Cable Parameters Research Articles

Underground XLPE coaxial cable length calculation and fault detection based on broadband impedance spectroscopy

Abstract Accurately determining the tested cable’s total length is important in cable fault detection and localization. Therefore, an iterative method of relative propagation coefficients based on broadband impedance spectroscopy is proposed to solve the actual length of the cable and a phase difference integral transform method for fault detection. First, the overall detection process framework is designed. Then, the cable distribution parameter model and the characteristics of the input impedance spectroscopy are analyzed. The calculation methods for determining the cable length and propagation coefficients are explained, followed by a demonstration of the fault localization process. Finally, the model LCR1000A impedance analyzer is used to measure cable length and actual faults in cables with lengths of 35 m, 100 m, and 500 m. The final fault location error is less than 0.67%, proving that the method can calculate the length of cables and various fault point locations.

Research on the Carrier Characteristics of Power Cables Considering the Aging Status of Insulation and Semiconducting Layers

The 10 kV XPLE cable is widely used in highly cabled transmission and distribution networks. It is necessary to closely monitor the transient current, harmonic content, and electric field distribution of each layer of the insulation and semiconductive layers of the cable when they age and deteriorate, so as to promptly carry out circuit breaking treatment and prevent safety accidents. Considering the frequency sensitivity and dielectric sensitivity of the distributed Runit, Lunit, Gunit, and Cunit parameters of long cables, this paper quantitatively analyzes the frequency variation of 10 kV cable parameters under different aging states. Reconstructing the frequency variation process of typical electrical quantities through MATLAB PSCAD joint simulation, constructing fault circuits for cable insulation and semiconducting layers, obtaining transient currents in each layer of the cable under aging conditions, and conducting total harmonic distortion (THD) analysis to provide theoretical guidance for the subsequent monitoring and fault diagnosis of distribution cable status.

Cable dimension determination using Finite Element Method Magnetic (FEMM) for three-core belted and gas insulated cables

A numerical approach utilizing the Finite Element Method (FEM) based freeware Finite Element Method Magnetic (FEMM) is employed to optimize the insulation thickness to diameter ratio (‘T/d’) for a three-core belted cable, enclosed by a grounded sheath, as well as for a gas-insulated cable (GIC) with a common enclosure. The method analyzes the maximum electric field (E-field) within the cable. The minimum E-field magnitude across three critical regions where the E-field at its peak is calculated for different ‘T/d’ ratios, and the optimal ‘T/d’ is identified by selecting the maximum of these minimum values. Analogs to single-core coaxial cable, for a three-core belted cable with a radius of 1 per unit (p.u.), the best ‘T/d’ ratio is 0.80 when subjected to a 1 p.u. Peak potential. Additionally, the optimal conductor radius and conductor-to-cable center dimension for common-enclosure gas-insulated cables are verified to be 0.18 and 0.5, respectively. This study provides a first-time investigation of the best ‘T/d’ ratio for three-core belted cables and verifies CGIC cable parameters using FEMM, where no analytical solutions are available. The results are validated by comparing FEMM with analytical and Charge Simulation Method (CSM) outcomes. Hence, the FEMM provides low computational cost and reliable results compared to commercial software. Through these simulation efforts, the study re-examines the stress within the belted and gas-insulated cables and the parameters that influence it. The FEMM method allows for precise control of both conductor and sheath potentials, ensuring no potential discrepancies between the applied and calculated values across the entire range of T/d ratios.

Influence of Cable and Overhead Lines Parameters on the of Transient Recovery Voltages of High-voltage Circuit Breakers

Influence of Cable and Overhead Lines Parameters on the of Transient Recovery Voltages of High-voltage Circuit Breakers

Elimination of the methodological error in measuring linear parameters of electrical cables for intrinsically safe systems

The necessity of monitoring the linear electrical parameters of cables for intrinsically safe applications is described and it is indicated that the manufacturer or supplier of cables must ensure that the cable parameters comply with current standards. The problem of unproductive consumption of cable products during its control is considered. It is noted that standard measurement methods for such a linear parameter as inductance are correct when using cable samples, the length of which is much shorter than the construction lengths. An analytical model of a cable line as an electrical facility with distributed parameters is investigated. The reason for the introduction of a limit on the length of the cable is shown, caused by the transition from a complete to a simplified model traditionally used in some standards.A systematic method for measuring the linear parameters of cables is proposed, based on an unconventional – reverse – solution, which consists in switching from the measured secondary parameters to the calculation of primary parameters. In this case, the secondary parameters are measured in accordance with the well – known standardized idling – short circuit method. The proposed method is practically free from the limitation of the length of cable samples. This allows you to control all finished cable products without cutting off samples for measurements. The measurement error does not exceed the limit set by the standards equal to 1 %. The results obtained provide non-destructive testing during acceptance tests of cable products intended for intrinsically safe systems.

Design and test of a compact twisted stacked YBCO cable for fusion application

To meet the application requirements of high magnetic field and high current in future fusion magnet systems, a compact twisted stacked tape cable with high current density is proposed. Three stepped grooves are evenly distributed around a circular former, and a 20+10 superconducting tapes configuration is arranged in each single groove. The performance of the cable under self-field is investigated through simulation modeling and experiment on a 1-meter sample. Firstly, the electromagnetic and mechanical properties of cables are studied through simulation. According to the simulation results, the prospective critical current reaches 5090 A under self-field at 77 K while the maximum von Mises stress and volumetric strain obtained from the simulation during the current-carrying process are within acceptable ranges. A sample with a twist pitch of 300 mm is fabricated, consisting of 18 superconducting tapes and 72 copper tapes. The measured and simulated results of the critical current of this sample are 1900 A and 1970 A respectively, with a deviation of 3.5 percent. The feasibility of the proposed cable has been preliminarily demonstrated through these experimental and simulation results. Subsequent research will be conducted on the optimization of cable parameters, including geometric dimensions and tape capacity, to achieve better performance.

High-frequency transients in buried insulated wires: Transmission line simulations and experimental validation

This paper presents experimental results on the transient response of a buried insulated wire subjected to fast transient signals. It reports measurements of voltage and current at the sending end, as well as the voltage at the receiving end of the insulated wire. The obtained experimental results are utilized to assess the accuracy of recent formulations proposed for computing the ground-return impedance and admittance of underground cables, which are important for simulation of transients using models based on the transmission line theory. The good agreement between measurements and simulations bolsters confidence in incorporating these newly proposed expressions for computing the cable's ground-return parameters into EMT-type simulators.

Analysis and improvement of power quality in the onboard electrical power systems within a self-propelled floating crane

This research addresses electromagnetic compatibility and power quality (EMC and PQ) challenges in shipboard electric power systems (SEPS) with dynamic positioning (DP) capabilities, focusing on the self-propelled floating crane (SPFC) “EXPERT 3.” Our goal is to enhance methodologies for evaluating power quality indicators (PQI) related to voltage and current waveform distortions, specifically in converter-based propulsion complexes (CBPCs) featuring variable-frequency regulated asynchronous drives (VFDs). We investigate harmonic current and voltage distortions, reactive power generation, and power factor (PF) in SEPS “EXPERT 3″ during the operation of VFDs with conventional semiconductor power converters (SPCs). A refined MATLAB model considers equipment and cable network parameters, validating distortion indicators at ship synchronous generators (SGs). PQI compliance with international maritime standards is verified at the point of common coupling (PCC) for various VFD configurations with pulse width modulated (PWM) SPCs and filter-compensating devices (FCDs). We propose an improved controlled FCD (CFCD) incorporating a resonance filter (RF) and a controllable reactor compensator (CRC). CFCD efficiency in various VFD configurations is experimentally validated. We analyze harmonic distortions of voltage and current, including high-frequency (HF) commutations in VFDs with input thyristor-based rectifiers (TBRs), considering parasitic ”phase-hull“ capacitances of cable line segments (CLS). Our study examines harmonics in CBPC-based SEPS in two sub-frequency ranges: low-frequency (LF) − 0 to 2 kHz and high-frequency (HF) − 2 kHz to 500 kHz.© 2017 Elsevier Inc. All rights reserved.

Optimization Study of Steady-State Aerial-Towed Cable Circling Strategy Based on BP Neural Network Prediction

This paper presents models for UAV aerial-towed cables in free-end and fixed-end configurations, crucial for tasks like communication and aerial charging. By establishing a quasi steady-state model, computational results on cable shapes are obtained. To accelerate computations, a backpropagation (BP) neural network prediction model is trained, significantly reducing the computation time. An evaluation function has been developed that integrates both aircraft performance and cable shape considerations to evaluate circling parameters across various states. This function integrates techniques such as BP neural networks and particle swarm optimization (PSO) to refine parameters such as velocities and bank angles for both free-end and fixed-end cables. The results show that the BP neural network accurately predicts cable shapes, achieving a maximum error of 5% in towing force and verticality. Additionally, PSO efficiently optimizes circling parameters, thereby enhancing the effectiveness of the evaluation function in identifying optimal solutions. This approach significantly improves the efficiency of determining optimal circling parameters for UAV aerial-towed cables, thereby contributing to their operational efficacy.

Impedance modeling of low-voltage cables considering capacitances and parameter uncertainty using finite-element method

Recent research presented methods to improve the calculation of low voltage cable parameters by using finite-element models due to increasing focus on power quality issues in distribution grids. However, the focus was mostly on series parameters and nominal frequency. In this paper the calculation of cable capacitances as well as their impact on harmonic impedance of a single cable and in a rural low voltage grid is discussed using detailed finite-element models. Moreover, the accuracy of geometric simplification was quantified. The results are used to compare and optimize existing analytical equations. Furthermore, sources of uncertainty in cable modeling were identified and their range of impact on impedance was subsequently studied to give recommendations regarding necessary study cases for a robust assessment of grid impedance.

Mechanisms of middle-frequency oscillations in an offshore wind farm induced by the converter current inner loops

Abstract Middle-frequency oscillation instability is one of the important issues that threats the safe integration of offshore wind farms. However, analytical explanations to key affecting factors and laws for the middle-frequency oscillation are not clear yet, which makes it difficult to avoid this kind of oscillation effectively. Therefore, in this paper, mechanism for the middle-frequency oscillation induced by the dynamics of converter current inner loops is studied in-depth. First, small-signal transfer function model for a general offshore wind farm integrated via AC submarine cable is established. Then impact of the AC submarine cable and control parameters of the converter current inner loops on oscillation stability of the wind farm is analysed via eigenvalue analysis. It is found that with the length of AC submarine cable increases, frequency for the open-loop pole of the AC grid decreases. When open-loop pole of the AC grid gets close that of the PMSGs on complex plane, the near strong mode resonance can cause middle-frequency oscillation of the system. Finally, effectiveness of the conclusions drawn is evaluated through nonlinear simulations.

Research on Overvoltage at the Wind Turbine Terminal

Abstract This article provides an in-depth analysis of the causes of overvoltage at the generator end and the existing overvoltage protection circuits. Due to the long cable connection between the generator and the converter, voltage reflection occurs during the power transmission process, resulting in overvoltage at the output end of the generator and the input end of the converter. A mathematical model and simulation model have been established to address this issue. Firstly, the transmission line theory is used to analyze the characteristics of PWM pulse transmission in long cables. The reasons for overvoltage at the generator end and the influence of cable distribution parameters on overvoltage are analyzed; Secondly, conduct theoretical calculations; Finally, establish a simulation model using Matlab/Simulink, and analyze the harm of motor terminal overvoltage to the wind power generation system through simulation.

Analysis of Resonance Mechanism of AC Submarine Cable Delivery System for Offshore Wind Power

Abstract Several resonant overvoltage accidents caused by machine-grid interaction in offshore wind power generation systems have led to significant economic losses over the years. To solve this problem, based on the equivalent distributed parameter circuit model of AC submarine cable delivery system, a method combining impedance simulation-time domain simulation and spectrum analysis is proposed to reveal the mechanism of resonant overvoltage and its influencing factors. First of all, considering the phase locked loop (PLL) model and the cable distribution parameter model, an impedance model of AC submarine cable delivery system for offshore wind power is established, which takes into account the dynamic characteristics of PLL and current loop, and provides a model basis for the theoretical analysis. Then, equations for current and frequency at the point of common coupling (PCC) are derived to analyze the mechanism of resonant overvoltage generation and the influence of submarine cable length and power grid strength on resonance. Finally, PSCAD is used to verify the resonance mechanism of AC submarine cable delivery system and its influencing factors.

Enhancing resilience in urban utility tunnels power transmission systems: Analysing temperature distribution in near-wall cable fires for risk mitigation

Urban utility tunnels are integral to the underground power transmission systems of cities. Enhancing the understanding of cable fire hazards within these tunnels is pivotal for fostering risk-resilient underground environments. This study delves into the temperature distribution characteristics of near-wall cable fires in urban utility tunnels. Employing a reduced-scale utility tunnel model, a series of fire experiments were conducted, focusing on the safety monitoring of horizontally arranged cables. Cone calorimeter tests were initially performed to ascertain the heat release rate of cable fires. The study meticulously considered cable spatial position parameters, such as cable height and near-wall distance, as dependent variables, and monitored real-time temperature changes within the utility tunnel under various fire scenarios.The findings reveal that the cable’s proximity to the wall significantly influences the fire temperature field. For instance, when a fire near the sidewall (at 1 cm) is compared to one in the middle of the tunnel (at 20 cm), the ceiling maximum temperature is reduced by 38.9 %. The sidewall’s limiting effect diminishes fire energy release, moderates vertical temperature decay, and enhances longitudinal temperature attenuation. The study introduces dimensionless mathematical models that account for the sidewall effect, quantifying the characteristics of fire-induced smoke temperature distribution in utility tunnels, such as ceiling maximum temperature rise, vertical smoke temperature profile, and longitudinal smoke temperature decay. The models’ predicted values closely align with the experimental results.These insights are pivotal for integrating cable numbers and spatial positioning in scenario-based fire prevention and mitigation strategies. The study’s implications extend to the design and operation of urban utility tunnels, emphasizing the need for strategic cable placement and the potential for mathematical models to inform risk mitigation measures. The research contributes to the advancement of sustainable urban development by providing a framework for enhancing the safety and resilience of critical infrastructure against fire hazards.

Stochastic stability analysis method for offshore doubly‐fed wind power systems considering frequency variation of power cable parameters

Stochastic stability analysis method for offshore doubly‐fed wind power systems considering frequency variation of power cable parameters

Modelling and dynamic characterisation of a double-pendulum overhead crane carrying a distributed-mass payload

In industries, cranes are commonly used for transportation of a distributed-mass payload (DMP). However, analysis of the dynamic characteristics of such a system is limited since most of the research work considered a point-mass payload. This paper presents modelling and analysis of dynamic characteristics of a double-pendulum overhead crane carrying a DMP with and without payload hoisting. Nonlinear dynamic models representing the crane in both scenarios are derived. The effects of varying cable lengths, and carrying different payload masses and lengths on the dynamics of hook and payload oscillations are also studied. Simulations are performed to observe the dynamic characteristics of the crane under several conditions, and experiments are carried out to validate the theory and simulation results, and to assess the accuracy of the derived nonlinear dynamic equations. The results demonstrate that the payload oscillation is significantly affected by changes in the cable lengths and DMP parameters. In addition, satisfactory agreements between simulation and experimental results are achieved, which indicate validity of the nonlinear models and good compliance with the theory. It is envisaged that the dynamic characteristic analyses of the crane can be beneficial in designing efficient controllers, especially in suppressing DMP oscillation.

Experimental research on the influence of HTS tape width and former type on the transverse compression performance of CORC cables

The huge transverse Lorentz force experienced by CORC cable during the operation of fusion projects may cause irreversible degradation of its current-carrying capacity. Therefore, it is particularly important to study the influence of cable parameters on their transverse compression performance, and use these influence laws to adjust cable parameters to improve the critical value of transverse compression load that CORC cables can withstand. Solid copper bar former CORC cables with a former diameter of 5.57 mm are produced using HTS (high temperature superconducting) tapes (manufactured by Shanghai Superconductor) of 4 mm and 5 mm width respectively. The experimental results show that the CORC cable wound with 5 mm wide HTS tape has a greater critical transverse compression load than the cable wound with 4 mm wide HTS tape. This indicates that using wider HTS tapes to wind CORC cables can effectively improve their transverse compression performance. A solid copper bar former CORC cable and a stainless steel spiral tube former CORC cable are also produced. Through transverse compression experiments, it is found that the critical transverse compression load of the solid copper bar former and the stainless steel spiral tube former CORC cable are 130 kN/m and 89 kN/m, respectively. This indicates that the solid copper bar former CORC cable has better transverse compression performance. In addition, we also compared the influences of flat and arc pressure blocks on the transverse compression performance of CORC cables, and this experimental results provided a basis for the selection of the bobbin structure when using CORC cables to make coils.

Research on distributed strain monitoring of a bridge based on a strained optical cable with weak fiber Bragg grating array.

The foundation of an intelligent highway network is the construction of a high-density distributed strain monitoring system, which is based on sensing elements that can sensitively capture external information. In this research, the development and application for the structure of a novel strained optical fiber cable based on the weak fiber Bragg grating (wFBG) arrays are discussed. A modulation and demodulation solution of wavelength division multiplexing combined with time division multiplexing is developed by utilizing the property by which the wavelength of the strained optical fiber cable is periodically switched. Further, the strain transfer model of the optical cable is analyzed hierarchically using the theory of elasticity. The strain transfer coefficients of the overhanging region and the gluing region are combined to deduce the sensitivity model of the strained optical fiber cable. Moreover, the finite element technique is integrated to optimize the structural parameters of the optical cable for high-sensitivity or large-scale range. The strained optical fiber cable based on wFBG arrays is applied to a steel-concrete composite bridge. The static and dynamic loading tests show that the sensing optical cable can be monitored for strain variation in order to realize the functions of lane identification, weighing vehicle tonnage as well as velocity discrimination.

Research on key technology to determine the exact maximum allowable current-carrying ampacity for submarine cables

The maximum allowable current-carrying ampacity (MACCA) of a photoelectric composite submarine cable in its design phase is usually patterned considering the weather. However, variations in sea temperature, the uncertainty of the cable's material parameters and the laying environment of the cable greatly influence its CCA. The impact of these factors can damage the cable, regardless of its quality. For this purpose, this paper proposes a developed iterative parameters correction method (IPCM) based on Chord principles, to determine the exact MACCA by means of finite element method (FEM). Different optical fiber temperatures of the cable are collected using Brillouin Optical Time-Domain Analysis (BOTDA); together with the material parameters of the cable, they are modeled in ANSYS modeling software. Then, the proposed approach is conducted before determining the exact MACCA. Results obtained from experiments performed on different data groups show that the mean error rate obtained with the proposed approach is just about 3.78, while that of the other four recent approaches, including AP1, AP2, AP3 and AP4 is about 4.59, 3.96, 4.13 and 4.80, respectively.

A Highly Distensible, Cable Loop-Driven Soft Robotic Gastric Simulator for Endoscopy Training

With the increased demand for endoscopic diagnosis in the upper gastrointestinal (GI) tract, gastric simulators have been developed for endoscopy training. However, most of them remain nonideal due to their static and nondistensible nature. This paper presents a new soft robotic gastric simulator, comprising mainly of a silicone-based stomach model that mimics the size and inner surface condition of a human stomach. It also features peristaltic effect on its stomach wall via five cable loop-driven mechanisms, sphincter mechanisms at two ends of the stomach model, and structural pathology phantoms that can be magnetically controlled for multi-location deployment. Finite element simulation of the stomach behavior was performed under different insufflation pressures to determine the cable loop mechanism design parameters. During the simulator evaluation, the performances of the sphincters and cable loop mechanisms were first characterized. The simulator was then actuated to provide sequential contraction across the stomach model at different contraction ratios, leading to intragastric pressures similar to those reported in the literature. Finally, a preliminary user study was performed to face validate the simulator in terms of its realism, usability, and usefulness for endoscopy training. It is envisioned that the soft robotic gastric simulator could be adopted in endoscopy training programs to replace the use of animal models.