Cable Parameters Research Articles

Novelty Underground Cable Model for Power System Transient Simulation

This paper presents an extension of the A-line model [11] for underground cables that takes into account the frequency dependence and includes the conductance matrix; the new cable model is named the U-Cable model. This paper also presents the mathematical development that supports the new U-Cable model; thus, following the methodology, it can be observed how the cable parameters are related to the construction of the final mathematical model. This model has the characteristic that the fitting is generated by real poles in a natural manner without forcing vector fitting to change to only real poles, which makes the developed model extremely stable from a numerical point of view. The numerical Laplace transform (NLT) and PSCAD software are used for comparison purposes. The reason for the use of the NLT is that, if it is properly programmed, it always yields a reliable solution. For the comparisons, a short-circuited line is simulated first, followed by a matched line and then an open line with a unit step. A second simulation is performed by changing the unit step to a three-phase sinusoidal source. A comparison of the results obtained from the proposed model with those of the NLT and PSCAD provides support and reliability to this model because the differences observed, in most cases, are barely perceptible. Thus, it can be concluded that the presented model is an additional option to the existing models.

Multi-Pair Cable Measurements for 5G Indoor Service Provisioning

This paper considers the 5G new radio (NR) indoor service provisioning scenario where the CPRI link terminates at remote radio unit (RRU) in the building and multi-pair cable, i.e. CAT-5, is used to provide connectivity between distributed antenna unit (DAU) and RRU. The paper focuses on the de-tailed methodology for multi-pair copper channel measurement including measurement equipment specifications, their respective settings, measurement parameters i.e. characteristics impedance, insertion loss (IL), far-end-crosstalk (FEXT) and near-end-crosstalk (NEXT). The measurements include the cables for next-generation multi-pair system, where multi-pair cables, i.e. CAT-5 cables, are used from the RRU to the DAUs in a building. Conventionally, many multi-pair cables share the same duct in a building and interfere with each other, therefore two parallel multi-pair CAT-5 cables of 50m each are considered for the measurement scenario. This setup result in 4 twisted pairs terminate at each DAU and this configuration is termed as next-generation multi-pair MIMO (NGMM). The number of twisted pairs is increased by using the Phantom mode circuit connected to the opposite ends of each CAT-5 cable and the resulting configuration is called next-generation multi-pair super MIMO (NGMSM). The cable parameters have been measured for frequencies up to 1 GHz and 250 MHz for NGMM and NGMSM, respectively. DL data rate of each configuration is examined by applying conventional block diagonalization.

Extraction of High-Frequency Power Cable Transmission Characteristics From Impedance Spectroscopy

This study develops a technique to extract the wave propagation properties of power cables from impedance spectroscopy. This method extracts the propagation constant, characteristic impedance, phase velocity, and RLGC Telegrapher's Equation parameters. The current study first proposes an initial method to extract high-frequency cable transmission characteristics by the impedance spectroscopy of open- and short-ended cables. Using this method, the propagation constant and phase velocity can be extracted accurately. However, the initial method is still problematic. The waveform of characteristic impedance is distorted due to the additional impedance of connection wire between measuring devices and the tested cable. Therefore, this study proposes a modified method, which can eliminate the influence of additional impedance and acquire the high-frequency cable transmission characteristics accurately. By obtaining the series impedance from cable geometry parameters and getting the propagation constant from impedance spectroscopy, the modified method can obtain the characteristic impedance by combining the series impedance and the propagation constant. The extraction is demonstrated for a YJV-8.7/15 kV-1*35 XLPE cable in the frequency range 300 kHz-100 MHz.

Design of High-Density Cable Parameters for Controlling Spatial-Mode Dispersion of Randomly Coupled Multi-Core Fibers

In this work, we propose design parameters for optimized high-density optical cables to control the spatial-mode dispersion (SMD) of randomly coupled multi-core fibers (MCF). The analytical results of our proposed cable demonstrated the controllability of the bending and twisting of the implemented optical fibers by means of tension that is applied for a bundled fiber while keeping the sufficient reliability. An optical characterization showed that appropriate cabling parameters resulted in SMD controllability and a 47% reduction of the SMD coefficient while avoiding undesired loss increase. C-L band transmission experiments using our optical cable showed no degradation of the Q-factor or mode-dependent loss (MDL). Our proposed cable design is beneficial for achieving an SMD-managed large-capacity and long-haul transmission link.

Research of electrical characteristics of increased uniformity LAN-cables

Formulation of the problem. At present, symmetric LAN cables are widely used in structured cabling systems (SCS) and fixed broadband access (BBA) networks in the world and in Russia. Practical experience of using LAN cables on real broadband access networks shows that high-quality transmission can only be achieved using high-quality highly uniform cables.Objective. Study of the dependence of the quality of LAN-cables on technological equipment and the quality of materials, which provide increased cable uniformity.Results. Based on the experimental studies carried out with the use of a modern measuring system, the main electrical characteristics of the transmission and the mutual influence of the most popular four-pair LAN-cable of the 5e category of the U/UTP4×2×0.52 type in the frequency range up to 100 MHz are determined. It is shown that to ensure high and stable transmission characteristics and mutual influence, modern technological equipment must be equipped with cable quality parameters automatic control systems and it is necessary to choose reliable suppliers when using domestic production materials.Practical significance. For the effective practical use of LAN cables on fixed broadband access networks and in SCS, it is very important to have high stability of electrical characteristics and their compliance with rather high established standards. This is possible only by ensuring high geometric and structural homogeneity of the structural elements of LAN cables.

Cable Shape and Construction Parameters of Triple-Tower Double-Cable Suspension Bridge with Two Asymmetrical Main Spans

Abstract Triple-tower suspension bridges with two asymmetrical main spans can adapt to complicated terrain conditions. If the top and bottom main cables with different sags are used on the two main...

Dimensional Parameters Design for Flexible Cable Drive Parallel Mechanism

In order to design the size parameters of flexible cable drive parallel mechanism quickly and accurately, a mathematical model of flexible cable drive parallel mechanism is established, and a design method of dimension parameters for flexible cable drive parallel mechanism is presented. By analyzing the kinematics and dynamics relation of the flexible cable drive parallel mechanism in the finite constraint space, the mathematical model of flexible cable drive parallel mechanism is derived, which includes the constraints of shape size, force and cable weight. The maximum effective working space of flexible cable drive parallel mechanism is calculated, and the dimension parameter value of flexible cable drive parallel mechanism is obtained. It provides the basis for fast and accurate design of key dimension parameters for flexible cable drive parallel mechanism.

A Proposed New Approach for the Assessment of Selected Operating Conditions of the High Voltage Cable Line

Calculation models for the selection of cable lines used for expansion and modernization in the energy system and energy transmission planning are recognized tools supporting decision-making in both the energy sector and energy policy. At the same time, the above calculation models contain a large number of correction factors taking into account the temperature of the external environment at various points, the mutual influence of which is not taken into account. This means limitations to today’s common approaches to solutions, especially with regard to the required safety buffer for cable line selection. To meet this challenge, this article presents a parameter that takes into account the change and difference in temperature at various points in the external environment in the analyzed cable line systems. The purpose of this paper was to develop a new approach to the selection of a cable line in order to minimize failure during operation. For this purpose, possible temperature cases that may occur during line operation in different countries and at different rated voltages have been identified. Simulation models for individual cable line layouts were developed and the extreme temperature cases of the line operation for the maximum negative and positive temperature difference between the cable core and the external environment were considered in detail. The development of the curve of the change of the correction factor for the difference in the operating temperature of the cable line will allow for a more precise selection of the cable line parameters and the shortening of the current calculation model in terms of cable selection. In addition, this article presents a comparison of the change in the value of the correction factor from the change in temperature of a selected phase of a cable line system.

Calculation of overhead and underground cable parameters at harmonic frequencies

This paper presents a new method for the comprehensive calculation of power cable parameters at the fundamental and harmonic frequencies and for the assessment of the power cable’s frequency responses. In spite of its growing technical importance, there seem to be very little information in the open literature about resonances in power cables, particularly, when it comes to the so-called supra-harmonic frequencies, which lie in the range 2–150 kHz. At harmonic frequencies, various phenomena, such as skin effect, ground and metallic return loops, a strong capacitive effect, long-line effects, geometric imbalances and cable cross-bonding have all a marked influence on the responses of both overhead and underground cables. The cable resistances and inductances vary in a nonlinear fashion with frequency, and the latter will cancel out with the cables’ capacitive effects at some specific frequency values giving rise to alternate resonant points along the frequency spectrum. All the relevant construction details of the cable together with its electrical and operational parameters need to be processed by suitable models and methods coded into software for the fast and accurate calculations of the frequency responses of the power cables. A computer program has been developed as part of this research, using the formula and methods outlined in the paper. The usefulness and accuracy of the new methodology are demonstrated by resorting to numerical examples.

Sensitivity of Cable Model Parameters for Traveling Wave Differential Protections in MTDC Systems

Multi-terminal HVDC systems equipped with multiple DC breakers require a protection system that selectively detects faults within a few milliseconds. In the development and application of such protection algorithms, time-domain simulation studies of various faults are essential when determining the setting and verifying the performance. However, when such protections are applied in practice, it should be expected that the models will not perfectly represent the behavior of the real system or transmission line, thereby possibly causing protections to operate unreliably. This paper presents a simulation process that evaluates the consequences for a protection algorithm when the transmission line parameters are varied. More specifically, the false differential current due to cable model parameter errors is evaluated in a traveling-wave differential protection applied in a multi-terminal HVDC system during an external fault. The purpose is to identify the most critical parameters and evaluate how inaccuracies influence the protection performance when applied in practice. It is shown that the parameters which significantly influence the propagation delay are critical for achieving the ideal performance - a strictly zero differential current during external faults.

INVESTIGATION OF THE INFLUENCE OF TWISTING METHODS MULTI-PAIR LAN CABLES ON THEIR ELECTRICAL TRANSMISSION CHARACTERISTICS

The need to study the infuence of twisting methods of cable core of multi-pair LAN cables on their main electrical transmission characteristics is justifed. Experimental studies of the electrical transmission characteristics of multi-pair LAN cables of category 5e in the frequency range up to 100 MHz have been conducted. The results of experimental studies of low-frequency and high-frequency electrical transmission characteristics of these LAN cables are presented. A detailed analysis of the results of experimental studies is carried out. It has been found that high-frequency transmission characteristics such as wave resistance and return losses are most afected by cable core twisting methods. Frequency behavior of these transmission characteristics is analyzed. It was shown that high geometric and structural uniformity of isolated cores, as well as the use of modern high-speed specialized equipment for twisting the pairs provide high transmission parameters of a four-pair LAN cable of category 5e. It was found that SZ twisting technology is unacceptable due to the introduction of geometric inhomogeneities in the manufacture of multi-pair cables. It is recommended to use unidirectional twisting bow-type stranders to minimize geometric inhomogeneities.

An accurate frequency-based method for identifying cable tension while considering environmental temperature variation

In this work, we study the influences of environmental temperature variation on the static and dynamic behaviours of cables, and we develop a very accurate method for identifying the tension of a cable while considering environmental temperature fluctuation. The dynamic equation of a cable that includes the sag effect, the inclination angle and thermal fluctuations is derived, and the numerical solution of temperature-dependent dynamic equations of the cable is obtained by using the finite difference method. The derivatives of the cable's dynamic characteristics with respect to the cable's systematic parameters and the environmental temperature are derived, which furnish an accurate parameter sensitivity method for identifying the tension of a cable subjected to a changing temperature environment. The results indicate that, when the sag-to-span ratio of a cable is between 10−3 and 10−1, the environmental temperature exerts a very important influence on the dynamic behaviours of the cable, not only because it changes the cable's tension but also because it changes the deformation of the cable's sag. In this case, the method proposed in this study is useful and practically important.

Assessing the effects of DER on voltages using a smart meter-driven three-phase LV feeder model

The increasing number of residential distributed energy resources (DER) is driving the need for distribution companies to routinely assess potential voltage violations due to excessive power injections. However, this task can be quite challenging in low voltage (LV) feeders due to the limited availability of modeling data. To this end, this work proposes a practical approach to assess the effects of DER on voltages by exploiting historical time-series measurements from smart meters and head of the feeder. First, the impedances of three-phase feeders are determined assuming knowledge of feeder topology and service cable parameters. Then, the resulting smart meter-driven model is used to compute voltages due to potential DER injections. The performance of the proposed methodology is assessed using a realistic Australian three-phase LV feeder with 40 single-phase customers. Results show that, while there is some error in the calculated impedances, customer voltages are sufficiently accurate for DER management purposes.

Co-optimization of ampacity and lifetime with considering harmonic and stochastic parameters by Imperialist Competition Algorithm

This study presents a novel probabilistic algorithm for the optimal placement of underground power cables to maximize lifetime and ampacity and minimize total cost of the cable system at the same time. In this paper, the Imperialist Competition Algorithm (ICA) and Monte Carlo (MC) simulation are used to solve probabilistic optimization problem. In our previous study, we have just considered probabilistic parameters that are effective on ampacity. However, In fact, we need to consider all the other parameters such as cable’s lifetime and harmonic of demand side for co-optimizing the ampacity and lifetime to obtain the best arrangement of cable system. The cost function of optimization has been improved relative to the last one. Cable lifetime and harmonic of power system, as two important design factors, have been added to cost function in this paper. The novelty of this paper is consisted of economic co-optimization of ampacity and lifetime simultaneously. Furthermore, all statistical variations of cable system parameters, ambient temperature, dimensions of native/backfill soil and uncertainty in demand side such as load current fluctuation and harmonic are considered as design parameters at the same time. Since, all design parameters are stochastic; the change of seasons and climate can modify these parameters along the cable system. Hence, this paper indicates the necessity of consideration of uncertainty parameters at the design phase by taking into account cable lifetime based on a probabilistic approach and avoid using deterministic value. For a better explanation of this method, a numerical example is reported by using corrugated aluminum sheath cable model.

Cable tension identification via nonlinear static inverse problem

A new identification technique is proposed to evaluate the tension of a cable using a static inverse approach that couples a universal cable model with displacement sensors, strain gauges and added masses that should preserve operational affordability. An inverse problem is formulated as the minimization of a data misfit functional based on the differences in terms of vertical displacements and axial strains between two equilibrium configurations of the cable, namely, one loaded and the other free. The inverse problem formulation echoes the parametric study of a non-conventional functional suggesting a way to identify the cable parameters, namely, its length, its axial stiffness, and its mass per unit length. The computational resolution of the inverse problem is implemented as a two-step identification procedure. First, the axial stiffness and mass per unit length are kept constant and the length of the cable is approximately found via a simple line search algorithm using finite differences to estimate the functional derivatives. Second, the other physical parameters are assessed using an adjoint method for which the direct problem, the adjoint problem, and the parameter sensitivities are defined as derivatives of a Lagrangian functional with respect to dual variables, primal variables, and parameters, respectively. Due to the ill-conditioning of the problem, the proposed method does not enable an exact parameter identification but yields a good tension assessment. An experimental test campaign conducted on a multilayered 21-m long stranded cable subject to several tension levels confirms the relevance of the proposed inverse method. A field test campaign of the method on three 120-m long cables of Bonny-sur-Loire (France) suspension bridge is also presented. It proves the reliability and affordability of the overall tension identification process.

3D nonlinear dynamic analysis of cable-moored offshore structures

The nonlinear oscillations of the floating structures anchored by cables are studied in three dimensions. The floating structure is anchored by four symmetric mooring lines and the mooring lines are fixed on the seafloor at the other ends. The stiffness matrix of 3D cable element has been established and applied to analyze the dynamics of the 3D floating structures anchored by cables. The complex compatibility conditions which relate the responses of the floating body and cables have been proposed. The equations of motion for the mooring lines and floating body are individually formulated. Then they are combined as an entire system by utilizing the compatibility conditions. At last, the entire system is analyzed numerically with horizontal harmonic excitations applied on the floating body. The amplitudes for both the responses of the platform and the maximum mooring force are studied as the excitation frequency changes. The responses of the platform and the maximum mooring force are also investigated for varieties of cable parameters.

Investment Cost Analysis with Structural Design of Concrete Duct Bank Power Cables

Capital investment in underground duct bank cables is very expensive. Therefore, the design and planning for underground power cables is important. It is often done with analysis of the power demands minimizing costs over the lifetime of the cables. This work presents an evaluation of underground power cable ampacity and the total costs during the anticipated operational life of the equipment. It was evaluated with variation of concrete duct bank dimensions. Analysis of ampacity depends on temperature. The thermal model of the current study uses a finite element method. The total costs evaluated by the economic model in terms of net present value analysis consist of the initial investment costs and the value of losses over the life of the cable. These were based on installation costs, load factors, annual load growth, the price of energy, the price of demand charges and the forecast discount rate. The results show that cable spacing parameters are a significant factor that influences ampacity. Ampacity can be improved while reducing the losses in power cables. This is because appropriate cable spacing can reduce the effect of Joule heating from neighboring cables. However, this leads to increased construction costs. The total costs of power cables over their lifetime can be reduced by decreasing the horizontal distance between the center of a casing pipe and the side edge of the concrete layer. This is because the contribution of reduced construction costs is more than that of the effect of increased losses. Therefore, the dimensions of the concrete duct bank significantly influence ampacity, the construction costs and the losses of power cables in an analysis of total costs over the lifetime of power cables.

Loss Simulation Analysis and Optimization of U-Groove Leaky Coaxial Cable

Leakage coaxial cable is a kind of coaxial cable with various slot structures on the outer conductor of the cable. It can transmit signal and transmit or receive signal and has dual functions of signal transmission line and antenna. Leakage cable has the advantages of strong environmental adaptability, uniform signal coverage, and less attenuation. It is not only widely used in closed or semiclosed space with high signal reception quality, such as tunnels, subway, underground parking lot, and elevators but also can realize security and theft-proof monitoring and protection in some areas, such as oil wells, mining fields and natural resource protection areas, military fortresses, museums, airports, banks, and schools. This paper introduces the classification and electrical parameters of leaky coaxial cables. On the basis of U-groove leaky coaxial cables, the relationship between the parameters of groove holes in U-groove and the loss of leaky coaxial cables is simulated and analyzed by HFSS software. The improved method of U-groove structure is obtained, and the curved hook-groove leaky coaxial cables are designed according to this method. The simulation results show that the coupling loss of the cable is lower than that of the U-groove leakage cable, and the transmission loss is still within the national standard. It lays a theoretical foundation for the design and development of leaky coaxial cable with low coupling loss.

On the Application of Modal Transient Analysis for Online Fault Localization in HVDC Cable Bundles

This paper presents the modal analysis of different HVDC cable bundles. Using modal theory, specific transformation matrices are presented, and the modal equivalent circuits are illustrated. The behavior of the resulting modes is studied in a wide frequency range, the impact of different cable parameters and burial configurations on the modal characteristics are analyzed. A concept for online fault localization in HVDC cable transmission based on the difference between the modal velocities and consequently the arrival times of the modal traveling wave initial peaks is presented. In this method, modal voltages and currents are used instead of direct measurements and the proposed concept uses one-sided measurement without needing to detect the second TW reflections. Multiple faults are applied to CIGRE HVDC models in PSCAD/EMTDC and the modal analysis is obtained in MATLAB. The impact of different sampling frequencies, fault resistance, fault location and different grounding schemes on the proposed modal fault location principle is analyzed. The theoretical results show the accuracy of the proposed modal fault localization concept for different HVDC cable bundles.

다양한 케이블 변수에 따른 동축 케이블의 HEMP 결합 신호 해석

In this study, we analyze the coupled signal for various cable parameters when a high-altitude electromagnetic pulse(HEMP) is incident on a cable connected to an EMP protection shelter. The structural conditions or operating environments vary depending on the purpose of use, such as to supply power or transmit communication signals to the internal devices of the shelter. Using the cable equivalent model and simulations, we interpret the coupled signal that is induced in the cable according to the presence or absence of a shielding layer, number and thickness of inner core wires, braiding conditions of the shielding layer, cable length, height from the ground plane, and whether the input terminal is grounded. We compare and analyze the induced current according to the cable parameters based on an RG58 coaxial cable.