Transmission Line Tower Research Articles

Study of direct and indirect risk assessment of landslide impacts on ultrahigh-voltage electricity transmission lines

Ultrahigh-voltage electricity systems are a vital part of energy networks, often across wide regions passing through mountainous terrains. The instability of slopes forming tower foundations along transmission lines poses a large risk to the entire energy network. Moreover, the tower foundations along extra-high-voltage electricity transmission lines are a very special type of element that are also highly vulnerable to landslides. In this study, an integrative risk assessment framework, including a hazard assessment, vulnerability analysis for the specified element at risk, and consequence estimation, is proposed to quantify the direct and indirect risks of landslides to power transmission lines. The Yanzi landslide, where a tower of the major ultrahigh-voltage transmission line from Sichuan (western China) to Shanghai (eastern China) has just been constructed, is taken as a case study. The correlation between landslide displacement and tower structure tilting is studied. In terms of the precipitation return period, factors of safety, failure probability, and deformation are simulated. A physical vulnerability curve is fitted by assuming a Weibull relationship between the horizontal deformation (hazard intensity) of the landslide and the tower inclination ratio. The total risk is calculated as the sum of the direct and indirect losses, among which the potential indirect risk due to tower damage is much greater than the direct risk. This work demonstrates the importance of landslide treatment strategies along electricity transmission lines by considering the potential indirect risks. The risk assessment model of landslides affecting ultrahigh-voltage electricity transmission lines proposed in this study could be useful for other types of indirect landslide risk evaluations.

Computational analysis of wildland fire resistance for transmission line tower

Finite element (FE) analysis of the transmission towers under a fire event and the accompanying wind is presented. Several key aspects (including temperature-dependent non-linear material properties, geometric non-linearity, member eccentricity due to the single-leg bolted connection, and the temperature-dependent connection behaviour in both the axial and the rotational directions) are considered. A quasi-static analysis is also employed in the FE model using the explicit solver available in Abaqus. The member temperature variation during a realistic fire event is derived analytically based on the fire intensity and the resultant vertical gas temperature distribution so that the effect of the realistic wildland fire can be input as a member temperature profile. First, fire design guidance in terms of the most critical heating and wind pattern, as well as the effect of fire-affected heights are provided based on the case study results. Then, further fire analysis is carried out to investigate the most critical fire scenario and to evaluate the vulnerability of the tower during a realistic fire event. Lastly, an evaluation of a commonly used spray-on thermal insulation and its effectiveness in reducing the member temperature and preserving ultimate strength during a catastrophic wildland fire event are presented. The FE simulations revealed that a 45-degree wind associated with partial side heating leads to a more critical degradation of the overall strength, whereas the effect of fire height is less obvious. In terms of the fire scenario, a longer fire duration associated with a slower wind is more critical for the fire resistance/rating.

Research on differentiated lightning protection application of power lines based on laser point cloud data

Abstract The collection and processing of data in lightning protection assessment of transmission lines takes a long time and accuracy is difficult to ensure. Therefore, a laser point cloud data registration method based on pole and tower material coordinate transformation is proposed for differential lightning protection evaluation of transmission lines. Using DBSCAN algorithm, combined with point cloud data voxel filtering and noise reduction methods, to achieve data segmentation of transmission line tower body. Based on the characteristics of the symmetrical structure of the tower body, the coordinate transformation method is adopted to achieve the registration of multiple point cloud data. The parameters in the tower structure are obtained by concatenating and fusing elements such as the wire point cloud, lightning protection line point cloud, and tower point cloud. After verification by lightning protection assessment, the proposed method simplifies the processing flow of data compliance detection during the assessment process, reduces the time cost of lightning protection assessment, and greatly improves the accuracy and effectiveness of lightning risk assessment results.

Failure intervention of transmission line tower primary legs using bi-angled cruciform retrofitting

Retrofitting has been suggested by researchers as an intervention measure against failure of transmission towers which needs to be done with minimal disruption. Retrofitting of the primary leg members of transmission line towers by bi-angled cruciform arrangement has been shown in literature to be effective. However, the influence of stresses and deformations existing in the leg member prior to retrofitting on the capacity of the final retrofitted member is not known. Therefore, this study assesses the effectiveness of bi-angled cruciform sections under preload conditions through experiment followed by a numerical study. The level of preload in the primary leg member with respect to its theoretical capacity, slenderness ratio and width-thickness ratio of the angle section were the parameters. The results suggest that bi-angled cruciform retrofit is more effective at lower slenderness and width-thickness ratios and the reduction in capacity of retrofitted member is more noticeable till 50 % preload after which the changes are not significant. While the former two parameters lead to lower load share in the retrofitting member, higher preloads however lead to more equal load share. The application of this retrofitting pattern is demonstrated numerically with a full-scale tower model simulated under code specified load cases. Critical load cases leading to tower failure before design loads were identified and the retrofitting was incorporated into the model for these load cases. The analysis showed that the final loads attained in these load cases improved by upto 70 % thus confirming the potential of this retrofitting technique in preventing tower failure.

Correlation between Temperature and the Posture of Transmission Line Towers

Ensuring the safety of transmission line towers is vital for human safety, power supply, economic development, and environmental protection. This study specifically examines how temperature affects tower inclination. Multifractal detrended cross-correlation analysis (MF-DCCA) is a combination of multifractal detrended fluctuation analysis (MF-DFA) and DCCA that reveals the multifractal features of two cross-correlated non-stationary signals. This paper adopts the MF-DCCA tool to investigate the cross-correlations between the internal temperature of an inclination sensor device and the posture of a transmission line tower. The tilt angle data in the x- and y-axes are used to measure the posture of the transmission line tower. We start by using Pearson correlation to assess the relationship between temperature and two inclination angles, followed by verifying their correlation with a p-value below 0.05 using first-order linear fitting. We initially assess the multifractal features of three time series using MF-DFA before MF-DCCA analysis. All exhibit multifractal traits with H(2)<0.5, indicating negative persistence, especially notable in the temperature series. Finally, we adopt the MF-DCCA approach to examine the multifractal cross-correlation between tilt-angle time series and temperature time series, and the results indicate the negative persistence of the cross-correlation between the time series. Furthermore, the multifractal cross-correlation of temperature and inclination data on the y-axis was also found to be stronger than on the x-axis based on features of the scaling exponent and symmetry exponent.

Study on Prediction of Lightning Impulses on Transmission Line Tower Due to Harsh Field and Variable Working Condition, Environmental Condition and Tower Footing Resistances

The current state of transmission system design and development is greatly hampered by over voltages caused by lightning. To mitigate over voltage problems, researchers must be nearly obsessive. Since lightning strikes transmission and distribution network components like lines and substations, personnel are also seriously put in danger. Lightning prediction holds great significance, in addition to Lightning Detection Networks (LDNs) that offer ample information regarding lightning activity. Through the use of a fuzzy forecasting system, we are able to determine the chance of lightning in the low, medium, and high range. The method used to forecast lightning threats is provided by this system.

A Fast and Accurate Mapping Method for an OPGW Tower Based on Hybrid Distributed Optical Fiber Sensing.

The combination of the dark fiber in existing Optical Fiber Composite Overhead Ground Wire (OPGW) with Distributed Optical Fiber Sensing (DOFS) technology can be used to enable online monitoring and provide early warnings of anomalies in high-voltage transmission lines. Accurate mapping of the optical cable length to the geographic coordinates of actual towers is a key factor in achieving this goal. This paper discusses the principle of using a DOFS system for transmission line tower positioning and presents four available positioning features. To overcome the limitations of single physical parameter positioning, this paper presents a self-developed hybrid DOFS that simultaneously captures Rayleigh backscattering and Brillouin scattering signals. Several physical parameters, including temperature, strain, and vibration, are acquired synchronously. Through hybrid multi-parameter analysis, the rapid and accurate positioning of OPGW line towers is achieved. Experimental results have shown that the proposed method, based on the hybrid DOFS system, can locate up to 82 towers, while the traditional method could only identify 12. The hybrid system was able to complete 80% of the tension towers in 40 h. This paper presents a novel multi-parameter localization method that has the potential to significantly improve the efficiency and reliability of grid operation and maintenance.

Comparative study of the foundation model of a 220 kV transmission line tower with different footing steps - Finite element analysis

Comparative study of the foundation model of a 220 kV transmission line tower with different footing steps - Finite element analysis

Monitoring and disaster prevention of high and steep sandstone slopes along highways under construction

High and steep sandstone slopes along highway line are at high risk of disasters such as landslides, cracking of support structures, and so on. The monitoring, early warning, and emergency response of such slope disaster face enormous challenges, especially during the rainy season. In this paper, intelligent monitoring, early warning and forecasting system were carried out for the high steep sandstone slope with a transmission line tower at the slope crest along the highway under construction in Guangxi, China. The automatic monitoring data, emergency rescue program and rescue effect were analyzed, and emergency rescue measures for high steep slope protection were taken. The research results show that timely access to disaster warning information can effectively support the analysis of disaster causes and the evaluation of disposal programs. Deep-hole monitoring of deformation characteristics can determine the stable state of slopes, and the tangent angle warning criterion can be used for early warning and prediction of high steep slope landslides. By analyzing the location of the sliding surface and taking timely emergency disposal measures such as layered counterpressure method and micropipes, the landslide activities can be effectively controlled to prevent further acceleration of slope collapse. This study can provide an important reference for the monitoring, early warning, forecasting and emergency rescue of sandstone slopes along highways under construction.

Simulation of electric potential distribution and assessment of personal safety risks near grounding devices of urban high-voltage transmission line towers

Simulation of electric potential distribution and assessment of personal safety risks near grounding devices of urban high-voltage transmission line towers

Insulation Strength Prediction of Transmission Line–Tower Gaps Using Interelectrode Electric Field Feature Set and Ensemble Learning

Insulation Strength Prediction of Transmission Line–Tower Gaps Using Interelectrode Electric Field Feature Set and Ensemble Learning

Traditional and alternative grounding system's impedance and resistance measurements of a 138 kV transmission line tower

One of the main causes of outages in transmission lines is lightning. To mitigate this occurrence, grounding electrodes are used at the base of the towers that make up the transmission lines. Since lightning is a phenomenon with components of low and relatively high-frequency energy (approximately up to 2 MHz), there is a certain complexity in accurately characterizing grounding systems. The primary parameter used to model a grounding system is the grounding impedance, which can be obtained through measurement. This paper presents measurements conducted on a 138 kV transmission line's traditional and alternative grounding system. The measured traditional grounding system consists of two horizontally buried copper grounding conductors and the alternative system comprises an electrode with four conductors encapsulated in concrete and buried vertically. The measurements were carried out using a 25 kHz earth resistance meter and impulse generators with waveform shapes of 1.2/50 μs, 1/70 μs, and 8/70 μs. Different measurement configurations are employed. The obtained measurements are compared with similar systems found in the literature, and the contributions of the concrete electrode to the grounding system are discussed.

Transmission line tower inclination measurement method based on three-dimensional laser scanning and inter frame difference

Abstract The purpose of this study is to propose a method based on three-dimensional laser scanning and frame difference technology to measure the inclination of transmission line towers, so as to realize accurate monitoring of transmission line structure. Firstly, the multi-scale Retinex algorithm is used to enhance and preprocess the transmission line tower image to improve the image quality. Secondly, the method of frame difference and background difference is combined to detect and identify the inclined tower. Finally, the point cloud data of inclined tower is obtained by using three-dimensional laser scanning technology, and the inclination of transmission line tower is calculated by coordinates. The experimental results show that this method has high accuracy and reliability, with an error of less than 0.15 × 10−5 and an inclination of less than 0.17°. It is proved that this method can improve the monitoring efficiency of transmission lines, has good effects in engineering practice, and can provide effective means for the safe operation of transmission line structures.

A Comparative Study on Lattice Tower Angle Member Capacities as Per Indian, American, and BSEN Standards

The transmission lines and Telecommunication networks are normally supported by lattice towers. Therefore, the reliability of these essentials depends much on the reliability of the towers and their foundations. In Both telecom and power transmission line sectors, the towers are mass-produced and generally based on optimized tower weight and foundation volumes. The weight of a tower is influenced to a great extent by the selection of tower configuration, choice of bracing patterns, choice of steel grade, and profile type. The towers in general are lattice types consisting of main legs, diagonals, horizontals, cross-arm members, and peak members. The telecommunication and power transmission line tower members are generally made of steel equal-angle sections. These tower members are modeled and analyzed as pin-jointed 3-dimensional space truss models and the members are subjected to axial forces, either axial compression or axial tension in nature. Estimation of member compression capacity is the most vital parameter in design as per respective local standards and proving those estimations during full-scale model tower testing if carried out. This paper presents the differences in axial compression capacity of angle members as per Indian, American, and European standards viz., IS: 802 (Part 1/Sec 2)-2016, IS 800-2007, ASCE 10-15 and BS EN 1993-3-1:2006.

Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Analysis and Design of Transmission Tower using Staad-Pro

A transmission tower, also known as an electrical power tower or utility pole, is a tall structure used to support overhead power lines for the transmission of electrical energy. Transmission towers play a critical role in the reliable and efficient transmission of electricity from power generation plants to distribution networks and ultimately to consumers. This abstract provides an overview of transmission towers, including their purpose, types, components, and key considerations in their design and construction. Transmission towers are designed to withstand various environmental and loading conditions, such as wind, ice, and seismic forces while maintaining the integrity and stability of the overhead power lines. Different types of transmission towers, such as lattice towers, tubular towers, and pole towers, are used based on factors such as voltage level, span length, and terrain conditions. Analysis of this transmission tower is administered using STAAD PRO The present work describes the analysis and design of a transmission line tower of 31 meters in height and 220KV double circuit viz. various parameters. The components of a transmission tower typically include tower legs, cross-arms, insulators, and hardware for attaching conductors and ground wires

Testing and Evaluation of Buckling and Tensile Performance of Glass Fiber–Reinforced Polymer Angle Section with Different Joints/Connections

Abstract The aim of this paper is to investigate the crushing and tensile performance of built-up glass fiber–reinforced polymer (GFRP) pultruded angle sections under compression and tension loads. For the compression test, two GFRP angle sections of size 50 × 50 × 6 mm were selected and maintained the e/d ratio of 5. GFRP angle sections were connected by two-bolt, three-bolt, four-bolt, adhesive, hybrid two-bolt, hybrid three-bolt, and hybrid four-bolt connections. For the tension test, single-lap joint and single-bolt connections were considered. The tension test is performed by angle-to-angle connection with an e/d ratio of 5. Also, the joints were connected by single-bolt connection, hybrid single-bolt with local glue, and hybrid single-bolt with epoxy connection. Based on the studies, the best joint and connection were considered, and a transmission line tower with various connections is modeled and proposed using ANSYS.

Research on Transmission Line Tower Tilting and Foundation State Monitoring Technology Based on Multi-Sensor Cooperative Detection and Correction

Research on Transmission Line Tower Tilting and Foundation State Monitoring Technology Based on Multi-Sensor Cooperative Detection and Correction

Research on the linkage technology of electric power operation field video and Beidou high-precision positioning terminal

In order to adapt to the trend of intelligent development in power operation sites and solve practical problems such as inadequate supervision of traditional power operation sites, this article mainly studies the linkage technology between power operation site videos and Beidou high-precision positioning terminals. Based on the application scenarios of the BeiDou positioning system in power operations, this paper summarizes the linkage technology between on-site video and BeiDou high-precision positioning terminals in power operations, and concludes that this technology is suitable for safety control of personnel in power operation sites, inspection and supervision of power lines, monitoring and early warning of inclined and collapsed transmission line towers. Research has found that the linkage technology between on-site video of power operations and Beidou high-precision positioning terminals can promote the intelligent development of power operations and achieve higher precision on-site control of power operations.

Projections of severe weather and the impacts on transmission line towers in Santa Catarina, Brazil, under future scenarios of global climate change

Transmission line towers are highly exposed to weather hazards. In southern Brazil, several damages to transmission lines have been reported due to severe weather events. Climate change projections indicate that the frequency and magnitude of extreme events may increase, making planning and adaptation of the transmission system exposure even more critical. In this work, we propose a severe weather index (SWI) as a proxy for detecting severe storms that can potentially result in extreme weather events. The SWI combines thresholds of instability indices based on observed severe events around the transmission tower-line systems. These indices were calculated using the downscaling by the Eta model at 20 km resolution of three global climate model projections and at 5 km of one global climate model for the historical period and the near future. The results show that the SWI captures the severe storms observed in the region. All downscaling projections agree with the increase of extreme weather events in the near future and the expansion of vulnerable areas. The constructed index can be employed to assess the risks and to plan the power transmission system better.