ABSTRACT Heavy construction machinery is essential for power infrastructure construction and maintenance, making safety distance measurement crucial for ensuring operational safety. Existing methods, which rely on target space mapping, face challenges such as error accumulation and limited accuracy. Motivated by this, this paper proposes a refined measurement method using high‐precision, anti‐interference LiDAR as the 3D data source. The method employs multi‐layer set abstraction for 3D feature extraction and introduces instance‐aware downsampling to homogenise point cloud features across targets of varying distances and sizes. Subsequently, an instance centroid prediction module aggregates contextual information to estimate precise spatial positions. Ultimately, by integrating optimal representative point selection with a distance calculation mechanism, the method achieves accurate minimum safety distance measurement for near‐electricity operations. Experimental results demonstrate superior accuracy in target location identification and distance measurement in complex scenes, outperforming existing methods. This approach provides theoretical and practical support for risk prevention in near‐electricity operations of heavy construction machinery.
ABSTRACT This study introduces an application of binocular stereo vision technology to achieve high‐resolution 3D visualisation of submillimeter discharge channels. The proposed method can capture the depth information of weak luminous discharges and provide 3D discharge trajectories, providing new insights into the discharge mechanism. The camera parameters are selected by a multi‐objective optimisation algorithm and calibrated using a micro‐chessboard, thus addressing the complex calibration challenges associated with imaging microscopic objects. The brightness threshold‐based point cloud filtering algorithm developed for this study improves the imaging quality of luminous channels under low‐light conditions. Experimental validation involving 3D reconstruction of complex branched discharge channels in SF 6 /N 2 mixtures reveals the key characteristics of the leader stepping mechanism. The accuracy and feasibility of the proposed method lay a solid foundation for future studies of discharge phenomena and the development of physical models of low‐probability breakdown events.
ABSTRACT The polymeric materials used in insulator sheds are prone to ageing under different environmental conditions, which can lead to flashovers and grid outages. The ageing process in composite insulators primarily involves changes in the microscopic properties of the materials. Ageing levels were determined based on the hydrophobicity of artificially accelerated ageing samples, and spectral lines ranging from 400 to 1000 nm were analysed at various ageing stages. This study employed sample entropy as the objective function and used Beluga whale optimization to determine the optimal number of decomposition layers, K , and the penalty parameter, α , for the variational mode decomposition, thereby achieving effective denoising in the spectral domain. The channel attention mechanism was able to better extract ageing status information from the spectral bands. By employing a long short‐term memory network with an adaptively weighted squeeze‐and‐excitation network, a high global accuracy of 95.48% was attained, outperforming traditional classification models. This approach successfully addressed the challenge of low evaluation accuracy resulting from the high spectral line similarity observed in severely aged levels. The trained model enabled the visualisation of ageing distribution at the pixel level within the sheds' structure, overcoming difficulties associated with detecting microscopic ageing states and providing comprehensive assessments of composite insulators. This research study significantly contributes to ensuring the safe operation of power grids and offers valuable insights for guiding the material selection and design of composite insulators in diverse environments, thereby presenting promising applications in various fields of electrical equipment condition monitoring.
ABSTRACT Polymer insulation exposed to natural environment inevitably face challenges from material ageing and surface insulating degradation. Surface treatment is an effective method to improve material performance, but traditional processing methods such as room temperature vulcanised silicone rubber (RTV) coating, are subjected to coating degradation after long time operation. Herein, we fabricated a stable cross‐linked Si‐containing (–SiO 4 ) film on polymethyl methacrylate (PMMA) insulation via eco‐friendly atmospheric pressure plasma techniques, and verified its thermal stability performance. By addition of hexamethyldisiloxane (HMDSO) and fluorescent agent in plasma, fragmenting–crosslinking of HMDSO as well as surface functionalising by plasma‐enabled reactions lead to the fabrication of fluorescent Si‐containing film. Accelerating ageing test demonstrates that the plasma‐modified PMMA remains steady hydrophobic performance after ageing. Although the surface insulating performance decreases with the ageing, the aged material still remains the higher flashover voltage compared with the original. It reveals that the Si‐containing film could convert thermal oxygen reactions into itself crosslinking process with the shift of –SiO 2 to –SiO 4 groups, which eventually leads to the variation of material surface performance. Overall, the plasma‐assisted Si‐containing film for surface modification has satisfactory thermal stability, which offers a new avenue for insulation enhancement and service life prolonging.
ABSTRACT Direct and accurate measurement of insulator near‐surface electric fields in gas‐insulated equipment is critical for understanding charge accumulation and insulation failure, yet it has been technically challenging. Optical sensing technology is renowned for its high sensitivity, wide dynamic range, strong resistance to electromagnetic interference and high integrability, providing a new approach. This study developed an integrated optical electric field sensor (IOES) based on the electro‐optic effect of thin‐film lithium niobate. By coupling an auxiliary micro‐ring on one waveguide arm, the linearity of the sensor exceeded 99%, the dynamic range surpassed 84 dB and the packaging size was optimised to the millimetre scale. A finite element simulation was conducted on the electric field distribution of a 126 kV cone‐type insulator to verify the reliability of IOES measurement results through comparison. Experimental verification showed the consistency of the electric field distribution above the insulator with the simulation. The high‐field section demonstrates high accuracy with an error margin of just 1.56%, whereas the low‐field section shows some deviation due to simulation parameters and the calibration curve. These results indicate that this optical electric field sensor holds great potential for measuring electric field distribution inside electrical equipment.
ABSTRACT In response to the current challenge of accurately determining the specific heating status of composite insulators with localised temperature rise using infrared detection technology, this paper proposes a novel diagnostic method. This method involves applying a disturbance to monitor the surface temperature rise data of composite insulators and establishing a relationship between the characteristic parameters of the temperature rise curve and the heating type of composite insulators. By leveraging the fact that the surface temperature rise rate of composite insulators is influenced by the heat source’s position, this approach aims to effectively distinguish between the two types of heating that cause localised temperature rise phenomena. The effectiveness of this method is validated through simulations and experiments, and relevant recommendations for engineering applications are provided.
ABSTRACT Multi‐chamber arc‐extinguishing devices have a simple structure and excellent arc‐extinguishing performance; thus, they have attracted considerable attention as lightning protection devices. However, the structural parameters of different models of the aforementioned devices vary, leading to inconsistent protection levels; therefore, the arc‐extinguishing characteristics of their chambers require further investigation. This study employed simulation and experimental methods to analyze the process through which devices with a semi‐closed short‐gap structure extinguish alternating‐current (AC) power frequency (50 Hz) arcs. First, a numerical model of AC arcs was established on the basis of magnetohydrodynamics theory using COMSOL Multiphysics software. This model was then used to simulate the dynamic arc plasma velocity, pressure and temperature within the extinguishing chamber of a device with a semi‐closed short‐gap structure. Subsequently, an experimental platform was constructed to conduct experiments involving extinguishing various magnitudes of continuous AC arcs in a fabricated semi‐closed short‐gap structure. The experimental and simulation results agreed with each other, demonstrating the effectiveness of the developed model. These results indicate that as the magnitude of an AC arc increases, the arc extinction time increases but remains within the time corresponding to half a cycle of the AC waveform.
ABSTRACT Ice accumulation on transmission lines poses a persistent threat to grid stability, yet precise technical guidance for the dynamic response during ice shedding under wind loads remains insufficient. In response to this issue, this study uses C++ to create a calculation program and obtains aerodynamic coefficients of ice‐covered conductors with crescent‐shaped cross‐sections through wind tunnel experiments. This study examines the effects of different simulation elements on ice‐shedding jump height and subsequent trajectory. Additionally, it analyses the dynamic response of conductors under various conditions of ice–wing coupling, establishing the relationship between amplification factors of the ice‐shedding jump height under near‐windless conditions. Field tests on different conductors were conducted to validate the findings, revealing an average calculation error of only 5.95%, thereby confirming the accuracy and applicability of the derived formula. This formula offers theoretical support for designing transmission lines in regions prone to heavy icing and high winds, and the proposed research approach is applicable to discussions of extreme operational conditions.
The condition assessment of oil-paper insulation is critical for oil-immersed power transformers, which are fundamental to the reliability of modern power systems. The primary limitation of traditional transformer ageing assessment lies in its macroscopic, whole-unit approach, which fails to account for the localised effects of nonuniform ageing (NUA) induced by temperature gradients. To address this, the influence of NUA must be explicitly incorporated into the evaluation process. An equivalent scaled-down model representing the main insulation of an oil-immersed power transformer was constructed in this paper. Frequency-domain dielectric response (FDS) measurements were then performed on the scaled model, as well as on oil-paper insulation (OPI) samples with different ageing states, including uniform and nonuniform ageing. The results reveal the FDS properties of nonuniformly aged OPI. Considering the geometric structure of an oil-immersed power transformer, an equivalent capacitance model was developed to characterise the NUA of the main insulation, which exists between windings with different voltage levels. Furthermore, a quantitative analysis method for the NUA state of the main insulation based on the principal component analysis (PCA)-grey wolf optimiser (GWO)-random forest (RF) algorithm was proposed, and the assessment results were experimentally validated. The maximum relative error of the assessment results was less than 6%. The findings of this study provide theoretical support for developing operation and maintenance strategies for the power system.
ABSTRACT This paper provides an overview of high‐temperature superconducting (HTS) cables in DC systems, with a focus on their deployment in high‐voltage DC (HVDC) networks. The assessment of HTS cable properties—such as extremely low electrical resistance, high current‐carrying capacity and a compact geometry—and their comparison with those of traditional cables is conducted in this paper. DC projects at various voltage levels, both implemented and ongoing, are studied, and data on technical specifications, project scales, and deployment challenges are presented. This analysis shows that, although initial capital expenses remain higher, notable benefits, including reduced footprint, high capacity and low‐loss power transmission, can offset upfront investments in utility‐scale deployments in the long run. Eventually, HTS technology stands as a promising enabler for next‐generation HVDC networks, supporting global efforts to meet rising electricity demand and carbon‐reduction targets.
ABSTRACT The pantograph–catenary system (PCS) is the only path for electrified railway trains to acquire energy. Catenary icing during winter is a common natural phenomenon, which usually leads to the deterioration of the current quality and severely affects the operational safety of trains. To address the effects of complex and harsh environments on the PCS, this study reviews and outlooks the problems of catenary icing from the three main aspects: the characteristics of catenary icing, the impacts of icing and the countermeasures. Firstly, the mechanism and characteristics of catenary icing, including the growth mechanisms, evolution patterns and prediction models are investigated. Secondly, the impact of catenary icing on pantograph–catenary current collection and catenary galloping is analysed, and new technologies for real‐time icing monitoring are discussed. Lastly, key technologies for catenary anti‐icing, de‐icing and active matching strategies are introduced. This review addresses the challenges of catenary icing and summarises the current research progress, providing a valuable foundation and practical guidance for advancing future studies in this field.
The breakdown characteristics of the novel eco‐friendly insulating gas CF 3 SO 2 F are fundamental to the design of gas‐insulated equipment. In this paper, the gas mixture parameters for CF 3 SO 2 F were optimised for different ambient temperatures in order to ascertain the insulation performance and liquefaction temperature constraints. To further assess its insulation properties, breakdown experiments were carried out under power‐frequency voltage (50 Hz), considering the influence of buffer gas types, the molar ratio of CF 3 SO 2 F and pressure. The results demonstrate that the breakdown voltage of CF 3 SO 2 F is 1.2–1.5 times that of SF 6 , and it increases with pressure in the range of 0.1–0.4 MPa. When compared to air and CO 2 , N 2 exhibits a superior synergistic effect with CF 3 SO 2 F. At an absolute pressure of 0.5 MPa, the 60% CF 3 SO 2 F/40% N 2 mixture shows similar insulation strength to SF 6 , but it can only be applied in environments above 10°C. Furthermore, the 12% CF 3 SO 2 F/88% N 2 mixture at an absolute pressure of 0.8 MPa has an insulation strength comparable to that of 0.5 MPa SF 6 , with a liquefaction temperature of −25°C. The results demonstrated great potential of industrial applications. At this configuration, global warming potential (GWP) of the gas mixture is only 4% that of SF 6 . The research provides a new solution for SF 6 gas substitution in gas‐insulated equipment.
Sulphur hexafluoride (SF6) decomposition gases are toxic and corrosive, making the removal of these impurities essential for ensuring equipment safety and personnel health. To address this issue, this work developed a robust TEMPO-oxidised cellulose nanofibril/chitosan (TOCNF/CS)@UiO-66-NH2 composite aerogel by in situ growth UiO-66-NH2 crystals within a TOCNF/CS matrix. The composite exhibits a hierarchical porous structure, high specific surface area (151.33 m2 & centerdot;g-1) and excellent mechanical elasticity, with 92.7% stress retention after 50 compression cycles. The adsorbent exhibits excellent adsorption performance towards SF6 decomposed products (SO2F2, SO2 and H2S). The synergistic microporous structure facilitates efficient gas diffusion and active site accessibility. These results highlight the potential of TOCNF/CS@UiO-66-NH2 as a high-performance adsorbent for capturing SF6 decomposed gases in electrical insulation systems.
To address the issue of low detection accuracy for zero-value insulators in distribution lines, this study proposes a novel method for detecting these insulators based on the electroluminescence effect. Through theoretical analysis and experimentation, it was found that the luminescence intensity of ZnS:Cu electroluminescent material varies with coating thickness (optimal at 0.3 mm), filler concentration (optimal at 63.6%) and BaTiO3 doping amount (20% by mass), exhibiting a trend of initially increasing and then decreasing. Furthermore, the luminescence intensity tends to saturate as the power-frequency voltage increases, with the critical luminescence threshold electric field determined to be 300 kV/m. A simulation model of the electric field of insulator strings in distribution lines was developed, indicating that the optimal coating area is located at the junction between the steel foot and the cement, with a coating width of approximately 5 mm. Experimental results under normal operating conditions demonstrate that all insulator coatings emit weak light, whereas zero-value insulator coatings do not emit any light. Finally, on-site tests were conducted on a 10-kV distribution line, where a zero-value insulator was successfully identified. These results effectively validate the high detection accuracy and practical value of the proposed method.
ABSTRACT In the fields of automotive electronics, power electronics, and aerospace, environmental conditions are often extremely harsh, particularly for materials that must endure high temperatures, high power and require high stability. The degradation of capacitance performance in polymer dielectrics under high electric fields and elevated temperatures is primarily attributed to the decrease in breakdown strength. To address this, a synergistic strategy combining molecular traps with adjustments to the conjugated structure has been developed to enhance the high‐temperature breakdown strength of polymer dielectrics. To address this, we developed a synergistic strategy combining molecular traps with conjugated structure modulation. Experimental and theoretical analyses reveal that polar groups induce deep electron traps via electrostatic interactions, whereas long‐chain flexible groups disrupt the conjugation, which alters charge transport mechanisms. Between aromatic rings in the molecular chain, altering the conductivity mechanism. Furthermore, dihedral angle adjustment regulates trap‐hopping distances, enhancing high‐temperature breakdown strength. As a result, the combined effects of electronic traps and conjugated structure optimisation lead to a discharge energy density of 7.87 J/cm 3 at room temperature and 5.99 J/cm 3 at 200°C, which is 60% higher than that of OD–PM. This performance surpasses most current polymer dielectrics. Our work establishes a molecular design framework to advance high‐temperature capacitive energy storage in polyimides, with direct relevance to harsh‐environment applications.
In plasma medicine and biological applications, plasmas typically deliver a complex combination of reactive chemical species and multiple physical energy components. However, establishing a unified and comparable dose metric to characterise their integrated biological effects remains a major challenge that continues to limit progress in this field. Although the Equivalent Total Oxidation Potential (ETOP) framework has been shown to effectively quantify biological effects dominated by reactive oxygen and nitrogen species (RONS), a consistent and physically transparent dose definition for physical energy channels-such as electric fields and ultraviolet (UV) irradiation-has been lacking. In this work, explicit physical definitions are established for electric field and UV irradiation doses, together with strategies for mapping these doses onto a unified ETOP scale and determining their corresponding weighting coefficients. By reanalysing multiple sets of inactivation experiments under mu s and ns-pulsed electric fields as well as UV irradiation, we demonstrate that experimental results that are highly scattered when expressed in terms of operational parameters collapse onto a single sigmoidal dose-response curve when described using the proposed equivalent dose definitions. Furthermore, based on the principle of equivalent biological effect, chemical, electric field and UV doses are quantitatively mapped onto a common ETOP dose axis, enabling the extraction of weighting coefficients for different types of reactive components. The extended ETOP dose framework proposed here provides a physically grounded, experimentally accessible and scalable approach for the unified quantification of plasma dose under conditions where chemical and physical energy channels coexist. This framework lays a foundation for dose comparison across different treatment modalities, parameter transferability and further development of plasma dosimetry.
ABSTRACT The low pressure in high‐altitude areas exacerbates the issue of audible noise (AN) caused by intense corona discharge on the conductor surface. This problem is a critical factor in the structural design and conductor selection for extra‐high‐voltage and ultrahigh‐voltage (UHV) AC transmission lines. The study of spectrum characteristics is vital for understanding the intrinsic properties of AN. However, there is a lack of studies on the AN spectrum properties of practical bundled conductors at high altitudes, which makes it difficult to accurately guide power line construction in high‐altitude regions. The high‐altitude UHV corona cage in Yangbajing, Tibet, was used in this work to investigate the noise spectrum properties of three conductor types: 6 × LGJ500, 8 × LGJ630 and 10 × LGJ630. The conductors' 1/3‐octave frequency noise characteristics and AN equivalent A‐weighted levels under different electric field strengths under heavy rain were measured. Then, the correlation between the 8‐kHz characteristic frequency level and the AN A‐weighted sound level in high‐altitude regions was investigated. Finally, the A‐weighted acoustic power levels of AN at three altitudes of Wuhan, Xining and Yangbajing were compared and analysed. The results of this study can provide certain guidance for power companies' high‐altitude power line designs.
High altitude electromagnetic pulse (HEMP), as a steep slope and high amplitude instantaneous energy shock, has stronger coupling and greater destructive power, which can easily cause the secondary control device of the substation to malfunction. In order to explore the anti-interference ability of the relay protection device to HEMP, a simulation model of electromagnetic radiation based on the actual physical structure was built, and the distribution characteristics of the electric field inside the device were explored under the influence of different excitation factors such as HEMP amplitude, incident angle, and polarisation direction. A radiation and conduction coupling test platform was built between the device and HEMP, and the HEMP threshold of the device malfunctioning due to radiated coupling interference was obtained by comparing the changes in the action characteristics of the device facing the same fault before and after irradiation. The tolerance of the device's power port under HEMP-conducted interference is verified. The test results show that when the peak irradiation of HEMP reaches 35 kV/m, the device begins to malfunction, and the tripping time in the face of the same fault is significantly prolonged. The operational reliability of relay protection devices is greatly reduced, which affects the safe and stable operation of the power grid.
Oil-pressboard system is the main insulation form of oil-immersed transformers, which is prone to partial discharge (PD) and subsequent faults due to contamination or moisture ingress. To investigate the evolutionary characteristics of PD streamers under varying voltages and insulation dimensions, streamer images were captured using a high-speed camera system. An image restoration algorithm was proposed, which integrates the Retinex theory with bilateral filtering and k-dimensional tree (KD-tree)-based methods. This algorithm allows for the enhancement of image contrast while ensuring that edge details are preserved and fragmented streamer channels are reconnected. By varying the applied voltage, needle-plate gap length and pressboard thickness, patterns in streamer area and the number of bifurcations were analysed. These variations were microscopically explained in terms of electric field distortion and the dielectric matching between oil and pressboard insulation. It was found that larger streamer areas are produced by higher voltages and longer needle-plate gaps. Additionally, under elevated voltages or prolonged energisation, multiple streamer patterns are generated due to the presence of photoionisation and bubble formation. Furthermore, an increased number of bifurcations is observed with longer gaps and more uniform dielectric matching between oil and pressboard. The results obtained here enrich the evolution mechanism of PD and provide theoretical guidance for the dielectric matching of transformer oil and pressboard.
