Characteristics Of Transmission Lines Research Articles

A Novel Trading Optimization Strategy of Source-load Bilateral Thermoelectric Spot Based on Industrial Parks Interior

With the continuous reform of the electricity market in the whole world, internal trading models in parks are generally studied in terms of load peaking, load flexibility and energy management. In this paper, the regional differential trading method is adopted for industrial users with different energy needs, and the interests of all parties within the industrial park are considered. Spot transactions involving surplus energy on both the supply side and the demand side are considered, and the weight allocation of transactions in each park is coordinated. Firstly, the way of circulating waste heat and power within the industrial park is analyzed from the composition of the trading system of the industrial park. The demand side is transported heat and electricity while the energy storage device is considered. The contact line is modeled on the basis of the energy transmission line characteristics. Secondly, the industrial park is disaggregated regionally using cascade analysis within the target area to decide load regulation mode between systems and modules. Thirdly, regional differences in trading are adopted for industrial users with different energy needs while the interests of all parties within the park are considered. Both sides of the supply side and the demand side participate in spot trading of surplus energy. The allocation of weights is coordinated for trading in the various industrial parks. Finally, The DICOPT solver optimizes operating costs and takes into account energy abandonment penalties. In the waste heat power transaction in the industrial park, the remaining power can be saved by 9.78%, and the waste heat can be saved by 4.35%. Numerical results from instances indicate that this method surpasses traditional trading approaches, aligning with the rigorous standards of scientific research.

Influence of Various Biomass Smoldering Flue Gas on Physical Characteristics of High Voltage Transmission Line

Through intelligent resistivity tester and universal tensile testing machine, the physical properties of steel-cored aluminum strand above smoldering biomass fuel were analyzed. The results show that compared with the original aluminum single wire, the resistivity of each aluminum single wire under each biomass smoldering condition increases, and the increase amplitude increases with the decrease of the height of the aluminum single wire. The height of the steel core aluminum strand has no obvious effect on the tensile strength before and after smoldering. When the height of the steel-cored aluminum strand from the combustible surface is 5 cm, the Young 's modulus of all aluminum single wires decreases, among which the Young 's modulus of aluminum single wires after smoldering Eucalyptus leaves and poplar sawdust decreases the most. When the height of the steel-cored aluminum strand from the fuel surface is 15 cm and 25 cm, the Young 's modulus of the aluminum single wire after smoldering of different fuels varies (224.4-821.9 MPa). When the height of the steel-cored aluminum strand from the combustible surface is 5cm, the flue gas temperature is high, and the outer aluminum strand of the steel-cored aluminum strand can absorb a certain amount of heat, thereby causing a small shape change occurrence.

Front Cover: Equivalent transmission line characterization and multi‐layer material measurement analysis of the signal conversion process in the pulsed electro‐acoustic method

Front Cover: Equivalent transmission line characterization and multi‐layer material measurement analysis of the signal conversion process in the pulsed electro‐acoustic method

Prediction method for response characteristics parameters of isolated-span overhead lines after ice-shedding based on finite element simulation and machine learning

In response to the problem of insufficient research on the prediction for response characteristics parameters of isolated-span transmission lines under various ice-shedding modes, study on the prediction for ice-shedding response parameters of isolated-span overhead lines is conducted in this paper based on finite element simulation and machine learning. Firstly, the finite element simulation model of isolated-span overhead line is established and verified. Seven model input parameters are determined by considering 12 typical ice-shedding modes and ice-shedding labels are introduced. Six key output parameters reflecting the electrical and mechanical characteristics of the ice-shedding transmission line are obtained by feature extraction. Secondly, the output parameters of the ice-shedding transmission line under different input parameter conditions are obtained by using the finite element simulation method. A total of 1400 sets sample data are constructed. Then, four typical regression prediction models of BP (Back Propagation Algorithm), RBF (Radial Basis Function Algorithm), SVM (Support Vector Machine Algorithm) and RF (Random Forest Algorithm) are established to predict the key output parameters of ice-shedding transmission lines. Finally, the optimal prediction model for ice-shedding response characteristics parameters of isolated-span transmission lines is selected and the application effect is analyzed by actual ice-shedding case. It is found that the RF prediction model is the optimal prediction model among the four regression prediction models. The prediction method for ice-shedding response characteristics parameters of isolated-span transmission line proposed in this paper can accurately predict the response characteristics parameters of ice-shedding transmission lines which can provide some references for the safe operation of isolated-span transmission lines in heavy ice areas.

Characteristics of multi-span transmission lines following ice-shedding

Numerical simulation method for dynamic responses of multi-span transmission lines with evenly and unevenly distributed ice following ice-shedding from full and partial span in the cases without and with wind loads, is presented and verified by reduced-scale modeling tests. Jump envelop, dynamic swing parameters, maximum reactions on tower and tensions in conductors are defined to depict the dynamic response characteristics of transmission lines following ice-shedding. The characteristics of multi-span lines with various parameters following ice-shedding are numerically studied, meanwhile a dataset is built. Using the dataset and the back-propagation (BP) neural network algorithm, prediction models for the dynamic response characteristics providing instructions for the design of electric insulation clearance and strength of transmission lines in ice zones are established and the software is developed.. The suitability of the prediction model and existing methods are discussed.

Machine learning-based fault diagnosis for high-voltage transmission lines

In order to comply with the speed and diversification process of human economic and technological development, the power system gradually develops in the direction of intelligence and complexity, and it is urgent to combine transmission line fault diagnosis methods with machine learning pattern recognition problems in order to reflect the representative characteristics of transmission lines under different operating conditions and different operation modes. In this paper, a convolutional neural network (CNN) model is established for transmission line fault diagnosis, and a series of parameters such as weights, bias, learning rate, batch size and loss function of the proposed CNN model are debugged through experimental comparison, and the best CNN model structure is determined through experimental comparison and debugging, and the recognition accuracy is higher than other traditional machine learning algorithms, which can be as high as 98.38%, with validity, practicality and advancedness.

Equivalent transmission line characterization and multi‐layer material measurement analysis of the signal conversion process in the pulsed electro‐acoustic method

AbstractThis paper studies the equivalent transmission line model of the pulsed electro‐acoustic (PEA) method with its applications. Based on the consistency of acoustic wave behaviour inside lossy acoustic materials and voltage wave propagation in transmission line, an equivalent simulation model of the PEA system is developed, whose reliability is verified by the output from the transducer and amplifier models and the comparison with measured waveforms. For the problem of acoustic impedance mismatch between different modules, simulation indicates that the unequal impedances of semiconducting electrode and sample can affect the amplitude of the measured signal at the upper electrode side, and the reflected acoustic waves caused by the transducer can affect the charge waveform. Further simulation for multi‐layer materials finds that the reflected acoustic waves of different samples and sound absorbing module can superimpose on the charge signal. Accordingly, a selection criterion is proposed to avoid the effect of the reflected waves at the interface. As for the acoustic reflection caused by internal charge, it needs to be dealt with sequentially in calibration process, starting from the result inside the sample near ground electrode. The research can provide a foundation for analyzing the acoustic properties of the PEA method.

Dynamic Response Characteristics of Isolated-Span Transmission Lines After Ice-Shedding

Dynamic Response Characteristics of Isolated-Span Transmission Lines After Ice-Shedding

Research on foreign body detection in transmission lines based on a multi-UAV cooperative system and YOLOv7

The unique plateau geographical features and variable weather of Yunnan, China make transmission lines in this region more susceptible to coverage and damage by various foreign bodies compared to flat areas. The mountainous terrain also presents great challenges for inspecting and removing such objects. In order to improve the efficiency and detection accuracy of foreign body inspection of transmission lines, we propose a multi-UAV collaborative system specifically designed for the geographical characteristics of Yunnan's transmission lines in this paper. Additionally, the image data of foreign bodies was augmented, and the YOLOv7 target detection model, which offers a more balanced trade-off between precision and speed, was adopted to improve the accuracy and speed of foreign body detection.

Analysis of the Characteristics of Radio Frequency Power Transmission Lines Using a Voltage Current Probe in Low-Pressure Discharge

Analysis of the Characteristics of Radio Frequency Power Transmission Lines Using a Voltage Current Probe in Low-Pressure Discharge

Research on Speed Control Methods and Energy-Saving for High-Voltage Transmission Line Inspection Robots along Cable Downhill

To ensure the safe operation of high-voltage transmission line inspection robots during downhill descents without power and extend their range after a single charge, this paper proposes an energy-saving speed control method for the inspection robot’s walking wheel motor on downhill slopes by integrating feedback braking and fuzzy PID control. By combining the parameter equation of the overhead catenary line and the structural characteristics of the overhead transmission line, this paper analyzes the relationship between the driving torque of the inspection robot’s wheels and the horizontal displacement along the transmission ground wire before and after descending. Based on this analysis, a speed control and energy recovery scheme is developed for the inspection robot, which combines front-wheel feedback braking with rear-wheel regenerative braking. The fuzzy PID method is utilized to adjust the PWM duty cycle to achieve energy-efficient speed control of the inspection robot’s rear walking wheels. Additionally, to improve the energy density and specific power of the robot’s energy storage unit, a composite power source consisting of lithium batteries and supercapacitors is employed to recover energy from the front walking wheels through feedback braking. The combined simulation results indicate that, compared to fuzzy control and PID control, fuzzy PID control better regulates the robot’s speed under varying slopes, wind resistance, and cable roughness. A downhill speed control system for the inspection of the robot’s walking wheel motor was designed, and its effectiveness was validated through simulated high-voltage line experiments. The fuzzy PID control was demonstrated to effectively maintain the rear walking wheel speed within the targeted range during downhill descents. When descending along a fixed 30° angle cable, the fuzzy PID control resulted in an increase of 5.28% and 14.26% in the state of charge (SOC) of the supercapacitor compared to PID control and fuzzy control, respectively. Moreover, when descending along fixed angle cables of 10°, 20°, and 30°, as well as a variable angle cable ranging from 30° to 0°, the SOC of the supercapacitor increased by 17.55%, 26.25%, 38.45%, and 31.29%, respectively. This demonstrates the effective absorption of regenerative braking energy during the robot’s downhill movement.

An enhanced sensitive power differential protection for series compensated transmission lines in renewable generation intensive power systems

Series compensation is widely used to improve the electrical characteristics of long transmission lines and increase the power transfer capability. However, the insertion of a series capacitor introduces various phenomena that affect the performance of traditional distance relays. Moreover, the fault characteristics of renewable generation systems coupled with generation outputs that vary with weather patterns produce additional complications to the protection of transmission lines. This paper proposes the application of an enhanced sensitive power differential protection (SPDP) algorithm to the protection of series compensated transmission lines. The algorithm incorporates a criterion that improves the security of the protection by inhibiting the SPDP algorithm from operating for faults external to the protected line. Performance of the enhanced SPDP algorithm has been evaluated on a test system built in Digsilent Powerfactory software. Various in-zone and out-of-zone fault cases were simulated at different compensation levels and fault resistances. The results showed that the enhanced SPDP protection technique can detect in-zone faults along practically the entire transmission line (99.99 %) for compensation levels up to 90 %. The method operated reliably for faults with resistances up to 330 Ω.

Comprehensive Condition-Information-Based Risk Assessment Method for Power Transmission Line

The traditional risk assessment methods do not adequately consider the specific operating environment and characteristics of a power transmission line. Therefore, a new risk assessment method considering the information of comprehensive conditions is proposed in this paper. First, a risk assessment model is designed via statistical methods based on the information on preceding failures and defects of a power transmission line. Then, the quantization processes of the state parameters of components in the transmission line are formed to get the risk assessment results considering historical failure information. These results are of failure probability meaning. Finally, the influences of the operating age of equipment in the transmission line, the position of the transmission line, the service time, and the working condition of the grid on the risk value of the transmission line are analyzed. An empirical example shows that the suggested method can predict the risks of transmission lines and offers a way for maintenance scheduling and equipment replacement.

Newly Designed Identification Scheme for Monitoring Ice Thickness on Power Transmission Lines

Overhead power transmission line icing (PTLI) disasters are one of the most severe dangers to power grid safety. Automatic iced transmission line identification is critical in various fields. However, existing methods primarily focus on the linear characteristics of transmission lines, employing a two-step process involving edge and line detection for PTLI identification. Nonetheless, these traditional methods are often complicated when confronted with challenges such as background noise or variations in illumination, leading to incomplete identification of the target area, missed target regions, or misclassification of background pixels as foreground. This paper proposes a new iced transmission line identification scheme to overcome this limitation. In the initial stage, we integrate the image restoration method with image filter enhancement to restore the image’s color information. This combined approach effectively retains valuable information and preserves the original image quality, thereby mitigating the noise presented during the image acquisition. Subsequently, in the second stage, we introduce an enhanced multi-threshold algorithm to separate background and target pixels. After image segmentation, we enhance the image and obtain the region of interest (ROI) through connected component labeling modification and mathematical morphology operations, eliminating background regions. Our proposed scheme achieves an accuracy value of 97.72%, a precision value of 96.24%, a recall value of 86.22%, and a specificity value of 99.48% based on the average value of test images. Through object segmentation and location, the proposed method can avoid background interference, effectively solve the problem of transmission line icing identification, and achieve 90% measurement accuracy compared to manual measurement on the collected PTLI dataset.

Risk assessment models of power transmission lines undergoing heavy ice at mountain zones based on numerical model and machine learning

To deliver the cleaner energy, such as water, wind and solar power, from the remote mountainous areas to the power load areas, overhead power transmission lines are widely employed around the world. It is not an easy job to guarantee the safety of the long distance power transmission with hundreds or even thousands of kilometers of lines, especially crossing heavy ice zones at mountains. In this work, a numerical model to simulate the static and dynamic responses of transmission lines undergoing heavy ice is proposed and validated. Using the model, parameter study under different line sections depending on the mountain terrains, height difference and tension in conductors is carried out. It is obtained that the ice-induced dynamic characteristics of transmission lines at mountain zones are highly different with those of traditional design standard, with more complicated and dangerous. Therefore, to assess the risk level of transmission lines at mountain zones, the numerical model is used to gather the big dataset. Then, five machine learning-based models, including three tree-based and two artificial neural network (ANN)-based models, are developed and compared to find the optimal one. It is found that the multi-layer feed-forward deep ANN (MLF-DNN)-based model behaves optimal with the best evaluation scores. Based on the models, the predominant input parameters to affect the risk level are obtained and some suggestions to improve the ice resistance for the design and operation of transmission lines at mountain zones are proposed.

Research on electromagnetic scattering characteristics of high voltage transmission lines considering rough surface

With the continuous construction of the UHV power grid in China, the electromagnetic scattering of electromagnetic waves from random rough surfaces will have a certain impact on the passive interference of high-voltage transmission lines. To solve the problem of solving the propagation law of electromagnetic scattering in the electromagnetic interference of high-voltage transmission lines to radio stations, this paper is based on the approximation method and moment method of electromagnetic scattering, This paper explores the influence of lossless rough surface and lossy rough surface on the passive interference of high-voltage tower line, focusing on the influence of sea level and dielectric constant of seawater on the electromagnetic scattering characteristics of the target under the sea background, and obtains the general law.

Transmission line characterization and modeling for electronic circuits and systems design

Channel bandwidth-limited high-speed links or interfaces make circuit solutions not efficient. Both recent and subsequent links (SerDes-Serializer/Deserializer) design demand efficient and effective coupling between future circuit design, communication, and optimization. The challenges vary and new solutions are needed. In this article, an analytical wireline model is presented to predict electronic path loss towards adequate designs of electronic circuits and systems. An open loop system analysis is adapted in this paper. Our model was tested against different channels: a legacy channel with via stub discontinuity and FR4 dielectric, and a more recent microwave-engineered channel without stub and NELCO 6,000 dielectric, a very good matching attained. Good agreement was observed between our model and electromagnetic full-wave simulation data, as a result showed high level of applicability to thin-film microstrip line for adequate circuit design. The model is recommended for electronic engineers for adequate and faster interfaces and high-speed links designs.

Performance Evaluation of Broadband Characterization of Coupled Transmission Lines Even- and Odd-Mode Propagation Constants Using Differential and Common Mode S-Parameters

This work encompasses some relevant issues that arise when using a broadband method to characterize the even and odd mode propagation constants of symmetric microstrip coupled lines using four-port pure-mode differential and common mode S-Parameters. Correct excitations of differential and common modes play a significant role in experimental results. From these 4-port measurements, parameters corresponding to the even and odd modes can be extracted from the multi-mode generalized S-parameters obtained by the vector network analyzer. Differential and common mode sub-matrices are considered as two independent equivalent 2-port transmission lines. The method will be applied to extract the propagation constants of even and odd modes of coupled microstrip transmission lines. A discussion is included on ensuring the correct excitation of the modes in the structure and avoiding possible unwanted effects such as radiation, that negatively affects the final estimation, both in phase and attenuation. Two figures of merit are defined to evaluate how transitions affect the performance of the method. These figures of merit allow a reasonable estimation of how the final experiment is affected by selected excitation of modes. To assess the theory presented, two sets of seven lines of different lengths are manufactured. The experimental results show an excellent agreement, both with electromagnetic simulations and with the analytical model used, for the phase constant in the improved case of 30° bends, and an improvement in the useful bandwidth of the attenuation constant. This fact verifies the correct functioning of the method. In addition, the measurements are presented in the range of 0.01–67 GHz, which represents a significant advance in bandwidth for this type of structure.

Experimental study on the galloping characteristics of single ice-coated transmission lines under oblique flows

Galloping of ice-coated transmission lines is occasionally observed under oblique wind directions. However, most current investigations on the galloping mechanisms are for flow perpendicular to the span of the transmission lines. In order to address this gap, this research studies the galloping characteristics of ice-coated transmission lines under oblique flows based on wind tunnel tests. The wind-induced displacement of an aero-elastic iced-coated transmission line model was measured with a noncontact displacement measurement equipment in a wind tunnel at different wind speeds and directions. The results show that galloping is characterized by elliptical trajectories and negative damping, which is more likely to occur under oblique flows than the direct flow (0°). At 15° wind direction, a galloping in vertical direction was observed at wind speeds above 5 m/s. At 30° wind direction, galloping was observed over the entire range of the tested wind speeds. Moreover, the galloping amplitudes under oblique flows are observed to be larger than that at the direct flows. Consequently, when the wind direction between the major winter monsoon azimuth and the lateral direction of transmission line route is between 15° and 30°, appropriate anti-galloping devices are highly recommended in practice.

Corona current and audible noise characteristics of HVDC transmission lines and their relationship at high‐altitude

AbstractThe audible noise (AN) of HVDC transmission lines, as an external manifestation of the corona discharge, intensifies with the increase of altitude. In high‐altitude area, the AN has been a key factor in determining the type of conductors for transmission lines. In order to study the characteristics of corona current and AN of HVDC transmission lines at high‐altitude, we erected a HVDC test line at an altitude of 4300 m, and carried out AN and corona current tests under different voltages. Through the test, the basic data of AN and corona current of HVDC test line at high‐altitude were obtained. Based on the corona current curve, the corona inception electric field strength of the conductor was proposed. The relationship between the equivalent A‐weight sound level and the high‐frequency noise component was clarified. The relational expression of the AN and corona current for the HVDC test line were suggested. The research results show that, there is a relatively fixed difference of about 7–8.3 dB between the equivalent A‐weight sound level and the 8 kHz sound pressure level at altitude 4300 m, and a clear logarithmic relationship between the equivalent A‐weight sound level and the average value of the corona current.