UHV Transmission Lines Research Articles

Study on corona discharge on the grounding wire of ±1100 kV transmission line during the downward lightning flash

The atmospheric space electrical field has nonlinear distribution characteristics during thunderstorm activity, which influences the ground surface electric corona of UHV transmission lines. In this paper, the corona discharge model of ground wire of ±1100 kV UHVDC transmission line is established considering the combined effect of ground lightning process and working voltage. With the combined action of thundercloud electrical field and DC voltage, the positive conductor suppresses the electric corona of the upper shied wire, and the negative conductor enhances the discharge of the upper shied wire. The corona current of the right shied wire is 54.7 μA/m larger than that of the left shied wire. When the down leader develops, the leader voltage, the line operating voltage and the thundercloud voltage work together, and the electric corona on the surface of the conductor and shied wire of the transmission line increases rapidly. The corona current increases 102 times on the left shied wire's surface and 103 times on the right shied wire's. Considering the environmental factors and the development of the downgoing leader at the same time, the degree of electric corona on the surface of the shied wire is weakened when the humidity in the space increases, but the overall value of the corona current is much higher than the thundercloud electrical field. When the wind speed increases, the degree of electric corona on the surface of the shied wire is aggravated. The corona current on the surface of the left shied wire is 37.13 μA/m, and the one of the right shied wire is 109.33 μA/m. The corona current value of ground surface increases with the increase of wind direction.

Finite Element Analysis of UHV Transmission Line Stringing System Based on APDL

Nowadays, the tension stringing construction is used in UHV transmission lines. However, in the tension stringing system of UHV transmission lines, due to the flexibility of cables, such as guide ropes, ground wires, etc., in systems, the vibration will be occurred during the construction process. In order to analyze the vibration, the finite element analysis method is required for the system. In this paper, a certain position in the stringing process of the first and the last electric tower of the third section of a 1000kV UHV project was taken as the research object, the setting of constraint conditions, modal analysis and power spectrum analysis were carried out for the fast simulation calculation using APDL, the ANSYS parametric design language. It can be concluded that this method can improve efficiency of modeling and simulation and realize the rapid finite element analysis.

Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Simulation analysis of synthetic electric field of UHV transmission line under mountain fire condition

Factors such as high temperature, charge density and charged particles have a major impact on the insulation strength of the transmission line gap. When the DC transmission line is in normal operation, the surface of the conductor is easy to adsorb dirt due to the environmental influences, so the local electric field strength is larger than the critical field strength of the corona discharge, and the gas molecules in the air are ionized to form space charges. The electric field of the space charge is superimposed with the electric field of the wire and the earth (nominal electric field) to form a synthetic electric field. In this work, the calculation model of the synthetic electric field is created and the influence of mountain fires on the synthetic electric field of the transmission line is simulated and analyzed. The influence of flame temperature, charge density, particle type and shape on the electric field is simulated and investigated. The law of variation of the electric field of the transmission line in mountain fire under different factors is obtained. The distorting effect of particles on the electric field under the UHV DC transmission line is simulated. The distorting effect of particle size and particle chain on the synthetic electric field is obtained and the simulation results are compared to the calculation results.

Preparation and application of corona noise-suppressing anti-shedding materials for UHV transmission lines

Abstract With the continuous expansion of the construction scale of the State Grid and the gradual improvement of people’s awareness of environmental protection, the power contradictions and disputes caused by the North–South Power Transmission and Transformation Project have become increasingly prominent, which has attracted widespread attention from all walks of life. This study focuses on the development of conductive silicone gel for UHV transmission lines using carbon fiber (CF) powder, carbon black (CB), and carbon nanotubes as fillers, and organic silicone polymer as the matrix. The aim was to address the issues of corona noise and detachment. We prepared a series of conductive silicone gels with different proportions of CF and CB conductive fillers and conducted a comprehensive analysis of their electrical conductivity, tensile performance, hydrophobicity, and rheological properties. The research results demonstrated that the maximum electrical conductivity of the conductive silicone gel was achieved when the CF and CB contents reached a ratio of 2:1. In the case of a 70% organic silicone polymer gel, the electrical conductivity reached 0.73 S/cm, while it increased to 1.17 S/cm in an 80% organic silicone polymer gel. This indicates that optimizing the proportion of fillers can significantly enhance the electrical conductivity of the conductive silicone gel, meeting the requirements of UHV transmission lines. Additionally, the study evaluated the tensile performance, hydrophobicity, and rheological properties of the conductive silicone gel. The results showed that the 70% organic silicone polymer gel exhibited a tensile strength, Young’s modulus, and elongation at a break of 678.6 MPa, 1.3 MPa, and 15.22%, respectively. The corresponding values for the 80% organic silicone polymer gel were 129.9 MPa, 1.6 MPa, and 55.89%. This indicates that the conductive silicone gel possesses excellent mechanical properties and ductility, enabling it to withstand stress and deformation in UHV transmission lines while providing anti-detachment effects. In summary, this study successfully developed a conductive silicone gel that meets the requirements of UHV transmission lines. By optimizing the ratio of CF and CB contents, the electrical conductivity of the gel was maximized. Furthermore, the conductive silicone gel exhibited favorable tensile performance, electrical conductivity, and anti-detachment effects, effectively addressing corona noise and detachment issues in UHV transmission lines. These research findings are of great significance for the design and application of UHV transmission lines.

Cable crimping intelligent measuring device

The rapid development of China’s economy has promoted the development of the power industry, and more and more UHV transmission lines have been put into construction. With the expansion of the cable scale, the power industry’s requirements for cable quality have also increased. In the construction of power transmission and transformation lines, the crimping of cables is an important link that affects the entire line. On the basis of the traditional crimping measurement method, this paper designs an intelligent measuring device for cable crimping, which uses STM32 microcontroller as data processor and integrates various digital measuring tools. The device is used in the cable crimping construction and quality inspection process. Improve the efficiency and quality of cable crimping construction, and realize the integration, digitization and informatization of cable crimping data measurement.

Application of Transmission Line Tower Foundation Protection in Power Engineering

The area of mountains, hills and plateaus in China accounts for about 69% of the total land area of the country. It is inevitable that the UHV and HV transmission lines under construction will be built in areas with complex geomorphic characteristics. This paper mainly describes the application of transmission line towers in practical projects, from geological survey, tower stability to foundation reinforcement solutions.

Research on passive interference of UHV transmission lines based on tower modeling

At present, a large number of high-voltage transmission lines have gradually become a key factor that interferes with the quality of surrounding radio communications. In the study of passive interference of transmission lines, the modeling of iron towers affects the accuracy of calculation results. In order to provide reliable data reference for the research of protective measures and interference suppression methods, aiming at the line model of transmission line tower, taking the tower structure and auxiliary angle-steel as variable factors, this paper studies its influence on the calculation results of passive interference. Three tower models with typical structures and obvious differences are selected, and the models using only the main material and the auxiliary material angle-steel are established respectively. The calculation results of passive interference under different frequency incident waves are compared. The final conclusion shows that with the increase of incident wave frequency, the passive interference caused by the three transmission tower models increases gradually, and the effect of auxiliary angle-steel is more and more obvious.

Design and optimization of carbon fiber eight-wire lifter with exterior cladding structure

The UHV eight-wire lifter is an important tool in frequent use for the construction and maintenance of UHV transmission lines, which is made of titanium alloy and weighs about 40 kg. Due to high-weight, the work efficiency is greatly reduced. In this paper, the design of a lightweight UHV eight-wire lifter is proposed by using carbon fiber cladding structure. The effects of three factors on the maximum load-bearing load of the carbon fiber exterior cladding structural member are excavated through the failed experiment of the carbon fiber exterior cladding tensile and shear test pieces and the finite element progressive damage numerical calculation. The orthogonal experiment is employed to obtain the optimal cladding structure of the eight-wire lifter with a carbon fiber exterior coating cladding. After that, carbon fiber eight-wire lifter is developed and subjected to mechanical tests. The test results show that the performance of carbon fiber eight-wire lifter meets the mechanical performance requirements of eight-wire lifter. Compared with the titanium alloy eight-wire lifter, the maximum load-bearing load of the carbon fiber eight-wire lifter is increased by 20.5%, and the weight is decreased by 37.5%.

Research on Independent Live Replacement Method and Equipment for Suspension Clamp of ±800kV Transmission Line

UHV transmission lines are of great significance to the long-distance transmission of electric energy. Suspension clamp is a common hardware of line tower, and its maintenance method has large load transfer and low working efficiency. Aiming at this problem, the independent live replacement method of suspension clamp is put forward, the safety is analyzed, and the simulation analysis and test verification of the developed equipment are carried out. The results show that the research results can greatly reduce the transfer load and improve the working efficiency, which is of great significance to this type of maintenance.

Research on Live Working Method of Helicopters on UHV Transmission Lines

Research on Live Working Method of Helicopters on UHV Transmission Lines

Susceptibility Analysis of Land Subsidence along the Transmission Line in the Salt Lake Area Based on Remote Sensing Interpretation

As the influence of extreme climate and human engineering activities intensifies, land subsidence frequently occurs in the Salt Lake area of Qinghai Province, China, which seriously threatens the stability of the UHV transmission line crossing the area. Current susceptibility analyses of land subsidence disasters have mostly focused on the classification of land subsidence susceptibility and have ignored the differentiation of susceptibility among different land subsidence intensities. Therefore, the land subsidence susceptibility map does not meet the operation and maintenance management needs of the UHV transmission line, let alone planning and designing of new lines in the Salt Lake area. Therefore, in this study, we proposed a susceptibility analysis of different land subsidence intensities along the transmission line in the Salt Lake area. The small baseline integrated aperture radar interferometry (SBAS-InSAR) method was used to obtain the land subsidence along the transmission line based on 67 Sentinel-1 remote sensing interpretation datasets from 2017 to 2021. Based on a combination of K-means clustering and the transmission line specifications, four annual land subsidence intensity grades were identified as 0~−2 mm/year, −2~−10 mm/year, −10~−20 mm/year, and <−20 mm/year. In addition, eight geological environmental factors were analyzed, and a multi-layer perceptron neural network (MLPNN) model was used to calculate the susceptibility of the different land subsidence intensities. The area under the curve (AUC) and practical examples were used to verify the reliability of the different land subsidence intensities susceptibility mapping. The AUC values of the four subsidence intensity grades showed that the results were accurate: the <−20 mm/year grade produced the largest AUC (0.951), with the −10~−20 mm/year, −2~−10 mm/year and 0~−2 mm/year grades producing AUCs of 0.926, 0.812, 0.879, respectively. At the same time, the susceptibility classification results of different land subsidence intensities were consistent with the interpretation and site tower deformation. The results of this study provided the distribution of land subsidence susceptibility along the transmission line, distinguished the susceptibility of different land subsidence intensities, and provided more detailed subsidence information for each transmission tower. The results provide important information for transmission line tower planning, design, protection, and operation management.

Research on the Influence of Various Attribute Factors on Passive Interference in UHV Transmission Lines Based on Orthogonal Test

Considering the problem of passive interference caused by electromagnetic scattering effects of transmission lines to neighboring radio stations and other communication equipment, this paper refines the passive interference calculation model for UHV transmission lines. The solution calculation is carried out by the Method of Moments, and the law of passive interference effect of the tower structure, auxiliary angles, and ground roughness under different frequency incident waves, is summarized. By designing an orthogonal test, the degree of influence of the above attributing factors on passive interference results in the established joint model of three towers with two stall distances was explored by using Analysis of Variance. The results demonstrate that both auxiliary angles and rough ground show a pattern of enhanced electromagnetic scattering effect with increasing plane wave frequency in single-factor analysis. When multiple factors are combined, the rough ground has a significant effect on the results. This method effectively evaluates the passive interference influence factor while reducing the modeling and simulation engineering and provides a reference for the passive interference prediction in subsequent practical projects.

Investigation on the Critical Wind Speed of Instability Failure of UHV Transmission Tower-line Coupling System under Typhoon

Wind is one of the most destructive external loads of transmission lines, and typhoon-caused severe damage or even destruction of electric power facilities occurred frequently. In order to research the critical wind speed of instability failure of UHV transmission tower-line coupling system under typhoon, the UHV transmission line in Zhejiang is chosen as the research subject and a finite element model of the UHV tower-line coupling system is established. By using the improved generalized force calculation method, the dynamic response of the transmission tower is converted to the static response. Then the LRC method is used to calculate the equivalent static wind load of the tower and obtains the wind response of the UHV transmission tower-line coupling system. The results show that under the typhoon wind field, the component at the junction of the tower head and the body first reaches the supercritical state. Specifically, when the wind speed at 10-meters height reaches 31m/s, the profile component of the tower head will be damaged. With the increase of wind speed, the damaged area of the tower head also expends. When the wind speed at 10-meters height reaches 37m/s, the main load-bearing component of the tower head-body junction will lose its stability, which will directly threaten the safety of the transmission tower.

Numerical Analysis on the Sub-Span Oscillation of Iced Eight-Bundle Conductors During Galloping

Under the excitement of wind loads, UHV transmission lines are subject to two types of vibration phenomena, namely, sub-span oscillation and galloping. This phenomenon can easily lead to conductor breakage, interphase flashover, fatigue damage to fittings, and even lead to tower collapse and disconnection accidents. The numerical analysis method is used to analyze the sub-span oscillation characteristics of the eight-bundle conductor during galloping. The results of the numerical simulation are compared to explore the influence of wind speed, span length, initial angle of wind attack, and turbulence intensity on the galloping line, looking for movement characteristics between each sub-conductor. The results provide a reference for research on the galloping principle of UHV transmission line and anti-oscillation to further improve the resistance of the power grid against disaster ability.

Improved Electrogeometric Model of UHV Transmission Line Based on Long Gap Discharge and Its Application

Based on long air gap discharge test data and lightning return stroke observation data, an improved electrogeometric model (EGM) considering terrain conditions is established and verified to analyze the lightning shielding performance of UHV transmission lines. The striking distance formula is modified as rs = 0.13 (I2 + 40I)0.814. In this paper, the lightning shielding failure rate of three-phase conductors of EHV and UHV transmission lines calculated by the improved EGM model is consistent with the lightning observation data of actual transmission lines in Japan and the scaled lightning discharge simulation experimental results of UHV transmission lines in plains and mountainous areas of China, which verifies the applicability of the improved EGM model to evaluate the lightning shielding performance of large-scale UHV transmission lines. The improved EGM model is applied to evaluate the influence of tower type and slope steepness on the shielding failure tripping rate of UHV transmission lines. The shielding failure tripping rate of the SZ322 tower is higher than that of the SZT1 tower, and the shielding failure tripping rate of UHV transmission lines is greatly affected by slope gradient and increases with the increase of slope gradient.

Simulation Research on Die Forging Process Optimization of the FDN Type Anti-vibration Hammer Head in UHV Transmission Lines

Traditional anti-vibration hammer heads are mainly manufactured by gravity casting technology, which has many internal defects and limited mechanical properties, which cannot meet the technical requirements for higher-strength anti-vibration hammers in the construction of UHV transmission lines. Die forging is an advanced material forming process for producing low defect and high strength anti-vibration hammer. However, the process parameters should be strictly controlled to realize the complete filling of forgings and reduce the damage of forgings and dies.In this paper, the die forging process of the FDN type anti-vibration hammer head was simulated by using Deform-3D software platform, and the optimal forging process parameters were proposed as follows: the diameter of the blank is 65mm, the length of the blank is 184mm, the pressing speed of the upper die is 200mm/s, and the preheating temperature range of the blank is 800?∼1000?. The mechanical properties of the anti-vibration hammer after process optimization met the requirements of the corresponding strength grade products.

Numerical Simulation of Wind-induced Swing Angle of 1000kV Transmission Line Suspension Insulator Strings Considering Dynamic Response

The wind-induced swing angle of insulator strings directly affects the electrical insulation performance and the construction cost of the UHV transmission project. However, due to not considering the fluctuating wind pressure, the calculation results of wind-induced swing tend to be conservative when adopting the recommended guidelines of standard especially in the face of severe weather. This paper simulates the transient wind field of strong winds based on time-space correlation characteristics and constructs the fluctuating wind load distribution model exerting on the UHV transmission line. Then a refined finite element model of the multi-span transmission line including the entire tensile section is established. And the swing angle of the insulator strings calculation formula is fitted based on the calculation results of the wind-induced swing response. The calculation result shows the swing angle decreases with the increase of ice thickness, and the magnified coefficient of the wind-induced swing angle at the target tower under the basic wind speed of 15m/s is 1.03.

Design and Mechanics Analysis of Tools for Live Replacement of UHV Whole String Insulators

The experimental results show that the method can effectively detect the contamination degree of the contact net insulator The replacement of whole string insulators is difficult tasks of live working for UHV transmission line and still remain blank. Based on the structure and layout of straight string and tensile string insulators of UHV transmission lines, this paper proposes design of tools for live replacement of the whole string insulators. Through three-dimensional simulation and analysis, the force characteristics of the various tools are determined, and developed the tools for live replacement of the whole string insulators of UHV, and the mechanical test of the tools are carried out. The test results confirm the feasibility of the tool design and the reliability of the mechanical simulation model proposed in this paper, which provides technical supports for the live replacement of UHV whole string insulators.

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.