Extra High Voltage Transmission Lines Research Articles

Boundary Protection Based on S-Transform Considering Fault Factors

Boundary protection is a protection that takes advantage of the characteristic that signals will be attenuated when passing through the “line boundary”. The location of the traps and current transformers in the structure of extra-high voltage (EHV) transmission lines makes it difficult to apply current-based travelling wave protection in engineering practice. If the protection is put into use, it is necessary to carry out a large number of engineering modifications to the existing transmission lines, which greatly increases the economic cost. And after simulation, the protection will be misjudged under weak fault conditions, and it has low reliability. After analyzing the influence of fault factors, a boundary protection method using high-frequency voltage component energy is proposed. The fault signal is processed by S-transform, and the transient voltage energy is normalized with the initial fault phase and transition resistance. The reduced characteristic quantity is used to construct a criterion to judge the fault condition of the protection line. This protection eliminates the influence of fault factors on transient protection. The ATP-Draw 6.0 simulation results based on the proposed protection scheme show that the protection scheme can distinguish internal and external faults, and can work normally under weak faults with high reliability.

Power frequency shunting property of whole group 500kV UHV Series compensated MOVs containing 10 Served and 1 New MOVs

Metal OxideVaristors(MOV) are widely used as protective devices of series compensation capacitor banks for Extra-High Voltage and UHV (Ultra High Voltage) large capacity long-distance transmission lines. As MOVs work in the strong nonlinear part of the V-I curve, the aging and deterioration degree of different MOVs in parallel connection are different, leading to one or two MOVs in the entire heavy-duty group being the first to be damaged. The uniformity of current is an important criterion for how to control the power frequency shunting of multiple parallel MOVs for series compensation capacitor banks. In order to investigate whether replacing damaged MOVs with newly manufactured MOVs of the same specifications can meet the uniformity requirements, the power frequency reclosure tests are carried out with an average voltage peak of 166.3 kV on MOV group with 10 served and 1 new MOV for the first time with actual 500 kV MOVs. Research finds that when the DC (Direct Current) U2mA mean absolute error of MOVs is 0.2%, the current mean absolute error is about 6%. After testing, the temperature rise of each MOV ranges from 22.9 to 36.3 °C. The test results in this paper provide a direct data basis for confirming the criterion of DC reference voltage and shunt uniformity at large power frequency current on actual 500 kV series compensation MOVs apparatus.

Electric and Magnetic Fields Analysis of the Safety Distance for UAV Inspection around Extra-High Voltage Transmission Lines

The deployment of small unmanned aerial vehicles (UAVs), or drones, for transmission line inspections, has brought attention to the potential impact of electromagnetic fields (EMFs) on UAV operations. This work describes a mathematical model based on the finite elements method (FEM), designed to examine the electric and magnetic fields produced by extra-high voltage (EHV) conductors. The current study extends the analysis to encompass both electric and magnetic fields and evaluates the safe distances for UAVs operating near 345 kV, 500 kV, and 765 kV transmission lines. The electromagnetic environment around these EHV transmission lines was simulated using electrostatic, magnetostatic, and transient magnetic modules within the QuickField software 6.6. Electric and magnetic profiles were estimated using 2D finite element analysis, including a numerical simulation for phase-to-phase fault EMFs for the above transmission lines. These results were then cross-verified with theoretical calculations at specific intervals and further validated using the EMFACDC analytical method developed by the International Telecommunication Union. This comprehensive assessment concludes that precise distance considerations are necessary to ensure UAV safety during power line inspections, mitigating potential risks from EMF interference.

LEGAL OVERVIEW OF COMPENSATION FOR LAND IN THE DEVELOPMENT OF PT. PLN'S SUTET TOWER NETWORK IN THE TAKTAKAN DISTRICT OF SERANG CITY, BANTEN PROVINCE

The implementation of land compensation to the community for the construction of the Extra High Voltage Transmission Network (SUTET) by PLN falls under the Ministry of Energy and Mineral Resources (ESDM). The Ministry of Energy and Mineral Resources released Ministerial Regulation (Permen) ESDM number 13 of 2021 regarding Free Space and Minimum Clearance Distance for Electric Power Transmission Network and Compensation for Land, Buildings, and/or Plants Located in the Free Space of Electric Power Transmission Network. This regulation was enacted by Minister of ESDM Arifin Tasrif on June 17, 2021, and took effect upon its promulgation on June 17, 2021. With this regulation, the rights of the community whose land is traversed by the transmission will receive compensation. However, the regulation does not comprehensively address the impact of the development and compensation for the transmission lines of 500 kV or 150 kV, leading to injustice and legal uncertainty. PLN's responsibility for the land value of the community affected by the construction of the SUTET transmission network is limited. In providing compensation to the community whose land is traversed by the Extra High Voltage Transmission Line (SUTET), PT PLN follows existing regulations. PLN refers to Ministerial Regulation No. 01.P/47/MPE/1992 on SUTET Free Space and SUTET for Electricity Distribution Article 5 paragraph (3) concerning land for establishing support structures, including buildings and plants on that land, which must be cleared and compensated.

Ferroresonance mitigation for the unconventional rural electrification system

This paper presents a solution to the observed ferroresonance (FRR) phenomenon for both energization switching and load shedding conditions in an unconventional rural electrification system. The energy is extracted from the electric field surrounding an extrahigh voltage transmission line. Ferroresonance occurs in the power transformers of the distribution substation, and the existing solution cannot be directly applied. The mitigation method consists of the insertion of a shunt resistor when the FRR starts. The robustness of the method is shown in a time-domain simulation implemented in PSCAD/EMTDC.

Amplitude Based Pilot Protection for Transmission Line

Abstract: Distance protection and differential protection schemes are the two primary types of protection schemes employed in gearbox line protection today. However, industrial practice has shown that commonly used gap prevention techniques are limited in tripping speed and selectivity. The timing of the samples in each of the two relays located at the gearbox line terminals also affects the differential protection mechanism. On the other hand, pilot safety schemes using only the communication link to exchange local decision-making about fault conditions are not affected. These method include protection of Extra High Voltage (EHV) and Ultra High Voltage (UHV) transmission lines. Synchronization of time. The problem of creating a fast and accurate fault detection system for the safety of EHV/UHV transmission lines, which is crucial in present power systems, is the subject of this master's thesis. The protection method described in this thesis is the foundation for the detection and analysis of waves travelling wave along transmission at fault initiation. This method compares the arrival of the first traveling waves at both ends of the protected line with respect to direction. This will establish whether the fault is located in the safe zone or not. Based on high voltage transmission network safety requirements a suitable phase sequence algorithm is developed to control single phase tripping. Finally, through simulations conducted in the MATLAB environment, practical design concerns for incorporating the newly proposed protection algorithm into a numerical relay unit are investigated.

Deep-Learning-Based Semantic Segmentation Approach for Point Clouds of Extra-High-Voltage Transmission Lines

The accurate semantic segmentation of point cloud data is the basis for their application in the inspection of extra high-voltage transmission lines (EHVTL). As deep learning evolves, point-wise-based deep neural networks have shown great potential for the semantic segmentation of EHVTL point clouds. However, EHVTL point cloud data are characterized by a large data volume and significant class imbalance. Therefore, the down-sampling method and point cloud feature extraction method used in current point-wise-based deep neural networks hardly meet the needs of computational accuracy and efficiency. In this paper, we proposed a two-step down-sampling method and a point cloud feature extraction method based on local feature aggregation of the point clouds after down-sampling in each layer of the model (LFAPAD). We then established a deep neural network named PowerLine-Net for the semantic segmentation of the EHVTL point clouds. Furthermore, in order to test and analyze the performance of PowerLine-Net, we constructed a point cloud dataset for the EHVTL scenes. Using this dataset and the Semantic3D dataset, we implemented network parameter testing, semantic segmentation, and an accuracy comparison of different networks based on PowerLine-Net. The results illustrate that the semantic segmentation model proposed in this paper has a high computational efficiency and accuracy in the semantic segmentation of EHVTL point clouds. Compared with conventional deep neural networks, including PointCNN, KPConv, SPG, PointNet++, and RandLA-Net, PowerLine-Net also achieves a higher accuracy in the semantic segmentation of EHVTL point clouds. Moreover, based on the results predicted by PowerLine-Net, the risk point detection for EHVTL point clouds has been achieved, which demonstrates the important value of this network in practical applications. In addition, as shown by the results of Semantic3D, PowerLine-Net also achieves a high segmentation accuracy, which proves its powerful capability and wide applicability in semantic segmentation for the point clouds of large-scale scenes.

Design and Test of Quad-Bundle Spacer Damper Based on a New Rubber Structure

Aiming at improving the handling efficiency and acquiring the satisfactory antivibration effect and damping performance, a quad-bundle spacer damper of 500 kV extra high voltage transmission lines was designed and developed based on a new rubber structure. Firstly, a mathematical vibration model of the spacer damper was constructed, and the structures of the defect-prone parts of the spacer damper were analyzed. Then, the structure was optimized based on the defect analysis, the clamp with fast installation as well as removal and the damper joint with superior performance were designed. On this basis, a new quad-bundle spacer damper was developed. Last but not least, the handling efficiency of the new quad-bundle spacer damper was evaluated, and performance tests were conducted according to the IEC standards. The evaluation and test results show that the handling efficiency, antivibration effect, and damping performance of the new quad-bundle spacer damper are significantly improved compared with those of the regular quad-bundle spacer damper, which provides a guarantee for the safe operation of 500 kV extra high voltage transmission lines.

Analysis and Damping of Sub-Synchronous Oscillations in a 250 MW DFIM Hydro Unit Connected to Series Compensated 765 kV Transmission Lines

Increasing energy consumption has required a greater need for connections between the grid and nonconventional energy sources. Recently, doubly fed induction machine (DFIM) fed hydro power units are increasingly connected to the power system due to the requirement of large energy storage option and cost-effective converter solution in the variable speed units. On the other hand, stability related issues are raised in the power system due to the sub synchronous control interaction (SSCI) that occurs between radially connected DFIM, and series compensated transmission line. This article focuses on analysis of resonance stability in a doubly fed induction machine (DFIM) based hydropower system. The controller of the rotor side converter is tuned using a dampness optimization approach. Additionally, optimized SSCI damping controller in the grid side converter is designed to attenuate the sub-synchronous oscillation (SSO) of the DFIM. Time domain simulation analysis is conducted for this research to validate the SSCI mitigation in the DFIM-based hydro units. In MATLAB/Simulink environment, the efficacy of the proposed system with 250 MW DFIM and a series compensated 765 kV extra high voltage transmission line is tested. To scale down the model and check SSO in the 2.2 kW DFIM system, a practical demonstration is carried out in the Lab.

Analisis Destruction Test Tower Sutet dibandingkan dengan Software Ms Tower dan SAP 2000

The transmission line system which is currently growing rapidly in Sumatra, requires a reliable interconnection network to meet the electricity demand for the West Sumatra region. PT. PLN as a provider of electricity businesses in Indonesia conducted planning and destruction tests to design a new model Extra High Voltage Transmission Line (SUTET) tower with specification of 66.6 meters height, slim type tower, 275 kV, lattice BB+15, quadrapole zebra (435/55 mm2) 2 cct. This research aims to study tower collapse behavior caused by working loads, analyze and compare the suitability level of tower deformation and natural frequency among MS Tower, SAP 2000 space truss analysis, SAP 2000 space frame analysis with destruction test results. SAP 2000 space frame deformation analysis shows that the tower is unstable in the Leg section. The analysis of natural frequency and the mode shape in the SAP 2000 space frame analysis is close to the value of the natural frequency destruction test with a deviation of 30%. The tower collapse occurred due to imperfection geometry on the legs section, resulting in a global collapse. Improvements in the form of adding equal angle to the hip bracing were carried out, the result was able to withstand a load case load of 9870 up to 100%. Space frame analysis on SAP 2000 is closer to MS Tower, this can be seen from the deformation and natural frequency values that approach each other from the two analyses.

Procena mesta nastanka kvara na električnom vodu primenom veštačkih neuralnih mreža

This paper deals with the application of neural networks to fault location on extra-high voltage (EHV) transmission lines. A relatively simple power system, consisting of two 220 kV power grids connected with one transmission line, has been modelled using MATLAB/Simulink software. Simulating different fault scenarios (fault types, locations, resistances, and inception angles), the proposed neural network fault locator was trained using various sets of terminal line data (line-to-line voltages and phase currents). Feedforward networks have been employed along with the backpropagation algorithm. An analysis of the neural networks with a varying number of hidden layers and neurons per hidden layer has been performed in order to validate the choice of the neural networks in each step. All analyses were carried out using Neural Network Toolbox.

Исследование практических аспектов ОМП на ЛЭП сверхвысокого напряжения по векторным измерениям на базе RTDS

Application of Phasor Measurement Unit (PMU) is a modern technology in electric power systems with quite a few possible applications. Remote identification of fault location (FL) at extra-high voltage transmission lines is one of the possible applications of PMU. The number of research works dedicated to this issue is rather limited. Also, there is no in-depth analysis of the PMU digital filter performance in case of short circuit; some factors that affect the FL accuracy are not covered; and the number of methods to identify FL remotely is insufficient. The current research goal is to study all the above-mentioned issues. The research has been conducted using the methods of mathematical modeling of fault-initiated transients represented with a real-time digital simulator RTDS (including the RSCAD software). A total of 16 FL expressions both in Russian and foreign scientific papers have been analyzed. Monte-Carlo method has been used to assess the impact of various factors on the FL accuracy. The PMU functionality presented in the RTDS simulator has been used to obtain required synchrophasors. A typical timespan of faults at extra-high voltage transmission lines has been deduced (it turns out to be at least three cycles of the fundamental frequency component). Dynamic characteristics of both M and P class PMUs have been thoroughly examined. The authors have made a conclusion that PMU-based FL is as accurate as that provided by conventional FL units. The influence of some major factors on the FL results has been investigated as well. PMU-based FL is considered to be a promising application. At the same time, P filter class PMUs are primarily used. One is to avoid getting synchrophasor data of different class PMUs at the line terminals. The obtained results are meant to be introduced to improve the PMU-based FL accuracy, especially in the context of processing real PMU data.

Algorithm for Solving Trip‐Out Rate Due to Shielding Failure of Bent Transmission Line

Accurate assessment of lightning protection performance of extra high voltage transmission lines is important for transmission line design and different lightning protection. Based on the electro‐geometrical model, this paper introduces the angle influence factor, and presents an algorithm for shielding failure trip‐out rate of angle tower, and the existing algorithm is expanded. By establishing the three‐dimensional geometric model of the angle tower, the electrical geometric relations of conductors and ground wires on both sides are analyzed, respectively, and the projection area algorithm for shielding failure is modified. To further verify the application value of the calculation algorithm, the change of the shielding failure trip‐out rate of the typical angle tower with the bending angle of transmission line and the tower height in a 500 kV transmission line is analyzed. The analysis results show that the trip‐out rate of the outside corner is higher than that of the inside one, and with the increase of the angle and the height of the tower, the trip‐out rate shows an upward trend. When the tension tower height is 71.5 m and the angle increases from 0° to 80°, the outside shielding failure trip‐out rate increased by 10.9% and the inside decreased by 9.3%. Compared with the classical electro‐geometrical model calculation, the difference of trip‐out rate is 4.3% when the bending angle is 80°. When the tangent tower height is 70 m and the angle increases from 0° to 40°, the shielding failure trip‐out rate on the outside increased by 5.9% while the inside decreased by 6.2%. The research results provide a simple algorithm for solving bending transmission line and give some reference for lightning protection design of EHV transmission lines. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

On Real-Time Detection of Line Sags in Overhead Power Grids Using an IoT-Based Monitoring System: Theoretical Basis, System Implementation, and Long-Term Field Verification

For overhead power grids, unexpected serious line sagging of extra-high voltage transmission lines would easily lead to major blackouts. Different direct and indirect sag measuring methods have been proposed, but they all have their own limitations. In this study, an Internet of Things (IoT)-based sag-monitoring system is proposed, which is able to perform real-time detection of line sags. The whole system has been deployed on two 161-kV lines for long-term field testing. The effectiveness of the proposed sag-monitoring system is verified through both theoretical calculation and field measurements. In this sag-monitoring system, a sag-sensing module is equipped with an embedded triaxial accelerometer to detect line sags at different spans of a single circuit. A catenary equation that takes temperature dependency into consideration is derived, so the measured accelerometer parameters can be converted to accurate line sag values. The long-term testing results show that the proposed sag-monitoring system yields an average error of 2.09%. The average differences between the sag values coming from the proposed system and a commercial sag measuring device are relatively small (between 0.57% and 4.14%), which proves that the sag values provided by the proposed system are reliable and accurate in the long-term testing. In addition, compared to the other existing sag measuring methods, the advantages of employing the proposed system are high measurement accuracy, and enabling wide field implementation, online monitoring, long-term field operation, and real-time transmission.

Jump height of an iced transmission conductor considering joint action of ice-shedding and wind

Ice shedding from conductors may cause a significant vertical vibration of a transmission line, which may lead to interphase flashover and thereby endanger power transmission. To design a reasonable electric insulation clearance, it requires an accurate estimation of the largest jump height of a conductor following ice shedding, which might be affected by wind actions. This study investigates the coupling effects of wind action and ice shedding on the jump height of an iced conductor. Wind tunnel tests were carried out to obtain aerodynamic force coefficients of the iced conductor with crescent sections. The dynamic responses of a practical extra-high voltage (EHV) transmission line subject to joint actions of ice-shedding and wind were analyzed by numerical simulation. The influence of wind actions, accreted ice thickness, and ice shedding rate were investigated and discussed on the largest jump height of conductors. An empirical formula for estimating the largest jump height was proposed considering the ice-wind joint effects. The accuracy and applicability of the proposed formula were validated through experimental and simulation data.

Induction mechanism and propagation characteristics of current in line conductors due to an electron avalanche

Transfer of bulk electric power required in the modern world can be realized only through Extra High Voltage and Ultra High Voltage transmission lines. The scenario is dominated by overhead lines in which electromagnetic noise generated by corona is an important concern. Corona-induced currents propagate along line conductors producing electromagnetic noise, which is essential to be quantified. Towards this end, the present work aims to investigate basic mechanism of current induction using an isolated avalanche developing under space charge modulated background field. Beginning with the complete electric field produced by an avalanche, the corresponding induced currents are quantified, and the structure of electric and magnetic fields is extracted. The well-known time-domain electric field integral equation is employed for the purpose. The basic issue with long transmission line modelling is amply demonstrated. Since single avalanche is the basic mechanism behind corona, general inferences drawn are applicable for corona on transmission lines.

ANALYSIS AND DESIGN OF SECURITY SOLUTIONS IN INTERNET NETWORK

As a primary protection of high voltage (HV) and extra high voltage (EHV) transmission line, distance protection needs to operate as fast as possible for faults inside its protection zone, whilst it also must be able to discriminate between internal and external faults to prevent unnecessary disconnection of the healthy lines. The operational performances of distance protection during dynamic conditions are specified in the latest IEC 60255-121 standard. The standard describes different tests that need to be performed using a transient network simulator and how the test results to present. In this paper, an implementation of the dynamic testing of distance protection based on the IEC 60255-121 standard will be presented. The network modelling and the simulation of test cases described in the standard are implemented using ATP-EMTP. The test results of two distance relays show that depending on the dynamic conditions, the operational performance of the relay might be affected. In some situations, the operating time of the relays was delayed, while, in other conditions, the accuracy of impedance measurement is affected causing the relay to overreach

Study on Improved CG Algorithm for Reradiation Interference Calculation of Transmission Steel Tower

With the development of extra-high voltage and ultra-high voltage transmission line in China, the reradiation interference generated by induced current on the surface of transmission steel tower becomes more serious to the radio station in the vicinity. In this paper, the calculation method for reradiation interference of transmission steel tower based on method of moment is analyzed. And in order to reduce the impedance matrix storage data in the memory space and the number of iterations in the calculation, the preprocessing of matrix sparse and diagonal norm precondition is presented to improve the performance of the conjugate gradient algorithm for the reradiation interference calculation. The reradiation interference of a standard 500 kV transmission steel tower is calculated using the improved conjugate gradient algorithm. And the results show that the algorithm enhances the convergence and stability after preprocessing and is suitable to calculate the reradiation interference of super-large metal truss structure target.

Comparative Analysis of Measures and Technical Means for Suppressing the Aperiodic Current Component in Circuit Breaker

Electromagnetic transients are considered in the implementation of three-phase automatic reclose on the transmission line of extra high voltage 750 kV. The influence of automatic shunting of phases and pre-insertion active resistance for limiting the characteristics of the aperiodic component of the current, which obstructs the transition of full current through zero, is evaluated. The paper analyses measures taking into account the effect of changing the degree of compensation of charging power and the angles of switching on an SF6 circuit breaker. Sub-schemes of disconnected undamaged phases of the extra high voltage transmission line for the investigation of the aperiodic current component have been developed. The values of the pre-insertion active resistances of different connection and automatic shunting of the phases are determined at which there is an effective reduction of the characteristics of the aperiodic component of the current. In the software environment, a model was developed and switching transient processes were simulated in the 750 kV transmission line. Operating modes that are potentially dangerous for SF6 circuit breakers are determined and recommendations are given to avoid them. Currently the technical and economic requirements for power transmission lines designed for the transport of electricity from large power plants and for the communication of powerful energy systems are increasing. Today there is the importance of reducing specific investment in the construction of new and reconstruction of existing lines. The solution of these issues is associated with the maximum use of power lines by increasing their power transfer capability and controlling modes, especially in operating emergency conditions and post-emergency operation of power systems.

Effects of the rainfall rate on corona onset voltage gradient of bundled conductors in alternating current transmission lines in high-altitude areas

Corona onset voltage gradient (COG) of bundled conductors is an important factor to be considered when designing extra-high voltage (EHV) and ultra-high voltage (UHV) transmission lines. For alternating current (AC) transmission lines, the electromagnetic environment degrades and the energy loss is greater on rainy days, which becomes more obvious with increasing altitude, therefore, it is particularly important to investigate corona onset characteristics of bundled conductors under rainy conditions in high-altitude areas. Based on an UHV corona cage established in Qinghai Province, China at an altitude of 2200 m, corona onset characteristics of nine types of bundled conductors generally used in EHV and UHV AC transmission lines were measured at a rainfall rate of up to 15 mm/h. Moreover, COG was obtained by using the tangent method. Changes in COG with rainfall intensity and corona characteristics with structural parameters of conductors at the saturated rainfall rate were investigated. Finally, considering sub-conductor radius, the number of sub-conductors, and rainfall rate, an empirical prediction equation for COG of bundled conductors with 4, 6 and 8 sub-conductors and cross-sectional areas of 400, 500, 630, and 720 mm2 was proposed, which could provide a reference for the design of overhead transmission lines in high-altitude areas.