Ultra High Voltage Transmission Research Articles

Research on the Protection Scheme of a High-Speed Railway Crossing 1000 KV Ultra-High Voltage Transmission Line

The high-speed railway project and the ultra-high-voltage transmission project represent two crucial components of China’s “new infrastructure”. As the construction of these two projects progresses rapidly, it is inevitable that instances of intersections will occur. Extreme conditions may cause damage to ultra-high voltage transmission cables. When a high-speed train passes by an ultra-high voltage transmission line, it poses a serious safety hazard. To address this issue, engineering examples were utilized to examine the protection structure scheme, protection distance, protection load, and construction procedures when a high-speed railway intersects a 1000 KV ultra-high voltage transmission line. A shed structure form and construction method for the electric power protection were proposed to ensure the safe operation of the high-speed railway while also achieving the safe and rapid construction of the high-speed railway protection structure in the safety zone of the approaching 1000 kV ultra-high voltage transmission line. The results indicated that the protection of high-speed railway crossings and 1000 kV ultra-high voltage transmission lines primarily focuses on line-break protection. The concrete shed structure with a straight wall and a flat roof was designed to meet the requirements of high-speed railway crossings. The line-break protection method enables the construction of an automatic warning protection corridor and a complete movable trolley quickly and safely within the safety zone near the transmission line. The implementation effect is, therefore, positive. It can be used as a reference point for other projects of a similar nature.

The resource curse in energy-rich regions: Evidence from China's ultra-high voltage transmission

Coordinating the energy mix transition with environmental protection is essential for reducing climate risks. Long-term fossil fuel exploitation and utilization result in increasing ecological risks in energy-rich regions. While ultra-high voltage (UHV) transmission is considered a key tool for promoting long-distance energy consumption, its ecological impact has received little attention. Using city-level panel data from 2005 to 2019 in China, this study examines the impact of UHV transmission on eco-environmental quality in energy-rich regions. The empirical results show that UHV transmission reduces eco-environmental quality in energy-rich regions. This effect is particularly pronounced in regions with more abundant fossil energy sources, underdeveloped economies, and weak environmental regulations. Mechanism analysis finds that UHV transmission promotes the expansion of power generation in energy-rich regions, followed by lagging industrial structure, weakening eco-environmental governance and intensifying resource exploitation. These findings suggest that increasing the utilization of renewable energy and strengthening environmental regulation are essential for achieving sustainable development in energy-rich regions.

INCREASING THE ACCURACY OF THE POWER LINES MODELING BASED ON PMU

The article discusses the modeling of power lines based on PMU data to assess the state of overhead lines. Current approaches to solving the problem are analyzed. The advantages and disadvantages of these approaches are presented. It has been established that when modeling power lines are traditionally represented in the form of a - circuits scheme, which leads to methodological modeling errors. To reduce the methodological error of modeling, overhead lines (OHLs) can be presented in the form of equations with distributed parameters, which allows for maximum accuracy. However, distributed line equations contain hyperbolic functions and reduce performance in real-time simulations. Based on this, it is noted that the selection of an adequate mathematical model of overhead lines with the appropriate accuracy of synchronized vector measurements in real time when assessing the state of power lines is an important stage of modeling. The article discusses overhead line models using equations with distributed parameters, a -circuits, an equivalent - circuits and chain -circuits depending on the number of links. The results of calculating the mode based on the modeling accuracy using the example of a 500 kV overhead line are presented, as well as the results of comparing various equivalent circuits. It is shown that when modeling overhead line modes based on the results of PMU measurements, representing power lines as chain circuits with links 50 km or less in length is appropriate, since it makes it possible to obtain a model accuracy that is adequate to the PMU measurements. Methodological errors in modeling ultra-high voltage transmission lines using the equations of long lines have been studied. The obtained results can be used for monitoring, analysis and operational management of the electric power system

Simulation Analysis of Corona Pulse Propagation along the Line Based on an Actual Transmission Line

Abstract In the partial discharge test of the shunt reactor of the ultra-high voltage transmission line, the corona discharge caused by high voltage interferes with the test. To further study the propagation rules of the corona pulse on the line side in the transmission line during the ultra-high voltage partial discharge test, based on the parameters of an actual transmission line, the ATP-EMTP electromagnetic simulation software was used for modeling. The propagation rules of corona pulses in the transmission line were analyzed in detail through the simulation model. As the propagation distance increases, different frequency components show different degrees of attenuation. The higher the frequency is, the faster it attenuates.

Research on Influencing Factors and Wind Deflection Warning of Transmission Lines Based on Meteorological Prediction

Transmission lines are affected by external environmental factors such as strong winds and ice cover. In recent years, extreme weather events have increased, leading to recurrent disturbances in transmission lines because of wind deflection. These incidents have resulted in significant financial losses and have disrupted regular industrial and domestic activities. In this paper, the ANSYS Workbench 2020 R2 finite element analysis platform was used to establish a transmission line-hanging insulator string system model. Calculations on transmission lines were conducted considering variations in different stall spacing, height differences, wind speed, and the wind attack angle. The impact of these diverse factors on the wind deflection of insulators was scrutinized, leading to the derivation of patterns describing how the wind deflection angle shifts in response to changes in stall spacing, height differences, wind speed, and the wind attack angle. Based on the generalized linear regression network and particle swarm improved support vector machine algorithm, a meteorological prediction-based early warning method for wind deflection of transmission lines was proposed, a transmission line wind deflection early warning model was established, and the practical effect of the model was evaluated. The outcomes of this study provide crucial data for the formulation and development of ultra-high voltage (UHV) and extra-high voltage (EHV) transmission networks. Furthermore, they can contribute to the advanced detection of wind deflection issues.

Meteorological Characteristics of a Continuous Ice-Covered Event on Ultra-High Voltage Transmission Lines in Yunnan Region in 2021

Yunnan plays a pivotal role in transmitting electricity from west to east within China’s Southern Power Grid. During 7–13 January 2021, a large-scale continuous ice-covering event of ultra-high voltage (UHV) transmission lines occurred in the Qujing area of eastern Yunnan Province. Based on ERA5 reanalysis data and meteorological observation data of UHV transmission line icing in China’s Southern Power Grid, the synoptic causes of the icing are comprehensively analyzed from various perspectives, including weather situations, vertical stratification of temperature and humidity, local meteorological elements, and atmospheric circulation indices. The results indicate a strong East Asian trough and a blocking high directing northern airflow southward ahead of the ridge. Cold air enters the Qujing area and combines with warm and moist air from the subtropical high pressure of 50–110° E. As warm and cold air masses form a quasi-stationary front over the northern mountainous area of Qujing due to topographic uplift, the mechanism of “supercooling and warm rain” caused by the “warm–cold” temperature profile structure leads to freezing rain events. Large-scale circulation indices in the Siberian High, East Asian Trough, and 50–110° E Subtropical High regions provided clear precursor signals within 0–2 days before the icing events.

Research on resistance detection robot for UHV tension insulator string

Insulator inspection robots can realize automatic and rapid inspection of insulators of ultra-high voltage transmission lines, which is an important guarantee equipment for the continuous safe operation of the national power grid. Aiming at the needs of ultra-high voltage insulator string inspection, an insulator robot is designed to realize efficient and stable insulator string motion and insulator detection, and the main work includes proposing a new insulator string motion robot configuration and realizing its string motion and inspection functions in the form of a physical prototype. It has been proved that the robot has a large motion load and strong motion performance, and can be adapted to the complex working conditions consisting of a variety of insulators within a certain size range.

Startup control strategies for pre-fabricated synchronous condensers using static frequency converters

In ultra-high voltage transmission systems, a considerable number of dynamic reactive power compensation devices must be equipped. Synchronous condensers are capable of providing substantial amounts of dynamic reactive power. Therefore, distributed prefabricated synchronous condensers can be deployed in ultra-high voltage transmission systems to supply reactive power support to the power grid. The start-up of synchronous condensers can only be achieved through external means. Currently, there are multiple start-up methods available for small-capacity prefabricated synchronous condensers. With the rapid advancements in frequency conversion technology and power electronics, static frequency converters (SFCs) can be utilized to initiate synchronous condensers. This paper investigates the principles of SFC start-up and coordinated control while also configuring protective devices for SFCs based on their structural characteristics and operational principles. A validation platform consisting of one SFC starting two synchronous condensers was established to analyze their start-up time, yielding results demonstrating the ability of SFC-driven distributed small-capacity synchronous condensers to rapidly adjust the power quality of the power grid.

Nonlinear Performance of Steel Tube Tower in Ultra-High Voltage Transmission Lines under Wind Loads

As complex, statically indeterminate structures, transmission towers are subject to complex forces and are usually simplified into truss structures that only consider the effects of axial force. When the load and deformation of a tower are small, it is reasonable to carry out analysis according to the linear elasticity theory. However, the height of an ultra-high voltage (UHV) transmission tower is significantly large, meaning that the calculation result according to the current elastic analysis method often has a large deviation from the actual stress of the structure. With the influence of the bending moment at the end of the member, a numerical model is established considering the influence of geometric nonlinearity and material nonlinearity in this paper. The stress distribution characteristics and development law of UHV transmission towers in linear and nonlinear stress states are analyzed and studied. The real tower test and elastoplastic ultimate bearing capacity analysis show that the elastoplastic analysis is closer to the actual tower. The UHV steel pipe tower designed according to the linear elasticity and small deformation theory has a large safety margin under the design load, resulting in a significant waste of materials. Under the action of heavy load, the tower exhibits strong nonlinearity, and the influence of geometric and material nonlinear factors should be fully considered when designing the structural components in UHV transmission towers.

Development of Corona Prevention Coatings for 750kV Substation in Operation

A single acrylic resin has poor conductivity and toughness, but strong hydrophilicity, which limits its application in high-voltage transmission corona prevention. In response to this issue, this article investigates the preparation of four types of acrylic composite conductive coatings with different additions of carbon fiber powder, multi-walled carbon nanotubes, and nano titanium dioxide. Through experimental testing, compare and analyze the effects of various fillers on the mechanical properties, conductivity, hydrophobicity, and heat resistance of acrylic composite conductive coatings. The experimental results show that the acrylic conductive coating prepared with thermoplastic acrylic resin as the matrix, carbon fiber powder and multi-walled carbon nanotubes as conductive fillers, and nano titanium dioxide as a self-cleaning agent has excellent performance characteristics in all aspects, and is suitable for corona prevention in ultra-high voltage transmission. This acrylic composite coating can be used to repair burrs and scratches on the surface of transmission lines, fill gaps in stranded wires, and achieve the goal of reducing the local electric field of high-voltage transmission lines to prevent wire corona.

Influence of Ultra-High-Voltage hybrid reactive power compensation on interruption performance of circuit breakers under different faults

For extremely large ultra-high-voltage (UHV) power transmission and distribution lines with typical project using hybrid reactive power compensation (HRPC), single-phase earth fault (1LG), three-phase ground fault (3LG), phase-to-phase fault (2LS), and two-phase grounding fault (2LG) often occurs. Circuit breaker is one of the most critical equipment of UHV transmission system. And the interruption performance is crucial to circuit breakers’ breaking capability. In this study, formal expressions of the indicators for the interruption performance of the circuit breaker are deduced in case of different faults based on the equivalent-valued parameter circuit based on the structure a UHV demonstration project. The simulations are used to validate the accuracy of formal expressions. Then, the influence of such factors as the location of the fault and the degree of HRPC on the interruption performance of the 1LG, 2LG, 3LG, and 2LS is analyzed. Finally, the interruption performance of circuit breakers under different faults are compared. A quantitative evaluation of the influence of changes in the relevant indicators on the interruption performance of circuit breakers can provide a technical basis for choosing the appropriate design of the circuit breaker in light of the application as well as equipment development and assessment.© 2017 Elsevier Inc. All rights reserved.

Detection of decomposed gases in SF6 surge arrester contaminated conditions in ultra-high voltage transmission lines based on Ta-doped defective h-BN nanosheet: A DFT study

SF6 surge arrester on ultra-high voltage transmission lines plays a critical role in the entire power transmission system. They not only protect electrical equipment from the dangers of high transient over voltages, but also bear the responsibility of maintaining the safety and stability of the transmission lines. Detecting the decomposed gases under polluted conditions inside SF6 surge arresters is of paramount importance. In this paper, based on extensive investigations and the application of density functional theory and 2D materials, we conducted a study on the detection of decomposed gases (HF, H2S, SOF2) in SF6 surge arresters for ultra-high voltage transmission lines under polluted conditions using Ta-doped defective h-BN nanosheets gas sensor. Revealing the adsorption and sensing mechanisms of these target gases on h-BN sensors through band structure, density of states, projected density of states, and differential charge density analysis. The results showed that Ta metal particle modification significantly improves the electronic activity of defective h-BN, substantially reducing the band gap values from 4.560 eV to 0.153 eV and 0.912 eV in the B atom and N atom defective oping systems. Meanwhile, Ta-doped defective h-BN exhibits strong selectivity and sensitivity to three decomposition components, with the adsorption capability ranking as SOF2 > H2S > HF, all of which are physical chemisorption types. Furthermore, in terms of various adsorption parameters, defective h-BN’s adsorption ability far surpasses other materials, offering broad prospects for practical applications. The results of this work contribute to the development and application of Ta-doped defective h-BN sensors for the detection of decomposed gases inside SF6 surge arresters under polluted conditions.

Including Shield Wires in the Analysis of Transient Processes Occurring in HVAC Transmission Lines

The article presents an analysis of electromagnetic transient processes in long ultra-high voltage transmission lines, taking into account shield wires. It was shown that EMTP and Matlab/Simulink software are currently widely used in the study of transient processes in power lines. The EMTP software package uses the finite element method when integrating the equation that mathematically models the distributed parameter transmission line. The Matlab/Simulink software uses the d’Alembert method. In both cases, it is not known how the boundary conditions for the partial differential equation that mathematically models the transmission line are determined. The power line is analyzed as a distributed parameter system, described by a second-order partial differential equation. The advantage of the proposed method of calculating the boundary conditions for the abovementioned equation is the use of boundary conditions of the second and third types of Neumann and Poincaré, which allowed us to take into account the mutual influence of shield wires and phase conductors of the line in one power system. On this basis, the methodology for obtaining time domain graphs, spatial distributions, and traveling wave distributions of voltages and currents for phase conductors and line shielding wires is presented. The results of a computer simulation of transient processes when switching on the power line, taking into account controlled phase commutation and under single-phase earth fault conditions, are presented. All calculation results of transient processes presented in the article were obtained exclusively using numerical methods.

Can inter-provincial transmission reduce regional carbon emissions? Evidence from China

Plagued by worsening pollution in load centers along the eastern coastal regions such as Beijing-Tianjin -Hebei, China is reducing local coal-fired power plants in those regions and relying more on inter-regional power transmission. In recent years, China has accelerated the construction of the West-East Electricity Transmission Project and planned and constructed a number of Ultra-high Voltage (UHV) transmission lines. However, how the impact of inter-regional transmission on carbon emissions needs empirical verification. This paper aims to study the carbon emission reduction effect of inter-regional transmission under nested models of the spatial econometric model for panel data. The empirical results show that although the non-dynamic spatial econometric analysis can find the carbon emission reduction effect of inter-provincial transmission, the long-term effect obtained by the dynamic spatial econometric analysis indicates that the inter-provincial transmission can bring about a slight increase in carbon emissions. The inter-provincial power transmission needs to be supported by sustainable share growth of renewable energy to achieve the targeted mitigation of carbon emissions.

Enhanced semi-automated Bayesian modal identification approach for Ultra-high voltage transmission towers

The accuracy and efficiency of the modal identification for Ultra-high voltage (UHV) transmission towers under harsh operational environments is seriously affected by environmental noises. In general, the initial natural frequency drowned in the noises is evaluated by the experience of engineers before performing a Bayesian modal identification approach. It will lead to potential errors and limitations to the application of the Bayesian modal identification approach. In this study, a coherent clustering enhanced semi-automated Bayesian modal identification method is proposed and then implemented in the operational modal analysis of an instrumented UHV transmission tower under ambient excitation. The coherent clustering is adopted to obtain the quantitative value of the initial natural frequency, in place of the empirical evaluation. Then, the Fast Bayesian Fast Fourier Transform (FBFFT) method could accurately identify the most probable values (MPV) and the corresponding posterior uncertainty of modal parameters. Moreover, the first ten modes of the UHV transmission tower are identified, and the results of modal parameters are compared to the stochastic subspace identification (SSI) method. The results show that the coherent clustering enhanced semi-automated Bayesian method could accurately identify modal parameters with posterior uncertainty, even for modes weakly excited. The proposed method could provide a reliable basis for the modal updating, damage detection, and dynamic reliability assessment of UHV transmission towers.

Effect of Traveling Waves on Seismic Behavior of Fault-Crossing Transmission Tower-Line Systems

Ultra high voltage (UHV) transmission tower-lines systems (TTLSs) are responsible for the crucial function of transmitting and distributing electrical power over long distances, which inevitably traverse active tectonic faults when passing through seismic areas. This paper investigates the seismic behaviors of the fault-crossing UHV TTLSs, taking into account the traveling wave effects of fault-crossing ground motions. Furthermore, three scenarios (i.e. the fault located at the midspan, the side span, and the one side) according to the location of the faults relative to the TTLSs, are designated to investigate the effects of fault-crossing locations on the seismic behaviors of the fault-crossing TTLSs. The results indicate that the traveling wave effects may amplify or weaken the seismic responses and collapse of the near-fault and fault-crossing TTLSs, and the effects on the longitudinal displacement responses of the TTLS are significantly greater than those in the transverse direction, but they do not affect the distribution of the collapse weak position of the TTLSs across the fault. Besides, the effect of traveling waves on the seismic behaviors of the transmission tower further away from the fault is greater than that relatively closer to the fault. This study of the impact of the traveling wave effects and fault-crossing locations on the TTLSs serves as a valuable reference for seismic behaviors of the UHV TTLSs crossing faults.

Study on the Effect of Anti-galloping Device with Cubic Stiffness and Particle Damping

The galloping of iced conductors is a common disaster of overhead conductors. Most traditional anti-galloping devices lack a nonlinear dynamic vibration absorber; hence, they have a limited anti-galloping effect. In this study, we designed, optimized, and tested an electric power fitting and an anti-galloping device with cubic stiffness and particle damping for ultra-high-voltage (UHV) transmission lines. We built a nonlinear dynamic model of the coupling galloping system comprising split conductors and anti-galloping devices. The harmonic balance method obtained the steady-state analytical solutions and corresponding averaged equations. The test spans in the laboratory were used to design the test program and equipment. We verified the accuracy of the nonlinear dynamic model and the harvesting effect of the anti-galloping device with cubic stiffness and particle damping. The theoretical and experimental results were highly consistent, and in the range of (0, 2] Hz, the anti-galloping device reduced the galloping amplitude. Therefore, cubic stiffness and particle damping can effectively improve the anti-galloping ability of UHV transmission lines, prolonging their service period.

Effects of Common In-Service Defects of Different Insulators on Radio Frequency Interference Emission from 765 kV Insulators String

Worldwide utilities are preferring Ultra-High Voltage (UHV) transmission lines for transmitting electric power from generating stations to load centres. This long-distance UHV transmission line uses porcelain, glass and composite insulators. Fault-free operation of these insulators is vital to provide reliable service to consumers. Any defects on these insulators may lead to outages and affect the reliability of the supply system. To ensure reliability, utilities are continuously monitoring the condition of transmission line insulators. Nowadays in addition to providing reliable and quality power to the consumers, the utilities are keen on measuring and reducing The Radio Frequency Interference (RFI) from transmission lines. Under normal operating conditions, the RFI of the insulator string may be less than the specified limit. However, evolving inservice defects and deposition of pollutants on the surface of the insulator may increase the RFI level, sometimes it may exceed the specified limit also. This higher emission may affect the operation of nearby other electronic equipment. In this present work, an attempt is made to measure and compare RFI from healthy and defective 765 kV single I suspension string in the shielded indoor laboratory. It was observed that defects and pollutants deposited on insulators have induced corona/spark or gap discharges at the operating voltage level, which in turn increases the intensity of RFI.

Fragility analysis of an ultra high voltage transmission tower in saline soil subjected to wind loads

The wind resistance of transmission towers is not only affected by wind load, but also by service environment. This study uses the world’s second Ultra High Voltage Direct Current transmission project – Xinjiang ±800 kV Tianzhong Line UHV DC transmission project – to develop a fragility analysis method for transmission towers in saline soil under wind loads to investigate the change of wind loads fragility of transmission towers in long-term service in the saline soil environment. It develops a tower-line-foundation (3 T-2L-F) system model considering soil-structure interaction. In addition, this research addresses the durability damage of the transmission tower using field investigation data and material degradation models and analyzes the influence of various durability damage components on the natural vibration mode of the basic of 3 T-2L-F model. Finally, it builds the structure-wind samples utilizing a Latin hypercube sampling method and explores the time histories analysis, the pushover analyses, and the time-varying fragility analyses considering the uncertainty of materials and wind loads. The findings indicate that the 3 T-2L-F model accurately simulates the actual situation of the transmission tower. The fragility of a transmission tower subjected to wind loads is proportional to the degree of material damage and the strength of wind loads.

The impact of ultra-high voltage projects on carbon emissions in China.

The inter-regional ultra-high voltage (UHV) projects are crucial for power systems. Carbon emissions associated with the power sector cannot be ignored. In this paper, based on the panel data of 198 prefecture-level cities in China from 2009 to 2019, a multi-period difference-in-difference model is developed for the first time to examine the impact of UHV projects on carbon emissions. Empirical results show that UHV projects increase overall carbon emissions. This impact can also be achieved through the mechanisms of the scale of power generation and the level of economic development. Heterogeneity research demonstrates that the carbon emissions issue of UHV projects is more significant in cities with low levels of economic development and a large proportion of secondary industries. Extensibility research shows that UHV projects have a more significant impact on carbon emissions in power-sending cities than that in power-receiving cities. The more clean power the UHV transmission lines transmit, the less impact on carbon emissions. This study not only enhances our understanding about the impact of UHV projects on carbon emissions, but also provides inspiration for the low-carbon pathway transition.