Transmission Line Insulators Research Articles

Research on Non-destructive Testing Method for Aging of Sheds of Composite Insulators

As an important part of external insulation of transmission and distribution lines and substation equipment, silicone rubber insulators are generally used because of their strong anti-pollution flashover ability, excellent hydrophobicity, and lightweight. It is one of the effective means to obtain the aging degree of sheds quickly and accurately to prevent operation accidents. From the micro and macro perspectives, firstly, this paper uses the traditional scanning electron microscopy and dielectric loss factor test to classify the aging degree of 11 high-voltage side sheds samples of silicone rubber insulators running on-site for 0~11 years. According to the different experimental principles, the aging degree of each experimental method is divided into four grades. Then, the detection method based on terahertz time-domain spectroscopy is proposed to realize a nondestructive evaluation of the aging grades of sheds of silicone rubber insulators. Finally, through comparison, it can be found that the THz absorption coefficient spectra can find the characteristic quantity of classification of aging levels of silicone rubber materials: The aging levels of the silicone rubber samples increase, and the absorption peak at 1.32 THz in the absorption spectra show a downward trend. According to the characteristic quantity, 11 samples can also be divided into four aging grades, and the results are consistent with the previous experiments.

The 3D model construction method of overhead transmission line based on GIM

With the continuous progress of power grid digitization, Building Information Model (building information modeling, BIM) technology can no longer meet the application display requirements of power grid engineering. Power grid information model (grid information model, GIM) technology uses parameterization to build a 3D model, which reduces redundancy and is conducive to the digital transfer of the project. This paper briefly analyzes the structure of the GIM data model. It carries out research on 3D parametric modeling of overhead transmission line ground wire, tower, foundation, and insulator string based on GIM. It uses a 3D graphics engine to realize the visual rendering of ontology 3D models. On this basis, a 3D scene construction method of overhead transmission line engineering based on GIM is proposed, which provides reliable technical support for digital power grid applications.

Effects of Common In-Service Defects of Different Insulators on Radio Frequency Interference Emission from 765 kV Insulators String

Worldwide utilities are preferring Ultra-High Voltage (UHV) transmission lines for transmitting electric power from generating stations to load centres. This long-distance UHV transmission line uses porcelain, glass and composite insulators. Fault-free operation of these insulators is vital to provide reliable service to consumers. Any defects on these insulators may lead to outages and affect the reliability of the supply system. To ensure reliability, utilities are continuously monitoring the condition of transmission line insulators. Nowadays in addition to providing reliable and quality power to the consumers, the utilities are keen on measuring and reducing The Radio Frequency Interference (RFI) from transmission lines. Under normal operating conditions, the RFI of the insulator string may be less than the specified limit. However, evolving inservice defects and deposition of pollutants on the surface of the insulator may increase the RFI level, sometimes it may exceed the specified limit also. This higher emission may affect the operation of nearby other electronic equipment. In this present work, an attempt is made to measure and compare RFI from healthy and defective 765 kV single I suspension string in the shielded indoor laboratory. It was observed that defects and pollutants deposited on insulators have induced corona/spark or gap discharges at the operating voltage level, which in turn increases the intensity of RFI.

Review of Surface Charge Accumulation on Insulators in DC Gas-Insulated Power Transmission Lines: Measurement and Suppression Measures

Gas-insulated power transmission lines (GILs) can replace cables and overhead transmission lines, playing an important role in DC transmission systems. However, the influence of surface charge accumulation on insulation reliability cannot be ignored as the operational voltage of the DC GIL increases. In this paper, the measurement methods for the insulator surface potential are summarized, including, dust maps, the Pockels effect method, and the electrostatic probe method. Then, a typical surface charge inversion algorithm is introduced. The main influencing factors of surface charge accumulation are analyzed, such as the applied voltage, insulation gas, insulator shape, and temperature. The charge accumulation pathway is revealed. Furthermore, methods for inhibiting the accumulation of surface charges and promoting the dissipation of accumulated charges are introduced to reduce the surface charges on insulators. Finally, the development direction of DC GIL insulators is predicted. We anticipate that the online monitoring of surface charge distribution, clarifying the percentage of charge accumulation pathways, and optimizing the insulator casting process will be the research directions for the insulator surface charge topic in the future. This article provides a comprehensive understanding of the surface charges of GIL insulators and a reference for the insulation design of DC GILs.

Monitoring of Composite Insulators in Transmission Lines: A Hydrophobicity Diagnostic Method Using Aerial Images and Residual Neural Networks

Hydrophobicity detection is of great significance to the condition monitoring of composite insulators, is an important guarantee for the safe operation of transmission lines. Therefore, this paper proposes a hydrophobicity diagnosis method based on an improved residual neural network. The method consists of an improved residual neural network, an image quality booster, and an image enhancement module. Among them, the improved residual network reduces the convergence time of the model by adding the Focus algorithm. The image quality booster uses a deconvolution algorithm to effectively solve the image distortion problem. At the same time, the image enhancement module improves the generalization ability of the model through the GEM algorithm. On the other hand, the method locates the diagnostic area of composite insulators in a weakly supervised manner and is able to evaluate the hydrophobicity level of insulators at different locations simultaneously. Field tests show that this method can well meet the actual maintenance needs and eliminate the judgment difference of manual detection. Compared with current hydrophobic detection models, the method has greater advantages in terms of detection accuracy and operating speed.

Preface

The 2023 2nd International Conference on the Energy Internet and Energy Interactive Technology (EIEIT 2023) took place via virtual form in Nanjing, China from May 26th to 28th, 2023, with the attendance of about 50 people.EIEIT 2023 focused on research areas such as Renewable Energy, Power Quality and Power Experience, Regional Energy Internet, Energy Management Technology, etc. The main goal was to bring together scientists, researchers and developers engaged in fields concerning energy to bridge the gap between research needs and advanced technological solutions.EIEIT 2023 provided an opportunity for researchers and related personnels to present their recent theoretical developments as well as practical applications, discuss unsolved problems and find solutions to them. It fostered research and development in energy internet and energy interactive technology.The program of the Conference was divided into three parts. First day of the Conference was devoted to registration for all the participants. The second day was focused on opening ceremony, keynote speech, oral and poster presentation, as well as discussion on the speeches and the whole meeting. Academic investigation took place during the third day of the Conference.We would like to highlight the main developments presented at the Conference and introduce the prominent speakers. Keynote speaker of the Conference Professor Ismail Musirin (Universiti Teknologi MARA, Malaysia) presented a report on Computational Intelligence Applications in Power System Load Shedding. He mainly dealt with researches on the algorithms and techniques development in solving problems in Power System involving voltage stability, economic power dispatch, renewable energy optimization, and application of artificial intelligence in power system, and he has got 22 years of research experience in the field of Power System Engineering. Associate Professor Norzanah Rosmin (Universiti Teknologi Malaysia, Malaysia) described Hybrid Energy Storage for Virtual Inertial Support in Wind Application System. Associate Professor Nor Asiah Muhamad (Universiti Teknologi Brunei, Brunei) demonstrated her speech on Harmonic Components Analysis of Emitted Ultraviolet Signals of Aged Transmission Line Insulators under Different Surface Discharge Intensities.Finally, we would like to thank the members of the Technical Program Committee and the Local Committee for giving such an opportunity to share scientific ideas and new developments at the Conference and Universiti Putra Malaysia, Malaysia for its friendly support. Last but not the least, our special acknowledgement also goes to the editors and staff of Journal of Physics: Conference Series, for their kindness and assistance in publishing this paper volume.The Committee of EIEIT 2023List of Committee Member is available in this pdf.

Flashover characteristics and altitude correction of railway insulators at high altitude and polluted areas

The reduction of electrical performance of railway insulators at high altitude and polluted areas affects the safe operation of the railway. A lot of studies have been carried out on transmission line insulators at home and abroad, but whether the results can guide the design of railway insulators has not yet been determined. This paper takes the railway insulator QBG-25/16 as the research object, experimentally studied the lightning impulse and AC pollution flashover characteristics of the railway insulator under low air pressure, analyzed its insulation configuration under high altitude and pollution environment, and finally proposed its altitude correction method. The results show that the flashover voltages of the insulator decrease in a power function as the air pressure decreases, and decrease in a power function as the salt deposit density increases, and the air pressure influence characteristic index and pollution influence characteristic index are related to voltage type, air pressure and salt deposit density. The tested insulators do not satisfy the requirements for insulation strength at certain high altitude and polluted areas. Finally, the altitude correction method for railway insulators is given. The results of the study provide guidance for the selection of external insulation for electrified railway systems at high altitude.

Deep-Learning-Based Detection of Transmission Line Insulators

At this stage, the inspection of transmission lines is dominated by UAV inspection. Insulators, as essential equipment for transmission line equipment, are susceptible to various factors during UAV detection, and their detection results often lead to leakages and false detection. Combining deep learning detection algorithms with the UAV transmission line inspection system can effectively solve the current sensing problem. To improve the recognition accuracy of insulator detection, the MS-COCO pre-training strategy that combines the FPN module with a cascading R-CNN algorithm based on the ResNeXt-101 network is proposed. The purpose of this paper is to systematically and comprehensively analyze mainstream isolator detection algorithms at the current stage and to verify the effectiveness of the improved Cascade R-CNN X101 model by combining the mAP (mean Average Precision) value and other related evaluation indices. Compared with Faster R-CNN, Retina Net, and other detection algorithms, the model is highly accurate and can effectively deal with the false detection, leakage, and non-recognition of the environment in online special detection. The research in this paper provides a new idea for intelligent fault detection of transmission line insulators and has some reference value for engineering applications.

АЭРОДИНАМИЧЕСКАЯ ТРУБА 3-АТ-17,5/3 ФИРМЫ УНИКОН. ПОЛВЕКА В ЭКСПЛУАТАЦИИ

The wind tunnel with a long working part, designed for experimental solution of problems of energy, civil, industrial construction, as well as assessment of environmental indicators of projected and existing facilities, has been in operation for 50 years. The issues of wind pressure on the projected main buildings and auxiliary buildings, tower cooling towers, coal conveyor galleries of powerful thermal power plants, supports, phases and garlands of insulators of unique power transmission lines in dimensions of 1150 kilovolts (AC) and 1500 kilovolts (DC), issues of snow drifts of electric conversion complexes, warehouses of thermal coal have been resolved. It is shown that with certain wind directions relative to the studied object, the wind pressure in the local areas of the roof and facades can exceed 4 (four) or more times the values recommended by regulatory documents. The aerodynamic parameters of high-rise and unique buildings and complexes have been studied under the conditions of mutual influence of individual buildings in the complex, and recommendations have been developed for the purpose of wind and snow loads on buildings and structures. The results of model studies in the wind tunnel 3-AT-17.5/3 of the UNICON company are the basis for the Temporary Recommendations of the MDS 20-1.2006. Methods have been developed and proposed to reduce the volume of coal dust removal from the surface of open warehouses of thermal coal, as well as from the surface of rock dumps during open-pit coal mining. During the half-century period of technical operation, all non-metallic components of the wind tunnel have become physically obsolete, nodes with movable elements have worked out their resource, which required a deep modernization of the aerodynamic channel.

EFFECT OF DISCHARGE CURRENT MAGNITUDE ON EFFECTIVENESS OF OVERHEAD POWER LINE PROTECTION AGAINST DIRECT LIGHTNING STROKES

In this paper the efficiency of lightning shielding provided by single overhead ground wire mounted atop of a double circuit self-supported 220 kV lattice power transmission line tower with a total height of 37.115 m was examined. According to the electro-geometric concept, each phase conductor of a power transmission line has an area where the overhead ground wire does not provide full protection against a direct lightning strike. The width of this unprotected area depends on the design and dimensions of overhead power line tower, the expected magnitude of the lightning current and decreases with increasing magnitude of the discharge current. The lightning protection effectiveness of upper and middle phase conductors was studied. The values of the minimum lightning current, capable of causing an insulation flashover in case of the lightning shielding failure were calculated. The minimum values ​​of the lightning current at which complete shielding is achieved have also been determined. It was found that for upper phase conductor the minimum current at which a complete lightning shielding is achieved is 7.597 kA, and it is smaller than minimum current of 8.604 kA capable to cause an electrical flashover of the transmission line insulation. For middle phase conductor the lowest current at which a complete lightning shielding is achieved is 5.976 kA, that is much smaller than minimum current of 9.206 kA leading to an insulation flashover. The results show that the specified overhead power line is protected from dangerous lightning currents. However, computations show that downward lightning flashes having a smaller current magnitude are able to bypass the shield wire and hit the phase conductors. In this regard, due to unpredictable nature of lightning, to improve the lightning protection of power lines, other measures can be applied, including the use transmission line arresters mounted on or near towers at individual points of the power line. When thunderstorm activity increases due to global warming, strengthening of lightning protection measures is justified.

Ultraviolet pulse pattern for different types of insulator material during surface discharge activities

In the past, there were several different types of discharge detection methods that have been employed for the detection and monitoring of surface discharge activities at transmission line insulators. However, the existing detection system does not work well when the discharge activity is weak and sensitive to surrounding temperature and environmental conditions. The recent development of surface discharge detection devices that have been employed currently are ultraviolet (UV) imaging and UV pulse devices but the former is known to be expensive. In this paper, a UV pulse sensor which is known as the R2868 UVTRON Flame Sensor has been employed to assess the effectiveness of the sensor for detecting the electrical discharge activity of the insulator surface. The samples used for the electrical discharge generation testing and measurement are the 11 kV glass and porcelain pin-type insulators. The tests have been conducted by exposing both the insulations to dry and wet conditions with each of them subjected to a variety of applied voltages across the samples. It was concluded that the experimental works had been successfully conducted and the sensor was sensitive and effective in detecting the electrical discharge activities on both two samples.

The Detecting System and Method of Quasi-Distributed Fiber Bragg Grating for Overhead Transmission Line Conductor Ice and Composite Insulator Icing Load

Transmission lines icing is destructive to the operation of the power grid. There is a lack of methods to monitor overhead transmission line conductors and insulators for icing load simultaneously. In this paper, we implanted six optical fibers with three quasi-distributed FBGs each into the interface of a 110kV composite insulator and built an icing detection system, and proposed three ways for measuring overhead transmission lines icing load. A method for quasi-distributed FBG to differentiate between the measurement of running insulator umbrella and conductor icing load was proposed and validated. The effect of the number of implanted optical fibers on the measurement accuracy was studied. The results show that the relative error of simulated insulator umbrella skirt icing load measurement is -7.3%∼-2.7%. The 200m-span running conductor insulator umbrella skirt icing load measurement relative error is -11.5%∼-3.8%; the relative error of conductor ice measurement is -16.5%∼9.0% and absolute error is -0.83∼1.5mm. The composite insulator with an optical fiber embedded can accurately warn of serious icing on the conductor, with two can achieve the conductor icing measuring absolute error of about ±1mm. As for accurately measuring both the umbrella skirt and the conductor icing, it is necessary to implant six optical fibers.

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.

Intelligent Identification Method of Hydrophobic Grade of Composite Insulator Based on Efficient GA‐YOLO Former Network

AbstractThe hydrophobia of composite insulators is a parameter closely related to insulation performance. As an essential index to measure the pollution flashover resistance of composite insulators, the hydrophobic grade is of great significance to maintaining transmission line insulators. To judge the hydrophobic grade of composite insulators accurately and efficiently and to solve the problem of difficult extraction of fine‐grained feature information and high similarity between classes in the data sets of anti‐hydrophobic grade recognition, an end‐to‐end intelligent identification method of the hydrophobic grade of composite insulators based on Efficient GA‐YOLO Former network is proposed. This method introduces Swin Transformer—a multi‐head self‐attention mechanism with shifted windows, into CNN, which helps the model better understand the multi‐scale global semantic information of images through cross‐layer interaction. The efficient BiFPN structure is introduced in the neck part to realize the bidirectional cross‐scale connection and weighted feature fusion in the feature extraction process. By integrating the GAM attention mechanism to amplify the significant cross‐dimensional acceptance region, the model can learn more subtle details that are more difficult to distinguish, improving model efficiency and detection accuracy. Combined with the target detection algorithm, a system for evaluating the hydrophobic grade of composite insulators on transmission lines is designed, which can realize the real‐time measurement of the hydrophobic grade of composite insulators and has practical engineering application value. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Insulator defect detection algorithm based on improved YOLOv5

Aiming at the problems such as small target scale, complex background, difficult detection, false detection and leakage detection of aerial insulators in transmission lines, this paper proposes an insulator defect detection algorithm based on improved YOLOv5. Firstly, CBAM attention module is added to the backbone network of YOLOv5 to improve the feature extraction capability of insulator pictures. Secondly, in the feature extraction part, PANet structure is replaced by BiFPN structure to make full use of the underlying feature information. Finally, the improved K-means algorithm is used to determine the prior frame and improve the defect detection accuracy of the insulator. Experimental results show that this method can improve the identification accuracy of insulator defect detection in transmission lines.

Analytical prediction of quasi-static responses of transmission lines under moving downbursts: A nonlinear model with linear approximation

Downbursts wind are believed to be responsible for most of weather-related transmission line failures worldwide. Based on a theoretical model of a hinged single-span transmission line structure under moving downbursts, this paper studies downburst -induced vibration of a multi-span transmission line-insulator system (MSTLIS). Firstly, a nonlinear analytical framework for quasi-static responses of the MSTLIS under moving downbursts is established, and linearized equations of the MSTLIS under moving downbursts with time-varying mean wind speeds are derived. Then, the influence line functions of the insulator tension and displacement of the MSTLIS are derived, based on which the quasi-static responses of the MSTLIS under fluctuating wind is calculated. A case study on a six-span transmission line-insulator subsystem is conducted. The proposed nonlinear analytical model and the approximate linearization approach is verified by finite element model (FEM) results. The proposed analytical framework with linear approximation is accurate and more efficient than FEM, and hence has a great potential for real application.

Experimental Study On Bird Streamer Flashover for V-Type Insulators of DC Transmission Line in High Altitude Area

In order to obtain the bird streamer flashover characteristics in high altitude areas, the discharge of DC V-type string insulators was studied in high-altitude test base at 4300 m in Tibet. The study results show that medium viscosity bird streamer is easy to form a continuous channel and cause flashover. The flashover probability of positive polarity transmission lines is slightly higher than that of negative. The conductivity of bird excrement almost has no effect on the flashover probability in the range of 1.9∼20.9 mS/cm. To increase the vertical air gap distance can reduce bird streamer flashover probability. Based on the experiment results, the recommended vertical air gap distance values of ±400 kV DC transmission line were proposed. Considering the influence of wind and bird streamer falling angle, the protection radius was set 3.5 m at 3500∼5000 m altitude area. Bird streamer flashover is a mixed discharge of air gap breakdown and the surface discharge along the bird streamer channel, at the altitude of 4300 m area, the minimum breakdown potential gradient is about 2.1 kV/cm, and the discharge between bird streamer and shielding ring can be approximately equivalent to rod-rod gap discharge.

Dielectric response—A nondestructive approach to probing the micro‐interface of aluminium hydroxide filled silicone rubber composites for outdoor insulation

AbstractComposite polymer dielectrics have strong electrical, mechanical, thermal and environmental properties but experience both high electric fields and harsh environmental conditions as outdoor insulation. The present investigation of the stress‐strain characteristics and morphology of the fracture cross‐section reveal the risk of a weakly bonded interface between the aluminium hydroxide (ATH) filler and silicone rubber used for insulators in transmission lines and substations. Dielectric response measurements are proposed as a non‐destructive probe of the interface quality. An analysis, based on the Dissado–Hill model, indicated that the introduction of ATH interfaces gave rise to a quasi‐DC process, in which charge transport is in the form of hopping along the weakly bonded interfaces. A schematic plan is proposed that would allow such an analysis to be used to obtain quantitative information correlated to the status of the weakly bonded interface for the diagnosis of micro‐interface quality in ATH‐filled silicone rubber and dielectric composites in general.

An Improved Algorithm for Insulator and Defect Detection Based on YOLOv4

To further improve the accuracy and speed of UAV inspection of transmission line insulator defects, this paper proposes an insulator detection and defect identification algorithm based on YOLOv4, which is called DSMH-YOLOv4. In the feature extraction network of the YOLOv4 model, the improved algorithm improves the residual edges of the residual structure based on feature reuse and designs the backbone network D-CSPDarknet53, which greatly reduces the number of parameters and computation of the model. The SA-Net (Shuffle Attention Neural Networks) attention model is embedded in the feature fusion network to strengthen the attention of target features and improve the weight of the target. Multi-head output is added to the output layer to improve the ability of the model to recognize the small target of insulator damage. The experimental results show that the number of parameters of the improved algorithm model is only 25.98% of that of the original model, and the mAP (mean Average Precision) of the insulator and defect is increased from 92.44% to 96.14%, which provides an effective way for the implementation of edge end algorithm deployment.

Design and Implementation of Transmission Line Insulator Online Monitoring Platform Based on Image Analysis

The safe operation of insulators directly determines the safety level and reliability of the entire system. In this paper, digital image processing technology is used to analyze and process insulator images, and the performance of composite insulators is comprehensively evaluated from three aspects: degree of deterioration, surface pollution, and degree of water repellency, which is used as the basis for judging insulator detection. For this purpose, an insulator online monitoring system based on telemetry image analysis is specially designed to determine the degree of aging, surface pollution, and hydrophobicity of insulators and to conduct practical tests. At the same time, the system can realize the offline operation of the insulator live, avoid the danger of climbing and live trial operation, and ensure the personal safety of power maintenance personnel. The system hardware uses advanced integration technology and high-performance and reliable equipment. The software is developed using popular development tools, is simple to operate, and has important engineering value.