Transmission Line Method Research Articles

A fault location method for DC transmission line based on the distributed parameter model considering line parameter uncertainty

Addressing the impact of whether line parameters can be accurately obtained and the errors due to environmental influences on the accuracy of fault location for DC transmission line, this paper proposes a fault location method based on the distributed parameter model that accounts for uncertainty in line parameter. To address the challenge of accurately obtaining DC transmission line parameters, a high-order derivative-based parameter estimation method is introduced to determine unknown equivalent parameters of the DC transmission line. Additionally, an optimization algorithm is incorporated to dynamically correct parameter errors, thereby enhancing parameter stability and constructing an accurate line model. Based on this, theoretical derivations confirm the applicability of the Tellegen's quasi-power theorem in the normal operation and internal fault equivalent models of DC transmission line. A fault location function is established based on the relationship between the line's Tellegen quasi-power characteristic and fault distance. The proposed method's effectiveness and accuracy are validated using a DC system model built on the PSCAD/EMTDC simulation platform. Simulation results indicate that the proposed method can locate faults under different fault conditions.

Structure and Mechanical Properties of Microwave-Absorbing Co-C Coatings Obtained by Magnetron Sputtering

This article is devoted to the study of microwave-absorbing properties of Co-C coating applied by magnetron sputtering. This article presents the main results of the manufacturing of a Co-C coating by magnetron sputtering, and the evaluation of experimental and computational research data on the relationship between the structure and properties of the obtained films. The structure of Co-C systems has been modeled to control the resulting structures using X-ray diffraction analysis. The structural-phase state of the resulting thin-film Co-C systems and the microwave-absorbing properties of coatings were studied using the transmission line method, consisting of a vector network analyzer, an air coaxial line, a software program, and an external computer. It has been established that on the resulting Co-C film the reflection coefficient in the frequency range of 8.2–12.4 GHz varies in the range of 900 → 718 mU, with reflection losses of −0.86 → −2.57 dB, and a standing wave coefficient of 19 → 6.8. An analysis of the obtained data indicates the presence of losses of electromagnetic energy in the studied frequency range.

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.

Backup protection method for half-wavelength transmission lines based on inverse-time characteristic

The advantages of ultra-high voltage (UHV) Half-wavelength AC transmission (HWACT) technology are achieving full-line reactive power self-balancing without the need for reactive power compensation equipment along the line and avoiding the Ferranti effect. Recently, this technology has gained considerable attention worldwide. While numerous main protection methods that were tailored to the unique operational characteristics of HWACT lines have been proposed, backup protection for HWACT has been overlooked relatively. As a transmission line requires both main and backup protection for safe and reliable operation, this paper analyzes the necessity of backup protection for HWACT lines and proposes a method based on inverse-time backup protection. This method relies on the rate of change of current (RCC), determines faults by calculating the initial value of the change rate of the fault current, and applies inverse-time characteristics to remove faults. This protection method demonstrates good quick-acting properties by adopting the RCC in the initial phase of a single-end fault without the need for dual-end communication. A large number of simulation results validated that this method was smaller affected by fault distance, initial fault phase angle, transition resistance and fault type, making it an effective protection approach for main protection failures.

A physics-informed data-driven fault location method for transmission lines using single-ended measurements with field data validation

Data driven transmission line fault location methods have the potential to more accurately locate faults by extracting fault information from available data. However, most of the data driven fault location methods in the literature are not validated by field data for the following reasons. On one hand, the available field data during faults are very limited for one specific transmission line, and using field data for training is close to impossible. On the other hand, if simulation data are utilized for training, the mismatch between the simulation system and the practical system will cause fault location errors. To this end, this paper proposes a physics-informed data-driven fault location method. The data from a practical fault event are first analyzed to extract the ranges of system parameters such as equivalent source impedances, loading conditions, fault inception angles (FIA) and fault resistances. Afterwards, the simulation system is constructed with the ranges of parameters, to generate data for training. This procedure merges the gap between simulation and practical power systems, and at the same time considers the uncertainty of system parameters in practice. The proposed data-driven method does not require system parameters, only requires instantaneous voltage and current measurements at the local terminal, with a low sampling rate of several kHz and a short fault time window of half a cycle before and after the fault occurs. Numerical experiments and field data experiments clearly validate the advantages of the proposed method over existing data driven methods.

Impact of Silicon Dioxide Periodic Grating Structure on Electrical Properties of Graphene

Our study breaks away from the conventional focus on 3D transistor structures, aiming to explore the potential of two-dimensional materials. Graphene, a key player of two-dimensional materials, draws significant attention due to its exceptional electrical properties and chemical stability. Rather than delving into the intrinsic properties of graphene, our research focuses on examining the impact that other materials in contact with graphene have on graphene’s behavior. With a thickness of just one atomic layer, graphene's band structure is easily influenced by materials in contact with it, giving rise to the Surface Charge Transfer Doping (SCTD) effect. Our study involves the utilization of e-beam lithography to define 140 nm gratings and RIE to etch into SiO2 substrates. Subsequently, graphene is transferred onto these SiO2 gratings. Within these grating regions, in other words, graphene is supported by SiO2, while other part of the graphene is suspended. By strategically forming alternatively supported/suspended type of graphene in period of 140 nm through these gratings, our aim is to unravel the impact on the electrical characteristics of graphene along both the vertical and horizontal axes. In vertical direction, we measured contact resistance between graphene and metal; in horizontal, we measured the difference of Id-Vg curve caused by the grating structure under graphene channel. This exploration emerges from the quest to harness novel properties in the face of evolving fabrication methodologies.To have 140 nm grating, we chose e-beam lithography in defining the nano grating pattern. Initially, a clean wafer was coated with chromium, and e-beam resist Zep-520A was spin-coated and soft-baked. Subsequently, using e-beam lithography, we defined the periodic pattern. Following this, ICP-RIE was employed for dry etching of chromium, and the resist was removed. Then, ICP-RIE, with chromium as the hard mask, was utilized for dry etching of SiO2. Finally, the chromium was immersed in a chromium etchant solution, resulting in a periodic grating structure with a depth of 100nm on SiO2. This marks the completion of the first part of the fabrication process. In the second part of fabrication process, we transferred graphene, prepared through CVD, onto the SiO2 substrate with periodic gratings defined through etching. We employed optical lithography to define patterns for transmission line method (TLM) measurements. These patterns were aligned with positions defined by e-beam, ensuring that the graphene-metal contact positions precisely coincided with the underlying grating structure. Utilizing TLM, we measured the contact resistance, enabling the study of the impact of the grating on the electrical properties of graphene in the vertical direction. The fabrication flow can be schematically shown in Fig. 1.By using ELS-7000 (E-beam writer) and Oxford ICP-RIE, we successfully achieved ~140 nm grating structure on silicon dioxide with depth of 100nm, which is observed on SEM as shown in Fig. 2. Then we measured the I-V curve by 4200A-SCS and calculated contact resistance by TLM. The preliminary results of the contact resistance measurement are shown in the Fig. 3. The I-V curve shows that as the channel length increases, the total resistance increases, which is aligned with the assumptions of TLM. We can further calculate the contact resistance through the Y-axis intercept of channel length-resistance curve. With the same process, we can explore the electrical variations of graphene with graphene-metal contact resistance and current-voltage relationship. Figure 1

A Fast ion Flow Field Calculation Method of UHVDC Transmission Lines Based on Adaptive Iteration Factor and Half-Error Term

A Fast ion Flow Field Calculation Method of UHVDC Transmission Lines Based on Adaptive Iteration Factor and Half-Error Term

Research On Bird Nest Detection Method of Transmission Line Based on Yolov8

Research On Bird Nest Detection Method of Transmission Line Based on Yolov8

PGE-YOLO: A Multi-Fault-Detection Method for Transmission Lines Based on Cross-Scale Feature Fusion

PGE-YOLO: A Multi-Fault-Detection Method for Transmission Lines Based on Cross-Scale Feature Fusion

A Lightweight and Efficient Multi-Type Defect Detection Method for Transmission Lines Based on DCP-YOLOv8.

Currently, the intelligent defect detection of massive grid transmission line inspection pictures using AI image recognition technology is an efficient and popular method. Usually, there are two technical routes for the construction of defect detection algorithm models: one is to use a lightweight network, which improves the efficiency, but it can generally only target a few types of defects and may reduce the detection accuracy; the other is to use a complex network model, which improves the accuracy, and can identify multiple types of defects at the same time, but it has a large computational volume and low efficiency. To maintain the model's high detection accuracy as well as its lightweight structure, this paper proposes a lightweight and efficient multi type defect detection method for transmission lines based on DCP-YOLOv8. The method employs deformable convolution (C2f_DCNv3) to enhance the defect feature extraction capability, and designs a re-parameterized cross phase feature fusion structure (RCSP) to optimize and fuse high-level semantic features with low level spatial features, thus improving the capability of the model to recognize defects at different scales while significantly reducing the model parameters; additionally, it combines the dynamic detection head and deformable convolutional v3's detection head (DCNv3-Dyhead) to enhance the feature expression capability and the utilization of contextual information to further improve the detection accuracy. Experimental results show that on a dataset containing 20 real transmission line defects, the method increases the average accuracy (mAP@0.5) to 72.2%, an increase of 4.3%, compared with the lightest baseline YOLOv8n model; the number of model parameters is only 2.8 M, a reduction of 9.15%, and the number of processed frames per second (FPS) reaches 103, which meets the real time detection demand. In the scenario of multi type defect detection, it effectively balances detection accuracy and performance with quantitative generalizability.

Junctionless Structure Indium-Tin Oxide Thin-Film Transistors Enabling Enhanced Mechanical and Contact Stability.

In recent years, considerable attention has focused on high-performance and flexible crystalline metal oxide thin-film transistors (TFTs). However, achieving both high performance and flexibility in semiconductor devices is challenging due to the inherently conductive and brittle nature of crystalline metal oxide. In this study, we propose a facile way to overcome this limitation by employing a junctionless (JL) TFT structure via oxygen plasma treatment of the crystalline indium-tin oxide (ITO) films. The oxygen plasma treatment significantly reduced oxygen vacancies in the ITO films, contributing to the significant reduction in the carrier concentration from 4.67 × 1020 to 1.39 × 1016. Importantly, this reduction was achieved without inducing any noticeable structural changes in the ITO, enabling the successful realization of ITO JL TFTs with an adjustable threshold voltage. Furthermore, the ITO JL TFTs demonstrate good stability and reliability under various bias stress conditions, aging in the air atmosphere, and high-temperature processes. In addition, the ITO JL TFTs exhibit low light sensitivity due to the wide bandgap of ITO and further suppression of Vo defects, making them suitable for applications requiring stable performance under light exposure. To compare and analyze the flexibility of the JL structure and conventional structure with additional source/drain (S/D) junction in ITO TFTs with nonencapsulation, we utilized mechanical simulations and transmission line method (TLM). By employing the JL structure in ITO TFT through carefully optimized oxygen plasma treatment, we successfully mitigated stress concentration at the S/D-channel interface. This resulted in a JL ITO TFT that exhibited a change in contact resistance of less than 20% even after 20,000 bending cycles. Consequently, a stable and flexible ITO TFT with field-effect mobility (μFE) of 12.74 cm2/(V s) was realized, outperforming conventionally structured ITO TFTs with additional S/D junction, where the contact resistance nearly tripled.

Research on Anti-breakage Target Detection Method of Transmission Line based on Improved YOLOv5

Abstract Illegal construction operations and sudden outbursts in transmission corridor protection areas pose a threat to the safe and stable operation of transmission lines. It is very important to identify the transmission line breakage risk to guarantee power grid security. The existing target detection model has many parameters and a large capacity, which makes it difficult to implement the deployment of edge terminals and cannot detect the risk of transmission line outbreaks in real time. This paper proposed a transmission line anti-breach detection method based on improved YOLOv5. Firstly, the CSPdarknet53 module is replaced with a lightweight MobilenetV3 module to reduce the model parameter number. The SPP module is replaced by SimSPPF module to realize the fast conversion of multi-scale image convolution features. Finally, the ECA attention mechanism is introduced to improve the ability of the model to focus on key features, thereby improving the overall performance of the model. Experiment results show that the proposed method has a smaller parameter number and a mAP value of 97.77%, which is the best overall performance, and provides support for the realization of outbreak risk warning of transmission lines based on edge intelligence.

Novel traveling wave fault location method for HVDC transmission line based on wavefront frequency

The key of traveling wave (TW) fault location (FL) method is the calculation of TW velocity and the calibration of TW wave head. In order to achieve high-precision FL, detailed transmission line (TL) parameters are needed to accurately calculate the TW velocity. In view of the problem that the existing high-precision TWFL methods are highly dependent on the calculation of TW velocity, the paper contributes to following aspects: (i) the mapping relationship between wavefront frequency and fault distance/fault pole is constructed; (ii) a neural network model suitable for FL and fault pole identification is designed, which is optimized by Particle Swarm Optimization (PSO) algorithm and Levenberg–Marquardt (L-M) algorithm; (iii) a complete FL scheme is proposed. In order to verify the FL accuracy of proposed method, an ±800 kV bipolar high-voltage direct-current (HVDC) transmission system model is constructed using PSCAD/EMTDC. According to the simulation results, the errors of FL is less than 0.2 km and the accuracy of fault pole identification is 100%. For the problems of fault type, fault resistance and noise, the proposed method shows high robustness.

Hole transport mechanism at high temperatures in p-GaN/AlGaN/GaN heterostructure

This Letter reports an investigation of hole transport in p-GaN/AlGaN/GaN heterostructures through experimental and theoretical analyses under varied conditions. Highly non-linear current–voltage (I–V) characteristics, obtained via the linear transmission line method measurements, are utilized for this study. At low bias voltage, the transport can be ascribed to the Schottky nature of the contact, while at high bias, the conduction is observed to be governed by space-charge limited current (SCLC). The Schottky characteristics (Schottky barrier height and non-ideality factor) and the SCLC exponent were analyzed for devices with varying contact spacings and at different high temperatures. The SCLC exponent, m, is in the range of 2≤m≤4 depending on the applied voltage range, revealing the existence of the trap states in the channel region. The findings of this work indicate that the charge injection, field-induced ionization, and trap states in the p-GaN channel are critical factors in the current transport of p-GaN/AlGaN/GaN heterostructure.

30‐3: Direct Observation of 2 Delta L in a‐IGZO TFT Using Scanning Capacitance Microscopy

Herein, we have directly investigated a 2 delta L as the diffusion length in a‐IGZO TFT using a scanning capacitance microscopy (SCM) technique at the cross section of TFTs instead of indirect normal transmission line method (TLM). Moreover, we revealed that the difference of 2 delta L leads the variation of total parastic capacitance in devices, which play a key role in the properites of EL currents in case of display devices.

A high-precision hazard ranging method for transmission lines based on laser point cloud

Abstract To ensure the safe operation of the line, it is necessary to discover the hidden danger in time and accurately. This paper proposes a high-precision hidden danger-ranging method for transmission lines based on the laser point cloud. This method uses LiDAR to form a data acquisition system, which is installed in the fixed position of the transmission line channel power tower to obtain the point cloud data of the channel field at regular intervals, according to a certain rule. Two ends of the suspension points and some of the conductor point cloud data are used to fit the whole conductor in three-dimensional space and carry out the precise hidden danger ranging through the fitted conductor combined with the point cloud data and ranging. By comparing the original conductor point cloud data with the fitted conductor data to verify the reliability of the conductor fitting, and verifying the feasibility of the conductor arc prolapse measurement method based on the measured arc prolapse of the conductor and the distance to the ground, it can provide more timely and effective early warning information for the safety of the transmission line channel.

Study on Optimization of Placement Method for Transmission Line Monitoring Devices Based on Probability of Meteorological Disasters

Abstract To ensure the reliability and safety of the power grid system, it is of great significance to carry out electric meteorological monitoring for transmission channels. In this paper, a method for optimizing the placement of transmission line monitoring devices based on the probability of meteorological disasters is proposed. By considering the climatic characteristics near the transmission line, the probability of occurrence of adverse meteorological faults for each transmission tower in the transmission line is analyzed and calculated by using existing meteorological and GIS elevation data. Meanwhile, the historical failure data and voltage levels of transmission lines are combined to achieve the optimization of the installation position of monitoring devices in transmission channels. This method was applied to a 220 kV transmission line for practical analysis, achieving dense monitoring in areas with high failure rates and sparse monitoring in areas with low failure rates.

Fault Distance Measurement Method Based on Wavelet Energy Spectrum and BWO Algorithm Optimized CNN-GRU Hybrid Neural Network

Aiming at the problems such as noise interference in the current fault ranging methods for flexible DC transmission lines, a single-ended intelligent fault ranging method is proposed as a hybrid neural network based on wavelet energy spectrum and BWO algorithm to optimize the multi-head attention mechanism of CNN combined with gated recurrent unit GRU. First, the correlation between wavelet spectrum energy and fault distance is analyzed, and wavelet packet decomposition is used to extract the wavelet packet energy spectrum feature vector as the model input of the neural network. Second, the hybrid neural network model is constructed and trained to mine the deep fault information in the time series, and the parameters of the hybrid neural network model with added multi-head attention are optimized using the iterative optimization search of the beluga algorithm to achieve fast and accurate positioning of the fault distance. Finally, the network is trained using the constructed four-terminal Zhangbei flexible DC transmission system model to collect data, and the experimental results prove that the method has high distance measurement accuracy, strong anti-interference ability and generalization ability, and a certain degree of resistance to transition resistance.

A New Method for Anti-Interference Measurement of Capacitance Parameters of Long-Distance Transmission Lines Based on Harmonic Components

In the context of strong electromagnetic interference environments, the measurement accuracy of the capacitance parameters of transmission lines under power frequency measurement methods is not high. In this paper, a capacitance parameter anti-interference measurement method for transmission lines based on harmonic components is proposed to overcome the impact of power frequency interference. When applying this method, it is first necessary to open-circuit the end of the line under test. Subsequently, apply voltage to the head end of the tested line through a step-up transformer. Due to the saturation of the transformer during no-load conditions, a large number of harmonics are generated, primarily third harmonic. The third harmonic components of voltage and current on the tested transmission line are extracted using the Fourier transform. The proposed method addresses the influence of line distribution effects by establishing a distributed parameter model for long-distance transmission lines. The relevant transmission matrix for the zero-sequence distributed parameters is obtained by combining Laplace transform and similarity transform to solve the transmission line equations. Using synchronous measurement data from the third harmonic components of voltage and current at both ends of the transmission line, combined with the transmission matrix, this method accurately measures the zero-sequence capacitance parameters. The PSCAD/EMTDC simulation results and field test outcomes have demonstrated the feasibility and accuracy of the proposed method for measuring line capacitance parameters under strong electromagnetic interference.

Enhancing transmission type frame structures: A BBO algorithm-based integrated design approach.

The stable and site-specific operation of transmission lines is a crucial safeguard for grid functionality. This study introduces a comprehensive optimization design method for transmission line crossing frame structures based on the Biogeography-Based Optimization (BBO) algorithm, which integrates size, shape, and topology optimization. By utilizing the BBO algorithm to optimize the truss structure's design variables, the method ensures the structure's economic and practical viability while enhancing its performance. The optimization process is validated through finite element analysis, confirming the optimized structure's compliance with strength, stiffness, and stability requirements. The results demonstrate that the integrated design of size, shape, and topology optimization, as opposed to individual optimizations of size or shape and topology, yields the lightest structure mass and a maximum stress of 151.4 MPa under construction conditions. These findings also satisfy the criteria for strength, stiffness, and stability, verifying the method's feasibility, effectiveness, and practicality. This approach surpasses traditional optimization methods, offering a more effective solution for complex structural optimization challenges, thereby enhancing the sustainable utilization of structures.