insulation materials are inferior to their electrical breakdown characteristics with penetration. Therefore, electrical breakdown accidents in a superconducting apparatus could occur as a form of creepage discharge rather than electrical breakdown with penetration. In this study, we conduct dielectric experiments on the penetration and creepage discharge characteristics of epoxy resin and polypropylene laminated paper under cryogenic temperature by using three kinds of electrode systems. The first is for creepage discharge experiments along the surfaces of solid insulation materials in liquid nitrogen. The second is for creepage discharge experiments across the interface between two different solid insulation materialsmaking contact in liquid nitrogen. The third is for experiments of electrical breakdown with penetration on solid insulation materials in liquid nitrogen. Dielectric experiments are conducted with an absolute pressure of 0.1 MPa under alternating current and lightning impulse voltages. Experimental results for electrical breakdown characteristics of solid insulation materials with penetration are compared with the creepage discharge characteristics on the surface and interfaces between solid insulation materials. Moreover, the criteria for electric field intensities at creepage discharge voltages in various conditions are deduced as empirical formulas. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
12. A CO-SIMULATION MODEL FOR THE OPERATING MECHANISM OF A HIGH-VOLTAGE CIRCUIT BREAKER.
- Author
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Li, X.-F., Zhao, D., Yi, L., Wu, Z., Zhang, Y., and Shuai, C.-G.
- Subjects
FINITE element method ,STRESS concentration ,ELECTRIC discharges - Abstract
The reliability of high-voltage circuit breakers (HVCBs) depends critically on the dynamic characteristics of their hydraulic operating mechanisms (OMs). However, previous analyses have been limited to discrete components due to the lack of models capturing multi-physics couplings. This paper proposes a novel co-simulation approach for hydraulic OMs that enables system-level analysis. Specifically, the hydraulic system is modelled using the lumped parameter method, and the transmission mechanism is modelled via finite element analysis. The subsystem models exchange inputs and outputs through shared memory, realizing coupling without compromising simulation performance. Experiments on a 550 kV HVCB validate that the model accurately captures OM transient responses. The co-simulation framework has diverse capabilities, including predicting dynamics under varied operating parameters and quantifying stress distributions and response evolution patterns. Overall, this paper proposes an advanced multi-physics analysis capability for hydraulic OMs to support reliabilityoriented design and optimization. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. Dielectric and Thermal Conductivity of Epoxy Resin Impregnated Nano-h-BN Modified Insulating Paper.
- Author
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Yang, Hongda, Chen, Qingguo, Wang, Xinyu, Chi, Minghe, Liu, Heqian, and Ning, Xin
- Subjects
- *
EPOXY resins , *SPACE charge , *DIELECTRICS , *ELECTRIC discharges , *ELECTRIC fields , *DIRECT currents - Abstract
Epoxy resin-impregnated insulation paper (RIP) composites are used as the inner insulation of dry condenser bushing in the ultra-high voltage direct current (UHVDC) power transmission system. To improve the dielectric properties and heat conductivity of RIP, hexagonal boron nitride (h-BN) nano-flakes are added to the insulation paper at concentrations of 0–50 wt % before impregnation with pure epoxy resin. X-ray diffraction (XRD), scanning electron microscopy (SEM) observations, thermal conductivity as well as the typical dielectric properties of direct current (DC) volume conductivity. DC breakdown strength and space charge characteristics were obtained. The maximum of nano-h-BN modified heat conductivity reach 0.478 W/(m·K), increased by 139% compared with unmodified RIP. The DC breakdown electric field strength of the nano-h-BN modified RIP does not reduce much. The conductivity of nano-h-BN modified is less sensitive to temperature. As well, the space charge is suppressed when the content is 50 wt %. Therefore, the nano-h-BN modified RIP is potentially useful in practical dry DC bushing application. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
14. Effect of Temperature on Space Charge Distribution of Oil–Paper Insulation under DC and Polarity Reversal Voltage.
- Author
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Chen, Qingguo, Zhang, Jinfeng, Chi, Minghe, Tan, Peng, and Sun, Wenxin
- Subjects
- *
ELECTRIC fields , *ELECTRIC distortion , *SPACE charge , *ELECTRIC discharges , *DIRECT currents - Abstract
The electric field distortion caused by space charge is an important factor affecting the operation reliability of oil–paper insulation in a converter transformer. To study the accumulation and decay characteristics of the space charge within oil-impregnated pressboard under DC and polarity reversal voltage, and consider the possible operating conditions of the converter transformer, the space charge behavior of oil-impregnated pressboard was measured by the pulsed electro-acoustic (PEA) method in the temperature range from −20 °C to 60 °C. The effect of temperature on the accumulation and decay characteristics of space charge is also analyzed. The space charge accumulated within the pressboard at low temperature is mainly homocharge injected by the electrode, while heterocharge formed by ion dissociation counteracts some of the homocharge at high temperature. Thus, the space charge of pressboard first increases, then decreases, with an increase in temperature. However, slow decay of the space charge causes severe distortion of the electric field distribution in the pressboard during voltage polarity reversal. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
15. Bidirectional Power Control Strategy for On-Board Charger Based on Single-Stage Three-Phase Converter.
- Author
-
Sun, Li, Wang, Xin, and Ma, Chenglian
- Subjects
AC DC transformers ,BATTERY chargers ,ELECTRIC vehicle batteries ,ELECTRIC discharges ,POWER density ,ELECTRIC vehicles - Abstract
To solve the problems of large switching losses and the need for large-capacity electrolytic capacitances in three-phase DC/AC on-board chargers for vehicle-to-grid (V2G) applications, this paper proposes a single-stage bidirectional high-frequency isolated converter that eliminates the need for large-capacity capacitances. Combined with the proposed modulation scheme, it can theoretically reduce the switching loss by about two-thirds with the three-phase converter compared with the conventional modulation scheme, improving the converter's operating efficiency and power density. Firstly, based on the characteristics of the proposed topology, a hybrid modulation scheme is proposed, which combines a phase-shift modulation scheme based on double modulation waves and a sawtooth carrier with a 1/3 modulation scheme, and the theoretical feasibility of the hybrid modulation scheme is verified using a mathematical modeling equation. Secondly, this paper provides a detailed analysis of the four operating modes of the two full-bridge circuits and the commutation process of the three-phase converter within 1/6 of the fundamental frequency cycle (P
1 modulation interval). Then, the control strategy is given for the constant-current and constant-voltage charging and constant-current discharging for electric vehicle batteries. Finally, simulation results verify the correctness of the proposed topology and modulation scheme in vehicle–grid interaction. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
16. V2G Strategies to Flatten the Daily Load Curve in Seoul, South Korea.
- Author
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Choi, Sangbong, Kim, Changsoo, and Sung, Backsub
- Subjects
ELECTRIC charge ,ELECTRIC discharges ,ELECTRIC power distribution grids ,ELECTRIC vehicle charging stations ,ELECTRIC vehicle industry ,ELECTRIC automobiles ,ELECTRIC vehicles - Abstract
In order to meet the increasing demand for electricity to maintain electric vehicles (EVs) worldwide, this paper aims to improve our understanding of the impact of the load on the power grid generated by the charging and discharging of electric vehicles. The rapid development of the electric vehicle (EV) industry offers new economic and environmental benefits, such as mitigating global warming by reducing carbon dioxide. On the other hand, however, we will face the reality that the emergence of such large-scale EVs will undoubtedly put additional strain on the power grid. In this context, solving the problem of excessive power usage associated with charging large electric vehicles and reducing the impact on the grid is paramount. Accordingly, in order to meet the increasing demand for electricity to maintain electric vehicles (EVs) worldwide, this paper aims to improve our understanding of the impact of the load on the power grid generated by the charging and discharging of electric vehicles. A V2G strategy is presented with the goal of flattening the daily load curve by considering the charge and the discharge positions of EVs. First, in this paper, based on the estimated share of electric vehicles, we set the assumption that EVs travel to work in the morning and leave work in the afternoon. Second, we develop an efficient V2G strategy to equalize the daily load curve due to charging and discharging of electric vehicles in Seoul by applying a system marginal price (SMP) and time-of-use (TOU) rate system. The EV charging/discharging load and existing load using V2G modeling are added up, all daily load curves are calculated and analyzed based on the 2030 and 2040 EV share scenarios for Seoul, and the grid load is leveled. The analysis suggests measures to minimize the impact of EV loads on the power grid according to the V2G strategy based on charging and discharging plans. Overall, this paper aims to smooth the grid's daily load curve and avoid grid overload by applying appropriate SMP and TOU plans; we also present an efficient V2G strategy, established through charge and discharge modeling and EV charge and discharge management techniques, in order to minimize grid expansion. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
17. First mode negative streamers along mineral oil-solid interfaces.
- Author
-
Ariza, David, Becerra, Marley, Hollertz, Rebecca, Wagberg, Lars, and Pitois, Claire
- Subjects
MINERAL oils ,ELECTRIC discharges ,CHARGE measurement ,ELECTRODES ,POLYETHYLENE terephthalate - Abstract
This document presents an experimental study on the propagation of first mode negative streamers along mineral oil-solid interfaces. Samples made of an oil impregnated kraft paper and a low-porosity paper made from cellulosic micro and nano fibrils, as well as different polymeric films (low density polyethylene (LDPE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF)) are used as the solid. A comparison of the length, charge and velocity of streamers for all different mineral oil-solid interfaces is reported. It is shown that streamers propagate longer and faster along mineral oil-solid interfaces with low surface roughness, low porosity and higher electrical permittivity than mineral oil. Those streamers show a quasi-continuous injection of charge in the early stage of their propagation. This quasi-continuous charge injection consists of a sequence of small charge steps separated by few tens of nanoseconds in between. In comparison, the streamers that propagate along surfaces with similar permittivity to the mineral oil have lower injection of charge and higher stopping voltage conditions than streamers propagating free in the liquid without any solid barrier. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
18. Design of Underwater Compressed Air Flexible Airbag Energy Storage Device and Experimental Study of Physical Model in Pool.
- Author
-
Ren, Xiangang, Peng, Wanlang, Wang, Zhuo, and Ma, Hongwen
- Subjects
ENERGY storage ,AIR bag restraint systems ,COMPRESSED air ,GLOW discharges ,ELECTRIC discharges ,COMPRESSED air energy storage - Abstract
Renewable energy is a prominent area of research within the energy sector, and the storage of renewable energy represents an efficient method for its utilization. There are various energy storage methods available, among which compressed air energy storage stands out due to its large capacity and cost-effective working medium. While land-based compressed air energy storage power stations have been constructed worldwide, their efficiency remains low. Underwater compressed air energy storage has the potential to significantly enhance efficiency, although no such device currently exists. This paper presents the design of an UWCA-FABESD utilizing five flexible air bags for underwater gas storage and discharge. Additionally, it introduces the working principle of the adiabatic underwater compressed air energy storage system and device. Furthermore, a small-scale physical model with similar functionality was designed and manufactured to simulate the charging process of the air bag in onshore charging and discharging tests as well as posture adjustment and lifting arrangement tests, along with underwater charging and discharging tests. These experiments validated the related functions of the designed underwater compressed air flexible bag energy storage device while proposing methods for its improvement. This research provides a new approach to underwater compressed air energy storage. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Characterization of Single Frequency Fiber-Laser-Based Ultrasound Sensor.
- Author
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Zhu, Wei, Lu, Qiang, Yang, Bo, Tian, Rui, Luo, Hao, Cai, Chao, Yan, Zhijun, and Zhao, Luming
- Subjects
ELECTRIC power systems ,ELECTRIC discharges ,FREQUENCY response ,SIGNAL-to-noise ratio ,DISTRIBUTED feedback lasers ,DOPING agents (Chemistry) ,FIBER lasers - Abstract
In this paper, we demonstrated a distributed feedback fiber-laser- (DFB-FL) based ultrasound detection system with a high signal-to-noise ratio (SNR), high sensitivity and wide frequency response range. The DFB-FL was fabricated by UV-inscribing a π phase-shifted grating in the Erbium–Ytterbium co-doped fiber using the phase mask method. The theory of DFB-FL and the sensing principle has been discussed and analyzed. The sensing signal was demodulated via an unbalanced Mach–Zehnder interferometer (MZI) system. The experimental results showed that the sensitivity of the sensor reached 75.18 mV/kPa and the flat frequency response range covered over 30 MHz, which covered the ultrasonic detection frequency range of abnormal discharge in the electric power system. The SNR of this DFB-FL was 42.9 dB, and the corresponding noise-equivalent pressure was calculated as 0.12 kPa. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. Optimizing EV Battery Management: Advanced Hybrid Reinforcement Learning Models for Efficient Charging and Discharging.
- Author
-
Yalçın, Sercan and Herdem, Münür Sacit
- Subjects
REINFORCEMENT learning ,ELECTRIC vehicle batteries ,BLENDED learning ,HYBRID electric vehicles ,BATTERY management systems ,LITHIUM-ion batteries ,ELECTRIC discharges - Abstract
This paper investigates the application of hybrid reinforcement learning (RL) models to optimize lithium-ion batteries' charging and discharging processes in electric vehicles (EVs). By integrating two advanced RL algorithms—deep Q-learning (DQL) and active-critic learning—within the framework of battery management systems (BMSs), this study aims to harness the combined strengths of these techniques to improve battery efficiency, performance, and lifespan. The hybrid models are put through their paces via simulation and experimental validation, demonstrating their capability to devise optimal battery management strategies. These strategies effectively adapt to variations in battery state of health (SOH) and state of charge (SOC) relative error, combat battery voltage aging, and adhere to complex operational constraints, including charging/discharging schedules. The results underscore the potential of RL-based hybrid models to enhance BMSs in EVs, offering tangible contributions towards more sustainable and reliable electric transportation systems. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
21. Numerical Study of Fluid–Solid Interaction in Elastic Sluice Based on SPH Method.
- Author
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Zhang, Jianwei, Wang, Bingpeng, Jiang, Qi, Hou, Ge, Li, Zhirui, and Liu, Hongze
- Subjects
FINITE element method ,FLUID pressure ,EXPERIMENTAL literature ,LIQUID surfaces ,ELECTRIC discharges ,CURVES - Abstract
In this paper, the fluid–solid interaction problem involving structural movement and deformation is considered, and an SPH (smoothed particle hydrodynamics) interaction method is proposed to establish a numerical fluid–solid model and to correct the particle velocities in the momentum conservation equations. It is found that, when the smoothing coefficient is equal to 0.93, the similarity of the free surface curves reaches up to 91.9%, and calculations are more accurate. Under the same working conditions, the classical model of elastic sluice discharge is established based on the SPH method and the finite element method, and the validity and accuracy of the model based on the SPH method are verified by analyzing the flow pattern of the sluice discharge, the opening of the elastic gate, and the change trend in the free liquid surface curve. On this basis, a number of characteristic points on the sluice gate are selected based on the SPH model to investigate the change rule of pressure at the fluid–solid interface, and the results are as follows: (1) based on the numerical model established by the SPH method, the flow pattern of the water, the opening of the elastic gate, and the change in the free liquid level curve are all in better agreement with the experimental results in the literature than those of the finite element method, and the computational results are also better; (2) the pressure of the solid on the fluid at each characteristic point is equal to the pressure of the fluid on the solid, which satisfies the principle of action–reaction and laterally verifies the nature of the dynamic boundary between the fluid and the solid, further verifying the validity of the program; and (3) in the process of sluice discharge, the elastic sluice presents a large force at both ends and a small force in the middle, meaning that the related research in this paper can act as a reference for flow–solid interaction problems related to sluice discharge. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. A three‐stage economy optimization method for the aggregator based on electric vehicle user response volumes.
- Author
-
Lin, Hui, Zhou, Yichen, Li, Yonggang, Zheng, Haoyang, Yang, Yang, Zhen, Xinghao, Bian, Zhaoyuan, and Yue, Ziyi
- Subjects
ELECTRIC discharges ,ENERGY demand management ,CARBON offsetting ,ELECTRIC vehicle charging stations ,ELECTRICITY pricing - Abstract
With the development of intelligent distribution networks and the proposal of the carbon peaking and carbon neutrality goals, the importance of demand‐side management for the improvement of flexible power operation systems is becoming increasingly prominent. To solve the problems of the excessive peak–valley load differences, the insufficient utilization of demand‐side resources, and the unreasonable pricing of aggregators, this paper proposes a three‐stage economy optimization method for the aggregator based on EV(electric vehicle) user response volumes. To gain the advantages of different types of EVs while increasing the dispatchable capacity, the contract mode between the aggregator and EVs is divided into three categories: complete dispatching, rolling reward and punishment mechanism dispatching, and free dispatching. Based on the cloud model, considering loss aversion, the user's own time flexibility, and the impact of the tariff set by the aggregator on the user's decision‐making, we introduced indicator weights to obtain the improved cloud model. Based on the improved cloud model, a user response volume model is obtained. Then, the aggregator performs a three‐stage pricing optimization operation for EVs based on the bid‐winning peak shaving capacity. In the first stage, the attraction between EVs and charging stations is determined based on the law of gravity, and the charging and discharging reward electricity price is set. In the second stage, the dynamic electricity price of three types of EVs and the charging punishment electricity prices of the rolling reward and punishment mechanism dispatching type are determined. In the third stage, the electricity price of the rolling reward and punishment dispatching EVs is further optimized based on their lack of peak shaving capacity. The method proposed in the paper has been verified to be effective in increasing aggregator profits, increasing EV dispatch capacity, and reducing EV charging costs through the example analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
23. Microwave-induced electric discharges on metal particles for the synthesis of inorganic nanomaterials under solvent-free conditions
- Author
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Anubhav Agarwal, Vijay Tripathi, Leela S. Panchakarla, and Harit Kumar
- Subjects
Materials science ,Oxide ,General Physics and Astronomy ,Nanoparticle ,02 engineering and technology ,lcsh:Chemical technology ,010402 general chemistry ,lcsh:Technology ,01 natural sciences ,Full Research Paper ,microwave synthesis ,law.invention ,Nanomaterials ,chemistry.chemical_compound ,law ,electric discharges ,transmission electron microscopy ,Nanotechnology ,lcsh:TP1-1185 ,General Materials Science ,Electrical and Electronic Engineering ,lcsh:Science ,nanomaterials ,lcsh:T ,Graphene ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,0104 chemical sciences ,Nanoscience ,Amorphous carbon ,Chemical engineering ,chemistry ,Transmission electron microscopy ,lcsh:Q ,Nanorod ,0210 nano-technology ,lcsh:Physics ,Microwave - Abstract
Microwave irradiation of metals generates electric discharges (arcs). These arcs are used to generate nanoparticles of Cu and Ni and one-dimensional nanorods of CuS, ZnF2, and NiF2 protected with fluorinated amorphous carbon. We have also synthesized reduced graphene oxide and partially rolled graphene by this method.
- Published
- 2020
24. Effects of Different Oxidation Methods on the Wetting and Diffusion Characteristics of a High-Alumina Glass Sealant on 304 Stainless Steel.
- Author
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Chen, Changjun, Sui, Liwei, and Zhang, Min
- Subjects
GLASS sealants ,STAINLESS steel ,WETTING ,ELECTRIC discharges ,POWDERED glass ,ELECTRONIC packaging ,VACUUM tubes - Abstract
Glass-to-metal seals are a very important element in the construction of vacuum tubes, electric discharge tubes, pressure-tight glass windows in metal cases, and metal or ceramic packages of electronic components. This paper presents the influence of different pretreatment methods on the high-temperature wettability of 304 stainless steel by high-alumina glass sealing. The pretreatment of the steel included laser surface melting and pre-oxidizing. The bonding characteristics of glass and stainless steel directly depend on the wettability in terms of the measured wetting angle, the type of oxide formed at the stainless steel surface, and the microstructural changes during the manufacturing process. The oxide film thickness on the stainless steel surface was evaluated to determine the optimal parameters. The film was wetted with high-alumina glass powder at different temperatures. The results showed that pre-oxidation decreased the wetting angle from 56.2° to 33.6°, while for the laser-melted surface, the wetting angle decreased from 49.8° to 31.5°. Scanning electron microscopy (SEM) revealed that the oxide film on the laser-melted surface was thicker and denser than that formed on the pre-oxidized surface. The present work shows that laser surface melting has a greater beneficial influence on the wetting and diffusion characteristics of 304 stainless steel sealed by high-alumina glass. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. Online Detection of Hydrogen Fluoride under Corona Discharge in Gas-Insulated Switchgear Based on Photoacoustic Spectroscopy.
- Author
-
Wan, Liujie, Zhao, Xiaohe, and Li, Kang
- Subjects
PHOTOACOUSTIC spectroscopy ,CORONA discharge ,HYDROGEN fluoride ,SPECTRAL lines ,ELECTRIC discharges - Abstract
Internal discharge and overheating faults in sulfur hexafluoride (SF
6 ) gas-insulated electrical equipment will generate a series of characteristic gas products. Hydrogen fluoride (HF) is one of the main decomposition gases under discharge failure. Because of its extremely corrosive nature, it can react with other materials in gas-insulated switchgear (GIS), resulting in a short existence time, so it needs to be detected online. Resonant gas photoacoustic spectroscopy has the advantage of high sensitivity, fast response, and no sample gas consumption, and can be used for the online detection of flowing gas. In this paper, a simulated GIS corona discharge experimental platform was built, and the HF generated in the discharge was detected online by gas photoacoustic spectroscopy. The absorption peak of HF molecule near 1312.59 nm was selected as the absorption spectral line, and a resonant photoacoustic cell was designed. To improve the detection sensitivity of HF, wavelength modulation and second-harmonic detection technology were used. The online monitoring of HF in the simulated GIS corona discharge fault was successfully realized. The experimental results show that the sensitivity of the designed photoacoustic spectroscopy detection system for HF is 0.445 μV/(μL/L), and the limit of detection (LOD) is 0.611 μL/L. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
26. An improved NSGA‐II for the dynamic economic emission dispatch with the charging/discharging of plug‐in electric vehicles and home‐distributed photovoltaic generation.
- Author
-
Wu, Peifeng, Zou, Dexuan, Zhang, Guoyun, and Liu, Hao
- Subjects
ELECTRIC discharges ,PLUG-in hybrid electric vehicles ,PHOTOVOLTAIC power systems ,ELECTRIC vehicles ,HYBRID electric vehicles ,ENERGY storage ,ENERGY consumption - Abstract
This paper investigates four energy utilization scenarios with or without home‐distributed photovoltaic generation (HDPG) to reduce the generation cost and pollutant emission of the dynamic economic emission dispatch with the charging/discharging of plug‐in electric vehicles (DEED‐PEV). The first scenario considers valley filling for the charging of PEVs. The second scenario combines valley filling and peak shaving for the charging and discharging of PEVs. The third scenario adds peak shaving of HDPG to the first scenario, followed by the peak shaving with the discharging of PEVs. The fourth scenario rearranges the distribution of photovoltaic (PV) power for the third scenario, and the PV power in the afternoon is stored by a photovoltaic energy storage system (PESS) and consumed in the evening. A universal procedure is designed for the valley filling and peak shaving of the four scenarios, which is beneficial for determining the filled and shaved loads with respect to certain time intervals. An NSGA‐II method based on a modified crossover and an elimination of individuals (NSGA‐II‐MCEI) is proposed for the multiobjective optimization of DEED‐PEV. The modified crossover can improve the convergence of NSGA‐II‐MCEI, and the elimination operator can maintain the evenness of the nondominated solutions. According to experimental results, scenario 4 achieves cost savings of 95386.62 $, 85636.87 $, and 6776.85 $, respectively, for Scenarios 1, 2, and 3, and it reaches emission reductions of 27617.64 kg, 17252.71 kg, and 220.98 kg, respectively, for scenarios 1, 2, and 3. Also, scenario 4 outperforms the other three scenarios for three weather conditions such as sunny day, cloudy day, and rainy day. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. In-Situ Metabolic Profiling of Different Kinds of Rheum palmatum L. by Laser Desorption–Dielectric Barrier Discharge Ionization Mass Spectrometry Imaging.
- Author
-
Xiao, Xue, Guan, Xiaokang, Xu, Zhouyi, and Lu, Qiao
- Subjects
MASS spectrometry ,MATRIX-assisted laser desorption-ionization ,MASS spectrometers ,SPATIAL resolution ,LASERS ,PHYSIOLOGY ,ELECTRIC discharges ,GAMMA ray spectrometry - Abstract
With its high resolving power and sensitivity, mass spectrometry is considered the most informative technique for metabolite qualitation and quantification in the plant sciences. However, the spatial location information, which is crucial for the exploration of plant physiological mechanisms, is lost. Mass spectrometry imaging (MSI) is able to visualize the spatial distribution of a large number of metabolites from the complex sample surface in a single experiment. In this paper, a flexible and low-cost laser desorption–dielectric barrier discharge ionization-MSI (LD-DBDI-MSI) platform was constructed by combining an LD system with an in-line DBDI source, a high-precision sample translation stage, and an ambient mass spectrometer. It can be operated at a spatial resolution of 20 μm in an atmospheric environment and requires minimal sample preparation. This study presents images of in-situ metabolic profiling of two kinds of plants from different origins, a wild and a farmed Rheum palmatum L. From the screen of these two root sections, the wild one presented five more endogenous molecules than the farmed one, which provides information about the differences in metabolomics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Early Warning of High-Voltage Reactor Defects Based on Acoustic–Electric Correlation.
- Author
-
Gao, Shuguo, Xing, Chao, Zhang, Zhigang, Xiang, Chenmeng, Liu, Haoyu, Liu, Hongliang, Shi, Rongbin, Wang, Sihan, and Ma, Guoming
- Subjects
PARTIAL discharges ,K-nearest neighbor classification ,NOISE control ,FUSION reactors ,SIGNAL detection ,NUCLEAR reactors ,ELECTRIC discharges - Abstract
Traditional high-voltage reactor monitoring and diagnosis research has problems such as high sampling demand, difficulty in noise reduction on site, many false alarms, and lack of on-site data. In order to solve the above problems, this paper proposes an acoustic–electric fusion high-voltage reactor acquisition system and defect diagnosis method based on reactor pulse current and ultrasonic detection signal. Using the envelope peak signal as the basic detection data, the sampling requirement of the system is reduced. To fill the missing data with partial discharge (PD) information, a method based on k-nearest neighbor (KNN) is proposed. An adaptive noise reduction method is carried out, and a noise threshold calculation method is given for the field sensors. A joint analysis method of acoustic and electrical signals based on correlation significance is established to determine whether a discharge event has occurred based on correlation significance. Finally, the method is applied to a UHV reactor on the spot, which proves the effectiveness of the method proposed in this paper. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. Migration mechanism of grouting slurry and permeability reduction in mining fractured rock mass.
- Author
-
Zhengzheng, Cao, Pengshuai, Wang, Zhenhua, Li, and Feng, Du
- Subjects
GROUTING ,LONGWALL mining ,HORIZONTAL wells ,PERMEABILITY ,GLOW discharges ,ROCK permeability ,ELECTRIC discharges ,SLURRY - Abstract
In order to solve the water and gas discharge hazard caused by gob water and harmful gases (such as CO), the method of grouting overburden fractures is adopted to achieve the purpose of safe and efficient mining production in coal mines. This paper carries out the experimental research on the permeability reduction effect of grouting in fractured rock mass, expounds the relationship between gas flow rate and pressure gradient, seepage pressure and permeability, confining pressure and permeability, and analyzes the permeability change law of fractured rock mass before and after grouting. Besides, the grouting migration and permeability reduction model of fractured fine-grained sandstone is constructed by combining grouting test and numerical simulation, which reveals the dynamic evolution law of rock mass permeability in the grouting process. The results show that the permeability of the grouting rock sample decreases from 700–13,000 to 15–300 mD than that of the ungrouting rock sample, and the decrease is more than 95%, which indicates that the sealing performance of grouting slurry is better. Besides, numerical simulations show that the initial permeability of rock samples is 971.9 mD, and the permeability decreases to 45.79 mD after 1800s, and the permeability decreases to 95.3%, which is basically consistent with the experimental results after grouting. The greater the grouting pressure is, the better the grouting effect is. With the increase of the grouting pressure, the increase of the grouting effect is no longer obvious. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Carbon-Based Functional Nanomaterials as Tools for Controlling the Kinetics of Tribochemical Reactions.
- Author
-
Ozimina, Dariusz, Kulczycki, Andrzej, Janas, Dawid, Desaniuk, Tomasz, and Deliś, Maciej
- Subjects
FULLERENES ,CHEMICAL kinetics ,NANOSTRUCTURED materials ,ELECTRIC charge ,ELECTRIC discharges ,JET fuel - Abstract
The aim of this article is to experimentally determine the role of the environment, consisting of a base oil (PAO), carbon nanomaterials, and optional other additives, as well as the kind of metal in contact with the lubrication film, in the stimulation of zinc dialkyldithiophosphate (ZDDP) additives' effectiveness during protective film formation. This paper focuses on the role of carbon nanostructures in energy transportation and conversion during tribological processes. An antistatic additive (ASA) (not used in lubricating oils) for jet fuels was added to disturb the process of energy conduction (electric charges) through the lubricant film and thus determine how this disturbance affects the kinetics of the ZDDP triboreaction and, consequently, the linear wear. To achieve this research goal, two types of tribological testing devices were used: an Anton Paar tribometer (TRB) and a triboelectric tribometer (TET). The novelty of the present research is in the use of the method for disturbing the flow of charge/energy through the lubricant film with an antistatic additive for jet fuels, ASA, to influence the impact of this energy on the antiwear properties of ZDDP. The following conclusions were drawn: (1) carbon-based nanostructures, i.e., CNTs, AuCNTs, graphene, and fullerenes, are able to change the rate of chemical reactions of ZDDP during tribological processes; (2) CNTs have the ability to catalyze tribochemical reactions of ZDDP, while graphene and fullerenes are not able to perform this effectively; (3) AuCNT takes the role of an inhibitor during ZDDP's triboreaction; and (4) by discharging electric charge/energy, ASA, in cooperation with CNT and AuCNT significantly reduces the rate of the ZDDP reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Characteristics of annular surface dielectric barrier discharge with microsecond pulse under water-covered condition.
- Author
-
Xu, Yaozong, Lai, Yundong, Qin, Junting, and Gong, Ziyi
- Subjects
ELECTRIC field effects ,DIELECTRICS ,GLOW discharges ,POWER resources ,ELECTRIC discharges - Abstract
Surface dielectric barrier discharge (SDBD) has wide applications in flow control, wastewater treatment, and biomedicine. The dielectric surface of an SDBD actuator is generally attached to the water droplets during applications. Thus far, only a few studies have been conducted on the effects of water covering the dielectric surface on the discharge characteristics of SDBD. Therefore, the effects of water droplets on the discharge of an SDBD actuator based on a repetitive microsecond pulse power supply were investigated in this study. The results show that a filament micro-discharge channel forms between the light and dark regions at the internal edge of the SDBD high-voltage electrode and develops toward the center of the dielectric surface in the region without water droplet coverage. SDBD in the water-covered region was divided into two stages. This paper compares the electrical characteristics of SDBD with and without water droplet, and explores the electric field distortion effect of water droplet endpoints through 3D simulation.Based on the theories of water droplet polarization and gas discharge, the effects of water droplets on plasma development and surface charge accumulation under water-covered condition were analyzed. The water droplet plays a similar role as a "secondary electrode" during the discharge process. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. The calibration of sharp-crested weirs with a horizontal edge used for measuring flows in partially full pipes.
- Author
-
Kubrak, Janusz, Kubrak, Elżbieta, and Binio, Joanna E.
- Subjects
WEIRS ,OPEN-channel flow ,WATER levels ,CALIBRATION ,ELECTRIC discharges ,WATER use ,WATER leakage - Abstract
This paper presents the results of a laboratory study on the discharge capacity of sharp-crested weirs fitted with a horizontal edge in pipes during open-channel flow conditions and clean water used to measure the outflow. Such sharp-crested weirs are mounted in pipes and are used to control the inflow to separators. The stream profile does not correspond to the profile given by Bazin for sharp crested weirs in channels. A desired location of the water level measurement point for flow rate calculations was provided. Discharge curves were identified for three sharp-crested weirs of 0.0465, 0.0634 and 0.0771 m in height, installed in the pipe of 0.1534 m in diameter and inclinations of 0.5 and 1.0%. The discharge curves for weir flow with free nappe does not show a significant effect of the pipe slope on the weir discharge capacity. The non-dimensional formulas for the discharge capacity of the sharp-crested weir were found as general polynomial regressions. The results indicate that the calibrated sharp-crested weir with a horizontal edge placed in a pipe can be used to control the flow. Due to the scale effect, relationships obtained from the calibration cannot be generalised to other pipe diameters and weirs heights than those analysed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Identifying future district heating potentials in germany: a study using empirical insights and distribution cost analysis.
- Author
-
Manz, Pia, Fleiter, Tobias, Billerbeck, Anna, Fritz, Markus, Alibaş, Şirin, and Eichhammer, Wolfgang
- Subjects
HEATING ,CLIMATE change ,ELECTRIC discharges ,CAPITAL costs - Abstract
District heating will play an important role in the transition towards climate-neutral heating. Various studies on modelling the energy system show that district heating and the related expansion of the networks can have different levels of importance. A main reason is that the costs for distribution grid expansion are not well or not at all considered and empirical evidence for a threshold for cost-effective distribution costs is missing in such studies. In this paper, we aim to improve empirical evidence allowing to improve the representation of future district heating expansion in energy systems models. For that, the current status of district heating is analysed in high spatial resolution for Germany. The results show that with the currently accepted average costs, a large range of the possible future market share of district heating for buildings between 17-52% is possible by 2050, with the parameters of the connection rate and the renovation rate of the building stock. We conclude that the district heating share could be increased by the factor of 2 to 5 in the future, proving the importance of climate-neutral district heating in the transition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Experimental Study on The Performance of External Open-Circuit Failure Gas Discharge Tubes under Power-Frequency Follow Currents.
- Author
-
Lu, Hao, Chen, Yuhang, Li, Hongchang, Zheng, Chuanxiao, and Hu, Heng
- Subjects
GLOW discharges ,HEAT of combustion ,SOLDER joints ,POWER resources ,OPEN-circuit voltage ,TUBES ,ELECTRIC arc ,ELECTRIC discharges ,HEAT transfer - Abstract
A short-circuit fault in the gas discharge tube (GDT) is one of the latent hazards of electrical equipment. It may cause the ignition of electrical equipment. Therefore, based on the existing GDT, an improved external open-circuit failure gas discharge tube (EOFGDT) which can remove short-circuit (SC) failure is presented in this paper, and its structure and working mechanisms are introduced. This EOFGDT can utilize the combustion and heat transfer of continuous arcs due to SC failures to increase the temperature of its end electrode, so as to induce a solder joint failure, by which the elastic sheet on the solder joint becomes disconnected from the end electrode, forming an external gap that reduces the rising speed and amplitude of the recovery voltage across the arc gap, and eventually forms an open circuit (OC) within the structure. The EOFGDT SC condition was simulated and a test of the EOFGDT ability to remove SC faults by using an 8/20 µs impulse current generator coupled with a power-frequency power supply test bed was conducted. The experimental results show that the magnitude of the SC follow currents, power-frequency voltages, and the impulse currents are positively correlated to the OC response time, which is greatly affected by the power-frequency follow currents. When the SC current reaches 30 A, the EOFGDT OC response time is about 350 ms. The experimental waveform is consistent with the screen result of the OC response time of the EOFGDT, which proves the effectiveness of EOFGDTs for the inhibition of SC follow-current failures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
35. Status and Development of Research on Orderly Charging and Discharging of Electric Vehicles.
- Author
-
Zhang, Zhaoyun and Lv, Linjun
- Subjects
ELECTRIC charge ,ELECTRIC discharges ,OPTIMIZATION algorithms ,DATA security ,RESEARCH & development ,ELECTRIC vehicles - Abstract
As the scale of electric vehicles continues to expand, the charging load of electric vehicles into the network has become an issue that cannot be ignored. This paper introduces the concept and development of ordered charging based on the current background of ordered charging research. The application architecture of ordered charging is summarized, and the advantages and disadvantages of centralized, distributed, and hierarchical control architectures are introduced. The current status of research on orderly charging is analyzed at four levels: steps and methods of load modeling for orderly charging, optimization objectives of orderly charging, optimization methods of orderly charging, and practical projects of orderly charging. The methods of load modeling for orderly charging are summarized, different optimization objectives of grid operation for orderly charging are introduced, and the advantages and disadvantages of different optimization algorithms are compared and analyzed. Practical projects on orderly charging illustrate the great potential of orderly charging. This paper points out four problems of communication, data security, market mechanism, and the number of charging stations that orderly charging is currently facing and proposes feasible solutions. The development prospect of orderly charging being more environmentally friendly, energy-efficient, intelligent, and safe is proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
36. Bi-Directional Cuk Equalizer-Based Li-Ion Battery Pack Equalization Control Strategy Research.
- Author
-
Wang, Xiaolu, Tan, Zefu, Cai, Li, Lei, Guoping, and Dai, Nina
- Subjects
ELECTRIC vehicle batteries ,LITHIUM-ion batteries ,ENERGY consumption ,POWER resources ,ELECTRIC discharges ,DYNAMIC testing - Abstract
For the secure usage of battery charging and discharging within electric vehicles, the study of cell pack equalization technology is essential. Therefore, in this paper, an improved Bidirectional Cuk equalizer (BCEQ) structure based on a variable-domain fuzzy PID (VFPID) control equalization strategy is recommended in stages. With the new equalization topology, only half of the capacitive and inductive components are needed to transfer energy between any two individual cells in the power supply. In addition, the proposed VFPID control strategy further improves the efficiency of the equalization model by dynamically adjusting the magnitude of the equalization current parameters. Through simulation experiments, the improved topology was capable of substantially lessening the equalization time and increasing energy utilization by more than 4%. In comparison with the fuzzy PID (FPID) algorithm, around 27.3% faster equalization times can be achieved with the VFPID algorithm; the VFPID algorithm also performed well under the Dynamic Stress Test (DST) condition, demonstrating that the topology and equalization strategy suggested in this paper can successfully address the inconsistency of the FPID algorithm. It has been revealed that the topology and equalization methodology offered in this paper is effective in solving the battery pack inconsistency. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. Research on Deterioration Mechanism and High-Precision Modelling of the Core Loss for Amorphous Alloys after Wire-Cut Electric Discharge Machining.
- Author
-
Yang, Xinyu, Qiu, Shuheng, Wang, Yuheng, Zhao, Pengfei, Gao, Yunpeng, Wang, Haifeng, and Zhang, Chi
- Subjects
ELECTRIC metal-cutting ,AMORPHOUS alloys ,ELECTRIC discharges ,MAGNETIC domain ,MAGNETIC declination ,ELECTROLYTIC corrosion - Abstract
Amorphous alloys (AAs) have the advantage of low core loss. Thus, they can be used in high-speed motor applications. However, compared with the nominal performances, the performance of the wire-cut electric discharge machine (W-EDM)-processed AA iron core changes significantly, which limits its popularization. This paper focuses on the performance degradation mechanism of the AA ribbon caused by W-EDM and establishes a modified core loss model after machining. First, a 308 × 15 mm ribbon-shaped AA sample machined by W-EDM was prepared. The characterization and analysis of the magnetic properties, phase, magnetic domain, nano-indentation, micro-morphology, and composition were carried out. In this paper, by analysing the variation in the magnetic domain distribution based on domain width and nano-mechanical properties, it is proposed that the performance degradation range of AA ribbons processed by W-EDM is within 1 mm from the edge. By comparing the microscopic morphology and chemical composition changes in the affected and the unaffected area, this paper presents a mechanism for the property deterioration of W-EDM-processed AA ribbons based on electrochemical corrosion. Finally, a modified loss model for W-EDM-processed AAs is established based on the division of the affected area. This model can significantly improve the accuracy of core loss estimation in the medium- and high-frequency bands commonly used in high-speed motors. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. Editorial for Special Issue Symmetry in Physics of Plasma Technologies.
- Author
-
Kukushkin, Alexander B.
- Subjects
SYMMETRY (Physics) ,PLASMA physics ,ELECTRIC discharges ,FUEL cycle ,THERMONUCLEAR fusion ,PLASMA diagnostics - Abstract
This Special Issue collected papers on hot topics in the field of controlled thermonuclear fusion (CTF), including review papers and research articles. The second paper in this group, the research paper [[2]], is devoted to the universality of stochastic clustering of materials irradiated with plasma in thermonuclear fusion devices. References 1 Khripunov B.I., Koidan V.S., Semenov E.V. Thermonuclear Fusion Reactor Plasma-Facing Materials under Conditions of Ion Irradiation and Plasma Flux. [Extracted from the article]
- Published
- 2023
- Full Text
- View/download PDF
39. Comparison of Distinct Discharge Modes for Ozone Production in a Novel DBD Configuration With Three Flat Electrodes.
- Author
-
Firoozabadi, Ehsan Azimi and Hosseini, Seyed Mohammad Hassan
- Subjects
OZONE generators ,ELECTRIC discharges ,ELECTRIC potential ,PLASMA gases ,DIELECTRICS - Abstract
In this paper, a new configuration of dielectric-barrier discharge (DBD) reactor with three electrodes was manufactured and used to produce ozone. Designed flatly, this reactor is capable of establishing three different discharge modes from type of the volume and surface discharges, without modifying its internal structure. The aim of presenting this paper is to experimentally analyze the three discharge modes and their combination using a second channel to produce ozone. The two reactor channels are identical in terms of dimensions, material, and manufacturing process. Two frequency-adjustable pulse generators of the same electrical characteristics and two high-voltage transformers were used in the course of the experiments. The applied sinusoidal voltage is from 0 to 12 kVp-p. The frequency range was determined and fixed for all three discharge modes for the highest ozone concentration at a fluctuation rate of 1 L/min. Effects of increasing the applied voltage on the obtained concentration from the three different discharge modes were experimentally analyzed. Using the provided inlets–outlets, the effect of flowing gas through the length and width of the discharge area on ozone concentration was investigated, and appropriate flow directions were determined for the flowing gas under either of the three discharge modes. Experimentally results have been done for this three discharge modes as well as hybrid modes. The maximum ozone production rate achieved up to 14.52 g/h in the series combination of two different volume discharge. At 96% oxygen purity, ozone production yield, in two modes volume discharge VaDBD and surface discharge SDBD, have been improved up to 529.87 g/kWh. However, the total input power of the entire system is 120.2 W. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
40. Effect of Mesh Geometry on Power, Efficiency, and Homogeneity of Barrier Discharges in the Presence of Glass Dielectric.
- Author
-
Gnapowski, Ernest, Gnapowski, Sebastian, and Pytka, Jaroslaw
- Subjects
ELECTRIC discharges ,OZONE ,ELECTRIC power production ,ELECTRIC breakdown ,ELECTRODES - Abstract
This paper will describe the influence of mesh geometry on the homogeneity of discharges, power, and efficiency of ozone generation. Homogeneous discharges increase the efficiency of the generation of ozone. Geometry of mesh electrodes affects the power and type of discharges, concentration, and efficiency of the ozone generation. The analysis of selected results indicates the need for the use of mesh electrodes with a small cross section at least $0.1\times0.1$ mm2 mesh to obtain a homogeneous discharge. The mechanism by which the geometry of mesh electrodes on the homogeneity of discharge is illustrated in this paper. Homogeneous discharges increase the efficiency of the generation of ozone that reduces the cost of ozone production. The results of the experimental studies show an increase in the average efficiency of 60% of the ozone generation and a 20% reduction in the demand for power with the constant concentration of ozone, justifies the problem. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
41. High Voltage Electric Pulse Drilling: A Study of Variables through Simulation and Experimental Tests.
- Author
-
Zhang, Qingyu, Wang, Guanglin, Pan, Xudong, Li, Yuefeng, He, Jianqi, Qi, Yue, and Yang, Juesuan
- Subjects
VOLTAGE ,ELECTRIC drills ,HIGH voltages ,TECHNOLOGICAL innovations ,WATER jets ,ELECTRIC discharges - Abstract
With the deepening of drilling depth, the difficulty of drilling engineering increases gradually due to the complex geological conditions. The traditional mechanical drilling method shows the problems of high energy consumption, low efficiency, long cycle and high cost. Because of the characteristics of rock, the high abrasiveness of rock causes great wear to the bit, which becomes an important factor affecting the drilling rate. High voltage electric pulse (Abbreviated as HVEP later in this paper) drilling technology is a new technology developed in the past several decades. The technology uses plasma channel, water jet or shock wave generated by high voltage electric pulse discharge to break rock. It has the characteristics of environmental protection, directional breaking, easy control of rock breaking process and fast speed in the face of complex hard rock. In this paper, the mechanism and technology of rock breaking by high voltage electric pulse method in deep drilling are studied, and the functional test is carried out. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. Application of Artificial Intelligence for EV Charging and Discharging Scheduling and Dynamic Pricing: A Review.
- Author
-
Chen, Qin and Folly, Komla Agbenyo
- Subjects
TIME-based pricing ,ARTIFICIAL intelligence ,ELECTRIC discharges ,LOGISTIC regression analysis ,SCHEDULING ,CONGESTION pricing - Abstract
The high penetration of electric vehicles (EVs) will burden the existing power delivery infrastructure if their charging and discharging are not adequately coordinated. Dynamic pricing is a special form of demand response that can encourage EV owners to participate in scheduling programs. Therefore, EV charging and discharging scheduling and its dynamic pricing model are important fields of study. Many researchers have focused on artificial intelligence-based EV charging demand forecasting and scheduling models and suggested that artificial intelligence techniques perform better than conventional optimization methods such as linear, exponential, and multinomial logit models. However, only a few research studies focused on EV discharging scheduling (i.e., vehicle-to-grid, V2G) because the concept of EV discharging electricity back to the power grid is relatively new and evolving. Therefore, a review of existing EV charging and discharging-related studies is needed to understand the research gaps and to make some improvements in future studies. This paper reviews EV charging and discharging-related studies and classifies them into forecasting, scheduling, and pricing mechanisms. The paper determines the linkage between forecasting, scheduling, and pricing mechanism and identifies the research gaps in EV discharging scheduling and dynamic pricing models. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. Validation of the Lightning Fractal Model Based on the Attachment Probability Experiments Using Rod-Rod Air Gaps.
- Author
-
Guo, Jun, Yang, Tian-Yi, Guo, Si-Yu, Zhang, Xu-Dong, Wang, Bang-Yong, Xie, Yan-Zhao, Wu, Jian, and Jing, Yan
- Subjects
LIGHTNING protection ,FRACTAL dimensions ,ELECTRIC lines ,LIGHTNING ,SYSTEM safety ,ELECTRIC discharges ,ELECTRIC fault location - Abstract
Direct lightning poses a serious threat to the safety of power systems. In recent years, the lightning fractal model, which can reflect the fractal characteristics and randomness of lightning leaders, has been gradually applied to direct lightning protection for substations, transmission lines, etc. However, since few studies have linked simulations with experiments, the reliability of the lightning fractal model in terms of attachment probability prediction lacks experimental verification. In this paper, a series of attachment tests are carried out under a rod-rod gap. The equivalence between simulation tests and natural lightning is discussed, and the influencing factors of the attachment results are investigated. The attachment probability is simulated and compared to the test value under each test configuration. The test results show that the fractal dimension of discharge channel is consistent with the observation results of natural lightning. Under different configurations, the test value of attachment probability basically conforms to the simulation value. In general, the dispersion of the test results is slightly greater than the simulation results, but the average probability differences are all within 10%. The test results strongly indicate that the lightning fractal model is of good reliability in the prediction of strike probability. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
44. Design and Construction of a High-Current Capacitor Bank for Flash Graphene Synthesis †.
- Author
-
Ramírez, Juan, Yépez, Esteban, Pantoja-Suárez, Fernando, Acurio, Eliana, Pérez, Fabian, and Basile, Leonardo
- Subjects
CAPACITOR banks ,GRAPHENE synthesis ,RESISTANCE heating ,ELECTRIC discharges ,ELECTRIC capacity - Abstract
This paper introduces the design and fabrication of a versatile capacitor bank developed specifically for its integration within the innovative flash joule heating (FJH) technique, aimed at synthesizing graphene. The capacitor bank offers two adaptable configurations, providing options for capacitance at 180,000 µF and 68,000 µF, combined with a maximum charging capability of 400 V. This equipment facilitates the swift conversion of carbon-containing materials into graphene by harnessing transient current discharges. The proposed capacitor bank facilitates the execution of comprehensive research pertaining to graphene production from diverse carbon sources, opening an opportunity for advancing exploration within this rapidly evolving field of study in Ecuador. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. High-power sub-picosecond filamentation at 1.03 µm with high repetition rates between 10 and 100 kHz.
- Author
-
Löscher, Robin, Moreno, Victor, Adamou, Dionysis, Kesim, Denizhan K., Schroeder, Malte C., Clerici, Matteo, Wolf, Jean-Pierre, and Saraceno, Clara J.
- Subjects
ELECTRIC discharges ,FIBERS ,LASERS - Abstract
Filamentation has extensively been explored and is well understood at repetition rates <1 kHz due to the typical availability of multi-mJ laser systems at a moderate average power. The advent of high-power Yb-lasers opened new possibilities for filamentation research. However, so far, high average power Yb systems have mostly been explored to increase the driving pulse energy to several hundreds of mJ and not at significantly higher repetition rates. In this paper, we study, for the first time, long filaments at unprecedented high repetition rates of 10, 40, and 100 kHz using a 500-W Yb-doped thin-disk amplifier driver operating with sub-700 fs pulses. We compare the filament length, density hole, and fluorescence at a constant peak power but different repetition rates and find a strong dependence on filament length and density depletion with repetition rate. Our analysis reveals the emergence of a significant stationary density depletion at repetition rates of 40 and 100 kHz. The corresponding reduction in the breakdown threshold by increasing the laser repetition rate observed in our study signifies a promising avenue for enhancing the efficiency and reliability of electric discharge triggering in various scenarios. Using capacitive plasma probe measurements, we address the limitations of fluorescence imaging-based measurements and demonstrate a systematic underestimation of filament length. This work contributes to a deeper understanding of the interplay between laser repetition rates, filamentation, and heat-driven density depletion effects from high-repetition-rate high-power laser systems and will contribute to guiding future research, making use of filaments at high repetition rates. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
46. Partial Discharge Localization through k-NN and SVM.
- Author
-
Sekatane, Permit Mathuhu and Bokoro, Pitshou
- Subjects
MISSING data (Statistics) ,SUPPORT vector machines ,K-nearest neighbor classification ,ELECTRIC power transmission ,GAS analysis ,ELECTRIC discharges ,PARTIAL discharges - Abstract
Power transformers are essential for the distribution and transmission of electricity, but they are prone to degradation due to faults early on. Partial Discharge (PD) is the most significant pointer of insulation breakdown in high-voltage apparatus. Dissolved Gas Analysis (DGA) is a commonly used technique for detecting and diagnosing PD. However, DGA data often contain missing values, which can significantly affect the accuracy of PD diagnosis. To mitigate the issues of missing values, this paper proposes using the k-Nearest Neighbors (kNN) technique to impute the missing values in the dataset. Further, it combines kNN with a Support Vector Machine (SVM) to detect the possibility of a PD source in the high-voltage apparatus. The approach was evaluated on a real-world DGA dataset and achieved high classification performance and discriminatory power for distinguishing between PD and non-PD instances. The effectiveness of the missing value imputation technique was evaluated, and the proposed approach demonstrated improved accuracy and precision compared to methods without imputation. The proposed approach offers a current solution for PD analysis in power transformers using DGA data with missing values. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
47. A data-driven approach for exploring partial discharge inception voltage of turn-to-turn insulation in inverter-fed motors.
- Author
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Li, Peiyi, Zhang, Xihai, Wang, Peng, Wang, Jian, and Shang, Zeyi
- Subjects
PARTIAL discharges ,GLOW discharges ,ELECTRIC discharges ,VOLTAGE ,FINITE element method - Abstract
This paper aims to propose a novel data-driven approach for exploring the partial discharge inception voltage (PDIV) of turn-to-turn insulation in inverter-fed motors. To this end, the gas discharge theory-based finite element method is investigated to simulate the state of turn-to-turn insulation, and a comprehensive database is established concerning the structural and environmental factors. Subsequently, a bisected deep belief network (BDBN), which combines with deep belief networks (DBN) and the bisection method, is proposed to explore PDIV. Specifically, DBN is designed to distinguish the discharge state of turn-to-turn insulation, and the testing applied voltage is adaptively adjusted to explore PDIV by the bisection method. The experiment result demonstrates the effectiveness and reliability of BDBN in exploring PDIV of turn-to-turn insulation in terms of precision. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
48. Experimental and Numerical Analysis of a Hybrid Thermal Management Concept at Different Discharge Rates for a Cylindrical Li-Ion Battery Module.
- Author
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Shahid, Seham and Agelin-Chaab, Martin
- Subjects
LITHIUM-ion batteries ,PHASE change materials ,PHASE transitions ,NUMERICAL analysis ,ELECTRIC discharges ,THERMAL analysis ,THERMAL batteries - Abstract
In this paper, an experimental and numerical study was conducted to analyze the performance of a hybrid thermal management concept for cylindrical lithium-ion battery modules at various discharge rates. The proposed concept consists of primary cooling through phase change material (PCM) and secondary cooling through vertical liquid channels between the PCM and airflow at the top of the cells. Two experimental studies were performed to obtain the temperature and heat flux profiles. In addition, the thermal performance of the battery module was obtained for 1 C, 2 C, 3 C, 5 C, and 7 C discharge rates using the numerical study. The results show that the maximum temperature was limited to ~30 °C. Additionally, the temperature uniformity in all the discharge rates was maintained below 5 °C. Finally, a meager amount of PCM was utilized during all the discharge cycles. At 1 C none of the PCM changed its phase, whereas at 2 C, 0.32%, 3 C, 0.14%, 5 C, 0.3%, and at 7 C, 0.12% of PCM changed its phase. The proposed hybrid concept can maintain the thermal environment required by the Li-ion cells for effective performance. Furthermore, this concept does not require excessive pumping fluid power and high air velocities, which reduces the energy required for the operation of the thermal management system, thereby increasing the available energy for propulsion. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
49. A novel analytical technique for determining inflow control devices flow area in CO2-EOR and CCUS projects.
- Author
-
Rezvani, Hamed and Rafiei, Yousef
- Subjects
OPTIMIZATION algorithms ,ENHANCED oil recovery ,GLOW discharges ,ELECTRIC discharges ,OIL wells ,GAS condensate reservoirs - Abstract
CO
2 -EOR is one of the principal techniques for enhanced oil recovery (EOR). The CO2 injection not only promotes oil recovery but also leads to greenhouse gas discharge reduction. Nonetheless, a key challenge in the CO2 flooding process is a premature CO2 breakthrough from highly permeable zones. In recent years, Inflow Control Devices, ICDs, have been used as a potential solution to mitigate an early gas breakthrough. The key and important parameter in ICDs installation is obtaining its opening flow area. The common ways to obtain the ICD flow area such as utilizing optimization algorithms are very complicated and time-consuming, and further these methods are not analytical. The aim of this work is to solve the mentioned challenges—postpone the breakthrough time in gas injection and present an easy, fast, and analytical technique for obtaining ICDs flow area. This paper presents a new analytical method for obtaining inflow control devices flow area for injection wells in an oil reservoir under CO2 -EOR in order to balance the injected CO2 front movement in all layers. Then, in order to compare the advantages and disadvantages of the presented technique with other methods such as optimization algorithms, a case study has been done on a real reservoir model under CO2 injection. Later, the results of studied scenarios in the case studied are given and compared. The results show that by utilizing the proposed method recovery factor is raised by improving sweep efficiency, and the breakthrough time is more postponed compared to the other methods about 400 days. Further, the ICD flow area calculation takes 2 min by presented analytical techniques, but the optimization algorithm takes 4040 min to run the simulation model to find the ICD flow area. In the end, the findings of the presented analytical formula can help to set the ICD flow area very fast without the simulation and help researchers for a better quantitative understanding of parameters affecting the ICD flow area by the given formula such as reservoir permeability. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
50. Prediction of NOX Concentration in Nonthermal Plasma-Treated Diesel Exhaust Using Dimensional Analysis.
- Author
-
Allamsetty, Srikanth and Mohapatro, Sankarsan
- Subjects
DIESEL motor exhaust gas ,NITROGEN oxides ,ELECTRIC discharges ,NON-thermal plasmas ,NONLINEAR statistical models - Abstract
Application of the nonthermal plasma (NTP) technology for NOX removal from diesel engine exhaust has already been experimentally proved to be an efficient method at laboratory level. The NOX removal efficiency depends on various electrical and physical parameters, and very few studies have been carried out to predict it with the variation in those parameters. In this paper, an approach has been made using dimensional analysis to predict the NOX concentration with the NTP treatment, based on its dependence on various operating parameters. A relation has been obtained between NOX concentration and 11 numbers of parameters affecting NOX removal so as to form dimensionless groups. A mathematical model has been established using the experimental data and nonlinear regression technique. Experiments are conducted to validate this model with variations in the parameters voltage, flow rate, temperature, discharge gap width, and initial NOX concentration. The predicted NOX concentration values have been found to be well matched with the experimental results. The rms errors for the test data are found to be 4.64%, and in ppm, it is 9.58. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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