Vacuum surface flashover at high voltage limits the development of vacuum interrupter (VI) toward high voltage and miniaturization. In order to improve the vacuum surface flashover voltage of the VI, the Al(2)O(3 )coatings is constructed at the shield ring to suppress electron emission, and Cr2O3 coating is constructed on the surface of the ceramic shell to suppress secondary electron multiplication by atmospheric plasma spraying. The effect of the coatings on the vacuum surface flashover characteristics is studied. The conditioning characteristics of flashover voltage and voltage-current waveforms under positive impulse voltage before and after coating construction are compared. The change of work function before and after the construction of alumina coating at the shield ring and the change of secondary electron emission coefficient before and after the construction of Cr2O3 coating on the surface of ceramic shell were measured. The results show that the construction of Al(2)O(3 )coating at the of the shield ring improves the surface flashover voltage of the VI. The insulation characteristics of the 40 mu m thick Al(2)O(3 )coating are better than that of the 20 mu m thick Al(2)O(3 )coating, but the vacuum surface flashover characteristics of the 100 mu m thick coating are deteriorated. The construction of Al(2)O(3 )coating at the end of the shield increased the work function of the shield ring from 4.51 to 5.39 eV. Cr2O3 coating along the surface of the ceramic shell reduces the maximum secondary electron emission coefficient of the ceramic shell from 6.4 to 1.49, thus improved the surface insulation characteristics of the VI.

The 3D evolution of key plasma parameters in a vacuum arc strongly affects the arc interrupting capacity of vacuum circuit breakers. However, traditional 3D diagnostics methods are typically based on the optically thin assumption, neglecting spectral broadening caused by the absorption effect. This limits accurate identification of internal radiation characteristics and spatial parameter distributions of the arc, thereby hindering the deeper understanding of arc evolution mechanisms. To address this issue, we proposed a 3D absorption correction algorithm considering spectral broadening. The algorithm first reconstructed the 3D emission coefficients of characteristic spectral lines at 510.6 nm and 515.3 nm using a tomography reconstruction method, and then calculated the upper-level atomic densities of characteristic spectral lines as well as the electron temperature. A modified collisional radiative model (CRM) was then employed to compute the electron density and population distribution, from which the line profiles and full width at half maximum (FWHM) were derived. Based on these parameters, the absorption coefficients and optical depth were obtained, and the Lambert–Beer law was applied to correct the radiation intensity. The results indicate that, after 3D absorption-corrected reconstruction with spectral broadening, the electron temperature, electron density, and atomic population in the axial magnetic field arc exhibit significant asymmetry. The peak electron temperature reaches 13 500 K, and the maximum electron density is 1.29 × 10 23 m −3 . Spectral broadening leads to a decrease in electron temperature, while its effect on electron density is minimal. In addition, the upper-level atomic densities are more sensitive to spectral broadening than those of the lower levels.

Optical emission spectroscopy (OES) is an effective method for measuring crucial physical parameters in the vacuum arc, including electron temperature, electron density, and excited state atomic density. However, the presence of the absorption effect challenges the accurate identification of spectral information, potentially leading to measurement errors in these physical parameters. To overcome this limitation, we developed an absorption correction algorithm based on a collisional radiative model (CRM), using OES-derived electron temperature and density as inputs. The CRM was employed to compute the population distribution of copper atoms and the escape factor, which quantifies the absorption effect. Radiation intensities were then corrected using the Lambert-Beer law. The corrected results reveal that electron temperature ranges from 0.7 to 0.85 eV, with higher values near the anode. The excited state densities at 510.6 nm and 515.3 nm exhibit similar spatial trends, with greater densities in the near-anode region. Additionally, the escape factor is lower at 515.3 nm than at 510.6 nm and decreases with increasing distance from the cathode, indicating a stronger absorption effect toward the anode.

The rapid and accurate prediction of the zero point of short-circuit current holds importance for the restriction and elimination of generator faults. In this paper, a rapid zero-prediction algorithm for short-circuit current based on the Extreme Learning Machine (ELM) is proposed. Firstly, the principle of the ELM network along with its training and zero-prediction procedures are introduced. Subsequently, a three-phase short-circuit simulation model of the generator is established to validate the zero-prediction capability of the ELM network. The results indicate that when the sampling window length for zero-crossing point prediction is 2 ms, the prediction error of the first zero-crossing point under different initial fault phases is no more than 0.3 ms, and the prediction error of the second zero-crossing point is no more than 0.5 ms. In comparison with traditional algorithms, the ELM network significantly reduces the required prediction time and enables a faster zero-prediction. When contrasted with other artificial intelligence algorithms, the ELM network demonstrates advantages in training speed and the complexity of the network structure.

The tomography reconstruction technique has widespread applications in arc diagnostics. This technology relies on arc radiation, with the reconstruction results representing the particle density at upper energy levels. However, tomography alone is insufficient to obtain the particle densities of other excited states and the electron density. To address this limitation, a tomography reconstruction algorithm combining a feed-forward neural network with a collisional radiative model (CRM) was proposed. The algorithm first trained the neural network using the CRM results, and then the tomography reconstruction data were fed into the network to predict the three-dimensional distributions of particle density and electron density. Experimental results demonstrate that the average prediction error is less than 5

This paper introduces NODE-MLEM, a novel method based on physics-informed Neural Ordinary Differential Equations (NODEs), for the tomographic reconstruction of vacuum arcs. By modeling the reconstruction process as a continuous dynamical system described by a NODE, NODE-MLEM leverages neural networks to learn the complex mapping from projection data and the current image state to image updates. The method explicitly incorporates physical constraints derived from the Maximum Likelihood Expectation Maximization (MLEM) algorithm, primarily through data consistency in the loss function, significantly enhancing reconstruction accuracy and physical plausibility. Compared to traditional Convolutional Neural Network (CNN) approaches, NODEMLEM integrates physical model information (system matrix and projection data) to guide the learning of physically consistent reconstruction dynamics. It can also incorporate Total Variation (TV) regularization to improve spatial smoothness and noise suppression. Experimental results demonstrate NODE-MLEM’s superior performance in vacuum arc reconstruction, achieving a $25.78 \%$ PSNR improvement and increasing SSIM from 0.780 to 0.977 over conventional CNNs, closely approaching the quality of MLEM-TV reconstructions (average SSIM 0.989) but with a $\sim 136$-fold increase in inference speed. This highlights an excellent balance between accuracy and speed, effectively utilizing physical information to guide the learning process and offering a memory-efficient, high-performance solution for large-scale 3D reconstruction.

This paper aims to investigate the post-arc dynamics in vacuum circuit breakers by addressing the mutual interaction between plasma diffusion and external circuit parameters. A hybrid Maxwell-Boltzmann model is employed to self-consistently couple plasma physics with circuit simulation, overcoming the limitation of fixed transient recovery voltage assumptions in former simulation studies. The results reveal that residual charge at current zero modulates the charge absorption current at contacts, while supply voltage influences the electrical stress on plasma. Both factors affect the peaks of transient recovery voltage and post-arc current. The proposed coupled approach offers a computationally efficient framework for an in-depth understanding of the post-arc process of vacuum arcs.

The multibreak vacuum circuit breaker uses multiple short gaps to interrupt the fault current, greatly improving the dielectric strength, and is a viable method to realize high-voltage interruption. The metal vapor distribution near the current zero is crucial for the dielectric recovery process in the multibreak vacuum circuit breaker. Due to the complicated dielectric construction and the interaction between the breakers, the vacuum arc inevitably deviates from the axisymmetric distribution during the interruption process. The traditional diagnosis method limited to 0D or 1D is not sufficient to study the real distribution of metal vapor near the current zero. To address these issues, we developed a planar laser-induced fluorescence method to measure the 2D distribution of copper vapor near the current zero by detecting 510.6 nm fluorescence intensity. The results indicate that for the butt contacts, the copper vapor is diffused in the gap of the high-voltage break and aggregated on the cathode surface of the low-voltage break. The axial magnetic field and transverse magnetic field affect the 2D copper vapor distribution and eliminate the inconsistency, which is achieved by affecting the motion of charged particles and the ionization-recombination process. Furthermore, the copper vapor density exhibits a positive dependence on the arc current, and the magnetic field impacts the density increase rate and distribution mode.

Current power supply methods struggle to meet the needs for lightweight, isolated power delivery in high-voltage environments. To address this challenge, this paper proposes an Inductive Wireless Power Transmission Device Design for High-Voltage Systems. Initially, the design of the system is elaborated, utilizing an LC topology circuit to enhance both output power and efficiency. The reliability of the design was confirmed through simulation calculations. Subsequently, a prototype was developed that successfully delivered 75.5 W of output power with an efficiency of 94.3%. The experimental results indicate that the wireless power transfer system, as designed, successfully achieves high-power transmission with high efficiency while maintaining a high tolerance for insulation.

Vacuum breakdown research is pivotal in advancing modern technology. Prior to the vacuum gap breakdown, a pre-breakdown process occurs, wherein electron emission from the cathode plays a crucial role. However, electron emission is often limited by space charge effect to further development. Current research on space charge mainly focuses on steady-state processes, lacking a multi-physics model that pushes space charge in real-time based on electric field changes. Therefore, this paper established a thermal-electric field coupled model and developed code to link electron motion with electric field variations in real-time. The simulation of electron emission from micro-protrusions on the cathode surface within a vacuum gap investigates the effect of space charge on thermal-field emission. The results indicate that the pre-breakdown voltage and current under space charge constraints increased by 15.69% and 188.46%, compared to the unconstrained conditions. The cathode material affects the differences in pre-breakdown voltage and current between with and without space charge effects, and tungsten showing significantly greater differences compared to titanium. The non-uniform work function is more significantly affected by space charge than the uniform work function. The decrease in current density under uniform function is twice that under non-uniform function.

Micro-arc oxidation (MAO) is a promising technology for enhancing the wear resistance of engine cylinders by growing a high hardness alumina ceramic film on the surface of light aluminum engine cylinders. However, the positive and negative pulse coordination, voltage characteristic signal, hardness distribution characteristics of the ceramic film, and their internal mechanism during the growth process are still unclear. This paper investigates the synergistic effect mechanism of cathodic and anodic current on the growth behaviour of alumina, dynamic voltage signal, and hardness distribution of micro-arc oxidation film. Ceramic film samples were fabricated under various conditions, including current densities of 10, 12, 14, and 16 A/dm2, and current density ratios of cathode and anode of 1.1, 1.2, and 1.3, respectively. Based on the observed characteristics of the process voltage curve and the spark signal changes, the growth of the ceramic film can be divided into five stages. The influence of positive and negative current density parameters on the segmented growth process of the ceramic film is mainly reflected in the transition time, voltage variation rate, and the voltage value of different growth stages. Enhancing the cathode pulse effect or increasing the current density level can effectively shorten the transition time and accelerate the voltage drop rate. The microhardness of the ceramic film cross-section presents a discontinuous soft-hard-soft regional distribution. Multiple thermal cycles lead to a gradient differentiation of the Al2O3 crystal phase transition ratio along the thickness direction of the layer. The layer grown on the outer surface of the initial substrate exhibits the highest hardness, with a small gradient change in hardness, forming a high hardness zone approximately 20–30 μm wide. This high hardness zone extends to both sides, with hardness decreasing rapidly.

Supercritical carbon dioxide (scCO 2 ) has garnered significant attention due to its excellent insulating strength and transport properties. Current international research primarily focuses on its breakdown characteristics near the critical point in micron-scale gaps. However, variations in power source types and polarities result in breakdown voltage data that lack broad reference significance, and there is a lack of discussion on voltage dispersion. For the same gap distance, slightly non-uniform electric fields exhibit similar DC, power frequency breakdown voltages (amplitudes), and 50% impulse breakdown voltages, with no significant polarity effect in asymmetric electrodes, indicating these data are valuable references. In this study, an independent supercritical discharge system was established using sphere-to-plate electrodes to generate a slightly non-uniform electric field with a non-uniformity coefficient of 0.99. Breakdown experiments were conducted at a 0.3 mm gap. The breakdown strength of scCO 2 was compared with common insulating media, and the regularity of its breakdown voltage dispersion was discussed. The results provide experimental data and a theoretical foundation for the application of scCO 2 in switching technology.

With the increasing demand for transformer overload capacity in high percentage renewable energy power grids, higher requirements for high temperature resistance and high thermal conductivity of insulating materials for transformer windings have been put forward. However, most of the existing researches have achieved the homogenization of ceramic film by longer oxidation time, and the homogeneity of ceramic film produced by short-time oxidation is poor, which cannot meet the voltage resistance requirements of transformer windings. In response to this need, the aim is to study the uniform growth in different timing and spatial location environments. For the longitudinal growth characteristics of the film under different oxidation time and the lateral growth characteristics under different spatial positions, the growth process of the ceramic film is explained from both time and space dimensions. The growth and insulation characteristics of plasma electrolytic oxidation ceramic aluminum foil film are investigated and applied to dry-type transformers. The research in this paper provides a theoretical basis and engineering guidance for the development and application of ceramic insulated conductors in power equipment.

During the vacuum pre-breakdown phase, field emission serves as the primary physical process preceding the formation of plasma. This phenomenon, which cannot be observed optically, is referred to as dark current. The transition from electron emission to breakdown occurs in the dark current stage, highlighting its pivotal role in the development of breakdowns. However, a comprehensive understanding of dark current remains elusive. The objective of this paper is to elucidate the electrical characteristics of dark current, and thus identify the influence of field emitter parameters on electron emission. An experimental platform was established to record dark current in the pre-breakdown phase, facilitating the measurement of volt-ampere curves under various cathode structures. Subsequently, physical parameters of field emitters, including the field enhancement factor beta and effective emission area A(f), were determined using the Fowler-Nordheim theory. The results reveal a significant impact of dark current on beta, with an approximate fourfold increase in beta resulting in a dark current increase of at least three orders of magnitude. Furthermore, beta is influenced by factors such as the macroscopic shape of the cathode, the roughness of the cathode surface, and the presence of dielectric films. Additionally, there exists a positive correlation between A(f) and the intensity of emitted electron. In addition, the intensity of the dark current is limited by space charge effects, which weaken the electric field near the cathode surface, consequently reducing electron emission efficiency. Consequently, dark current does not entirely conform to the exponential growth trend predicted by field emission theory.

To optimize the performance of vacuum circuit breakers, it is critical to gain a comprehensive understanding of the intricate physical processes that occur during vacuum interruptions. One of these processes, postarc sheath expansion is of particular importance for dielectric recovery. Previous simulation studies have examined sheath expansion by assuming uniform residual plasma at current zero. However, this approach deviates from physical realism because the discreteness in the cathode spot typically causes a nonuniform plasma distribution. This distribution cannot be analyzed by previous 1D or 2D models. To address this deficiency, this paper presents a 3D hybrid simulation model that comprehensively considers the simulation of postarc sheath expansion with nonuniform residual plasma at current zero. The model differentiates between the treatment of ions and electrons to achieve an optimal balance between computational accuracy and efficiency. The model captures the inherent nonuniformity of the plasma distribution through 3D modeling. A comparative analysis was conducted on several factors that influence the sheath expansion rate, including plasma density, transient recovery voltage rate, and ion drift velocity. The study focused on the impact of nonuniformity in the residual plasma distribution. It was demonstrated that this nonuniformity can impede the overall sheath expansion and result in the local enhancement of the electric field. The simulation aims to study the postarc sheath expansion and provide insight into the underlying physical mechanisms that govern this complex process.

SF6 气体因其优异的绝缘和灭弧性能被广泛应用于各类电力设备中,对电力设备中的SF6 泄漏的监测及预警研究,不但对电力系统的安全稳定运行具有重大意义,还是建设生态文明实现碳中和的有力举措.为解决实际工程中出现的多种因素对气体泄漏监测的干扰,本文针对复杂环境建立了SF6 气体泄漏实验平台,获得不同条件下的气体泄漏红外图像数据集,并结合红外数据增强的Yolov4 算法实现了对SF6 气体泄漏监测.实验结果表明,在复杂环境中本文提出的监测模型对SF6 气体泄漏的监测精度为 80%,相对于当下主流目标监测模型,表现出更好的鲁棒性.同时,将Yolov4 算法与图像增强算法结合,可提升识别精度约 9.08%,优化了模型稳定性.然后分析在同一红外成像视角下发生多处SF6 泄漏的监测结果,结果显示多点泄漏的识别精度低于单点泄漏,但在工程中依旧具有实用性.最后对比红外相机不同安放位置对于气体泄漏识别的影响,发现当相机与泄漏点垂直时(θ =90°),本模型的识别置信度可达到0.95,而当相机处于泄漏点侧面时(θ = 10°),置信度降为0.51,但该精度依然满足实际监测需要.

Dry-type transformer is the key hub equipment connecting power generation platform and power consumption platform in marine power system. Partial insulation aging caused by transformer thermal effect is one of the important factors that adversely affect the operation stability. The new ceramic insulation winding prepared by micro-arc oxidation technology has the characteristics of high thermal conductivity and high temperature resistance, and is an ideal product to replace traditional organic insulation materials. Therefore, in this paper, the thermal characteristics and overload capacity of a ceramic insulated aluminum winding dry-type transformer are studied by combining heat flow coupling simulation and experiment. By comparing the temperature field and velocity field characteristics of traditional organic insulated dry-type transformer and ceramic insulated dry-type transformer, the influence of different winding materials on transformer heat dissipation under the same load condition is studied. The hottest spot temperature of ceramic insulated winding dry-type transformer is about 86% of that of traditional organic insulated transformer. The ceramic insulated dry-type transformer has a good overload capacity. Under the premise of meeting the H-class insulation, it can carry 1.4 times the rated load. Finally, the simulation results are compared with the experimental data of the ceramic insulated dry-type transformer. The accuracy of the results was verified.

To solve the power supply problem of high voltage equipment in electric power systems, this article proposes an innovative ultrasonic power transmission (UPT) insulator system with high-voltage insulation and power transfer capabilities. The design scheme of an UPT insulator system, which can achieve an insulation distance of a few meters, is introduced in detail. System characteristics and energy loss are analyzed using different insulation transmission materials based on the equivalent circuit model of an UPT system, and a circuit design method is introduced. Furthermore, the main causes of energy loss are analyzed by simulation, and the structure of an UPT insulator system is optimized to improve transmission efficiency. Finally, a prototype of the UPT insulator with a maximum transmission efficiency of 57.28% and an output power of 72.62 W is constructed. The total length of the insulator is 1 m, which ensures that it can withstand a dc voltage of 50 kV. In addition, the insulation distance of the proposed UPT insulator design can be further increased without impacting the system performance.

真空断路器广泛应用于中压电力系统中,利用触头线圈产生的磁场调控真空电弧是提高真空断路器开断能力的重要手段,然而目前的设计方法没有综合考虑阴极斑点动态运动与触头线圈磁场的耦合效应,影响其设计准确性和精度.本文建立了考虑阴极斑点与磁场耦合关系的触头磁场计算模型,根据阴极斑点分布计算触头间隙控制电弧的磁场,并由磁场推进阴极斑点运动.在四分之一匝线圈式触头下,分析了阴极斑点分布对触头磁场的影响,对比了考虑耦合关系对触头磁场计算结果造成的差异.仿真结果表明,在阴极斑点的初始扩散阶段,纵磁变化不明显,而横磁随阴极斑点扩散而变化;稳定燃弧时,考虑耦合关系与否的纵磁最大差值可达纵磁最大值的24.1％.本文所建立的模型以及计算方法为真空灭弧室触头提供了一种新的设计思路与方法.