kV Overhead Power Lines Research Articles

Numerical Analysis and Health Implications of Electric Fields from High Voltage Overhead Transmission Lines for Safety and Design Optimization

This paper calculates and analyses electric fields generated by high-voltage overhead power transmission lines. These fields have significant implications for safety and design considerations. The study utilises a numerical technique to determine the electric field distribution in regions containing multiple charges. Based on this method, a computer program is developed to calculate the electric field profile at ground level and two meters above ground level for both 400 kV overhead power lines. The results demonstrate the method's effectiveness in accurately computing the electric field intensity for various line configurations, making it applicable to any power line design. The paper also highlights the potential health effects associated with exposure to these electric fields, including leukaemia, breast cancer, cognitive impairments, and reproductive consequences. The proposed method can also be applied to other transmission lines, providing valuable insights into health considerations. The accuracy of the computation methods is validated using the finite element analysis method. This research contributes to the understanding and assessing ground-level electric fields, offering industry professionals and researchers valuable insights into the safety and design of power transmission systems.

Protection of workers against the magnetic field of 330-750 kV overhead power lines when performing work without removing the voltage under load

Protection of workers against the magnetic field of 330-750 kV overhead power lines when performing work without removing the voltage under load

Assessment of Additional Active Power Losses in 110 kV Overhead Power Lines in Non-Sinusoidal Operation Modes

Assessment of Additional Active Power Losses in 110 kV Overhead Power Lines in Non-Sinusoidal Operation Modes

Additional Power Losses Under Non-Sinusoidal Conditions in a 22 kV Overhead Power Line

Non-sinusoidal conditions in the electrical networks cause active power losses at the fundamental frequency, corresponding to the first harmonic, and at harmonic frequencies, which are a multiple of the fundamental frequency. Non-sinusoidal currents flow through network components and create additional active power losses. One of the non-sinusoidal current sources is electronic equipment used in industrial plants to control process equipment. In Vietnam, coal mines use frequency-controlled induction motors when processing coal. The induction motors consume non-sinusoidal current, which creates additional active power losses in the supply network. The harmonic active power does not perform useful work. It causes economic damage to both the supply network and industrial enterprises. The power supply systems in industrial areas of Vietnam, where coal is mined, are characterized by low power quality. Companies engaged in coal mining and processing are forced to pay for additional losses of active power due to the low power quality under non-sinusoidal conditions, which reduces the economic efficiency of the companies' operations. The paper presents a review of the literature on the assessment of additional active power losses in overhead power lines at harmonic frequencies. An example of calculating additional losses of harmonic active power is given for a 22 kV overhead power line, through which electrical energy is supplied to the coal grading plant of the Kua Ong-Vinacomin company. Additional losses are calculated using the measurements of harmonic voltage and current at the point of the supply network connection to the 22 kV overhead power line, through which electrical energy is supplied to the coal mine and the coal grading plant. To assess the influence of the electrical equipment of the coal grading plant on the power quality in the supply network, measurements were carried out on 0.4 kV buses of electrical substation of the coal mine.

Study of the influence of the parameters of modern grounding wires on the value of power losses in them for overhead power lines of 330-750 kV

Introduction. The problem of estimating power losses in grounding wires with built-in fiber optic cable for overhead power lines of voltage class 330-750 kV is relevant, while it is obvious that the amount of losses depends on the chosen brand of wire. Problem. In the article, an analysis of the influence of the parameters of grounding wires on the amount of losses that occur in them in the normal mode of operation of the overhead power lines is carried out. Goal. The purpose of the work is to determine the criterion for the selection of grounding wires with a built-in optical fiber cable under the condition of increasing the energy efficiency of electricity transmission. Methodology. To calculate power losses in grounding wires, the methods of electromagnetic field theory were used, while taking into account the location of phase conductors on various types of towers of operating 330-750 kV overhead power lines and the possible current load of such lines. Results. The paper analyzed the dependence of losses in the grounding wires of the overhead power lines on the ratio of its active and reactive resistances, determined in which range of this ratio the losses will be close to the maximum. It is shown that the amount of specific power losses in the grounding wires of 330-750 kV overhead power lines in its normal operating modes can range from 1.6 kW/km for the 750 kV lines to hundreds of W/km for the 330 kV power lines. Originality. For the first time, it is recommended to use grounding wires with built-in fiber optic cable with running active resistance in the range of no more than 0.25 Ohm/km, which will minimize power losses and increase the energy efficiency of the 330-750 kV overhead power lines. Practical value. The obtained results can be applied at the stage of designing new or modernizing existing overhead power lines in order to reduce losses and increase the energy efficiency of lines.

Исследование влияния переходного сопротивления на дистанционное определение места повреждения на основе одностороннего метода

Fault location on 110–220 kV overhead power lines is one of the main functions of modern relay protection devices. Currently, the actual errors of fault location based on emergency mode (EM) parameters in most cases are about 5 %. However, there are cases when they exceed 10–20 %. One-sided fault location based on EM parameters and improvement of its accuracy are important issues to study since there isn’t a communication channel on power lines for the transmission of emergency information everywhere. The main parameter that has a significant impact on the accuracy of fault location method is the transient resistance. The aim of the research is to study the effect of transient resistance on the one-sided fault location method based on EM parameters proposed by A.E. Arzhannikov. In the course of the study, the following tasks are set: assessment of the effect of transient resistance on the accuracy of the specified fault location method; determination of the polarizing value for fault location, which ensures greater accuracy of the method, including the presence of transient resistance at the place of a short circuit; defining a criterion to recognize the type of short circuit that does not depend on the transient resistance; development of a method to determine the value of the transient resistance at the fault location. To study and evaluate the errors of distance fault location based on EM parameters, a series of calculations of short circuit currents has been made for various transient resistances at the fault location and at various distances of the fault. The calculation of currents and data processing has been carried out in the ARM SRZA software package. A single overhead line with a voltage of 110 kV with a two-sided supply and a length of 70 km is chosen as the object under study. To perform the research, the primary converters are taken as ideal. The authors have obtained the estimation of the errors of the one-sided fault location method. It is proposed to use the zero-sequence current as a polarizing quantity in the indicated fault location method, which provides greater accuracy than the use of the negative sequence current. To ensure the stable operation of one-sided fault location based on EM parameters, especially in case of short circuit with significant transient resistances, the use of methods that are insensitive to transient resistances is justified. A parameter to identify the type of short circuit is proposed, the coefficient of the image Kobr. Its values are determined for each type of short circuit, a small dependence on transient resistances is found. A calculation substantiation is given for the value of the identification coefficient of two-phase faults (Phase-to-Phase and Phases-to-Earth) according to the ratio of negative and zero sequence currents. The authors have estimated the transient resistance at the fault site by the ratio of symmetrical components for the simulated power transmission line. The results of the study can be used to improve the existing methods of fault location based on EM parameters, namely: to improve their accuracy considering the transient resistance at the fault site; to improve their accuracy using a suitable polarizing value; to determine the type of short circuit more accurately by using the proposed identification parameter.

Имитационное моделирование воздушных линий электропередачи напряжением 610 кВ для исследования алгоритмов определения места возникновения однофазных замыканий на землю

As part of evolution of single phase to earth faults protection methods and tools in 6–10 kV networks the development of simulation study methods of these networks and their components becomes relevant. A significant direction in this area is upgrading of sensors installed directly on the wires and electrical transmission towers. These sensors are installed in the conditions of an electromagnetic field acting on them and dynamically changes both in time and space, especially during emergency modes including single phase to earth faults. Application of modern software offers a challenge for complex simulation study of electromagnetic fields distribution at the location of the measuring transducers in continuously variable electromagnetic environment. The above-noted statement determines the relevance of the research goal, which is the development of a simulation study method of 6–10 kV overhead power lines, the model of which is designed to study existing and create new single phase to earth fault location algorithms and devices. To solve the tasks set the methods of simulation study of overhead transmission lines and corresponding medium voltage networks in PSCAD and COMSOL Multiphysics software have been used. The general concept of design of a 6–10 kV network and an overhead transmission line simulation model is formulated. The geometrical parameters of the section of the model of an overhead power transmission line to simulate electromagnetic transients are selected, considering the frequency dependence of the line parameters (inductance and active resistance). The proposed model of the overhead transmission line is verified, and recommendations for its application are given. The developed “inductive” component of the proposed overhead transmission line model allows to provide high accuracy of calculation of transient components of currents and voltages during single phase to earth faults. It makes possible to use this model for the development and research of single phase to earth fault location algorithms. The developed approach to simulation study of an overhead transmission line is the field of interest for further research, as it makes it possible to calculate the components of the electric field which are observed during single phase to earth faults.

A Comprehensive Review on Distributed Feeder Protection Problems in the Gaza Strip 22/0.4 kV Overhead Power Distribution System – A Case Study

This paper provides a perspective on protective system at 22kV overhead feeders in Gaza distribution network using symmetrical components method and ETAP software. Electrical disturbances from high rate of outage feeders at the 22 kV overhead power lines frequently cause disruptions on the generating plant and customer loads. One sub-transmission feeder from a parallel set of ten 22 KV feeders (140 MW) in the Gaza west substation is selected as a case study in this research. Because the protection system lacks a data fault recorder (DFR), the paper calculates the fault currents at both the nearest substation bus and the last bus in the distributed feeder using the symmetrical components method and verifies the results by using ETAP software simulation. The results from calculating the minimum fault at the last bus indicated that the current protective parameters are reasonable and satisfied for detecting and interrupting the occurring faults. This author paper proposes increasing the fault clearing time at farthest feeder bus to make protective functions less sensitive by adjusting TMS to 0.08 for time overcurrent and earth fault and setting pickup level to 3.8 for instantaneously overcurrent. The design model is run on the selected feeder, and simulation results guarantee the proposed model's accurate performance for both overcurrent and earth faults after changing the fault clearing time. There will be no miscoordination of protective devices or operational risks while running the design model for the selected feeder with new settings. Gaza's distribution feeder network requires structural improvements to become more reliable and to reduce the high rate of feeder trip, and practical recommendations to improve current installation distribution grid are included in this paper.

ELECTRICITY TRANSMISSION AND ENVIRONMENT: EFFECT OF WIND LOADS ON LIGHTNING SHIELDING PERFORMANCE OF OVERHEAD POWER LINES

In this paper the estimation of wind load effect on the lightning shielding performance of overhead power lines was performed. According to electro-geometrical model any phase conductor has horizontal exposure width where this conductor is not protected against lightning by the overhead ground wire. A typical double circuit 220 kV lattice power transmission line tower was considered. Obtained results demonstrate that in the presence of thundercloud in windy conditions unprotected distance of phase conductor may increase due to deflections of phase conductors. Geometric locations of the conductor attachment points on the suspension insulator string and the lower point of the conductor sagging were calculated in the range of wind pressure from 0 to 800 Pa. This allowed to determine the exposure width values of a 220 kV overhead power line upper phase conductor in the same range of wind pressure values. The results show that for a minimum lightning current of 3 kA, the unprotected distance increases by 4.323 times from 4.167 m to 18.013 m when the wind pressure increases from 0 to 800 Pa (from 0 to 36.140 m/s). For a minimum lightning current of 5 kA, the unprotected distance increases by 7.735 times from 2.825 m to 21.851 m when wind pressure and wind speed vary in the same range. Although the transmission line is reliably protected against lightning strikes with currents greater than 16 kA at wind pressure of up to 200 Pa (18.070 m/s), when the wind pressure increases from 300 Pa to 800 Pa (from 22.131 m/s to 36.140 m/s), the unprotected area increases from 4.752 m to 26.204 m. In Summary, the results show that the influence of wind load must be taken into account in the tasks of calculating lightning protection of overhead power lines. Further efforts should be focused on studying the lightning shielding performance of overhead power lines of higher voltage classes.

OVERVIEW OF FACTORS AFFECTING THE ESTIMATION OF LIGHTNING SHIELDING PERFORMANCE OF OVERHEAD TRANSMISSION LINES

This paper examines the risk of lightning stroke to overhead transmission line. The estimation procedure for the lightning performance of overhead power lines is based on the selected lightning attachment model, available lightning parameter statistics, the transmission tower design and voltage levels, type of overvoltage and other characteristics. In this paper the overview of factors affecting the estimation of lightning shielding performance of overhead transmission lines was performed. Among the factors that can affect the estimation accuracy, one can list insufficiently accurate data on the ground flash density in the area of interest and lack of complete data on statistical distribution of lightning current magnitudes. The paper shows that the influence of wind on the increase in the horizontal exposed distance of the phase conductor is not also taken into account. In this research traditional electro-geometric model was used for estimation of lightning performance of 220 kV overhead power line. Results obtained suggest that swing of suspension insulator strings caused by strong winds may lead to increased risk of lightning shielding failure during thunderstorm. Calculation performed for 3 kA lightning current magnitude shows that at swing angle equal to –1 degree, the horizontal unprotected distance of phase conductor increases by 3.1%, that corresponds to 5.240 m uncovered width. When the swing angle is increased to –5 degree, the uncovered width is increased by 15.8% that corresponds to 5.885 m uncovered width. It is proposed that an increase in the risk of lightning shielding failure as a result of wind load can be accounted by applying an appropriate correction factor in expressions for calculation of shielding failure rate, shielding failure flashover rate, etc. Proposed correction factor should account frequency and strength of wind in the area of transmission line route and depend on transmission line voltage level and tower design. Further efforts should be focused on obtaining and justifying the numerical values ​​of this correction factor.

EMPIRICAL STUDIES OF EMERGENCY MODE PARAMETERS AND THEIR INTERACTION IN DETERMINING THE FAULT LOCATION IN NETWORKS WITH AN ISOLATED NEUTRAL VOLTAGE OF 6(10) - 35 KV

"This article considers experimental confirmation of quantitative characteristics of factors influencing the determination of the distance to the fault location in networks with an isolated neutral voltage of 6(10)-35 kV. Experiments were carried out on a 35 kV overhead power line, the selection of optimality criteria was provided, a mathematical model, an experimental plan, a method for analyzing measurement data to damage detection devices were developed, response surfaces were constructed in the Mathcad 14 program in the Pro/ENGINEER package. According to the results of the experiment on the parameters of the emergency mode, it was found out that the largest influencing factor is the value of the transient resistance at the point of wire breakage of a non-metallic earth fault. It is proved that with a transient resistance above the value of 50 ohms, the distance to the damage site is almost impossible to determine with remote devices that register the parameters of the emergency mode. Recommendations for the development of a mathematical model with the production of logical operations on fuzzy sets of an adaptive neuro-fuzzy system are formulated. It is proposed to apply the mathematical model developed in the future as a basis for designing the element base of the device for determining the location of damage, working on the principle of artificial intelligence with an adaptive nature of measurements under changing external conditions. Key words: experiment, single-phase ground fault, fault location, overhead power line, isolated neutral, contact resistance, network isolation. "

Operation Recommendations for Tension Joints and Clamps on a 63 kV Overhead Transmission Line Conductor Based on Experimental Tests

This study provides the operation recommendations for the tension fittings used on a 63 kV overhead transmission line conductor based on experimental tests. In this way, the tension fittings, including the dead-end clamp, the mid-span joint, and the repair sleeve, are assembled on the lynx conductor under different faulty and healthy assembly conditions in the laboratory. The lynx conductor is one of the widely used conductors in the 63 kV overhead power lines. The electric current injection test, along with thermal imaging and also tensile test, are conducted on the studied samples. The results show that the surface temperature of the lynx conductor is higher than the surface temperatures of the dead-end clamp and mid-span joint under normal and overload current conditions. Also, the crimping pressure of the aluminum and steel pipes less than the standard value, the crimping length of the steel cores of conductor less than the standard value, and the crimping length of the aluminum pipes more than the standard value can lead to a developmental defect which should be repaired or replaced at the first opportunity of the transmission line service outage. The repair sleeve is under more thermal stress than the dead-end clamp and mid-span joint, even in the standard assembly condition. A slight temperature difference of a repair sleeve compared with the same type fitting may be a severe operating condition. Also, the use of two consecutive repair sleeves to cover the conductor cut strands is not recommended. Furthermore, the loose connection of bolts at the junction of the jumper terminal to the dead-end clamp causes a very high temperature which should be repaired immediately. If the temperature difference between two defective and healthy dead-end clamp or mid-span joint is more than 13 °C, a critical defect is diagnosed; however, the temperature difference between two repair sleeve more than 7 °C indicates a critical operation condition for defective one.

Определение современных показателей надежности воздушных линий электропередачи 0,4-110 кВ

Reliability indicators for 0.4-110 kV overhead transmission lines need to be adjusted due to the lack of data on current values of reliability indicators for power system equipment. The authors’ analysis of offi cial statistical data on the number of emergency and scheduled outages in the branches of PJSC “Rosseti Tsentr” and “Rosseti Tsentr i Privolzhye” revealed deviations of the reliability indicators of electrical equipment of power systems and power grids from those presented in RD34.20.574. Also, the analysis showed that the standard presented no values of average downtime for planned outages of 0.4 kV and 6-10 kV overhead power lines. Reliability values of 0.4-110 kV overhead power lines were determined. Failure rate of 0.4 kV overhead lines made 6.2 to 7.04 year-1/100·km, of 6-10 kV overhead lines - 5.27 to 8 year-1/100·km. The “Orelenergo” branch, a failure fl ow of 35 kV overhead lines was 0.57 year-1/100·km, and 110 kV overhead lines - 2.83 year-1/100·km. The calculated value of the average restoration time for 0.4 kV networks was 1.88 h; for 6-10 kV networks - 3.1 h; 35 kV - 6.8 h; 110 kV - 9.5 h. The estimated average number of intentional outages for 0.4 kV networks was 0.1 year-1; for 6-10 kV networks 0.72 year-1; for 35 kV networks 0.4 year-1; for 110 kV networks 0.51 year-1. The average idle time of 0.4 kV overhead lines and 6-10 kV overhead lines amounted to 13.6 hours and 10 hours, respectively. The calculated average downtime of 35 kV overhead lines and 110 kV overhead lines amounted to 24.7 hours and 37.6 hours, respectively. The received data specify modern reliability values of electric 0.4-110 kV networks that can be used when planning measures on developing networks and reconstructing them.

Актуальные проблемы сохранения балобана в республике Казахстан

Актуальные проблемы сохранения балобана в республике Казахстан

Низкая эффективность «холостых» изоляторов, применяемых для защиты птиц на воздушных линиях электропередачи

The results of a special research carried out in the arid zone in the territory of the Republic of Kalmykia (Russia) demonstrate the low efficiency of “blank” insulators installed earlier on 6–10 kV overhead power lines (OPLs) as bird protection devices (BPDs). The materials of inspection of territories with different types of 6–10 kV power lines, not equipped with “blank” insulators and any types of BPDs, were used for a comparative analysis. It was found that on average that 1.62 dead birds (of all species) are encountered per one kilometer of 6–10 kV power lines equipped with “blank” insulators. For territories of similar power lines not equipped with additional insulators, the average frequency of encounters is 1.77 dead birds per one km of power lines. Thus, the use of “blank” insulators shows insignificant reduction of bird hazard – on average by 8% compared to the control, and cannotbe characterized as a measure sufficient to ensure the safety of wildlife during the operation of overhead power lines. Research shows that there are numerous cases in which the installation of “blank” insulators and their subsequent operation leads to the opposite effect – bird hazard of 6–10 kV overhead power lines equipped in this way increases.

Modeling and Simulation of High Voltage Power Lines under Transient and Persistent Faults

The work proposes an original method for modeling and simulating the triggering of 110 kV interconnection power lines in case of common faults, such as transient or persistent faults. Urban and industrial areas, surrounding urban areas, require a high energy consumption that is being supplied through 110 kV overhead power lines, responsible for distributing power to the industrial and domestic consumers. High voltage distribution power lines are most prone to failure, due to their exposure, affecting a large number of consumers if a fault occurs. Faults of power lines in service certify that currently there is no perfectly controllable operation mode in terms of load rating, environmental factors, insulation resistance, or mechanical resistance, which would allow total avoidance of faults, it is only possible to reduce the impact they have on the network as a whole. Mathematical models have been developed to determine the experimental voltage and current responses describing the fault propagation, expressed as a 7th-degree polynomial curve, as a second-order transfer function or as the Gaussian model type. By comparing these mathematical models, the most probable answers that can lead to the development of a control structure for rapid identification of a fault were obtained, with the possibility of triggering the line protection relay. In the final part of the manuscript, the viability of applying artificial intelligence techniques, for the approached fault management application, is proven. The developed control structure evaluates the nature of the fault and determines a faster reaction of the line protection causing an increase in the performance of the distribution service.

Oxide Nanostructured Coating for Power Lines with Anti-Icing Effect

This paper presents the results of the development of a technology to obtain a nanostructured coating for the protection of overhead wires and the possibility of their application in the electric power industry. The paper provides an analysis of available data on methods of combating ice in different countries, ways to protect the surface of metals from environmental influences, and new materials used for protection. We studied the possibility of using a protective nanostructured coating to protect overhead wires. A technology for obtaining a protective nanostructured coating based on silicon oxide and methods for applying it to the wire of overhead lines are proposed. The analysis of the elemental composition and surface morphology of overhead line wires with protective coating is carried out by scanning electron microscopy. The influence of the nanostructured coating on the high-frequency signal bandwidth and wire resistance using a PCIe-6351 data acquisition board, equipped with a BNC-2120 terminal module generating a frequency signal were determined using the National Instruments LabVIEW software package. The subject of the study was a 110 kV overhead power line with a protective coating developed in this work. By analyzing the calculation, we obtained the operating requirements of the developed nanostructured coating. As a result, we developed a protective coating satisfying the working conditions and investigated its properties. In the final phase of the experiment, we tested the electrical characteristics of overhead wires with the developed protective coating.

Quantitative analysis of the operational reliability of overhead power lines

The relevance of ensuring the efficiency of equipment, devices and installations (facilities) of electric power systems increases every year, becoming the most important problem of maintaining energy security. The decrease in work efficiency is due to a number of factors, but, above of all, due to an increase in the relative number of objects whose service life exceeds the standard value. An illustration of the methodology for quantifying, comparing and ranking the monthly average values of the operational reliability indicators of 110 kV and higher overhead power lines is given in order to identify and restore the wear of the least reliable lines.

An assessment of the potential effect of oil-and-gas 6 – 10 kV overhead power lines on bird mortality in the western Orenburg Region steppe

This paper calculates a possible damage to avifauna during the oil and gas production in the western Orenburg Region steppe. Based on field data on bird mortality by electrocution at 6 – 10 kV overhead power lines in the study area (3.22 individuals/km), we calculated possible values of bird mortality within the model site of oil and gas fields with a broad road and electrical network. The total estimated number of dead birds reached 432.64 individuals at the power lines of the model site with a total length of 134.36 km, and the estimated amount of damage was 991560 rubles. Birds pertaining to the Corvids, Accipitrids, and Falcons perished most frequently at unsafe power lines. When oil and gas fields are located near specially protected natural areas or in the Russian-Kazakh border zone, the estimates of bird deaths at unsafe power lines are supposed to be closer to actual values.

Методика оценки технического состояния опор воздушных линий электропередачи с учетом типовых эксплуатационных дефектов

Structure safety estimation via the results of modal testing is widely used in building field. However, overhead power line pylons are so specialised that it is not possible to expand existing standards so that those could be employed to assess pylon conditions. These standards do not contain any information about the pylon eigenvalues, methodology of full-scaled experiment execution or criteria to differentiate pylons with respect to the extent of the structure defects occurred. This means that it is necessary to develop a dedicated approach to estimating the safety of this type of structures. The method proposed boasts an additional advantage, that is, it takes into account the operating defects that are typical for the type of structures under consideration. The point of this method is comparing the computed and experimentally determined natural frequencies of overhead power line pylons. This comparison enables us not only to detect the defect type present in the structure, but also to find whether it is located closer to the base of the structure or in the latticework on one of the sides. The paper presents the results of using our method for estimating the safety of intermediate towers for a 110 kV overhead power line as represented by the SV-5 segment and states the advantages of using our method when planning real-time inspection of structures, as well as for monitoring select towers constantly.