Insulator Cleaning Research Articles

Dense-YOLOv7: improved real-time insulator detection framework based on YOLOv7

Abstract Due to various mechanical and electrical stresses caused by changes in environmental and power load conditions, insulators may fail, resulting in serious economic losses. Manual cleaning of insulators is subject to weather and environmental constraints and poses significant safety risks. Traditional insulator detection methods have problems such as slow detection speed and poor robustness. Therefore, this paper proposes a real-time insulator detection algorithm based on the improved YOLOv7. First, in order to effectively streamline the number of parameters, Dense-YOLOv7 adopts the dense connection concept of DenseNet to design DenseBlock. Second, replacing the loss function with Focal Loss to solve the problem of unbalanced matching of foreground and background sample quantities has improved the detection accuracy of the model. Finally, to address the issue of PReLU and LeakyReLU activation functions being insensitive to spatial information, the activation function is replaced with FReLU to improve the robustness of the model. The experimental dataset used in this paper is a combination of the Chinese Power Transmission Line Insulator Dataset (CPTLID) and our own dataset. The experimental results show that the improved algorithm in this paper has only 44.23 M parameters and a detection speed of 44.87 FPS, which is 4.8% less than that of YOLOv7 and 8.14% quicker than that of YOLOv7. Experimental results show that Dense-YOLOv7 can significantly streamline the model parameter size while maintaining high accuracy and effectively improve the detection speed, which can meet the application requirements of real-time insulator detection.

Prospects for creating a refined model of leakage current losses due to contamination on insulator surfaces

This paper is devoted to identifying the prospects for creating a model of leakage current losses due to contamination on insulator surfaces. The aim of this study was to find mathematical models that would describe leakage current losses accurately enough to assess their importance for the integrated power system of Ukraine. The existing, widely used methodology for calculating leakage current losses was evaluated and found to be inappropriate because it is based solely on the insulator resistance with a constant value of m, which does not reflect the actual situation. Therefore, in order to improve the existing model, another one is proposed, which takes into account all atmospheric phenomena that affect the conductivity on the insulator surface, including fog, drizzle, rain and dew, which are recorded using gradations. It was found that the wind speed and humidity of the contamination layer on the insulator surface have a significant impact. The graphs of the average power loss rate for a single wetting in a garland of insulators under different climatic conditions are presented. The methodology was used to calculate the power loss rate in a 35 kV AC network and is presented in the table. The results show that it is possible to dynamically determine losses depending on climatic conditions on insulators at any point, depending on the available meteorological data. The methodology for determining the conductivity of the contamination layer on the insulator surface has been revised. It is shown how the resistance of contamination is represented, the method of its calculation, which allows further determining the conductivity of contamination, and the effect of precipitation on the cleaning of the insulator surface from contamination. It is established that under direct precipitation, insulator cleaning is insignificant, and the humidity of the contamination layer increases, which increases its conductivity. The conclusions show that the model has a high potential and the need to take into account dielectric losses.

Preparation of Quaternary Ammonium Gemini Surfactant and Its Application in Insulator Cleaning

In this paper, quaternary ammonium salt type Gemini surfactant G12 was designed and synthesized, and its structure was characterized by infrared and nuclear magnetic resonance. The surface tension, permeability, emulsification ability and cleaning of insulator surface contamination in the composite system were tested, and the test results showed that it had low critical micelle concentration (cmc) and good emulsification performance. Due to the presence of rigid groups, the permeability is average. When quaternary ammonium Gemini surfactant G12 is mixed with permeant JFC-E, and is combined with auxiliary and organic solvent, the cleaning rate of insulators can reach more than 90%.

Towards Inspection and Cleaning on Capacitor Towers: Design and Implementation of Multi-task Operation Robot

Capacitors work in harsh environments, including strong electric fields, strong mechanical stress, and drastic weather changes for a long time. Solid, liquid, and gaseous dirt particles will be deposited on the surface of the electrical outer insulations, the electrical strength of the capacitor will be greatly reduced, and the health condition of the capacitor tower will deteriorate under the effect of harsh weather conditions, such as fog, dew, drizzle, and melting ice (snow). Based on the importance of the safe operation of substations, it is necessary to regularly evaluate the health condition of capacitors and complete operational tasks such as insulator cleaning, bolt tightening, and capacitance measurement. Considering the above situation and needs, we propose a solution of inspection and maintenance robot for capacitor towers in high-voltage substations by using automatic and intelligent technology to complete the above-mentioned tasks efficiently and reliably instead of manual work.

Study on the Contamination Characteristics of V-Type Double Suspension Rod Insulators Based on the Influence of Wake Flow

The insulators of the catenary of the Lanzhou-Xinjiang High-speed Railway in windy areas suffer from serious contamination, which has led to frequent flashover accidents. The catenary of the Lanzhou-Xinjiang High-speed Railway has adopted the unique external insulation of V-type double suspension rod insulators. To further determine the contamination characteristics of this type of insulator, a contamination simulation model of insulator is established in this paper based on the principles of fluid mechanics, which is used to analyze the contamination characteristics of the V-type double suspension rod insulators under the influence of wake flow. The research results show that wind speed directly determines the static pressure on the surface of the insulator, the wind speed and particle concentration are proportional to the contamination volumes on the windward and crosswind sides of insulator, while the particle size is inversely proportional to the contamination volume on the leeward side of the insulator. The direction of wake flow is consistent with the direction angle of external incoming flow, and the wake flow generating area affects the contamination characteristics of the insulator. When the incoming flow is at a prevailing wind direction of 0°, focus should be put on the windward and crosswind sides of the two insulators during insulator cleaning, and the contamination distributions on these two insulators are similar; when the incoming flow is at a prevailing wind elevation of 0°∼60°, focus should be put on the entire surface of 1# insulator and the windward and crosswind sides of 2# insulator during insulator cleaning.

Numerical Analysis and Experimental Study of the Laser Cleaning of Ceramic Insulator Contamination

Contamination flashover of insulators is one of the main threats to the safety of power systems, and regular cleaning of insulator surface pollution is an effective solution to this problem. In this paper, the laser cleaning of ceramic insulators is studied via simulations and experiments. The adhesion between a contamination layer and an insulator surface is estimated. A laser cleaning model for contaminated insulators is established, and a numerical analysis of the thermal stress field distribution characteristics of laser cleaning is carried out. Various factors that affect the thermal stress field distribution, including the laser power, laser scanning speed and thickness of the contamination layer, are also analysed. The optimal cleaning parameters for the best performance of laser cleaning are obtained through simulation and experiments. The result shows if the equivalent salt deposit density (ESDD) is 0.05 mg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the nonsoluble deposit density (NSDD) is 0.25 mg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the best cleaning effect could be achieved when the laser power is 100 W and the scanning speed reached 6000 mm/s.

Autonomous UAV System for Cleaning Insulators in Power Line Inspection and Maintenance.

The inspection and maintenance tasks of electrical installations are very demanding. Nowadays, insulator cleaning is carried out manually by operators using scaffolds, ropes, or even helicopters. However, these operations involve potential risks for humans and the electrical structure. The use of Unmanned Aerial Vehicles (UAV) to reduce the risk of these tasks is rising. This paper presents an UAV to autonomously clean insulators on power lines. First, an insulator detection and tracking algorithm has been implemented to control the UAV in operation. Second, a cleaning tool has been designed consisting of a pump, a tank, and an arm to direct the flow of cleaning liquid. Third, a vision system has been developed that is capable of detecting soiled areas using a semantic segmentation neuronal network, calculating the trajectory for cleaning in the image plane, and generating arm trajectories to efficiently clean the insulator. Fourth, an autonomous system has been developed to land on a charging pad to charge the batteries and potentially fill the tank with cleaning liquid. Finally, the autonomous system has been validated in a controlled outdoor environment.

Control and application of ultra-high voltage insulator cleaning and detecting robot

With the development of global energy Internet and demand for UHV transmission, uHV transmission lines will increase rapidly and become more and more important for national economic development. The uHV transmission lines will increase year by year and become increasingly important to the economic development of the country. It is necessary to study the cleaning and detection technology of transmission line insulators that the insulators of UHVDC transmission lines such as large leakage rate, low detection efficiency and difficult cleaning of insulators. Therefore, the development of uhv transmission line insulator hot-line cleaning robot and detection integration has important engineering significance and practical value to improve the level of the operation of the uhv power transmission engineering maintenance, safe and reliable operation of the protection of uhv transmission lines. In this paper, the research on the integrated robot for live cleaning and detection of uHV transmission line insulators will greatly promote the live operation of UHV transmission lines in China. It can be directly applied to the live operation of UHV DC and can be promoted nationwide.

Design and Experiment of Dry-Ice Cleaning Mechanical Arm for Insulators in Substation

Polluted flashover of insulators has always been a crucial hidden peril to the reliability of substation for supplying electricity. At present, the insulator of the substation is mainly cleaned manually in the case of power-cut, which greatly affects the reliability of power supply and operation safety. In this paper, an insulator dry-ice mechanical arm capable of electrified working is proposed. Under the regular operation of the power grid, the operator can remotely control the mechanical arm to clean the insulators of the substation with high-pressure gas mixed with dry-ice particles. This will not only ensure the regular operation of the power grid, but also greatly protects the safety of personnel. Considering the operation environment and high-voltage working conditions of the substation, the mechanism and control system of the dry-ice cleaning mechanical arm are designed, and the motion analysis, simulation, and strength analysis of the mechanical arm are carried out. Finally, the high-voltage-insulation test of the mechanical arm and the actual operation of the substation insulator cleaning working test are carried out, which proves that this mechanical arm can adapt to the operation environment of the substation, and the working is stable, safe, and reliable, which has an important application value to solve the problem in the cleaning of the substation insulator and other electrified equipment.

Study on Multi-influence Factors of Dry Ice Cleaning Effect Based on Orthogonal Test Method

In order to apply dry ice to the insulator cleaning in power systems, it is necessary to obtain the optimal parameter range of each of the influencing factors. In this paper, a six-factor, five-level orthogonal test method is used to obtain a representative test plan. The influence level of air pressure, dry ice flow rate, cleaning distance, cleaning time, nozzle rotation speed and cleaning time on the cleaning effect were obtained. Results revealed that the optimal range for each cleaning parameter is: air pressure 0.7MPa∼0.8MPa, dry ice flow rate 2.5kg/min∼3.0kg/min, cleaning distance 10cm∼15cm, cleaning angle 10°∼20°, nozzle rotation speed 5∼15r/min, cleaning time 30s∼36s.

Investigation on the Process of Dry Ice Cleaning Insulators

Compared with routine methods, the dry ice cleaning as an innovative, inexpensive and green cleaning technology, has excellent insulation and will not cause the pollution flashover accident. Due to the outstanding performance, the dry ice cleaning is very suitable for the insulator cleaning. In this study, the insulators were cleaned by dry ice with different cleaning parameters. The influence of different cleaning parameters on the dry ice cleaning was studied comprehensively. It is shown that reasonable air pressure, cleaning angle, dry ice mass flow, nozzle speed will improve the dry ice cleaning quality greatly, produce a high-efficiency performance. Furthermore, the dry ice cleaning can wash off the pollution of insulator surface effectively, give an obvious and ideal cleaning effect.

Online monitoring of medium voltage overhead distribution lines polluted insulators severity

This study describes online monitor of the pollution severity of heavy medium voltage overhead distribution lines polluted insulators. The suggested monitor works by sensing and analysing the leakage current bursts. If these bursts are judged by the monitor as corresponding to a potentially dangerous level, the monitor transmits an alarm signal to the service crew, so that they would clean the insulators of the line or substations in time before a sudden line outage occurs, with entailed excessive expense loss of power supply and annoyance to customer. Line insulator cleaning is thus carried out when necessary which adds to the economy of the power system operation. The suggested monitor based on the artificial neural networks which are fed by the leakage current bursts, and also the environmental conditions collected from the field. The hardware schematic is presented to act the function of online monitoring system.

A neural network-based estimation of the level of contamination on high-voltage porcelain and glass insulators

In harsh environments, such as those found in Saudi Arabia, the periodic washing of insulators which is a necessity to ensure continuity in a power supply is very expensive. The accurate estimation of the severity of contamination can help electric utilities to properly schedule such washing and thus reduce the expense of washing and prevent insulator flashover. This paper presents a neural network algorithm for detecting the contamination level of high-voltage porcelain and glass insulators. The algorithm is based on images captured using a digital camera. Two types of features are extracted from each image: histogram-based statistical features and linear algebraic features based on singular value decomposition. Using the extracted statistical features, linear algebraic features, or a combination of both, three neural networks scenarios were successfully designed to associate the insulator images with the appropriate contamination levels and thus the possibility of flashover. Tests of the proposed estimation algorithm demonstrated a high success rate in estimating the contamination level of insulators. Finally, the developed algorithm has been deployed at the high-voltage station at King Fahd University (KFUPM). This deployment will eliminate the need for human intervention in determining the timing and location of required insulator cleaning.

Investigating the Effect of Rainfall Parameters on the Self-Cleaning of Polluted Suspension Insulators: Insight from Southern China

The cleaning effect of heavy rain (the rainfall reaches 5 mm every day) on surface contamination of insulators is more effective than dew, fog, mist, and other light rain conditions which can initiate leakage currents and increase the likelihood of flashover. It is well understood that heavy rain can wash away contamination from the surface of high voltage (HV) insulators and thereby reduce the risk of pollution flashover. This study examines the cleaning effect of natural wetting conditions on HV insulators on four 500 kV transmission lines in Hunan Province, China. Historical meteorological data, monthly equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) measurements taken over a period of five years were analyzed to investigate the relationship between rainfall intensity and insulator cleaning. The measured data show that the ESDD/NSDD changes with the seasonal variation, which accumulates in dry season (January–April, about 117–122 days) and is washed off in the wet season (June–October, about 118–127 days). According to the measured data, the ESDD and NSDD on the surface of insulators were affected by the rainfall intensity (in the dry season it is about 1 mm/day and in the wet season it is about 5 mm/day). Based on a comparison of the four study sites, we propose a mathematical model to show the functional relationship between rainfall intensity and insulator self-cleaning capability. The mathematical model’s coefficient of determination (R2) is greater than 0.9 and the effective rate of self-cleaning capability reaches 80%.

A new monitor for pollution on power line insulators. Part 2: Simulated field tests

An apparatus is developed for monitoring the leakage currents drawn by an insulator chain of a power line or a busbar support in a polluted atmosphere. The apparatus monitors the insulator pollution by sensing and analysing the leakage current bursts. If these bursts are judged by the apparatus as corresponding to a potentially dangerous pollution level, the apparatus transmits an alarm signal to the service crew to allow them to clean the insulators of the line or substation in time before a sudden line outage occurs, with the entailed excessive expense, loss of power supply and annoyance to customers. Line insulator cleaning is thus carried out only when necessary, which adds to the economy of the power system operation. The apparatus design and construction were reported in Part 1 of the paper. It has undergone numerous tests with artificially polluted insulators in the high voltage laboratory. These tests are the subject of the present paper. The following Part, to be submitted, will describe field experience.

The Fundamental Characteristics of the Cleaning of Insulators by Powder Jet

The Fundamental Characteristics of the Cleaning of Insulators by Powder Jet

The characteristics and performance in service of high-voltage porcelain insulators

The paper discusses the electrical characteristics and performance in service of porcelain insulators for outdoor high-voltage apparatus. It is emphasized that if large power systems are to be operated with a minimum of breakdowns a carefully planned scheme of field testing, supplemented by laboratory investigation, is essential.Part 1 describes the laboratory apparatus and the field testing equipment used by the Central Electricity Board. For laboratory investigations, two outdoor high-voltage testing sets are installed, having maximum voltages of 85 kV and 250 kV. A test tower and rack are associated with each equipment, and continuous pollution tests can be made simultaneously on 60 insulators. Counters are installed on all the insulators to record the leakage-current “surges.”Field tests are made with the lines in service, with an apparatus consisting of a capacitance potential-divider and electrostatic voltmeter. The potential distribution on the insulator is measured, and faulty units are detected by the abnormally low potential-drop across them. The surge counter is also applied to equipment in service in order to indicate when insulator cleaning is necessary.Part 2 gives some of the results of investigations made with the apparatus and technique described in Part 1. Information is given regarding the performance of line insulators, post insulators and bushing porcelains. The behaviour of insulators in fog, and similar weather conditions, is discussed, and examples are given of the highly irregular potential distributions and leakage-current surge records obtained under such conditions. Comparative results are given for “normal” and “anti-fog” insulators. The mechanism of insulator flashover in fog is described in detail. The requirements of a good anti-fog insulator are discussed, and for an insulator for use in highly polluted and humid atmospheres a leakage path of 2 in. per kV of applied voltage is recommended. A new design of insulator unit is described in which the potential distribution is stabilized by resistors.Information, based on service experience, is given on the deterioration of insulators. With high-quality modern insulators, the rate of deterioration should not exceed 0.1% per year, but it is nevertheless essential to make field tests, as a single faulty unit may lead to the complete failure of the insulator string. Confirmatory tests made in the laboratory show that in most cases (approximately 90%) the field diagnosis of faulty insulators is correct. Deterioration takes the form of cracks in the porcelain head, and the mechanism of insulator failure due to cracking is described.The cause and characteristics of radio interference due to power lines are discussed, and data are given of the interfering field strength due to high-voltage lines operating in various weather conditions. Under the worst condition—fog—the interference increases by 40 db. above the fine-weather value. The attenuation of the interfering field is very rapid at right angles to the line, and a decrease of 25 db. occurs in 50 yd.; at this distance from the line, local broadcasting stations may be received virtually free from interference even under the worst weather conditions.

The electrical characteristics of 132-kV line insulators under various weather conditions

The insulation of high-tension lines in industrial areas is one of the major problems in the operation of high-tension systems. This paper gives the results of an investigation into the electrical characteristics of 132-kV insulators under various weather conditions in a district subject to atmospheric pollution. It was found that the steady value of the leakage current of an insulator chain varies between 0.2 and 1.0 mA, depending on the weather conditions. In fog or with dirty insulators under humid conditions the leakage current is very unsteady and continuous surging usually takes place, the magnitude of the current-surges often reaching 100 mA. These current-surges are due to surface discharges on the insulators and are usually self-extinguishing owing to the resistance of their path being increased by the heating effect of the current, but a severe surge may develop into a complete flashover. The frequency and magnitude of these current-surges provide a criterion by which to judge the performance of insulators. Information is also given on the surface resistivity of porcelain, the characteristics of some special types of insulators, and the cleaning of insulators.