UHV Transmission Research Articles

Research on electromagnetism scattered from electricity power supply towers based on orthogonal test designs

Abstract For the protection of transmission towers against electromagnetism interference to peripheral radio radar stations, this paper designs orthogonal tests to investigate the electromagnetism scattered efficiency of UHV transmission towers. The towers were mathematically modeled, and the influence of three main factors, tower spacing, frequency, and number of transmitting pylons, on the electromagnetism scattered is investigated. Each factor corresponds to three levels of study and nine sets of orthogonal tests were designed to greatly simplify the number of simulations. Three-factor analysis of variance was undertaken on test data and demonstrated that frequency was the main factor affecting electromagnetic scattering, with tower spacing being the next most influential and many towers the least influential. With the main and secondary effects in mind, the combination with the most significant effect of interaction effects on electromagnetic scattering was selected as the five towers with frequency 1400 kHz and tower spacing 200 m. The investigated outcomes lay the foundation and supply instructions for multi-factor analyses of electromagnetic scattering.

Design of the Internal Fuse Dimension for HV Shunt Capacitor in UHV Transmission Projects

Design of the Internal Fuse Dimension for HV Shunt Capacitor in UHV Transmission Projects

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.

Complex Deposit Slope Excavation Deformation Mechanism and Seismic Reinforcement Effect Evaluation

Background To further investigate the excavation deformation mechanism and remedial strategies for slope reinforcement in the southwest mountain area, the Baihetan-Jiangsu (Zhejiang) UHV transmission project deposit slope deformation reinforcement was used as a case study. Methods Deep displacement monitoring, on-site testing, and FLAC3D numerical simulation techniques were employed. The assessment of the deposit slope excavation deformation mechanism and the effectiveness of seismic reinforcement for different design options and pile parameters are conducted while analyzing the seismic reinforcement mechanism. Results and Discussions The results showed that (1) The deposit slope composed of “multi-genetic type soil” in the converter station is prone to deformation, where the dominant instability mode is “traction creep and tension failure mode.” (2) Both circular and rectangular anti-slide piles significantly reduce the amount of slope body deformation; employing circular anti-slide piles for addressing this type of deposit slope provides enhanced anti-slide retention and economic benefits. (3) Under the influence of an earthquake, the shear force and bending moment of the anti-slide pile first increase and then decrease with the increase of seismic intensity. Conclusion The distribution law of shear force and bending moment in a pile should be considered comprehensively in slope support design.

Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Research on Accelerated Corrosion Simulation Method of UHV Transmission Tower Foot

Research on Accelerated Corrosion Simulation Method of UHV Transmission Tower Foot

Research on Electromagnetic Scattering Influence of Transmission Towers on Medium Wave Antenna Based on the Characteristic Mode Theory

Electromagnetic scattering from UHV transmission towers is a major factor affecting the safety and stability of the surrounding antenna signal system. In this paper, the electromagnetic scattering effect of ±800 kV UHV DC transmission tower on the medium-wave antenna is investigated based on the characteristic mode theory (CMT). The simulation model of the tower and antenna is established, and the mode selection is carried out according to the percentage of the contribution of the characteristic mode to the total electromagnetic scattering. The effects of electromagnetic scattering under three conditions, namely, the number of towers, the distance between towers and antennas, and different frequencies, are investigated separately. The simulation results show that as the number of towers increases from 1 to 3, it leads to an increase in the electromagnetic scattering impact by about 49.5%. The shape distortion of the antenna’s directional map becomes more pronounced and is accompanied by the extension with the direction of the power line. The distance between the tower and the antenna is shortened from 500 m to 125 m, resulting in the growth of the influence of electromagnetic scattering by about 36.4%, and the directional gain of the antenna increases along the direction of the transmission line. As the frequency increases from 600 kHz to 1400 kHz, it leads to the rise of electromagnetic scattering effect of about 32.7% and the antenna directional map becomes more complicated. The research results will provide technical support for developing protective measures against electromagnetic scattering from UHV DC transmission towers to medium-wave antennas.

Bayesian Operational Modal Analysis with Interactive Optimization for Model Updating of Large-Size UHV Transmission Towers

Bayesian Operational Modal Analysis with Interactive Optimization for Model Updating of Large-Size UHV Transmission Towers

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.

The characteristics of positive corona discharge at different altitudes

With the vigorous growth of UHV transmission projects, transmission lines crossing high-altitude areas are inevitable, and the degree of corona discharge in high-altitude areas is more intense. The electromagnetic environmental problems caused by corona discharge have gradually become one of the key technical problems restricting UHV transmission in high-altitude areas. To investigate how height affects the positive polarity corona’s corona characteristics, using the movable small corona cage to carry out experiments at four altitude points in the range of 1120 m–4320 m, and measures the corona current pulse and radio interference level of 0.8 mm diameter fine copper wire under different positive voltages. Several conclusions can be drawn from the data analysis, including the following: The average current pulse amplitude grows with altitude, first before decreasing, and the current pulse repetition frequency rises along with altitude. The major conclusions of this essay can serve as a starting point for the study of the corona effect.

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.

Eiffel Effect on Towers of UHV AC Transmission Lines

The principle of Eiffel Effect on transmission towers was analyzed, and the necessity of considering Eiffel Effect on transmission towers, especially multi-loop transmission towers, was proposed. A comparative analysis on calculation methods for Eiffel Effect on tower mast structures both at home and abroad was conducted and the applicability of various calculation methods to transmission towers and their advantages/disadvantages are proposed. On this basis, the analysis method for Eiffel Effect on transmission towers is proposed. The Eiffel Effect was calculated by taking four tower types of EHV/UHV AC multi-circuit transmission lines on the same tower as examples, during which the stress state of member bar of each tower type after considering the Eiffel Effect, the influence of the intersection angle between the main members of the tower on the Eiffel Effect, and the minimum bearing capacity requirement of diagonal members etc. were analyzed. The analysis shows that: It is simple, reasonable and convenient to consider the Eiffel Effect on the tower with the rigidity-reduction method for engineering application; both the diagonal member and the diaphragm member of the tower are influenced by Eiffel Effect, where its influence on the latter is higher; it may be unsafe if designing the minimum bearing capacity requirement for the diagonal member with the internal force not less than 5% of the main members to satisfy the Eiffel Effect on the tower for the UHV transmission towers, and especially for the transmission towers with EHV/UHV AC multi-circuit transmission lines on the same tower.

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 the lightning shielding performance of strained angled tower for the [formula omitted]1100 kV UHVDC transmission project

Rigid jumper is usually used in the strained angled tower for the UHV transmission project, which makes the protection angle of the ground wire to the jumper end larger, thus the lightning shielding failure risk of the strained angled tower may increase. In order to study the lightning shielding performance of strained angled tower for the ±1100 kV ultra-high voltage direct current (UHVDC) transmission project, a numerical model for the simulation of lightning attachment to the strained angled tower was established based on the research results in the aspects of lightning downward leader, inception and propagation characteristic of upward connecting leader and so on. The maximum lightning shielding failure current and the shielding failure flashover rate (SFFOR) of rigid jumper were calculated under different line angles and overhead ground wire cross-arm lengths based on the proposed model. Results show that the lightning flashover of rigid jumper mainly occurs on the outer side while the rigid jumper on the inner side is in a good shielding state. When the cross-arm length of overhead ground wire on the outer side of J27104A1 tower with 90° line angle is greater than 21.7 m, the SFFOR of rigid jumper will be below 0.1 times/(100 km a), which can meet the operation requirement. The analysis provides technical references for the lightning protection design of strained angled tower for the UHVDC transmission project.

Research on Live Working Method of Helicopters on UHV Transmission Lines

Research on Live Working Method of Helicopters on UHV Transmission Lines