Glass Insulators Research Articles

Detection of overhead line glass insulator condition using dual function device and deep learning approach

This paper presents a design of a multifunction smart wireless device for online condition monitoring of transmission line insulators. The proposed device can measure the insulator leakage current and take images of the high-voltage insulation. Yolov5-based models and deep convolutional neural networks (DCCN) are developed to analyze and classify the measured data and estimate the insulator's health condition. We have developed and tested a prototype of the proposed device. The device can issue a real-time warning message when a sudden change takes place in the leakage current value. The control center or smartphones receive the collected data wirelessly. We analyze the transmitted data using the developed methods to detect any anomalies and take appropriate remedial action. The performance and feasibility of the developed device are assessed through extensive experimental analysis. Results attest to the robustness of the proposed device, which is easy to install for existing and future overhead transmission line insulators.

Assessment of electric field and potential distribution in contaminated glass insulators via numerical simulation

Assessment of electric field and potential distribution in contaminated glass insulators via numerical simulation

Self-induced Bose glass phase in quantum quasicrystals

We study the emergence of Bose glass phases in self sustained bosonic quasicrystals induced by a pair interaction between particles of Lifshitz–Petrich type. By using a mean-field variational method designed in momentum space as well as Gross–Pitaevskii simulations we determine the phase diagram of the model. The study of the local and global superfluid fraction allows the identification of supersolid, super quasicrystal, Bose glass and insulating phases. The Bose glass phase emerges as a quasicrystal phase in which the global superfluidity is essentially zero, while the local superfluidity remains finite in certain ring structures of the quasicrystalline pattern. Furthermore, we perform continuous space Path Integral Monte Carlo simulations for a case in which the interaction between particles stabilizes a quasicrystal phase. Our results show that as the strength of the interaction between particles is increased the system undergoes a sequence of states consistent with the super quasicrystal, Bose glass, and quasicrystal insulator thermodynamic phases.

Simulation and Experimental Analysis of Electrical Characterization of Cap-Pin Glass Insulator under Uniform and Non-Uniform Pollution Layers

This paper deals with the analysis of the electrical performance of the glass cap-pin insulator under pollution conditions. The experiments are conducted in accordance with the IEC 60815 standard using artificial pollution (a distilled water mixture with NaCl). Several levels of applied voltage are used to evaluate the impact of both uniform and non-uniform pollution. For the same conditions, simulations are carried out using the COMSOL Multiphysics environment. Of interest, Leakage current waveforms are extracted from the current density and compared to those obtained from experiments. A proposed process, which aims to predict the effectiveness of the simulation in selecting appropriate parameters, geometry, boundaries etc., is investigated, where the findings are closely match the real model. Therefore, the electric field distribution on the insulator surface is presented, and 3D representations are considered for better visualizing the influence of the pollution on the insulating system. Accordingly, arcing discharges are characterized by high levels of electric field stress for uniform pollution, and dry-band arcing is simulated to correspond perfectly with laboratory findings for non-uniform pollution. Finally, this paper provides valuable insights into the electrical stress on the insulator under the effect of pollution conditions.

Surface aging condition monitoring of glass insulators in substations based on laser transmission spectroscopy

Surface aging condition monitoring of glass insulators in substations based on laser transmission spectroscopy

Analytical Description of the Electric Field inside a High Voltage Glass Insulator

Research presented in this paper analyzes the accuracy and applicability of analytical expressions to describe the electric field of a high-voltage glass insulator. The metal cap and the metal pin of the glass insulator are represented by coaxial cylindrical electrodes. The insulating materials between them are modeled as coaxial hollow cylinders. Analytical expressions for the electric field in these insulating materials are derived. Using these expressions, the spatial distribution of the electric field in the insulating materials was determined. Suitable software, based on the finite element method (FEM), was used to determine the spatial distribution of the electric field in dielectrics in the same space. Both analyses were performed under quasi-static conditions, and the results of the analytical expressions were compared with the FEM results. Discrepancies between the results of the two mentioned analyses were observed. The reasons for the observed discrepancies and the applicability of the presented analytical expressions are commented on.

Quantifying Electric Charge on Cap-Pin Glass Insulator: Investigating the Impact of Pollution through Simulation and Experimental Approaches

The objective of this paper is to investigate the behavior of electric charges on cap-pin glass insulator under 50 Hz AC voltage. The study is conducted using COMSOL Multiphysics to understand the charge location, polarity, and parameters affecting their behavior. A 2D axisymmetric insulator design is used to visualize the overall charges on the insulating system (space charge) and along the insulating surface (surface charge density) under uniform and non-uniform pollution conditions. The research shows that the total charge accumulates over the surface area of the glass material. To quantify the amount of this charge, a simulation method based on using the surface integral of the electric displacement field over this area is introduced, which is supported by experimental tests. Comparing both simulation and experimental results provides insights into the simulation reliability and the parameters affinity used to those of the real model. Moreover, the simulation helps to identify the critical area where a high amount of charges is accumulated. The findings of this study are presented and examined.

Simulation based comparative analysis of electric field stress on insulated cross-arm

Insulated cross-arms for overhead transmission lines have become increasingly common in the past decade. The 3D finite element analysis (FEA) of the electric field distribution in insulated cross-arms is particularly intriguing due to the differences from conventional glass or ceramic insulators. The complex geometry of composite cross-arms, which feature four separate insulator strings and varying shed profiles, poses a challenge in modelling them using 3D FEA packages. The findings indicate that insulated cross-arms can operate within suitable parameters for traditional composite insulators. This paper presents and analyses the electric field distribution around an insulated cross-arm, which aims to replace existing high-voltage insulators and the steel cross-arms of transmission towers. The design of grading devices plays a crucial role in ensuring the safety of these structures. The use of grading ring devices at both ends of the insulator has proven effective in relieving stress on the insulator string under normal and abnormal conditions, enabling the insulated cross-arm to function effectively with conventional composite insulators. Significant reductions in electric field strength were observed, amounting to approximately 35.93 % inside the core, 31.14 % on the core surface, 35.64 % through the shed, and 16.67 % above the shed for compression members. For tension members, reductions from the low-voltage end to both ends were around 33.82 % inside the core, 38.55 % on the core surface, and 17.48 % through the shed. However, an 8.43 % increase was observed above the shed, indicating a deviation from the decreasing trend observed in other areas. These research findings provide valuable insights for designing and managing high-voltage systems, ensuring effective insulation and enhanced safety. It benefits electrical utilities and transmission line manufacturers by improving reliability and safety for overhead transmission lines.

Study on insulator defect detection based on improved YOLOv8

Given the problems of poor detection effect in aerial insulator images resulting in poor detection effect, a multi-defect detection algorithm for aerial insulators based on improved YOLOv8 is proposed. The algorithm first changed the FPN structure to BiFPN by introducing the upsampling and downsampling connections in the upstream and downstream of the feature pyramid, to enhance the interaction and information flow between characteristics at different scales. Secondly, the SPPF is improved by using the LSKA attention mechanism to enhance the ability to extract multi-scale features. Finally, for the detection of tiny fine particles, this paper reheavys the decoupling head and the lightweight decoupling head, extracts the key information above the space and channels, and implements a lower inference latency while maintaining accuracy. The algorithm detects the normal glass insulator, glass sheet dirt, glass sheet defect, polymer sheet dirt, polymer sheet defect, and polymer insulator in the aerial image, and simultaneously detects the flashover of the insulator. The experimental results show that the network used in the insulator defect data set detection accuracy (mAP) reached 87.8%, which increased by 2.6% compared to the benchmark model, and the calculation amount (GFLOPs) decreased by 24%. At the same time, after lightweight model parameters are reduced by 32%, based on the accuracy of the subsequent deployment of lightweight requirements, we can better detect insulators of different scales and different conditions.

Examining electrical equivalent circuit models of insulators in transmission lines under pollution conditions: a comprehensive study and analysis

This research presents a comprehensive study investigating the behavior of insulators in transmission lines under various pollution conditions. Utilizing equivalent electrical circuits, the analysis aims to understand the impact of pollution on insulator performance, which is crucial for maintaining the reliability and efficiency of power transmission systems. By providing valuable insights into the relationship between pollution and insulator behavior, this study contributes to the development of improved strategies for mitigating the effects of pollution on transmission lines, ultimately enhancing the overall safety and stability of electrical power networks. The study focuses on a digital model that enables the visualization of potential and electric field distribution within a series of glass insulators utilized in Algerian electrical grids. Initially, a parallel RC network equivalent circuit was devised and its parameters were determined through finite element analysis using Comsol Multiphysics. This equivalent circuit was subsequently integrated into ATP/EMTP software to simulate leakage currents, yielding satisfactory outcomes. The model was then incorporated into the isolator's equivalent circuit. Results from various simulations indicate that the occurrence of discharge along the dry strip impacts leakage current. Furthermore, the re-initiation of discharge on the contaminated insulator's surface is influenced by the pollutant deposit's conductivity and distribution. Therefore, understanding the pollution level is vital for accurately evaluating and sizing the insulator chain at the installation site.

Investigation on Pollution-Induced Flashovers of In-Service Insulators in Ethiopian Power Transmission Lines

Power transmission lines in Ethiopia are experiencing an alarmingly high frequency of unexplained outages triggered by environmental factors, which significantly undermine the reliability of the country’s power system. This paper presents investigations aiming to identify those among the unexplained fault records that have been caused by pollution induced flashovers. An identification method is developed, which associates the contextual fault features, such as information about the characteristics of the fault, fault location, and time of day, as well as month of its occurrence with local meteorological/climatic and environmental conditions. A total number of 4231 unexplained faults, recorded between 2015 and 2022, were analyzed. Among them, 1045 faults (24.7%) were identified as being most likely caused by pollution induced flashovers. The entire network suffered from more than 130 pollution-induced flashovers annually with a frequency of about 0.8 faults/100 km/year. The fault frequency strongly differed among the grid regions, being highest in the Northeast and lowest in the Southwest region. Moreover, the performed analyses also concentrated on the evaluation of the pollution performance of various insulator types employed in the network. The results indicate that porcelain insulators have the highest pollution-induced flashover intensity of 1.47 faults/year/1000 units, followed by silicone rubber polymeric composite insulators and glass insulators with the respective intensities of 1.21 and 0.83 faults/year/1000 units. These results indicate that despite the high expectations towards the pollution performance of silicone rubber polymeric insulators, their use in the Ethiopian climatic and environmental conditions appears to be unsatisfactory.

Nanosecond photography observation of the discharge process across the 220 kV/500 kV insulators in lightning impulse

Long air gap discharge is the basis for the study of lightning protection and external insulation design of high voltage lines. However, there is a lack of detailed and comprehensive observation of the long air gap discharge process at the ns-level, as well as higher voltage insulator discharge observations. In this paper, the lightning impulse discharge/flashover tests are conducted on 220 kV glass insulators and 500 kV glass/composite insulators. Firstly, the U50% test is performed to determine the U50% value of each insulator under standard lightning impulse, and 1.1U50%, slightly higher than U50%, is applied to ensure the breakdown of the insulator. Subsequently, emICCD is utilized with a very short exposure time (minimum 10 ns) to obtain repeated single shots of discharge images under different delays, exposure times and light intensity gain. These images were spliced together based on time sequence to create a continuous discharge process. The discharge processes of 220 kV glass insulator and 500 kV glass/composite insulator are compared and analyzed. The results show that in the early stage of discharge, the discharge processes at the low voltage end of both 220 kV and 500 kV glass insulators are more intense. Additionally, the downward leader is faster than the upward leader in the discharge process of 500 kV composite insulators.

Estimation of the Pollution Critical Level on the Surface of Glass Insulators Based on Leakage Current

Estimation of the Pollution Critical Level on the Surface of Glass Insulators Based on Leakage Current

Comprehensive Analysis of Insulator Performance in High Voltage Transmission Systems: Implications for Efficient Power Transfer

This research article examines the performance of insulators in high-voltage transmission systems, specifically focusing on their role in facilitating efficient power transfer along transmission lines. The study evaluates different types of insulators used in various geographical regions and assesses their withstand voltage characteristics. The research demonstrates that glass insulators outperform plastic and ceramic insulators in terms of electric field behavior. The study also investigates the behavior of AC-energized insulators in polluted and non-polluted conditions, providing insights for improving HVAC insulation design in polluted environments. The research recommends further experiments to examine insulator behavior under different applied voltage scenarios. Overall, the study emphasizes the importance of insulators in high-voltage transmission systems and provides valuable insights for developing advanced insulator technologies to enhance power transfer efficiency.

Anti-icing application of superhydrophobic coating on glass insulator

Insulators, as important components in transmission lines, are prone to disturb the safe running of the power system by the ice accumulation on surfaces. Traditional anti-icing coatings are difficult to practically apply to insulators. Here, superhydrophobic (SHP) coatings were fabricated on the glass insulator surface by spraying. We studied microstructure, wettability, water droplet bouncing behavior, and anti-glaze icing properties of SHP coating. The results demonstrated that SHP coatings had micro-nano rough structures. The excellent superhydrophobicity (contact angle of 165.2° and sliding angle of 3.7°) was achieved. The water droplet was easily adhered to the surface of the glass insulators. At the same time, individual water droplets could bounce away from the surface after impacting the SHP coating. In the glaze environment, water droplets sprayed onto the SHP coating merged with each other and slid off the surface. These significantly reduce the likelihood of freezing. Furthermore, the SHP coating could dramatically delay the glaze icing and decrease the icing area. The icing weight and icicle length were smaller than glass insulators. The SHP coatings prepared in this work display great potential for the anti-icing of glass insulators.

Design of superhydrophobic coatings fabricated by spraying for anti-icing

The icing of transmission lines has a serious impact on people’s lives and disrupts the secure and steady functioning of the power grid, causing huge economic losses. To retard the icing of transmission line glass insulators, we prepared coatings on a glass slide by spraying using epoxy resin, fluorosilicone resin, and hydrophobic silicon dioxide (SiO2). The study examined the microscopical morphology, wetting behaviour, and anti-icing and self-cleaning characteristics of coatings containing various SiO2 mass fractions. The findings indicated that the SiO2 mass fraction notably impacted the micro-nanostructure, anti-wettability, and anti-icing performance of coatings. In addition, the largest contact angle (168.2°), the smallest sliding angle (2.6°), and the longest freezing time (181.7 s) were measured for the superhydrophobic coating with SiO2 mass fraction of 34%, which was attributed to the most uniform microstructure. The superhydrophobic coatings fabricated through spraying exhibited good anti-icing and self-cleaning properties. This facilitates the anti-icing and anti-fouling of transmission line glass insulators.

Environmental Effects on Parameters of Leakage Current Equivalent Circuits of Outdoor Insulators

The performance of outdoor insulators in transmission lines may deteriorate due to aging and can even be enhanced by the presence of pollutants. Leakage current (LC) measurement is one of the most effective methods to diagnose the insulator condition, utilizing LC parameters such as magnitude and total harmonic distortion (THD). However, research on the interpretation of these parameters is still limited. This paper discusses the diagnostic method by simulation, employing the LC equivalent circuits of different types of insulators and examining the influence of environmental factors, such as humidity and pollutant levels. LC waveforms are first obtained through experiments on various insulator types, including traditional ceramic and glass insulators, advanced composite insulators, or the hybrid type of RTV silicone rubber-coated and conducting glazed insulators. Subsequently, simulations on the LC circuits of Suwarno’s and Kizilcay’s models are performed to obtain similar LC waveforms and properties. The values of the equivalent circuit parameters are then used to diagnose each insulator’s characteristics and environmental effects. The results indicate that composite insulators of epoxy resin or SiR have a larger intrinsic resistance of ~40 GΩ and nonlinear resistance (a few MΩ to tens of GΩ), representing high surface resistance of the insulators against water and pollutants. A comparison of these parameters is expected to indicate the severity levels of insulator condition. Doi: 10.28991/ESJ-2024-08-01-022 Full Text: PDF

Enhanced Detection of Glass Insulator Defects Using Improved Generative Modeling and Faster RCNN

The precise defect detections for glass insulators are of utmost importance to ensure their safety and functionality. Therefore, this study proposes an improved defect detection algorithm based on the optimized deep learning network. The collected glass insulator data was limited in size. Even after data augmentation, it remained insufficient for the training requirements of deep learning models. In this study, employing the improved Denoising Diffusion Probabilistic Models (DDPM) generative model to expand the glass insulator data. The glass insulator defect images generated by the improved noise-fitting network exhibit enhanced quality and high fidelity. Through manual selection and iterative experiments, a total of 1200 images were curated, constituting the glass insulator defect dataset for training and test of deep learning models. Faster RCNN was chosen as the defect detection model, and its VGG16 feature extraction network was replaced with ResNet50 to address the issue of gradient vanishing caused by excessive network stacking. Additionally, the Feature Pyramid Network (FPN) structure was introduced to enhance semantic extraction for different defect scales. The Kmeans++ algorithm was utilized to improve the proposal box generation parameters in RPN. Compared to the baseline Faster RCNN model's mAP of 72.7%, our improved version achieved a significant increase, reaching a mAP of 85.9%.

Analysis and Suggestions for the Self-blast Problem of Glass Insulators on Transmission Lines

By virtue of many advantages such as good self-cleaning ability, outstanding mechanical performance, and excellent anti-vibration-fatigue ability, the glass insulators have been widely used in various alternating-current and direct-current transmission lines. However, the self-blast incidents of glass insulators have frequently occurred in transmission lines with various voltage levels, seriously affecting the safe operation of transmission lines. Herein, the main causes of self-blast problem of glass insulators are summarized and analysed from different perspectives, and some corresponding suggestions have been proposed to reduce the self-blast of glass insulators. In addition, the relevant prospects are provided for the future research work about the glass insulators. The viewpoints in this article have important theoretical and practical significance for improving the safety and reliability of transmission lines and ensuring the stable operation of electrical power systems.

The Effect of Conductivity on Surface Leakage Currents on Iced-Covered Insulators

Insulators on power transmission systems today are vital to ensuring the reliable and effective operation of high-voltage lines. However, it is inevitable that insulators will encounter problems such as contamination and icing due to natural environmental conditions and environmental factors. Pollution layers and ice buildup that have developed on insulator surfaces have a detrimental impact on insulation performance, increase surface leakage currents, and result in power line failures or interruptions. This article focuses on understanding the phenomena of contamination and icing in insulators, evaluating their effects, and investigating methods that can be taken to prevent or reduce these problems. For this purpose, solutions with different conductivity values were sprayed on the insulators in the laboratory environment, and ice covering the insulator surface was provided. Leakage currents were investigated by applying an alternating voltage with mains frequency to the insulators. Data were obtained with the help of the LabVIEW program, and the relationship of leakage currents of porcelain, glass, and silicone insulators with conductivity was compared.