Extra High Voltage Transmission Research Articles

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.

Smart cost estimation: Empirical case for extra-high voltage transmission towers

Nowadays, electricity has become an integral part of human lives. Most of our daily appliances, tools, and personal belongings are inseparable from electricity. To ensure a proper electricity distribution with an efficient transfer capability, Extra-High Voltage (EHV) transmission towers are needed. To design such a structure, it is of utmost importance to account for the cost of said tower. However, the process to estimate the cost of EHV transmission towers is both time-consuming and strenuous on human labor since a lot of consideration have to be taken. To overcome this, an imperative requirement exists for a prompt, precise, and automated tool to replace the existing manual cost estimation method. This research endeavor aims to craft a tool using support vector regression (SVR) with the capacity to prognosticate construction expenses for projects involving EHV transmission towers. The exploration of pertinent literature has enabled us to amass historical data and delineate the attributes essential for estimating costs linked to EHV transmission tower construction. The investigation delves into a comprehensive dataset spanning the past decade in Taiwan. Within this timeframe, 317 EHV transmission towers were erected between 2009 and 2019. However, 79 of these instances are excluded due to incomplete information, thereby yielding 238 viable datasets (comprising 75 % of the overall total) to underpin the development of the SVR model. By configuring the parameters to C = 0.2 and γ = 0.1, followed by 5-fold cross-validation, the resultant SVR model attains a remarkable prediction accuracy of 97.91 %, on average. As a result, the proposed SVR-based model can effectively and accurately predict the cost of constructing an EHV transmission tower project and reduce the time spent on estimation, thus contributing to the enhancement of the resilience and robustness of the transmission network system.

Bayesian uncertainty quantification of modal parameters and RRF identification of transmission towers with limited measured vibration data

The resonant response factor (RRF) sensitive to modal parameters, including the damping ratio and frequency, is a critical parameter for wind-resistant design of extra high voltage (EHV) transmission towers, because it directly affects the calculation of the wind vibration coefficient. However, the research on operational modal analysis (OMA) of in-service EHV transmission towers is limited due to the high risk of field monitoring. Therefore, it is critical to determine the size of sufficient data samples or minimum monitoring duration for the OMA of a transmission tower. In this study, an investigation of uncertainty quantification in Bayesian OMA of EHV transmission towers with small data samples from the ambient dynamic test is carried out. The uncertainty of the resonant component factor for wind-resistance design is proposed and quantified, which could provide engineering designers with a reference for confidence levels. Firstly, a field test system is installed on a multipurpose EHV transmission tower with a closed-loop cat head and a pair of cross-arms, to gather the acceleration responses. Then, the OMA for the transmission tower is carried out by the fast Bayesian FFT (FBFFT) method to determine the modal parameters as well as the associated posterior uncertainty. The small sample analysis of OMA for the transmission tower is further performed to obtain sufficient data samples and minimum monitoring duration. Finally, the distribution of the RRF is presented with the different confidential levels. It is found that a sampling length of 600 s could fulfill the basic needs of accuracy in Bayesian OMA and the determination of RRF. The outcomes of this study may provide a reference for the wind-resistance design parameter selection of the similar type of transmission towers.

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.

A Novel Methodology for Fault Sensing in Presence of Power Swing for Transmission Line with Thyristor Controlled Series Compensator

Digital distance relaying is implemented in extra high voltage (EHV) transmission network for speedy and reliable fault detection. But it should not activate in case of slow transients known as power swings. However, for occurrence of any type of fault during power swing, the relay should sense the faulty condition and send trip command to concerned circuit breaker. The detection of fault in a transmission line network with TCSC during the power swing condition has become further complex due to transients generated by series capacitor and the metal–oxide varistor (MOV) protecting it. This paper firstly presents effect of TCSC on distance relay operation for varied TCSC degree of compensation and firing angle values. Further, a discrete wavelet transform-based fast acting fault and swing classification algorithm is proposed which can sense all types of faults during slow as well as fast power swing in first decomposition level and within 0.001 sec. The proposed utilizes optimized threshold values both for swing and fault sensing by using Honey Bee Optimization Algorithm (HBOA). The proposed novel algorithm is coded in MATLAB software and the test system comprising of 400kV, 50Hz parallel transmission line network along with TCSC is built using MATLAB Simulink environment with sim power systems toolbox. It is tested for high/low resistance faults, symmetrical/asymmetrical faults and close-in/far end faults by changing TCSC compensation level and firing angle value. The simulation results prove the accuracy of proposed methodology for swing and fault classification.

Transient current protection for transmission lines based on the Kalman filter measurement residual

This paper introduces a pilot protection method for two-terminal transmission lines based on the measurement residual of an extended Kalman filter designed to track alternate current signals. Transmission lines that interconnect generation plants to consumers are the primary equipment most susceptible to faults, and failing to isolate them correctly and promptly may lead to system collapse. In this context, the measurement residual allows for rapid fault identification and tripping. In addition, the proposed solution requires computing and communication resources typically available for pilot protection since it uses conventional sampling rates and has a low computational burden. This paper details the theory and application of the extended Kalman filter and the results of the proposed method when tested against different simulation scenarios. These scenarios were built on an extra-high voltage transmission system implemented in ATP/EMTP, varying fault impedance, inception angle, distance, phases involved, and fault type. It also presents a statistical analysis of these scenarios, including channel asymmetry, errors in the current transformers’ conversion rate, and noise. Besides, it describes an analysis of the proposed method regarding current transformer saturation, high impedance faults, zero-crossing faults, external breaker opening, and power-swing. Finally, it compares the solution with other algorithms in the literature. The results indicate that the proposed solution is fast, accurate, secure, and dependable.

Analysis of an accident of abnormal increase in pole bus differential current caused by DC line faults

This paper analyzes an accident of abnormal increase of pole bus differential current and pole differential current of a converter station caused by line fault of a ±800 kV extra high-voltage direct current transmission project. After a lightning strike caused a short circuit and grounding of the DC line, the sudden voltage change protection of the DC line was triggered and the DC full voltage restart was successful. The pole bus differential current and pole differential current of the converter station have reached the protection set but have not reached the protection delay set; therefore, the differential protection has not acted. This paper first introduces the configuration principles of pole differential protection, pole bus differential protection, and line voltage sudden change protection for extra-high voltage converter stations. Second, the operation of the DC protection under this fault was analyzed in detail, and the reasons for the occurrence of pole bus differential current and pole differential current were also analyzed in this paper. Then, the range of equipment that caused the abnormal increase in differential current was identified. Finally, the lightning strike model was built on the real-time digital system, and the fault was simulated and replicated. It was determined that the abnormal increase in differential current was caused by the discharge of the pole bus surge arrester caused by the second lightning strike on the DC line.

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.

A robust single ended disturbance detection scheme for superconducting fault current limiter integrated UPFC compensated line

The occurrence of short circuit events in a high voltage or extra high voltage transmission system may result in a fault current with high magnitudes. Additionally, the inclusion of Unified Power Flow Control (UPFC) contributes to fault current. In such a scenario, the use of Superconducting Fault Current Limiters (SFCLs) is very vital because of their better technical performance to limit fault currents. However, inclusion of SFCL may cause difficulties for existing disturbance detection units. To overcome such an issue, this manuscript aims for a new disturbance detection approach based on sliding window Singular Spectrum Analysis (SSA). The proposed method begins with the reconstruction of the fault signal using SSA and then computes the transient error by subtracting the reconstructed fault signal from the original signal. This transient error is used as a fault detection index (FDI) which is also used to classify the faulty section. The superiority of the presented technique is tested for two different UPFC compensated power networks equipped with two different SFCLs, modeled using EMTDC/PSCAD 5.0. The obtained results show the effectiveness of the addressed method, obtained by simulating different adverse scenarios (fault and non-fault) which justify the real-time application of the proposed protection method.

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.

Optimal reconfiguration for Extra high voltage transmission networks using an enhanced Brute-Force algorithm

Over the last decade, Extra high voltage (EHV) transmission networks are becoming excessively meshed to reliably accommodate different types of generation and meet the operational security constraints during steady state and transient conditions. However, excessive meshing, combined with the addition of new power plants, can result in short circuit levels that exceed the capability of switchgear components. As such, there is a growing need to limit, the degree of meshing to accommodate the short circuit capability of the existing network assets, thus avoid catastrophic implications that may lead to very expensive equipment damage and personal safety concerns during fault conditions. Under different network conditions, the operators may have to reconfigure the EHV transmission grid differently to avoid exceeding the short circuit rating of the network assets, while maintaining the grid reliability following the next contingency. This paper proposes a new deterministic optimization model for determining the best EHV transmission network reconfiguration for short circuit relief, while meeting the network steady state and transient security requirements. The optimization model is solved using an enhanced Brute force algorithm that limits the search space, hence improves the computation efficiency of the classical Brute Force technique. To test the accuracy and computation efficiency of the proposed optimization model and enhanced algorithm, the IEEE 39-bus model and a real-size practical EHV network model were used as testbeds. The results demonstrate that the algorithm managed to successfully identify optimum EHV grid reconfiguration that would limit the short circuit levels while satisfying the steady state and transient security requirements mandated by the network operators.

Control of a Hybrid Shunt FACTS Compensator for Voltage Collapse Prevention in Interconnected EHV Power Transmission Systems

This article presents the converter topology for a hybrid shunt compensator (HSC) and its control suitable for an extra-high-voltage (EHV) power transmission system that helps to prevent voltage instability/collapse in multimachine interconnected power systems. Similar compensators combining a static VAR compensator (SVC) and a static synchronous compensator (STATCOM) have been proposed in the literature for power factor correction and active filtering, which are issues mostly related to the distribution system. However, for application in EHV transmission and voltage stability, the existing hybrid structures may not be suitable. This article particularly focuses on the prevention of voltage collapse that takes place in large EHV power transmission systems due to the mismatch of system-wide reactive power generation and consumption. The HSC proposed here is formed by the series combination of a STATCOM having a voltage rating of just 0.15 p.u. and an SVC having a voltage rating of 0.85 p.u. A suitable control strategy is formulated for the HSC that results in a modified operating ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V\text{--}I$</tex-math></inline-formula> ) characteristic enabling the compensator to behave like a STATCOM (with a STATCOM of considerably low voltage rating) and inject constant current even when the voltage at the point of common coupling falls as low as 0.7 p.u.

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.

Electric Field Improvement for High-Voltage Bushings

Resin-impregnated paper (RIP) bushing has gained significant interest due to its extended application in Extra High Voltage (EHV) and Ultra High Voltage (UHV) electricity transmission systems. However, the design criterion of its overall structure, the geometry parameters of the condenser layers, and stress release devices, etc., are still not fully understood. This article proposes a unique electric field optimization technique to integrate both the analytical and the numerical methods. The charge simulation method (CSM) is employed to create the overall equipotential surface, within which the finite element analysis (FEA) is adapted to study the localized field enhancement effects, taking into consideration the multi-physics coupled fields. A case study is performed on an actual UHV bushing. The results are compared to the traditional methods, to demonstrate the benefit of the hybrid method.