Types Of Transmission Lines Research Articles

Influence of fast switching fault current limiter on electromagnetic transient of extra-high voltage transmission line

Abstract The rapid advancement of power systems has led to an increase in short-circuit currents. The short-circuit current can be effectively limited by adding a fast-switching fault current limiter. However, incorporating a current-limiting reactor into ultra-high voltage lines may impact electromagnetic transients. This study utilizes PSCAD/EMTDC electromagnetic transient simulation software to develop a typical 330kV transmission line model for simulation analysis. The paper aims to study whether the current limiting reactor will affect the switching overvoltage in the automatic reclosing overvoltage. The results show that the input of the current-restricting transformer efficiently constrains the magnitude of short-circuit currents and exerts minimal influence on the automatic reclosing overvoltage in ultra-high voltage transmission lines.

Phase sequence selection method of double-circuit transmission lines on the same tower based on a comprehensive index

Abstract The non-transposition erection of transmission lines will lead to the imbalance of electrical parameters, which will affect the protection and automatic reclosing. The best phase sequence arrangement is determined by comprehensively considering the comprehensive indexes (current imbalance, secondary current, and recovery voltage) of double transmission un-transposed lines with shared towers. PSCAD/EMTDC electromagnetic transient simulation software is applied to build a typical 750kV transmission line model for simulation analysis, and the comprehensive indexes under different phase sequence arrangements are studied. The analysis reveals that the arrangement of phase sequence exerts a significant consequence of the comprehensive index. The findings indicate that the margin and different secondary current and recovery voltage indexes, double transmission un-transposed lines with shared towers can be erected in the same direction or in different phase sequences to reduce the current imbalance.

Fault Monitoring and Analysis of Distributed New Energy Grids Using Simulation Data Models

Data analysis is essential for fault identification and detection in smart grids in order to maintain grid monitoring. Many DL algorithms have been developed recently for data analysis applications related to smart grids. To resolve these challenges, the study suggests a Deep Neural Network (DNN) for data-driven fault location detection and type of fault classification by exploiting the Modified Sand Cat Swarm Optimization (MSCSO) optimization. Here, the DNN is used to diagnose the faults and determine the position of the sites. Numerous synthetic field data sets derived from simulated models of different transmission line types are used for training and testing. The position and type of faults are predicted by the DNN classifier based on the fault signal features, in which the DNN weights are ideally tuned using a novel MSCSO optimization method that is the improved concept of Sand Cat Swarm Optimization (SCSO). Lastly, MATLAB/Simulink is used to implement the suggested DNN-based method for fault classification and its localization in transmission line. An intellectual IEEE 6-node network model is utilized to confirm the efficacy and reliability of these methods. The outcomes demonstrated its effectiveness in giving the system operator precise and detailed analytics for fault identification.

Joint diagnosis and validation of lightning risk for transmission lines by using multisource data

This study proposes an improved method for assessing lightning risk for typical 750-kV transmission lines in Northwest China. The method involves enhanced preprocessing of multisource parameters and a joint diagnosis of lightning risk; on the basis of the diagnosis results, a cause analysis is conducted to identify towers at high lightning risk. In this study, raw data on the following parameters were obtained and processed: line lightning withstand capability calculation parameters, lightning localization parameters, microtopography parameters, and distributed monitoring parameters. These data were then integrated into a comprehensive multisource database. Furthermore, this study established a model for calculating lightning withstand capability; the study considered the influence of altitude and optimized the classic electrogeometric model. The joint diagnosis method was validated using distributed monitoring data. Through this method, this study identified the characteristics of typical high-risk towers and the underlying factors contributing to the high lightning risk on transmission lines.

Analysis of gap distance of ultra high voltage AC transmission lines in areas with altitude above 2000m

Abstract Research on long-wave front discharge characteristics of lines and long gaps of substation equipment in high-altitude areas needs to be conducted in a systematic manner immediately in order to guarantee the safety and economy of high-altitude UHV lines with respect to external insulation. However, at present, the gap discharge test of transmission lines is mainly carried out in areas below 2000m above sea level. The actual test is challenging to conduct in the high altitude region, and the test data is incomplete. To further confirm the validity of extrapolation of existing altitude test data to high altitude areas, this paper conducts theoretical analysis based on the real test data under standard meteorological conditions provided by GB/T 24842 standard. The altitude correction methods in IEC 60071-2: 2018 and IEC 60060-1: 2010, the m-coefficient method and g-parameter method, are used to correct the lightning impulse, power frequency, and standard switching impulse of AC transmission line gaps. The discharge voltage in areas below 5000m above 2000m is obtained, and several significant discharge characteristic parameters are obtained. Based on the 50% discharge voltage requirements of various voltage types of 1000kV transmission lines, combined with the discharge voltage curves at multiple altitudes, the minimum air gap distance of transmission lines at the altitude of 2000m-5000m is obtained. The comparative analysis of the correction results of the two methods provides a way of thinking for the next step to carry out the true test of UHV AC transmission line gap discharge in higher elevation regions.

Application of Logistic Regression Model in Mental Health Evaluation: A Case Study of Farmers Working Under High Voltage Transmission Line (HVTL)

The current study examined the environmental impact of High Voltage Transmission Lines (HVTL) on human health, specifically the psychological health of farmers in Pakistan. The electric and magnetic fields that emanate from HVTL may have adverse effects on human health including psychological disorders. To investigate the probability of psychological disorders among farmers working under HVTL, the current study employed a logistic regression model considering the variables of gender, age, transmission line type, work duration, and prior health conditions. The results showed that women working under HVTL are more vulnerable to psychological disorders than men. Additionally, the probability of psychological disorders increases with age of the farmers, voltage magnitude, and duration of work under HVTL. The Female farmers aged between 46 to 69 years, working under a 220 KV HVTL for up to six hours daily, were at a significantly higher risk of experiencing psychological disorders. These findings highlighted the environmental impact of HVTL on psychological health of the farmers. Moreover, it also highlighted the need for adopting measures to mitigate the risk and protect both the environment and human health.

Modeling, analysis, and shielding of the electric field between extra-high-voltage AC transmission lines and oil pipelines

The static charges and induced voltages from extra-high-voltage alternating current transmission lines (EHVACTLs) on parallel oil pipelines (POPLs) raise the risk levels for people and animals. Thus, the objective of this paper was to reduce and/or mitigate the electric field which is concentrated on POPLs by using grounded shield wires under EHVACTLs. Three techniques are employed to reduce the electric field effects on POPLs of two distinct types of transmission lines (TLs), 500 kV and 220 kV. The first technique involves raising the tower’s height to improve the clearance space between the POPLs and the TL conductors. The second technique is increasing the horizontal distance between the POPLs and the nearest stressed conductors of the TL. The third technique involves placing shield wires beneath the stressed conductors of the EHVACTLs. The electric field under the EHVACTLs is calculated with and without the grounded shield wires using charge simulation method. The results of the first technique revealed that with increasing the tower height from 10 m to 15, 20, 25, and 30 m, the electric field decreased by 43.75%, 62.5%, 68.75%, and 75%, respectively. Herein, employing the second technique, the electric field intensity is reduced by 20% and 21% depending on the POPL placed at a distance from the right stressed conductor equal to the horizontal clearance between conductors of 500 kV and 220 kV, respectively. Besides, the results of the third technique proved that the shield wires under the EHVACTLs reduced the electric field intensity on the POPLs by 17.65% and 24.71% for 500-kV and 220-kV TLs, respectively.

Structural-equivalent mean recurrence intervals for NESC Rule 250B

Overhead lines in the United States are currently designed based on both deterministic and probabilistic loading concepts for ice and wind. These load cases are specified in the National Electrical Safety Code (NESC) (Institute of Electrical and Electronics Engineers, Inc. (IEEE), 2023). The deterministic loads for the continental United States are based on three loading districts: light, medium, and heavy, and the corresponding loads based on the specified weather criteria are to be used with specified structural load factors. In practice, the factored deterministic loads often control the design of a structure compared to the probabilistic loads which apply a load factor of 1.0. Furthermore, the deterministic loads are not associated with a Mean Recurrence Interval (MRI), thereby making the assessment of the reliability index cumbersome for structures controlled by these loads. A method to determine an equivalent MRI for these deterministic loads is presented, which involves associating the factored deterministic loads with a probability of exceedance based on location for ice and wind loads. The method is applied to a 230 kV transmission line including seven structure types and line angles, and for 26 locations across the continental United States, and a comparison of the equivalent MRI based on the deterministic loads is made to the probabilistic loads. Trends are presented which illustrate that the resulting equivalent MRI vary significantly among location and structure types. The findings highlight that different structure types of the same transmission line are associated with a wide range of equivalent MRI. Discussion is provided on the trends observed in case study and the inconsistency in structural reliability that could result from the application of deterministic ice and wind load criteria in NESC Rule 250B. It is not the intent of this paper to state what design MRIs are needed to ensure adequate reliability. The intent of this paper is to determine what range of structural equivalent MRIs overhead lines in the United States are currently designed to withstand.

Transmission Line External Breakage Early Warning Method Based on Electric Field Perception

To prevent construction machinery from intruding into the transmission corridor during operation and causing damage to the normal operation of the line, this paper uses the relationship between the horizontal distance of the boom measurement point at the minimum safe distance, the angle of the boom to the ground and the field strength as a comprehensive criterion to carry out an early warning of the transmission line breaking. The method studied in this paper can provide a simple and accurate distance warning method for various types of construction machinery when they work in the vicinity of different types of transmission lines.

A Safety Distance Warning Method for Transmission Lines Based on the Relationship Between Approach Angle and Field Strength

To prevent construction machinery from intruding into the transmission corridor, a distance early warning method based on the relationship between the approach angle and the electric field strength is proposed. First, use the simulation analysis to determine the installation position of the electric field sensor. Then, the relationship between the approach angle and the electric field strength at the minimum safe distance outside the transmission line for different voltage levels, number of loops, and loop arrangement are analyzed, and the approach angle and electric field strength are used as comprehensive criteria. Finally, the relationship between the comprehensive criteria of various types of transmission lines is analyzed. Through the method proposed in this paper, an effective control method can be provided for maintaining the minimum safe distance when the construction machinery works near the transmission line.

Topography Optimization and Buckling Test of Tension Plates in UHVDC Transmission Lines

Based on the dynamic response of a typical UHVDC transmission line section after ice-shedding and the topology optimization of the tension plate, topography optimization of the tension plate to maximize buckling load is carried out to obtain the optimized schemes with stiffener. Considering the optimization results and manufacture cost, three optimized schemes of the tension plate with stiffener, whose buckling load enhances more than 40% with a bit of weight increase, are proposed. Reduced-scale modeling method for tension plates was presented and the buckling tests of the reduced-scale original and one optimized tension plates were performed. It is demonstrated that the buckling loads of the tension plates measured by the tests are consistent with those by the numerical simulations, which verifies the correctness and efficiency of the numerical simulations for the nonlinear buckling and the optimization of the tension plate. The optimized tension plates with stiffener are efficient and can be utilized in real transmission lines.

A Novel Multiresonant Chipless RFID Tag for Directional Strain Measurement on Metal Surface

In this article, a radio frequency identification (RFID) sensor tag for real-time health monitoring of the magnitude and direction of metal surface strain is presented. The chipless RFID sensor tag is composed of metal foil and F4B substrate, which is low-cost and works stably in harsh environments for a long time. Through highly sensitive strain monitoring, the risk can be predicted in the early stage of defect generation. The proposed tag includes a C-type resonator array, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> -type transmission line, and tag antennas. The C-type resonator has different sensitivities in the electrical length direction and width direction. Then, based on this characteristic, the resonator array creates a plurality of characteristic signatures containing strain information by optimizing the geometric parameters of the resonators. The strain information is transmitted to the tag antenna through the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> -type transmission line to complete the wireless communication between the tag and the reader. Finally, the performance of the strain monitoring system is verified by an experimental study. The experiment shows that the average sensitivity of the resonators is −4.94 and 1.14 kHz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> in the electric length and width directions, respectively. When the strain is more than 150 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> , the relative error of magnitude is less than 12.7% and the absolute error of direction is less than 13.3°. Therefore, the proposed chipless RFID tag can monitor the amplitude and direction of strain with higher sensitivity and a simpler structure, for the key structures, such as the high-speed running gear.

An NO2 sensor based on WO3 thin films for automotive applications in the microwave frequency range

A microwave system dedicated to the detection of nitrogen dioxide in the harsh environment of the Norway highways is proposed. An optimized transmission line type of sensor coated with a tungsten trioxide thin film that changes its electrical properties under NO2 gas exposure is developed. The sensors' response (S) is given in °/GHz and it is calculated based on wideband measurements. The advantage of wideband measurements in comparison to a single value is based on multiple measurements taken at different frequencies, which greatly suppresses noise and enables measuring low target-gas concentrations within environments of high interfering compounds. Herein, the developed system works in 1.5 GHz – 4.5 GHz, and NO2 varies in the 0–20 ppm range. The optimal thickness of the gas-sensing layer is estimated to be around 410 nm taking the advantage of the magnetron sputtering technology with the glancing angle deposition technique. The advantage of the developed sensor is the possibility to work at ambient temperature without the need to heat up the sensors. The disadvantage of the developed sensors is longer response and recovery times; however, this issue will be a subject of research in the future.

Stability Behavior and Optimization of Tension Plates in Transmission Lines in Heavy Ice Zones

Finite element model of a typical ultra-high voltage direct current transmission line section, in which buckling collapse of the tension plate took place during operation, is established. In the finite element model, the tension plate and the connected hardware fittings are discretized with 3D solid elements and the sub-conductors, spacers, clamps and insulator strings with spatial beam elements. Dynamic responses of the line after ice shedding are numerically simulated and the maximum loads on the tension plate in the cases with different ice thicknesses and ice-shedding are obtained. Buckling behaviors of the tension plate are analyzed and the conditions leading to buckling collapse are discussed. Finally, the topology optimization of the tension plate is performed and two optimized schemes of the tension plate are proposed based on the optimization result and manufacture cost. Efficiency analysis demonstrates that the buckling loads of the optimized tension plates increase more than 20% nearly without increasing weight.

Optimization-Assisted CNN Model for Fault Classification and Site Location in Transmission Lines

The theme of the paper is to emphasize the detection and classification of faults and their site location in the transmission line using machine learning techniques which help to indemnify the foul-up of the humans in identifying the site and type of occurrence of fault. Moreover, the transient stability is a supreme one in power systems and so the disturbances like faults are required to be separated to preserve the transient stability. In general, the protection of the transmission line includes the installation of relays at both ends of the line that constantly monitor voltages and currents and operate unless a fault occurs on a line. Therefore, this paper intends to introduce a novel transmission line protection model by exploiting the hybrid optimization concept to train the Convolutional Neural Network (CNN). Here, the fault detection, classification and site location are diagnosed by using CNN which is trained and tested by making use of diverse synthetic field data derived from the simulation models of distinct types of transmission lines. Hence, the location and the type of faults will be predicted by the CNN depending on the fault signal characteristics which are optimally trained by a new hybrid algorithm named Chicken Swarm Insisted Spotted Hyena (CSI-SH) Algorithm that hybrids both the concept of Spotted Hyena Optimization (SHO) and Chicken Swarm Optimization (CSO). Finally, the proposed method based on CNN for fault classification and site location of transmission lines is implemented in MATLAB/Simulink and the performances are compared with various measures like classification accuracy, fault detection rate and so on.

A numerical analysis model for inception and propagation of positive upward leader from UHV DC transmission lines

As the upward leader from the transmission line plays a vital role in the interception of lightning downward leader, the proper description of upward leader characteristics is beneficial for improving the evaluation accuracy of lightning performance for UHV DC transmission lines. Based on the leader discharge theory, a novel numerical analysis model to simulate the inception and propagation process of positive upward leader from the transmission line was proposed. The model-based calculation results show good agreement with the data of laboratory long spark discharge, natural lightning observations and operation experience of transmission lines, which verifies the validity of this model. Moreover, the influence of operating voltage, protection angle and tower height on the upward leader characteristics for the typical UHV DC transmission line was analyzed. The results show that the lightning interception ability of upward leader from the positive polar conductor is enhanced with the increase of voltage level, protection angle, and tower height, which theoretically illustrates that installing the positive polar conductor closer to hillsides, adopting the negative protection angle and reducing the tower height are effective lightning protection measures for UHV DC transmission lines.

Semicoaxial Waveguide with Elliptical Cross-Section as New Type of Microwave Transmission Line

Semicoaxial Waveguide with Elliptical Cross-Section as New Type of Microwave Transmission Line

Test tube dedicated microwave liquid dielectric sensor for non-contact properties change monitoring and material characterization with tube exchange capability

The paper presents a novel measurement technique for non-contact properties change monitoring and material characterization which is suitable for in-progress monitoring of processes, especially ones using corrosive reagents or reactive materials. The method relies on sensing of dielectric properties of liquids contained inside a test tube at microwave frequencies by a quasi-parallel-plate transmission line type sensor. The theoretical study is validated with experimental data in terms of extracting complex effective permittivity and response reproducibility on an example of various alcohols. This is followed by measurements of ethanol-water and water-sodium persulfate solutions. The determined concentration-normalized differential reflection coefficient transfer curves for a discrete set of frequencies up to 2 GHz indicated sensitivity up to 14 dB/ml and −172 °/ml with a resolution in the range of 6–7 µl for the former solution and up to −17 dB/g and −31 °/g. The obtained results prove the usability of the developed method.

On the reconstruction of the attenuation function of a return-stroke current from the Fourier Transform of finite-duration measurements

A correct representation of the lightning current is crucial when the electromagnetic field radiated to a point of interest has to be computed. Based on the engineering models of Transmission Line type, such representation involves the knowledge of the return-stroke speed, the channel-base current, the channel height and the attenuation function. Whereas the first three quantities can be measured in different ways, no measurement technique can directly provide reliable information on the attenuation function. In the past decades, researchers have applied various strategies to address this problem. These strategies are all based on a common feature, i.e., the unknown function is postulated a priori and then validated through the comparison of the computed electromagnetic fields at one or more observation points with the corresponding measured waveforms. In this paper, we propose an alternative approach for the identification of the attenuation function: starting from appropriate measurements of the return-stroke speed, the channel-base current, the channel height and the radiated electromagnetic field, we first formulate an algebraic inverse and ill-posed problem, obtained from the discretization of integral equations relating the source to the radiated field in the frequency domain, and then we solve it by means of a Tikhonov regularization technique. The proposed framework is preceded by a detailed theoretical analysis, with special emphasis on the description and filtering of measurement noise and on the minimum duration of the measurement time-windows ensuring reliable results.

Transmission lines comparison: case of the actual three-phase against a potential nine-phase systems

The importance of power systems in our daily life is no longer needed to be demonstrated and the companies that practice in this field are among the largest in the world. Today, all these companies would like to transmit more electricity to consumers but are sometimes forced to build several lines in parallel with the main transmission line. Using this solution is not without impact for biodiversity and this way of doing has some limitations. This study compares the results obtained from four different types of transmission lines in order to optimize power transfer. Those lines are characterized by their power transmitted and their number of phase as well as their length. Lines 1 and Line 2 have 120 km length and carry 400 kV respectively in three-phase system for line 1 and in nine-phase system for line 2 while lines 3 and 4 have 600 km length and carry 750 kV respectively in three-phase system for line 3 and nine-phase system for line 4. Results show that the increase in the number of phases could help supplying up to eight and six times respectively for short and long transmission lines more load connected to the grid.