Abstract To better understand the streamer discharge characteristics within shielding sphere-plate gap in high-altitude converter halls, this study investigates effects of altitude and surface burrs on parameters during discharge. Tests are conducted at altitudes 2200 m 3400 m, utilizing a 1.6 diameter sphere with 5 plate under positive polarity impulse conditions.The results reveal that presence earlier initiation smaller increases optical power Moreover, higher result steeper rate increase...

Real-time and accurate supervision of contamination conditions composite insulators can effectively prevent the occurrence pollution flashover accidents ensure stable operation power system. In this article, a refined controllable artificial experiment is carried out, in which total 60 types pollutants (12 conditions) are formed by combining 20 equivalent salt deposit densities (ESDDs) at four levels three nonsoluble (NSDDs)/ESDD ratios to pollute insulators. Hyperspectral imaging technology...

This paper conducts experimental research and theoretical analysis on the effect of cellulose particle motion impulse breakdown in transformer oil. In experiment, spherically capped electrodes immersed bulk oil are used to form a quasi-uniform electric field. The tests carried out voltages for three contamination levels under four types impulses, 1.4/50μs, 14/220μs, 80/850 μs 240/2400 μs, obtained. results show that both waveshape level have an Longer duration or higher can lead decrease...

Due to long-term exposure high electrical field strength, heavy loads, and the complex climatic conditions in tropical coastal areas of China, widespread abnormal heating phenomena often occur operation composite insulators power transmission lines, posing a threat safe stable system. To study ageing process silicone rubber sheath high-field, high-humidity, high-temperature, high-salt-density environments along regions, this paper establishes humidity–heat–electricity–salt spray accelerated...

This paper investigates the deterioration of, and abnormal temperature rise in, GFRP core rod material of compact V-string composite insulators subjected to prolonged alternating flexural loading under wind-induced stresses. The axial stress on (Glass Fiber Reinforced Plastic) rod, resulting from transverse wind loads, is a focal point examination. By establishing model damage model, simulates computes evolution in outer arc insulator rods loads. Additionally, multi-factor coupled aging...

Abstract Long‐term exposure to moisture leads a gradual deterioration of performance and reduced service life glass fibre‐reinforced epoxy resin (GFRP) material in composite insulators. Therefore, it is necessary analyse the absorption characteristics GFRP evolution damage their internal interface properties. Moisture tests on rod used insulators obtain three‐dimensional diffusion coefficients are conducted. Atomic force microscopy was then employed system's fibre/matrix interfacial phase...

A method combined ensemble empirical mode decomposition, Volterra model and decision acyclic graph support vector machine was proposed to improve adaptability, feature resolution, identification accuracy when diagnosing mechanical faults in an on-load tap changer of a transformer. In detail, the decomposition algorithm applied decompose multi-channel vibration signals switchover process changer. Then, for state established based on time-frequency characteristics obtained through use...

Based on the analysis of principle and structure convolutional neural network (CNN) model in a deep learning theory system, an intelligent method for judging flashover porcelain insulator with ultraviolet discharge is proposed. In this method, chip was subjected to power frequency testing, spectra different states without discharge, weak coronal strong spark were captured by FILIN UV imager. The Alexnet convolution used predict state spectrum classification training identification...

Abnormal heating of composite insulators high-voltage transmission lines concentrate at its end, especially in a high-humidity environment. In order to study the influence end-sheath aging and moisture absorption on abnormal insulators, this paper, we first discuss appearance test, temperature rise dielectric characteristic test conducted 110 kV decommissioned insulators. Test results indicated increased with ambient humidity, but was not severely affected by surface contamination shed...

Abstract Transformers may suffer multiple short‐circuit impacts during long‐term operation, and axial instability is one of the typical types serious accidents caused by faults. The form winding‐block structure analysed, dynamic solution winding electromagnetic force obtained establishing three‐dimensional magnetic‐circuit‐force multi‐physical field coupling simulation model. influence strain rate on cushion block constitutive equation corrected, modified model verified impact test...

Composite insulators are extensively employed in transmission lines. Investigating the impact of shed configuration on contamination properties can offer scientific theoretical guidance for selection composite insulators. This paper integrates a semi-empirical mathematical expression, derived from experiments, describing collision rebound movement between micrometer-sized particles and electrical silicone rubber with flow field simulation. A deposition model is thus established, allowing...

Abstract Currently, commonly used external insulation materials for power products lack operational stability compared to high-temperature vulcanized silicone rubber. The excellent hydrophobicity of PTFE provides a direction further enhancing By utilizing fluorinated occupation directional design technology and improving the dispersion degree dispersed phase, we have successfully prepared fluorine After testing its flammability other aspects, material achieved HC1-level hydrophobicity,...

The morphologies and velocity of ionic wind induced by direct-current (DC) corona discharge were experimentally measured. DC voltage was applied to short air gaps high-voltage electrode-needle electrode grounding electrode-net generate coronas, so as allow the generation discharge. purpose study is optimise multi-needle-to-net structure improve keep it in a relatively stable state. For this purpose, influences various parameters on explored. research results showed that side length meshes...

To improve adaptability, feature resolution, and identification accuracy when diagnosing mechanical faults in an on-load tap changer (OLTC) of a transformer, the present research, wavelet packet energy entropy is used to describe information comprising vibration signal switch process OLTC, fuzzy weighted least squares support vector machine (CSA-fuzzy LSSVM) model based on cuckoo search algorithm proposed identify fault types. Specifically, according different importance sample data periods,...

At present, observing the temperature rise of composite insulators is an effective method for detection decay-like defects. However, ambient humidity will affect insulators, which cause problems in screening insulators. Therefore, it urgent to study principle and find out influence mechanism on rise. In this study, a four-electrode system designed measure surface current, volume current interface short sample intact under different humidity. Then equivalent circuit models samples 500 kV...

Abstract Abnormal heating of composite insulators on ultra‐high voltage (UHV) transmission lines is widespread under high humidity and heat in southern China. The infrared imaging technology can be used quickly effectively detect with abnormal determine their defect types. However, it may cause misjudgement when the images are not clear. A super‐resolution reconstruction method based improved generative adversarial networks (SRGAN) proposed this paper, dense residual network SRGAN perfected...

A new three‐dimensional (3D) analysis method is proposed as the existing two‐dimensional (2D) has low accuracy in analysing vibration characteristics of oil‐immersed shunt reactors, such ultrahigh‐voltage (UHV) reactors. First all, a set 3D laminated coordinate systems was defined based on silicon steel lamination rules, which anisotropy magnetic properties for rolling direction (RD), transverse (TD), and (LD) were considered. Then, mapping between space rectangular system established to...

The construction of ultra‐high‐voltage direct‐current power transmission projects in high‐altitude areas calls for the research into discharge characteristics air gaps valve hall a converter station such areas. Tests on switching impulse sphere‐plane gap were conducted at Yangbajing test base (Tibet, China) an altitude 4300 m conditions that there burrs 1.3 diameter shield balls. characteristics, under influences with different lengths and locations, obtained compared data from low‐altitude...

Fast and accurate positioning of partial discharge (PD) sources in transformer oil is very important for the safe, stable operation power systems because it allows timely elimination insulation faults. There usually more than one PD source once an fault occurs oil. This study, which has both theoretical practical significance, proposes a method identifying multiple The combines two-sided correlation transformation algorithm broadband signal focusing modified Gerschgorin disk estimator....

In this work, a combined photoelectric detecting system is established using devices such as photomultiplier, an electric field sensor based on optoelectronic integration, and high-speed camera. The used to measure the instantaneous optical power, spatial strength, image during discharge of 3-m-long sphere–plane gap under standard switching surge voltage positive polarity. test results show that initial streamer can be divided into strong weak ionization according rate rise power strength....

Lightning has a certain degree of potential threat to the safe operation overhead transmission lines. In order make targeted lightning protection arrangements and reduce impact on lines, it is necessary conduct risk assessments This paper proposes failure assessment method for lines based modified Dempster–Shafer theory. First, analyze historical data line, determine factors, use confidence express relationship between factor; then, entropy weight theory gray relational calculate value mass...

Abstract With continuous promotion of construction ultra high voltage DC projects in high-altitude areas, it is important theoretical and practical engineering significance to study long gap discharge characteristics at altitudes. As the initial key stage for development air discharge, streamer reflects randomness a certain extent, time delay are indicators reflect randomness. In this paper, we build photoelectric detection system based on photomultiplier tube integrated sensor, carry out an...

The deterioration of a composite insulator’s mandrel will cause serious power-grid accident, so it is necessary to find the defect as soon possible. Infrared imaging an effective means detect mandrel-deterioration defects, but sheath-aging defects trouble screen deterioration. Therefore, urgent distinguish two defects. In this paper, insulators that are out service with different heating characteristics tested and analyzed, temperature-rise analyzed by building simulation model. results show...

The condition and health of large oil-immersed power transformers' insulation have a direct impact on the safety stability grid. Therefore, it is crucial to investigate aging characteristics oil-paper in transformers. In this study, we developed computational model for reclosing current calculation multiphysics coupling models magnetic-circuit-force, electrostatic field, temperature field simulations. calculated resulted mechanical stress 8.71 MPa, an electric strength 2.26 × 106 V/m, 113.7...

With the fault of composite insulator, unidentified flashover occupies a considerable proportion, in which environment factor is more prominent. This paper addresses analysis wind tunnel test to simulate effect scrapping on studies influence extent different velocity and direction voltage insulator. At same time, researches mechanism under scrapping. In accordance with actual operation condition, whole divided into three type approval test: clean dry dirty conditions artificial pollution....