Transmission Cables Research Articles

Directional motion of water droplets enhances anti-icing failure of structural superhydrophobic surfaces

Preventing ice formation on solid surfaces is a crucial concern in various applications, such as aircraft de-icing and protecting electrical transmission cables. One approach to combat ice or frost formation involves the fabrication of superhydrophobic surfaces with micro- or nanostructures. However, some research suggests that the effectiveness of these superhydrophobic surfaces in preventing ice formation may be compromised under conditions of high humidity and low temperatures. Many researchers attribute the resistance of the wetting transition from the Cassie-Baxter state to the Wenzel state on superhydrophobic surfaces to Laplace pressure difference. However, according to molecular dynamics simulations and physical experiments, we find that the impact of Laplace pressure difference depends on the relative size of water droplets and air pockets on the structure. If the size of water droplets is smaller than the characteristic length of the air pockets, directional motion due to Laplace pressure difference and van der Waals force leads to water droplet aggregation and accelerates the ice formation and failure of anti-icing measures. Therefore, our research offers significant insights into the mechanical mechanisms that contribute to the failure of anti-icing techniques on structural superhydrophobic surfaces. This understanding is critical for the design of effective anti-icing or icephobic surfaces.

Effect of an electromagnetic field generated by power infrastructure on the spatial orientation of developing sea trout embryos Salmo trutta Linnaeus, 1758

In recent decades, rapid technological advancements have led to a growing influence of anthropogenic electromagnetic fields on aquatic ecosystems. These fields predominantly stem from energy infrastructure facilities such as wind farms, high-voltage lines, underwater transmission cables, and power plants. As a result, there has been increasing interest in understanding the effects of heightened electromagnetic fields on aquatic ecosystems and their inhabitants, including developing fertilized eggs. This study focused on examining the effects of electromagnetic fields generated by high-voltage lines and power transformers, which are integral to transmission nodes and power plants, on the directional axis of symmetry in sea trout Salmo trutta (Linnaeus, 1758) embryos and their survival rates. The research was carried out at “PGE Dolna Odra in Nowy Czarnów”, one of Poland’s largest power plants (53°12′34′′ N, 014°28′16′′ E). Two experimental sites were selected, with electromagnetic field values ranging from 1.36 to 5.28 μT at the first site and 8.97 to 14.18 μT at the second site. A control sample was also established in an area unaffected by anthropogenic electromagnetic fields. The study findings revealed that electromagnetic fields originating from energy infrastructure facilities significantly affect the spatial orientation of sea trout embryos. The embryos’ response was influenced to be influenced by both the strength and direction of the electromagnetic fields. At the first test site, lower field values caused deviations from the natural alignment axis in the geomagnetic field (north-south), resulting in a shift towards the primary field source. In contrast, the second test site, with higher electromagnetic field values, showed no significant spatial orientation in embryo alignment. Additionally, the study highlighted that higher electromagnetic field values accelerated the rate of embryogenesis but also led to an increased mortality rate among sea trout embryos.

Research and Analysis of the Cost of Right of Way for Conventional Overhead Transmission Lines and Power Transmission Cable

The study explores the pros and cons of adding these advanced conductors to transmission lines. This study examines the costs of procuring RoW for standard overhead transmission lines and power transmission cables. The report details the costs and considerations of obtaining land for power transmission infrastructure. Research has two main parts. The document begins with transmission asset owner’s RoW acquisition methods and rules. It explains the regulatory framework and mechanisms for securing land rights for power transmission infrastructure. The second section analyses costs in detail. It compares the economics of installing overhead transmission lines with power transmission cables, focusing on subsurface XLPE cables. The study examines how RoW acquisition affects adjacent land prices and the economic effects on TAOs and surrounding communities. The research also evaluates transmission line dismantling costs, including waste metal value, considering metal price changes. RoW costs persist after the transmission line's tenure. The paper also examines a replacement model that estimates RoW costs for switching from overhead transmission lines to underground XLPE cables for outmoded transmission infrastructure. This analysis seeks to illuminate RoW Acquisition's financial elements for power transmission decision-makers.

State of the Art in Wearable Wrist Exoskeletons Part II: A Review of Commercial and Research Devices

Manual handling tasks, both in daily activities and at work, require high dexterity and the ability to move objects of different shapes and sizes. However, musculoskeletal disorders that can arise due to aging, disabilities, overloading, or strenuous work can impact the natural capabilities of the hand with serious repercussions both in working and daily activities. To address this, researchers have been developing and proving the benefits of wrist exoskeletons. This paper, which is Part II of a study on wrist exoskeletons, presents and summarizes wearable wrist exoskeleton devices intended for use in rehabilitation, assistance, and occupational fields. Exoskeletons considered within the study are those available either in a prototyping phase or on the market. These devices can support the human wrist by relieving pain or mitigating fatigue while allowing for at least one movement. Most of them have been designed to be active (80%) for higher force/torque transmission, and soft for better kinematic compliance, ergonomics, and safety (13 devices out of 24, more than 50%). Electric motors and cable transmission (respectively 11 and 9 devices, out of 24, i.e., almost 50% and 40%) are the most common due to their simplicity, controllability, safety, power-to-weight ratio, and the possibility of remote actuation. As sensing technologies, position and force sensors are widely used in all devices (almost 90%). The control strategy depends mainly on the application domain: for rehabilitation, CPM (control passive motion) is preferred (35% of devices), while for assistance and occupational purposes, AAN (assistance-as-needed) is more suitable (38% of the devices). What emerges from this analysis is that, while rehabilitation and training are fields in which exoskeletons have grown more easily and gained some user acceptance (almost 18 devices, of which 4 are available on the market), relatively few devices have been designed for occupational purposes (5, with only 2 available on the market) due to difficulties in meeting the acceptance and needs of users. In this perspective, as a result of the state-of-the-art analysis, the authors propose a conceptual idea for a portable soft wrist exoskeleton for occupational assistance.

A Technology for Manufacturing Porous Fluoroplastic Insulation of a Signal Transmission Cable

A Technology for Manufacturing Porous Fluoroplastic Insulation of a Signal Transmission Cable

Strength-conductivity synergy via lean alloy design: A study on novel solid stir extrusion of an Al-2Cu-0.1 Nb-0.15Zr (∼wt.%) alloy

Aluminum alloys find wide applications in power and transmission cables, and electrical conductors due to their advantageous properties of high electrical conductivity, and lower cost per unit. However, the lower tensile strength compared to copper poses a challenge for the mechanical stability of aluminum-based cables. In this study, we addressed this issue by adopting a process-based alloy design approach, creating a lean alloy with a dilute composition of Al-2Cu-0.1 Nb-0.15Zr (∼wt.%). The alloy was processed using a friction stir based novel SolidStir® (SSE) technique, followed by low-temperature aging. The resulting aluminum wire exhibited improved strength (240 MPa) while simultaneously enhancing electrical conductivity (64%IACS). The study employed computational simulations (Thermocalc) and experimental techniques (differential scanning calorimetry and transmission electron microscopy) to thoroughly investigate the microstructure. Microstructural examinations revealed that the precipitation kinetics in SSE and SSE+aged conditions played a significant role in enhancing strength and electrical conductivity. These findings demonstrate the successful achievement of high strength and high electrical conductivity in aluminum wire through a lean alloy design approach.

Optimal floating offshore wind farms for Mediterranean islands

Offshore wind will play an important role in achieving the Green Deal's goals of green transition and renewable energy generation. The European Union (EU) has launched an initiative to support a clean energy transition towards sustainable and renewable energy production in the EU islands. In fact, the Mediterranean islands obtain most of their energy supply from imported fossil fuels, making electricity costs generally very high due to their remote location. In this paper, we compare the optimal offshore wind farm layout, type and number of wind turbines for four selected sites next to Mediterranean islands. Each layout is evaluated in terms of levelised cost of energy, taking into account aerodynamic wake and transmission losses in the productivity estimation and a detailed cost model. Aerodynamic losses are modelled using a Jensen kinematic wake model and an area overlapping model to consider partial wake shadowing between wind turbines, while transmission losses are estimated as Ohmic losses of the inter-array and export transmission cables. Compared to the state-of-the-art PyWake code, the in-house MATLAB wake model demonstrated higher computational efficiency and is integrated into an efficient optimisation algorithm consisting of several iterations of the Interior-point optimisation algorithm. Results show that offshore wind turbines can provide renewable energy at a competitive price, especially at the most energetic site with an LCOE about 80 €/MWh. The normalised optimal LCOE and capacity factor as a function of the number of wind turbines are not significantly influenced by the chosen location and reach a maximum difference of 2–3 %, showing that they mainly depend on the type of wind turbine. The lowest optimal LCOE depending on the number of wind turbines is reduced by about 10 % and 25 % by the higher rated wind turbine.

Graphene-like 2D Ti3C2Tx MXene/dodecyltrimethoxysilane coating for corrosion protection on aluminum alloy by designing multilayer structure

Corrosion of metals leads to great economic losses and safety hazards. To address the corrosion problem of Al alloy in aggressive medium, two-dimensional (2D) graphene-like MXene composite coatings are proposed to enhance the corrosion resistance. Despite great progress, it still faces challenge to design high-performance MXene-based composite coating via a facile strategy because of the complex surface functionalization, orientation control, and the conductivity of MXene. Herein, a multilayer Ti3C2Tx MXene/dodecyltrimethoxysilane (MXene/DTMS) coating is prepared by a layer-by-layer spraying method at ambient temperature to maximize the physical barrier of MXene nanosheets. As a result, the incorporation of MXene nanosheets can avoid the structural defects of silane coating after curing process, thereby improving the coating resistance and charge transfer resistance by ~11- and ~390-fold in comparison to Al counterpart, respectively. Beyond the traditionally complex surface functionalization and orientation control, the multilayer coating with complete coverage and strong physical barrier ability exhibits the high corrosion resistance with a impedance modulus of 3.74 × 107 Ω·cm2 in 3.5 wt% NaCl solution. The designed coating shows promising applications in surface protection on Al alloy used in transmission cable, shafts, gears, and blades for offshore wind turbines.

A Lightweight Series Elastic Actuator With Variable Stiffness: Design, Modeling, and Evaluation

This article proposes a lightweight variable stiffness actuator (LVSA) driven by a novel mechanism with four sliders on a shared crank (FS2C). The FS2C mechanism allows the LVSA to simultaneously regulate the preload of four springs using only one motor and hence achieves a wider-range continuous stiffness adaption with reduced weight. A cable transmission system is developed to remotely place motors and further reduce the influence of the LVSA on the mass distribution. A dynamics model is established to study the torque-deflection and the stiffness-deflection relations. Based on the model, a torque-stiffness controller is proposed. Experiments are carried out to validate the performance of the dynamics model, the controller, and the LVSA. The results indicate that the LVSA provides a range of stiffness from 0 to 988 Nm/rad with a weight of 0.412 kg, and the controller is accurate in adjusting the output torque and stiffness at relatively high speeds. The proposed actuator provides a solution for actuation systems that have to be lightweight with variable stiffness, such as wearable robotics and assistive exoskeletons.

Development of Simulation Model of Single-Phase Circuit Lock in the Digsilent Powerfactory Program

Abstract The most common types of damage in distribution networks with a voltage of 6-35 kV have been analyzed. It is shown that the majority of them are single-phase circuits, which can cause overvoltages at the point of damage and negatively affect electrical equipment, which can lead to a decrease in economic indicators. The methods of increasing the reliability of distribution networks with a voltage of 6-35 kV have been analyzed. The main attention is focused on the method of increasing reliability due to grounding of the neutral through an arc reactor, the main advantage of which in operation is the continuation of single-phase ground fault operation without disconnection of consumers. A simulation model of the distribution network in single-phase ground fault mode was developed and its main parameters were calculated. The DiGSILENT PowerFactory software complex is used as a simulation environment. A concrete example of parameter calculation when using the proposed simulation model in the DiGSILENT PowerFactory program, which contains 5 overhead and 5 cable power transmission lines with a voltage of 35 kV with a length of 10 to 100 kilometers. The use of this model will make it possible to study transient processes in the mode of single-phase grounding, to prevent emergency situations in distribution networks. The goal of the work ist development of the simulation model of the distribution network in the mode of single-phase circuit to land and the calculation of its basic parameters.

Technologies Related to Intelligent Grounding Box of High-Voltage Transmission Cable

The high-voltage cable line plays an important role in the transmission of electricity in the city network. The effective grounding of the high-voltage cable is of great significance to ensure the normal operation of the cable system. There is an increasing demand for the intelligence of grounding boxes of high-voltage transmission cables. In this paper, aiming at the heating problem of the grounding box, the overall design scheme and key technology of the cable intelligent high-voltage grounding box are proposed. The intelligent high-voltage grounding box has various electrical functions of the traditional grounding box. It also has cable circulation monitoring, waterproof, fireproof, anti-theft, and alarm functions. Remote control and management of intelligent grounding boxes can be realized through GPRS.

Design of Power Supply for Distributed Aero-engine Intelligent Control System

Compared with centralized power supply system architecture, distributed power supply architecture can better meet the requirements of distributed aero-engine intelligent control systems. The design of distributed power supply topology plays a vitally important role in the distributed power supply system. The paper presents an engineering design method of distributed power supply for the distributed control system in a certain aero-engine. The distributed power supply topology is developed. Based on this topology, the bus voltage level and the current of the distributed intelligent nodes are designed. The optimal selection method of transmission cable types between intelligent nodes is also provided based on the equivalent circuit of a distributed power supply system. The results show that the cable transmission loss and voltage drop meet the design specifications of electrical cable. The proposed distributed power scheme for the distributed engine control system results in minimal modifications, smaller transmission current, and lighter cables.

Diagnosis and Location of Cable Defects Based on Digital Reconstruction of Impedance Spectrum Under Pseudotrapezoidal PFM Excitation

Because the output voltage of the existing high-frequency instrument for the defect detection of long-scale transmission cable is too low, it is necessary to output both high-frequency and high-voltage excitation. A diagnosis and location method of cable defects based on pseudo trapezoidal pulse frequency modulation excitation and impedance spectrum digital reconstruction is proposed. A high-capacity pseudo trapezoidal excitation system based on SiC high-speed inverter is designed to measure the impedance spectrum up to the highest frequency of 7 MHz. Through digital reconstruction, the impedance spectrum with different cable defects can be obtained by the bandwidth extension within the range of 100 kHz - 63 MHz. Compared with traditional low-voltage sinusoidal excitation, the location results using the proposed time-space conversion function have a more minor interval oscillation and a faster convergence speed. The accuracy of defect location is improved by 80%, which verifies the effectiveness and accuracy of the proposed method.

Fault detection and localization in unshielded twisted pair cable based on observability analysis and reflectometry experimental measurements

In this paper, an efficient method is proposed for detecting and locating a soft fault, i.e. a physical degradation, in a Y-shaped network of unshielded twisted pair cables. The method uses jointly the observability analysis and time-frequency domain reflectometry experimental measurements. The fault detection consists in checking the consistency between the known characteristics of the cable under no-fault and faulty conditions, with the maximum value of a normalized time-frequency cross-correlation function computed on a sliding time window whose length is equal to the boundary exact observability time. The cable transmission speed and the wired network observability time are combined to locate precisely the fault. Soft faults are artificially created by connecting resistors of different values to the test cable. Experimental results show the efficiency of our fault detection and localization method.

Red rock crab (Cancer productus) movement is not influenced by electromagnetic fields produced by a submarine power transmission cable

Marine renewable energy (MRE) devices, such as ones that harness offshore wind and wave energy, are an effective supplement to traditional energy sources and can support the energy grid while combating climate change. As MRE development increases pace, it is important to anticipate impacts of these infrastructure projects on the marine environment. One potential impact is a localized change in electromagnetic fields (EMF) produced by energized submarine transmission cables. Though many marine species are sensitive to EMF, primarily for navigation and orientation purposes, strong conclusions about how EMF affects invertebrates are lacking. Organisms that traverse the seafloor close to energized submarine cables, such as crabs, may be subject to stronger EMF currents. The U.S. West Coast is both a hot spot for emerging MRE development as well as home to the largest crab fisheries in the nation, there is an obvious concern on the potential impact development will have on fisheries. Our primary objective was to verify the response of red rock crabs in the presence of energized cables similar to those associated with existing MRE installations while also controlling for environmental conditions. We quantified and mapped local magnetic fields near an energized cable, tested crab responses in cable and control areas using a two-choice experimental cage in situ and described and quantified variables that were most likely to affect crab responses, including water current direction/velocity and magnetic field strength. Our results were remarkably consistent with previous studies: 1) crabs showed no preference for crossing/not crossing the cable; 2) crabs preferred to travel to the west regardless of the presence/absence of an energized cable; 3) while crabs preferred to travel to the west even more frequently in the absence of an energized cable, cable crossing and travel direction preferences were not influenced by EMF; and 4) EMF produced by these cables were consistent over time and decay to background levels at a distance of less than 1 m. This information is critical to making informed and sustainable policy decisions about renewable energy development and ensuring that this technology can coexist with local fisheries as MRE development continues.

Comparison of Rational Krylov and Vector Fitting in Transient Simulation of Transmission Lines and Cables

This paper presents stringent comparisons between Vector Fitting (VFIT), Relaxed Vector Fitting (R-VFIT) and Rational Krylov Fitting (RKFIT) techniques in the fitting of transmission line and cable functions to rational forms while accounting for the frequency dependence of electrical parameters. The fitting procedures encapsulate new solution strategies to improve fitting performance. Various case studies are presented to assess the performance of RKFIT in terms of model order reduction, passivity violation and computing times. In addition, the use of RKFIT in obtaining the frequency dependent cable model (FDCM) is demonstrated for the first time together with a resolved case study that showed unstable behavior with the universal line model (ULM) methodology.

Performance Analysis of Different Grid Substations with Demand-Side-Management-Based Optimal Power Usage

This study is centered on analyzing the performance of two power grid stations in the southern grid zone of Bangladesh. Additionally, it encompasses the effect of a demand-side management simulation of grid line operation. Firstly, this paper briefly discusses the grid circle's interconnected grid system and the serving districts' generation capacity. An analysis of schematic diagrams and an examination of the current substations and transmission cables in place has been conducted. The maximum load research has been addressed at several significant grid sub-stations, examining the capacity of a specific grid zone and determining the necessity for expanding the corresponding grid infrastructure. This study presents a comprehensive analysis of the DSM employed in the grid substation, as well as an examination of the various possibilities of renewable energy installations within it. Additionally, this study encompasses the investigation of power transmission and the accompanying structures employed for transmission, as well as the analysis of the estimation technique and any other interconnected domains.

Evaluating cable tension distributions of CDPR for virtual reality motion simulator

This paper presents a study on modeling, analysis, and control of an over-constrained Cable-Driven Parallel Robot taking into account the deformation of the cable transmission system due to the elastic model of the transmission mechanism and the affection of tension distribution for cables. The Cable-Driven Parallel Robot is used for a virtual reality motion simulation system with a simulation cabin mounted on a moving platform. A nonlinear cable length controller with tension feedback is designed to control the cabin to move along a trajectory extracted from the virtual simulated environment. The tension distribution algorithm is integrated into the controller to compensate for the dynamic error caused by the two redundant cables and the elastic characteristic of the transmission mechanism. The tensions are calculated based on the constraints of the workspace, the structure of the system, and the force limits of actuators. The cable tension feedback control algorithm was tested on the concept Cable-Driven Parallel Robot, the experimental results show that the joint trajectories meet the desired moving trajectory with high accuracy, and the cable tensions are controlled in the optimal region to ensure safety and save energy, but still suitable for the control requirements of the virtual reality motion simulator system.

Chemical Property Evaluation and Tensile Strength Correlation of XLPE Insulators Based on Accelerated Thermal Aging

Cross-linked polyethylene (XLPE) cable is a representative power transmission cable. XLPE has excellent mechanical properties, chemical and heat resistance, and insulation. However, XLPE insulation deteriorates during operation due to electrical, mechanical, and thermal stresses. Among these, thermal stress is a major factor and reduces insulation properties due to a change in molecular structure. Therefore, XLPE characteristic evaluation by heat exposure is essential for power cable condition evaluation. Herein, deteriorated XLPE samples were characterized by tensile strength, X-ray diffraction, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and ultraviolet-visible spectroscopy after exposure to various temperatures and durations. Comparing the tensile strength with other analysis results yielded correlations. Each characteristic showed a linear relationship. The correlation between tensile strength and carbonyl index was the strongest, and the coefficient of determination, R2, was 0.9299. Therefore, these results will provide important information on chemical properties when establishing operational management standards for XLPE insulators in the future.

Research on Self-Stiffness Adjustment of Growth-Controllable Continuum Robot (GCCR) Based on Elastic Force Transmission.

Continuum robots have good adaptability in unstructured and complex environments. However, affected by their inherent nature of flexibility and slender structure, there are challenges in high-precision motion and load. Thus, stiffness adjustment for continuum robots has consistently attracted the attention of researchers. In this paper, a stiffness adjustment mechanism (SAM) is proposed and built in a growth-controllable continuum robot (GCCR) to improve the motion accuracy in variable scale motion. The self-stiffness adjustment is realized by antagonism through cable force transmission during the length change of the continuum robot. With a simple structure, the mechanism has a scarce impact on the weight and mass distribution of the robot and required no independent actuators for stiffness adjustment. Following this, a static model considering gravity and end load is established. The presented theoretical static model is applicable to predict the shape deformations of robots under different loads. The experimental validations showed that the maximum error ratio is within 5.65%. The stiffness of the robot can be enhanced by nearly 79.6%.