Cable Parameters Research Articles

A method for locating and diagnosing cable abrasion based on broadband impedance spectroscopy

Modern power systems contain different types of cables and that makes it important to diagnose defects before they result in faults. Existing cable inspection methods, such as dielectric loss measurement and partial discharge, still fail to detect and locate weak cable defects. This paper presents a novel non-destructive method for detecting wear and aging defects based on broadband impedance spectroscopy (BIS) is proposed. A digital model of the cable distribution parameters is developed in this paper. The effects of different angular wear defects on the impedance spectroscopy were compared, and the degree of defects was successfully distinguished by discrete Fourier transform (DFT). The severity of the defect can be determined from the difference in peak height at the defect location after normalization. By using DFT and the Chebyshev Window it was also possible to identify two defects in the cable within 0.47% deviation of the defect position.

Safety Analysis of Secondary Cable in Substation during Power Frequency Short Circuit

In order to study the safy of secondary cables in substation, the influences of soil resistivity, short circuit current, distance, grounding grid parameters and cable parameter on the core-to-sheath potential difference and shielding layer current are investigated. It is shown that the core-to-sheath potential difference and shielding layer current change little with soil resistivity, and increase linearly with the increase of short-circuit current, and decrease with the increase of distance. The core-to-sheath potential difference increases with the increase of side length of grounding grid and cable length.

Offline Reference Trajectory Shaping for a Cable-Driven Earthquake Simulator Based on a Viscoelastic Cable Model

In an earthquake simulator, which is a device for reproducing seismic waves, it is necessary to accurately reproduce the acceleration. In this letter, the authors propose an offline reference trajectory shaping method for precise acceleration control based on the dynamic model of an earthquake simulator, composed of a planar three-degrees-of-freedom cable-driven parallel mechanism, considering the effect of the viscoelasticity of a synthetic fiber cable. First, Flory’s model representing cable viscoelasticity was introduced into the dynamic model of the system constructed in the authors’ previous study, and a precise dynamic system model including the cable was derived. Next, the viscoelastic behavior of the cable including instantaneous elasticity and tension relaxation was measured experimentally, and the cable model parameters were identified. Based on these, a control method to accurately generate the desired platform acceleration by offline reference trajectory shaping was developed. The effectiveness of the method was confirmed through simulations and experiments.

Формализация потока восстановлений кабельных линий электропередачи в стохастических задачах оптимизации системы ремонтно-восстановительных работ

Problem formalization and solving in power supply repair and maintenance are essential for reliability and safety. This research reflects problem formalization and optimization with stochastic criteria and limitations. For the purpose of this research, we assessed failure elimination time as one of optimization parameters for 6(10) kV transmission lines. We have performed hypothesis testing regarding failure elimination time distribution and determined cable line quantitative parameters.

Fast Analytical Approaches for the Transient Axial Temperature Distribution in Single Wire Cables

In various technical areas, the requirements and the complexity of electrically conductive structures (cables and printed circuit board traces) and their insulating materials are increasing, which leads to higher demands on reliability. Therefore, better diagnosis and control functions are needed. Intelligent fusing strategies with electronic fuses, where the current flow can be switched by semiconductors, can play an important role. One approach is to monitor the insulation temperature in order to detect thermal overloads and switch off a current branch before the insulation is damaged. As especially in cables, a direct temperature measurement is troublesome, most approaches are based on current measurements. From a measured current, the cable insulation temperature can be derived using an electrothermal model. Those models can be very complex, especially when the transient and axial heat flow in a cable should be considered. The computational efforts for the commonly used numerical solution methods are high. Analytical approaches potentially reduce these efforts significantly. In this article, a new analytical approach for the calculation of the transient axial temperature distribution along an insulated single wire cable, considering the nonlinear temperature dependence of the cable parameters, is presented. It enables a precise and fast calculation of cable temperatures, e.g., for automotive cable harnesses. There it can be beneficial for the control of electronic fuses where computing resources are low. The cable insulation can be operated closer to the limits and the overload protection can still be guaranteed.

Study on Combustion Characteristics of Cable Based on Cone Calorimeter

Cross-linked polyethylene (XLPE) carries a high fire risk. In this paper, a cone calorimeter is used to carry out radiation ignition experiments, and the heat release rate (HRR), mass loss rate (MLR) and other combustion parameters of XLPE cables under three kinds of radiation intensity are measured. By comparing the ignition time and HRR of samples under different conditions, the following conclusions are drawn: (1) The ignition time of XLPE cables decreases significantly with the increase in external thermal radiation intensity. The critical ignition heat flux (CHF) is about 16.24 kW/m2. (2) The HRR curve of XLPE is consistent with the characteristics of hot, thick material. The HRR rises rapidly to the first peak after ignition and then rapidly decreases. Then, it slowly rises to the second peak. Finally, it slowly decays until the combustion stops. (3) The first peak values of HRR of XLPE under different radiation intensities are almost the same. The time for the second peak of HRR is shorter, and the value is larger with the increase in external thermal radiation intensity. (4) The cable ignition model is established, which can simulate the cable ignition time well under different radiant heat flow conditions. (5) Based on the mathematical model, the ignition time trend with the thickness of sheath layer and conductive core layer as variables is deduced.

Capacity Analysis of Cable Insulation Crosslinking Production Process Based on IoT Big Data

In the cable insulation crosslinking production process, the process quality is determined by multiple processes and multiple related process variables, and there are complex autocorrelation and cross-correlation among these process variables. In this paper, different process variables are studied. By implementing statistical process control on a univariate, single value control chart (I) and moving range control chart () are drawn, and process capability CP is analyzed to find variables with weak process capability for improvement. At the same time, based on the background of the continuous development of the Internet of Things and big data technology, this paper evaluates the complex autocorrelation and cross-correlation between the overall process variables, adopts the multivariate statistical process control technology, and combines the multivariate HOTELLING T2 control chart and MEWMA control chart to reflect the statistical characteristics of multiple variables, thus avoiding misjudgment or omission of process quality monitoring model. By studying the setting of cable production process parameters and quality standards, combined with the application of complete multivariate statistical process control (MSPC) around the evaluation results, process, and technical requirements, this research can provide effective guidance for the cable insulation crosslinking production process

Measurement and modeling of effective cable parameters of unshielded conductors

PurposeCables are ubiquitous in electronic-based systems. Electromagnetic emission of cables and crosstalk between wires is an important issue in electromagnetic compatibility and is to be minimized in the design phase. To facilitate the design, models of different complexity and accuracy, for instance, circuit models or finite element (FE) simulations, are used. The purpose of this study is to compare transmission line parameters obtained by measurements and simulations.Design/methodology/approachTransmission line parameters were determined by means of measurements in the frequency and time domain and by FE simulations in the frequency domain and compared. Finally, a Spice simulation with lumped elements was performed.FindingsThe determination of the effective permittivity of insulated wires seems to be a key issue in comparing measurements and simulations.Originality/valueA space decomposition technique for a guided wave on an infinite configuration with constant cross-section has been introduced, where an analytic representation in the direction of propagation is used, and the transversal fields are approximated by FEs.

Stability Parameter Range of a Tethered Unmanned Aerial Vehicle

In this study, the stability parameter range of a tethered quadrotor unmanned aerial vehicle (UAV) under the action of the transient wind field is numerically analyzed, which can provide a theoretical basis for the design and application of such systems. Three factors affecting the stability of tethered UAV system are determined, namely, cable tension, cable elongation, and UAV vibration velocity, and the corresponding judgment criteria are obtained. Specifically, the priority of the three criteria sequentially decreases. According to these criteria, the stability parameter range of the tethered UAV is examined under the cable parameters such as length, diameter, and elastic modulus and the environmental parameters such as the amplitude and period of the wind field. The results show that for designing the tethered UAV structure, by reducing the length of the tethered cable and increasing its diameter and elastic modulus, the working stability of tethered UAV system can be improved.

Simulation Analysis of Grounding Characteristics of Cable Based on ATP-EMTP

In order to improve the operation safety and stability of power cables, it is necessary to conduct targeted research on different grounding modes. Firstly, the appropriate cable parameters are selected according to the specific use, and the model is established in ATP-EMTP according to the selected cable parameters. Then, the availability of three grounding modes models of grounding at one end, grounding at both ends and cross-connection grounding (cable core grounding, shielding layer grounding and armor layer grounding) are compared and verified by simulation. Finally, by setting the shielding layers of different thicknesses as a comparison, the impedance and current characteristics of the cables under three different grounding methods are analyzed. The results show that the impedance values of the three grounding methods are basically the same. However, according to the current characteristics, when the shielding layer and the armored layer are cross-connected and grounded, the current of them is much smaller than that which is grounded by other grounding methods. Therefore, under the comprehensive consideration of economic benefits, this grounding is the best choice. This study provides guidance for the grounding mode of cable early laying, and provides reference for other cable related research.

Accurate Formulation of the Skin and Proximity Effects in High-Speed Cable System

An efficient transmission line model of high-speed cables is established, to predict its response at a high-frequency region (up to 20 GHz). Especially, an appropriate conformal mapping technique is applied to formulate the per-unit-length parameters of high-speed cables. Moreover, the skin and proximity effects of the conducting wires and the outer shield are derived in the closed form. As a result, the AC resistance/ inductance of all the conducting materials due to the skin and proximity effects are accurately incorporated for both layered and unlayered conductors. Furthermore, the mixed-mode S-parameters are precisely predicted for both balanced and unbalanced transmission line cables in the high-frequency region. In addition, the effects of the nonuniformities and cable geometry deformation on the mode conversions are also investigated. The proposed model is firstly validated with commercial software tools, COMSOL, FEKO, and HFSS; then, we further performed physical measurements to verify our new algorithm.

ケーブル系橋梁の維持管理のための振動計測に基づくダンパー付ケーブルの張力推定手法の開発

In the maintenance of cable structures, such as cable-stayed bridges, it is necessary to estimate the tension acting on the cables. In current Japanese practice, the cable tension is estimated using the vibration method or the higher-order vibration method from the cable’s natural frequencies. However, in recent years, the aerodynamic vibration of cables caused by wind has become a problem. To suppress the aerodynamic vibration, dampers are installed onto the cables. Because the damper changes the cable’s natural frequencies, the vibration method and higher-order vibration method are inappropriate for measuring the tension of a cable with a damper. This paper introduces a tension estimation method for a cable with a damper proposed by the authors. The authors’ method inversely estimates the tension and bending stiffness of the cable and damper parameters, simultaneously, from the natural frequencies. The validity of the method was confirmed by conducting numerical simulations and experiments.

Impact of MV Standards on Shipboard DC Cable System Size

There is rising interest in medium-voltage direct current (MVDC) power systems for several reasons, including compatibility with DC loads and avoidance of alternating current (AC) frequency synchronization issues when combining multiple source outputs [1]. However, few MVDC systems are currently in operation, and there is relatively little experience compared to the knowledge available for medium-voltage alternating current (MVAC) systems. Presently, IEEE Std. 1709 is the only standard that provides guidance for MVDC systems [2]. This work’s objective is to harmonize the information within MVAC standards to produce prospective design and test values for shipboard MVDC cables and evaluate their impact on cable system sizes. Standards for MVAC cable design and test parameters including Basic Lightning Impulse Insulation Level, Withstand Voltage, and cable insulation thickness are compiled to understand the range of parameter values deemed acceptable for MVAC cables. Based on existing shipboard MVAC standards and IEEE Std. 1709, this study produces prospective design and test values for a shipboard MVDC system with a 12 kV Nominal System Voltage. Additionally, a tradeoff was identified with the thickness of cable insulation where a small reduction in cable system size can be achieved but at the expense of substantially greater electric stresses within the insulation.

Adaptive Nonlinear Control of Generator Load VSC-HVDC Association

This paper studies the problem of controlling a long distance transmission system for huge amounts of electrical energy (Generator-Load VSC-HVDC). An adaptive controller is designed to meet two controller objectives: (i) regulating the continuous voltage at the end of the HVDC cable; and (ii) ensuring a perfect power quality and system stability, which can be achieved by continuously adjusting the active and reactive powers independently. The controller's robustness is addressed by considering various parameter uncertainties, such as DC cable parameter variations. Furthermore, since the DC load is usually located at great distances from the control unit, a high gain observer is designed to estimate the DC cable states, as well the current in the load. Thus, the output voltage and current of the VSC are the only accessible measurements. The theoretical analysis results are approved by numerical simulation within MATLAB/SIMULINK environment.

Destruction of polymer insulation and threshold amplitudes of current pulses of different temporal shapes for electric wires and cables in the low- and high-current circuits of pulse power engineering, electrical engineering and electronic devices

Goal. Development of engineering method for settlement of threshold amplitudes Impk of single-pulse current ip(t) of different temporal shapes for electric wires and cables with polyethylene (PET), polyvinylchloride (PVC) and rubber (R) half-length insulation, used in modern pulsed power engineering, electrical engineering and electronics in their low- and high-current circuits. Methodology. Basis of the theoretical and applied electrical engineering, electrical power engineering, electrophysics bases of technique of high-voltage and large pulsed currents, bases of low- and high-current electronics, measuring technique, electromagnetic compatibility and standardization. Results. Development of engineering method is executed on close calculation determination of threshold amplitudes Impk of single-pulse axial-flow current ip(t) of different temporal shapes for electric wires and cables with copper (aluminum) current-carrying parts and PET, PVC and R half-length insulation, used in the ow- and high-current circuits of pulsed electrical power engineering, electrical engineering and electronics. Electrothermal resistibility of half-length insulation of the examined cable and wire products (CWP), proper maximum to the possible temperatures of heating of current-carrying and insulating parts of the probed wires and cables and shutting out the offensive of the phenomenon destruction in the indicated insulation of CWP, was fixed based on this method. Calculation analytical correlations are obtained for finding in probed CWP of threshold numeral values of Impk amplitudes of pulses of current ip(t), time-varying both on aperiodic dependence of type τf/τp with duration of their front τf and duration of their pulses τp and by law of exponential attenuation sinewave. It is shown that at Imp>Impk destruction of their half-length insulation, resulting in the decline of service life of CWP, will come from the thermal overheat of current-carrying parts of the examined electric wires and cables. The examples of practical application of the offered method are resulted upon settlement for a radiofrequency coaxial cable RC 50-4-11 with middle sizes is easily soiled with continuous PET insulation of threshold amplitudes of Impk of standard aperiodic pulses of current ip(t) from nano-, micro- and millisecond temporal ranges of shape of τf/τp=5 ns/200 ns, τf/τp=10 μs/350 μs and τf/τp=7 ms/160 ms. It is shown that with the proper growth of parameter τp>>τf for flow on a continuous copper tendon and split copper shell of radiofrequency coaxial cable RC 50-4-11 with middle sizes is easily soiled indicated homopolar pulses of current ip(t) substantial diminishing of their threshold amplitudes of Impk (with 531,2 кА for the nanosecond pulse of current of type 5 ns/200 ns to 1.84 кА for the millisecond impulse of current of type of 7 ms/160 ms takes place). Originality. An engineering method is first developed for close settlement of threshold numeral values of Impk amplitudes of single-pulse axial-flow current ip(t) of arbitrary peak-temporal parameters for electric wires and cables with copper (aluminum) current-carrying parts and PET, PVC and R half-length insulation. Practical value. Application in electrical engineering practice of the offered engineering method for determination of threshold amplitudes Impk of the indicated pulses of axial-flow current ip(t) for the probed electric wires and cables will allow considerably to increase service life of examined CWP.

EXPERIMENTAL MEASUREMENTS OF FREQUENCY-DEPENDENT ACTIVE COMPONENT IMPEDANCES FOR HARMONIC STABILITY ASSESSMENT

Frequency-dependent impedance models are required for investigating the harmonic stability of power-electronic components in the frequency domain. The experimental measurement of components is a possible approach to determine the frequencydependent equivalent impedances. However, measurement techniques such as wideband impedance measurement of active components are not well established. Thus, this paper deals with the measurement or extraction of wideband impedances of active components such as inverters. The selection of test objects is focused on component types and models that have already been integrated into low-voltage grids in large numbers. For that, various measurements are performed in the low-voltage laboratory using commercial single-phase inverters. Additionally, this paper examines three different measuring techniques. Differences between the extracted impedances of various inverters are analysed and the influence of the cable impedance is determined. Furthermore, an aggregation of multiple inverters as a Thevenin equivalent is carried out and an analytical aggregation is compared with associated measurements. The results show that different measurement techniques can be used, yet not equally suitable for all frequency ranges. Differences in the measured frequency-dependent impedances are observed among various commercial inverters and as a consequence confirm the need for experimental measurements. It is also shown that the influence of the cable impedance can be taken into account analytically if the cable parameters are known. Besides, the analytical aggregation based on single component measurements is possible, provided that the grid impedance is negligible and the systems do not influence each other.

Simulation Analysis of Current in Metal Sheath of Power Cable Considering Temperature Characteristics

This paper proposes a cable broadband circuit model considering the temperature characteristics. This paper establishes the equivalent circuit model of the cross-bonded power cable and proposes the broadband parameter calculation method considering the temperature. The cable parameters are calculated by the vector fitting method. Based on the operating current and cable temperature data of the cable on a certain day, the simulation analysis of the cable sheath current considering the temperature is carried out using Simulink. Finally, the simulation results show that the cable sheath current is significantly affected by temperature.

Simulation study of 6–10 kV cable lines for transient processes calculation during earth faults

As a rule, researchers do not consider the dependence of the inductance of cable lines on frequency in their scientific papers devoted to the calculation of transient processes during single phase-to-ground fault in 6–10 cable networks. In some cases, it can lead to significant errors in evaluation of current and voltage transient components parameters. Therefore, it is an urgent task to estimate defined errors and the scope of application of frequency-independent equivalent circuits and models of 6–10 kV cable lines during calculation and simulation of transient processes in case of single phase-to-ground fault. The authors applied PSCAD / EMTDC software to study the effect of the frequency dependence of the inductances of 6–10 kV cable lines on the calculation accuracy of transient processes during single phase-to-ground fault. It allows to simulate electric power systems models with the usage of both frequency-dependent and frequency-independent cable line models with round conductors only. To check the adequacy of the frequency-dependent three phase cable model developed in PSCAD software, the authors have used a frequency-dependent model of 6–10 kV three-phase cable with sector-shaped conductors designed in COMSOL Multiphysics software. The authors have developed an approach to develop of 610 kV cable lines models with frequency-dependent and frequency-independent parameters. The authors have obtained error estimation in transient current and voltage parameters during single phase-to-ground fault in cable networks models that do not consider the frequency dependence on inductance (for discharge components the error is 1520 %, for charging components the error is equal to 510 %). It is shown that models with cable line parameters defined according to spreading speed of electromagnetic wave, can be used for approximate calculation of transient current and voltage to solve most of tasks of investigation of transient processes during single phase-to-ground faults. Application of the developed recommendations to determine three phase medium voltage cable lines parameters will increase the calculation accuracy of transient processes during single phase-to-ground faults in 6–10 kV cable networks. Only application of frequency-dependent models of cable lines allows us to provide required accuracy to develop methods of distant earth fault localization in 6–10 kV networks.

Cable Design and Development for the High-Temperature Superconductor Cable Test Facility Magnet

A large bore “High-Temperature Superconductor Cable Test Facility Magnet” for testing advanced cables and inserts in high transverse field is in its design phase. This magnet will be the core component of a facility for developing conductors and accelerator magnets operating above 15 T, an enabling technology for next-generation fusion devices using magnetic confinement of plasma and for future energy frontier colliders. The procurement of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductor, fabrication of cables, winding of coils, and assembly of the dipole magnet will be done at Lawrence Berkeley National Laboratory (LBNL) and the test pit and cryostat will be constructed at Fermi National Accelerator Laboratory. This article will present the conductor element of the LBNL project, specifically cable design parameters (based on the Bruker OST RRP <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\bigcirc \!\!\!\! {\hbox{R}}}$</tex-math></inline-formula> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting wire) and the development phase cable fabrication experience. Challenges of the cable fabrication will be discussed. The wire and cable planned for this magnet are similar to those under study for the Future Circular Collider and other large facility magnets. The successful fabrication of the development cable has positive implications for these other projects.

Analysis of the resonance phenomenon in unmatched power cables with the resonance surface response

Power converters are an essential part of modern power systems, giving flexibility to the power transportation and allowing the insertion of a wide range of different energy sources. One drawback of the converters is that the supraharmonic conducted emissions introduced by them can compromise the stability of these systems through electromagnetic interference (EMI). Electromagnetic compatibility (EMC) filters are used to prevent such problems. Nevertheless, these filters are designed to respect standards based on measurements in conditions considerably different from real applications. Particularly, if a converter is connected to electrically long cables its conducted emissions may be amplified by the resonance phenomenon. The method described in this paper allows the definition of a range for the filters input impedances where the conducted emissions in a long cable will not be amplified beyond established levels. In some cases the method allows the visualization of three-dimensional surfaces indicating the magnitude, frequency and position of the resonance phenomenon. In the general case these surfaces are defined on higher dimensions and can be analyzed with deterministic optimization algorithms. The originality of this paper resides in the generalized analysis of the resonance phenomenon, that it is based on frequency-dependent cable parameters and applies to unbalanced systems.