Electric Field Distribution Characteristics Research Articles

GOLD PLASMONIC ARRAY STRUCTURES FOR SENSING APPLICATIONS

This article is devoted to the theoretical study of the plasmonic properties of periodically arranged arrays of gold nanoparticles. The Comsol Multiphysics software, which is based on the finite element method, was used to build 3D numerical models for the simulation and conduct research. In this work the electric field distribution and optical characteristics of the spherical gold nanoparticles array were studied. Individual localized surface plasmon resonance modes are influenced when metallic nanoparticles are in the close proximity and as a result the electric near- fields can couple, resulting in a new hybrid mode. We mainly focused here on the investigation of two crucial questions, particularly, influences of the gap between the nanoparticles and the refractive index of the surrounding medium on the resulting optical response of the gold nanoparticles arrays. The array of periodically arragement gold nanoparticles is characterized by an enhanced local electric field between the nanoparticles, which is inversely proportional to the gap between the particles. The field strength and optical properties (reflection, transmission, and absorption) can be conveniently manipulated by changing the gap between particles. In additional, their potential applications as sensetive plasmonic sensors element have been considered. The studied structure has a significant potential for practical applications due to its wide range of the operating wavelengths and ease of the high-throughput fabrication. In the course of the study, it was established that the change in the distance between the surface of nanoparticles by 1 nm leads to a significant shift in the spectral transmission and reflection curves on the spectral range. In addition, these studies showed that an increase in the distance between the surfaces of nanoparticles leads to the decrease in the near-field interaction between gold nanoparticles in the array. Therefore, the obtained results can be successfully used in the manufacture of highly sensitive plasmon sensors with the possibility of controlling the sensitivity and the working spectral range.

Three-Dimensional Transient Electric Field Characteristics of High Pressure Electrode Boilers

An uneven electric field during the operation of an electrode boiler will lead to the emergence of a high field strength area and low field strength area in the furnace, which will endanger the safe and reliable operation and heating efficiency of the electrode boiler. A numerical study of three-dimensional transient electric field distribution characteristics in a 10 kV high-voltage electrode boiler was carried out. The distribution characteristics of the global electric field of the electrode boiler under the nominal voltage of 10 kV were studied, and the distribution law of the electric field of the electrode boiler under poor power quality, such as different bus voltage and three-phase voltage imbalance, was explored. The results show that the electric field distribution characteristics of the three-phase transient are more obvious in the section closer to the electrode disc, and the electric field distribution is the most uniform in the section that is 1.4 m away from the furnace water. In the case of poor power quality, such as different bus voltage and three-phase voltage imbalance, the points of the maximum electric field intensity of the four surfaces change periodically with time, and the greater the bus voltage fluctuation, the more severe the impact on the transient electric field. The three-phase voltage imbalance will shift the peak value of the electric field intensity. The decrease or offset of electric field intensity in the electrode boiler caused by poor power quality will directly affect its heating efficiency. The electric field simulation results have a specific reference value for improving the internal electric field distribution and on-site operation and maintenance of the electrode boiler.

Characterization of electric field distribution in valve-side casing of 500 kV converter transformer considering AC and DC mixed voltage

The converter transformer, as one of the indispensable core devices in the ultra-high voltage direct current (UHVDC) transmission system, exhibits highly complex electric field distribution characteristics within the valve-side bushing. In-depth research into the electric field distribution characteristics and variation patterns of the valve-side bushing under both alternating current (AC) and direct current (DC) voltage conditions is crucial for ensuring the reliable operation of the transmission system. This study focuses on investigating the electric field distribution of the valve-side bushing under AC and DC voltage excitations. A full-scale finite element model of the valve-side bushing of the converter transformer is constructed using finite element simulation software for modeling and research purposes. The results indicate that the internal electric field distribution of the bushing is generally similar under both AC and DC voltage excitations. However, in the SF6-filled region, a steeper voltage drop is observed under DC excitation compared to AC. The space charges generated in the DC electric field due to field polarization have a significant impact on the distortion of the electric field on the inner and outermost layer electrode plates. These conclusions provide theoretical guidance for the insulation design of the valve-side bushing in converter transformers at the 500 kV voltage level and similar ratings.

The Influence of Morphological Characteristics of Graphene on Its Field Emission Properties

Graphene is one of the most potential field emission cathode materials due to its excellent electrical, thermal, and mechanical properties, as well as rich edge structures. In this paper, we studied the growth parameters of graphene prepared by chemical vapor deposition, and prepared three kinds of morphologies of graphene: single-layer graphene, graphene islands, and graphene with buffer layers, and then we explored the influence of the morphological characteristics of graphene on its field emission properties, and analyzed the mechanism of the morphological characteristics of graphene on its field emission properties through COMSOL. Compared to single-layer graphene, the turn-on field of graphene islands, and graphene with buffer layers was 5.55 V/μm and 5.85 V/μm, respectively. The current density has also been increased to 40.3 μA/cm<sup>2</sup> and 26.4 μA/cm<sup>2</sup>. On the other hand, the field emission currents of single-layer graphene and graphene with buffer layers are more stable. In the 5-hour test, the current density only decreased by 2% and 4%, respectively. COMSOL simulation shows that the morphological characteristics of graphene have a significant impact on the electric field distribution characteristics and heat dissipation capacity. Graphene islands and graphene with buffer layers have exposed edges, leading to local electric field concentration and thus improving field emission properties. Graphene islands are distributed discretely on the substrate, without forming a continuous graphene film and lacking transverse heat dissipation channels, so the accumulation of heat will cause damage to the graphene emitter, and affect the stability of its field emission current. This study would be of great benefit to the understanding of the influence of the morphological characteristics of graphene on its field emission properties, and improving the field emission properties of graphene materials.

Influence of Bird Droppings Channel on Electric Field Distribution Characteristics for Catenary Positive Feeder Insulator String Under Windy Conditions

Influence of Bird Droppings Channel on Electric Field Distribution Characteristics for Catenary Positive Feeder Insulator String Under Windy Conditions

Effect of CZT Powder Burying CZT Crystal on Annealing in Cd Atmosphere

AbstractDue to the inevitable formation of the second phase of Te in the growth process of Cadmium zinc telluride (CdZnTe/CZT) crystal, the Te related defects are usually treated by Cd atmosphere annealing to improve the crystal quality. In this paper, the influence of different powder burying crystals on the annealing effect in Cd atmosphere is studied by analyzing the change of crystal surface components, removal effect of Te inclusion, electric field distribution and carrier transport characteristics. The results show that burying the crystal with powder helps to maintain the crystal surface composition in annealing, but the Te inclusion can be eliminated only by controlling the amount of powder. Moreover, it is found that the uniformly distributed Te inclusions tend to migrate to the surface during the annealing process, while the Te inclusions at dislocation or crystal boundary are difficult to eliminate. It is speculated that the internal Te loading is more inclined to the reaction of diffused Cd atom, which makes the Te inclusions decrease continuously. After annealing with proper amount of powder, due to the elimination of Te inclusion defects, the electric field distribution inside the crystal is more uniform and the carrier lifetime product is improved.

Research on simulation and detection of space electric field distribution of deteriorated insulators in three-phase over-head transmission lines

Operation accidents caused by deteriorated insulators occur from time to time, which poses a direct threat to the safe and stable operation of transmission lines. Much research has been done at home and abroad on the degradation mechanism of deteriorated insulators, the electric field distribution characteristics of insulator strings and the influence of deteriorated insulators on the space electric field, but there is little research on the influence of three-phase electrification on the space electric field of insulator strings. Therefore, this paper studies the simulation and detection of electric field distribution of deteriorated insulators in three-phase transmission lines. First, the difference between three-phase electrification and single-phase electrification on the space electric field of insulator strings is simulated and analyzed, and the influence of deteriorated insulators on the space electric field distribution of insulator strings under three-phase electrification is studied. Second, based on simulation results, a detection method for deteriorated insulators in three-phase overhead trans-mission lines is proposed, and a non-contact space electric field measurement device based on Unmanned Aerial Vehicle (UAV) is developed. Finally, a Unmanned Aerial Vehicle inspection system is used to test the transmission lines in combination with an electric power department, and the simulation results and the effectiveness of the proposed detection method are verified. Results show the electric field distribution of insulator strings is obviously different between three-phase electrification and single-phase electrification, and when the detection distance is 300 mm, the proposed detection method and device can effectively identify deteriorated insulators in three-phase transmission lines.

Assessing the impact of step gate oxide and gate electrode engineering on performance of β-Ga2O3 MOSFET for high frequency applications

In the present work, the advantages of step gate oxide and gate electrode engineering designs have been amalgamated with scaled β – Ga2O3 MOSFET for ultra-high frequency applications. Various device attributes such as channel potential, electric field distribution, output and transfer characteristics etc., have been studied using both analytical modeling and simulation approaches. Furthermore, the paper also explores numerous high frequency figure of merits such as cut-off frequency, gain bandwidth product and transconductance frequency product etc. Two-port parameters i.e., scattering parameters, Rollett's stability factor etc., and high-power metrics such as output power and power-added-efficiency etc., have also been investigated. The variation of device gain with frequency has also been studied. Furthermore, a thorough comparison is drawn between the proposed device, the device with only step gate oxide engineering and a uniform gate throughout, and the conventional device without any of these designs for fair assessment. It has been demonstrated that the proposed design is reliable and efficient with significant improvement in abovementioned figure of merits which makes it suitable contender for ultra-high frequency applications.

Discharge Characteristics and Numerical Simulation of the Oil–Gas Surface under DC Voltage

Low insulation strength at the oil–gas surface due to oil leakage and partial discharge of oil-immersed power equipment is a major threat to the safe and reliable operation of power systems. This paper investigates the initiation and development of the oil–gas surface discharge. The oil–gas surface discharge test platform was established, and discharge tests were carried out at different gap distances (1–2.5 mm). By coupling the electric field and flow field, the multi-layer dielectric discharge streamer model was built, and the characteristics of charge and electric field distribution at different gap distances were studied. The test results show that the liquid surface between the electrodes rises during the discharge process. Furthermore, the surface discharge voltage exceeds the air gap discharge voltage. With the simulation analysis, the oil–gas surface discharge is a typical streamer development process. Under 50 kV applied voltage and 2.5 mm gap distance, the average development speed of the streamer is 12.5 km/s. The larger the gap distance is, the greater the average streamer development speed is. The recording and numerical simulation of the discharge process are of great significance for exploring the mechanism of oil–gas surface discharge, optimizing the discharge process, and diagnosing partial discharges.

Physics informed neural networks for electric field distribution characteristics analysis

Electric field calculations based on the Poisson equation have been widely used in high voltage and plasma technology. However, in practical applications, the electric field distribution in space is relatively complex, and the simulation technology based on the traditional method is often a simplification of reality, which leads to a large error between the simulation and the actual measured value. In the actual application process, due to the limitation of measurement methods, it is necessary to infer the electric field data at other locations in space according to the measurement results. Physics informed neural networks (PINNs) are introduced into the electric field calculation. PINNs are considered partial differential equation solvers based on deep neural networks. In this paper, 2D and 3D electric field distributions are discussed and compared with the finite element method. A method of dividing the dielectric distribution based on the sigmoid function is proposed, which can be effectively used to construct the spatial electric field model of the homogeneous dielectric. The combination of the data and physical model based on PINNs establishes a method to solve the inverse problem of the relative permittivity in the electric field. The results show that PINNs can calculate the distribution of the electric field according to the physical equations and different types of constraints and parameters.

Research on Induction Measurement of Operators Approaching Charged Bodies in Complex Operation Scenarios

Aiming at the uneven distribution of the electric field and the difficulty in achieving low false alarms for operators approaching charged bodies in the complex operating environment in the power system, a mask region convolutional neural network (MR-CNN) based complex operation scene recognizer is first constructed in this paper to perform image feature extraction, target box regression, and classification training. Secondly, a simulated annealing-based mirror-image charge method is proposed to calculate the electric field distribution characteristics. The simulated annealing algorithm is used to optimize the number of charges of the mirror-image charges method to minimize the weighted sum of the calculation error and the electric field strength calculation time. Finally, the feasibility and effectiveness of the proposed algorithm are verified through simulation experiments.

Simulation Analysis of Emptying the Explosives in Projectiles with Electromagnetic Heating

This paper concerns a new method for projectile disposal by emptying the explosives in projectiles with electromagnetic heating. It explains the basic principles of the emptying technology via electromagnetic heating. A multiphysical analysis model coupled with an electromagnetic, thermal, fluid and phase transition model is established, and the explosive melting simulation is conducted based on this model. The dynamic phase transition process of the explosive from solid to liquid is simulated, and the electric field, magnetic field and thermal field distribution characteristics during the process are analyzed. Furthermore, the effect of excitation current characteristics on the phase transition of the explosive is given, which shows that the explosive melting process is controllable by setting the excitation current amplitude or frequency. This paper provides a new method for the disposal of end-of-life projectiles, which is more controllable, safe and environmentally friendly.

Electric field characteristics of shared towers and electric field distribution characteristics near 5G base stations

With the continuous promotion of domestic 4G network construction and the gradual arrival of 5G networks, the requirements of mobile communication networks on capacity and coverage are constantly improving, and the number of communication base stations is also increasing. Therefore, the “shared tower” with the function of a communication base station added to the existing high-voltage transmission line tower is becoming a new resource-sharing mode. There is no systematic study on the installation location of the shared tower base station on the high-voltage tower, which is not conducive to the application and promotion of “shared tower”. In this paper, the finite element simulation model of the tower installed with the base station is built. The electric field distribution near the tower with the base station, the electric field distribution characteristics under different base station installation quantities and different positions of the base station are mainly studied, and the electric field distribution near the surface of the base station is obtained. Combined with the electrical safety distance limit of communication equipment and iron tower, the influence of the installation location and quantity of the base station on the electric field near the base station is evaluated.

Research on Electric Field Detection of Degraded Insulators Based on a Sensitive Detection Method under Complex Operating Conditions

Insulators are the basis of the stable operation of transmission lines, and it is particularly important to regularly detect the insulation performance of insulators. After several years of research, contactless space electric field detection technology for degraded insulators, based on an unmanned aerial vehicles (UAV) platform, has developed rapidly. However, the existing technology is only limited to the typical vertical/horizontal state research category and cannot apply to complex operating conditions such as attitude disturbance and path tilt. This paper builds a simulation model of insulators at a voltage level of 220 kV by COMSOL finite element software and analyzes the space electric field distribution characteristics of degraded insulators and the influence of different surface conditions, attitude disturbance, path tilt, etc., on the space electric field distribution of insulators. To reduce the error of UAV detection under complex operating conditions of insulators, a method for detecting the electric field of degraded insulators based on sensitive insulators is proposed and verified by experiments. According to the research results, surface conditions of insulators have little influence on their space electric field, while the attitude disturbance and path tilt of UAVs have a great influence on the electric field of insulators. Sensitive insulators at a level of voltage below 220 kV are generally located at the low-voltage end. The principles of sensitive insulators are combined with the space electric field measurement method to measure the space electric field distribution, thus effectively judging whether there are degraded insulators in the string. The method specified in the paper greatly improves the accuracy and detection efficiency of the contactless electric field detection of insulators, which is of great significance for the promotion of the electric field detection method of insulators in practical applications.

Design of 66 kV dry-type step-up transformers for large capacity wind turbines

<p indent="0mm">The development of large-scale offshore wind power has become an inevitable trend in the current renewable energy development. Offshore wind power has moved from offshore to deep-sea, and the capacity of wind turbines has reached more than <sc>8 MW.</sc> The step-up transformer increases the output voltage of the wind turbine from <sc>0.69–1.4</sc> to <sc>35 kV</sc> and above, which is the key equipment of the wind power system. The deep-sea wind power is more than <sc>50 km</sc> away, and the voltage of the step-up transformer needs to be increased to <sc>66 kV</sc> and above. At present, the <sc>66 kV</sc> step-up transformer for offshore wind power generally adopts oil-immersed transformer technology, and <sc>66 kV</sc> step-up transformer with dry-type insulation is a blank product. Oil-immersed step-up transformers have the risk of oil leakage, which may cause fire or explosion accidents, while dry-type insulation step-up transformers have low fire risk, good explosion-proof performance, and new high reliability, and have significant technical advantages in offshore wind power applications. However, limited by the design method and manufacturing process technology, the traditional epoxy casting step-up transformer cannot solve the problem of excessive partial discharge under high voltage, which is caused by high-voltage winding interface defects, restricting the application of this technology in66 kV step-up transformers. This paper breaks through the technical limitations of traditional epoxy cast transformers, innovates from the insulation design mechanism, and proposes a new design method for a <sc>66 kV</sc>/10 MVA step-up transformer based on silicone rubber insulation. By analyzing the generation mechanism of the interface defect of the epoxy casting transformer’s high-voltage winding, a design method of high-voltage insulated shielding wires incorporating semiconducting shielding layers is proposed. The outer conductor of the wire is first wrapped with the semiconducting shielding layer, and then the insulating layer is wrapped. The semiconducting shielding layer and the insulating layer use same base materials. The semiconducting shielding layer can shield the conductor interface defects, the material of the semiconducting shielding layer is designed with the same base material of the insulating layer, so the two layers can be fully compatible, which can effectively suppress the interface defects. According to a certain winding form, the high-voltage insulated shielding wire is wound into a coil structure with a certain number of turns, then integrally cast silicone rubber insulation, forming the overall structure of the high-voltage winding. The high-voltage winding is designed with sheds structure, which increases the creepage distance along the surface, and realizes the high creepage insulation design with a compact height space. The <sc>66 kV</sc>/10 MVA step-up transformer structure is designed, taking into account factors such as insulation, electric field, magnetic field, heat dissipation, and structural strength, etc. The electric field, magnetic field and thermal field of the 66 kV/10 MVA step-up transformer under steady-state operating conditions were analyzed, the electric field distribution characteristics and maximum field strength parameters of the high-voltage winding were obtained, and the magnetic field distribution and thermal field distribution characteristics of the transformer were analyzed. The rationality of the step-up transformer design is verified by multiphysics analysis. The principle prototype of 66 kV transformers was developed, and AC withstand voltage and partial discharge tests were carried out. Under the test parameters of 55 kV/<sc>30 min,</sc> the partial discharge amount was less than 5 pC. The terminal-to-ground 120 kV/<sc>1 h</sc> withstand voltage test was carried out on the high-voltage winding, during the test, partial discharge amount is less than 5 pC, the performance is good, which verifies the feasibility of the design method.

Preliminary benchmarks and analysis of boundary conditions in a trenched microstructured silicon radiation detector

Microstructured neutron detectors have the benefit of enhanced neutron detection efficiency as compared to planar devices, achieved by etching 6LiF-filled trenches on the top surface of a silicon PIN diode. This sensor geometry results in a complex electric field distribution and depletion characteristics within the diode under reverse bias. For the first time on record, the effects of a fixed oxide charge on the microstructured device depletion characteristics and mobile carrier transport is investigated. Prototype detectors were fabricated with non-conformal surface doping. Capacitance voltage and current voltage measurements were performed for these prototypes and compared with COMSOL Multiphysics simulations. A spectral response from an 241Am alpha particle source was acquired and analyzed. It was found that monoenergetic alpha particles produce three prominent peaks in the pulse height spectrum output by the device. The peaks were confirmed by simulations to correlate with dead layers and incident trajectories into the microstructure. It was also found that significant differences in pulse rise time result, corresponding with events arriving in a low-field region in the fins and a high-field region in the bulk. Geant4 was utilized for radiation transport, interaction modeling, and benchmarking the spectral data. The results of this simulation work provide confidence in the ability to attain and benchmark electrical characteristics and spectral data for semiconductor radiation detectors employing complex microstructures.

Research on Electric Field Distribution and Voltage Equalization Characteristics of Tensile Insulator Strings in 750kV Substation

In the design process of the 750kV substation, the design of insulator strings is an important part. The design of insulator strings needs to ensure that the voltage borne by each insulator does not exceed its maximum voltage, the surface electric field strength does not exceed the discharge field strength, and the maximum economic benefits can be achieved simultaneously. In this paper, finite element calculation software is used to study the electric field distribution and voltage distribution of tensile insulator strings in 750kV substations. The relationship between the depth of the grading ring into the insulator string, the diameter of the grading ring, the diameter of the grading ring and the electric field distribution and voltage distribution of the insulator string is studied, and the recommended size of the grading ring for the 750kV insulator string is proposed to reduce the surface electric field strength of insulator strings and improve the voltage distribution of each piece of insulators. The research results have been applied to the 750kV substation designed by our institute.

Ultra-narrow and ultra-strong nanojet for nanopatterning and nanolithography

A numerical study has been performed on electric field profile features of photonic nanojet generated by a SiO2 microcylinder with a varied diameter. The study shows that a strong (44.2I0) nanojet with 0.7λ lateral width and 7.8λ length can be obtained, which, as a line light source, has a potential for application in fields of nanopatterning and nanolithography. Along with the study on a single-layer microcylinder, we further studied the characteristics of the nanojet generated by a two-layer microsphere consisted of an interior LiNbO3 microsphere and an exterior semiconductor layer, which have refractive indices of 2.34 and ~3.3 @ 500 nm, respectively. The study focuses on nanojet generation condition and the effects of refractive indices of microsphere materials and background, and working wavelength on electric field distribution characteristics of the nanojet. By immersing the two-layer microsphere into a proper liquid such as the de-ionized water, an ultra-long (>14λ), ultra-strong (>50I0) and narrow enough (0.56λ) nanojet could be created. All of the characteristics and effects are qualitatively interpreted in terms of ray optics in combination with Mie scattering theory.

Temperature and Electric Field Distribution Characteristics of a DC-GIL Basin-Type Spacer with 3D Modelling and Simulation

The temperature properties of real-type direct-current gas-insulated transmission lines (DC-GIL) with a basin-type spacer were investigated by the finite element method in this paper. A horizontally installed model was established and the temperature distribution was obtained with a 3D model. The specific heat capacity and thermal conductivity of the spacer were measured and applied in the simulation. The results show that the temperature of the convex surface was slightly higher than that of the concave surface. With an increase in the SF6 pressure, the temperature of the spacer decreased, which can be attributed to the improvement of convection due to increases in the heat capacity per unit volume. With an increase in the ambient temperature, the temperature of the spacer increased linearly. The temperature difference between the inner and outer parts of the spacer increased with increases in the load current. Besides, an obvious increase in the surface electric field strength appeared under the influence of the thermal gradient compared to the results without the thermal gradient. Thus, special attention should be paid to the insulation properties of the spacer considering the influence of temperature distribution. This study evaluates both the thermal and insulation characteristics of the GIL along with the spacer under various conditions.

Gradient structure design of zinc oxide varistor microsphere composites for efficient electric field grading

Both the functionally graded material and the nonlinear conductive material can be used for grading electric fields. If a nonlinear conductive material with a gradient distribution can be designed according to the electric field distribution characteristics, better control of the electric field distribution will be achieved. In this paper, we realize switching field graded design of zinc oxide (ZnO) varistor microsphere composites in an epoxy resin matrix. Chopped glass fibers were added to a ZnO varistor microsphere/epoxy binary system to form a three-dimensional network. The volume fraction of glass fibers was altered to modify the density of the three-dimensional networks. Under the influence of gravity, the three-dimensional network composed of glass fiber realized layer-by-layer inhibition of the sedimentation of ZnO varistor microspheres, thereby creating a gradient distribution of the ZnO varistor microspheres. Thus, we realized gradient distribution design of the adaptive composites composed ZnO varistor microsphere.