Power Transmission Cables Research Articles

An Insight on Right of Way and its Cost for Power Transmission Cable and Conventional Overhead Transmission Lines

This paper provides the complete information related to Right of Way (RoW) for the construction of new power transmission line (TL) in terms of present cost for overhead transmission line and underground XLPE transmission cable. The former part of the paper describes the general procedure and rules for acquisition of land for RoW by transmission asset owner (TAO) while in the later part the cost associated to acquire RoW and its impact on the cost of adjacent land have been detailed. It also discusses the actual dismantling cost including the cost of waste metal what TAO get after completion of lifecycle of TL due to increase in metal prices. In this paper cost of RoW after completion of lifecycle of TL is also highlighted. This paper compares the cost of RoW for overhead transmission line and underground XLPE transmission cable for construction of new TL. Also for old transmission infrastructure cost of RoW for change from overhead transmission line to underground XLPE transmission cable is detailed by application of replacement model.

Narrowband PLC SIMO-Based Interference Suppression With Zero-Forcing

A single-input multiple-output-based architecture is considered to support co-channel interference (CCI) suppression processing at the receiver, where narrowband (NB) outdoor power-line communications (PLC) in the 42-89 kHz frequency band are assumed. The phantom mode (PM) in a multiconductor power transmission cable is employed for transmission, and both the PM and the differential mode (DM) are used at the receiver. Transfer functions for the PM-PM and the PM-DM modes are modeled for short-range and long-range outdoor NB PLC topologies incorporating three-path propagation using a deterministic transmission-line modeling approach. An orthogonal frequency-division multiplexing (OFDM) waveform based on the PRIME standard is used for the desired and CCI signals. Interference suppression is achieved through a zero-forcing algorithm that leverages multichannel reception and requires channel state estimates for the interference signal. Stochastic network structures are further discussed to demonstrate the average interference suppression performance. Bit-error-rate performance is estimated in the presence of interference with and without zero-forcing suppression. Results indicate that the suppression algorithm leads to a more robust interference-tolerant receiver, particularly when the relative channel responses between modes for the desired signal and the interference signal are sufficiently different.

Cable Fault Recognition Based on the Wavelet Energy Spectrum of Mode Components

When a fault appeared in a power cable transmission line, the transient current with high frequencies would be produced in the system. Three independent mode components could be obtained by applying the phase mode transformation to the transient current. For different types of the faults, the three independent mode components have different features. Based on wavelet energy spectrum of mode components, a method for cable fault recognition is developed in this paper. First, the fault current is decomposed by using Karenbaue transformation matrix. Then, wavelet transformation is uses to obtain the coefficients of the high frequency components which reflect the original signal high frequency energy. Finally, based on the wavelet energy spectrum method and the detailed coefficient manipulation, the equivalent norms of the mode components are obtained. Compared with the traditional fault recognition method, the new method depends less on zero mode component in two-phase short to ground state, and it can recognize the fault class in the cases of different fault positions, different fault path resistances and different inception angles.

Partial Discharge Simulation and Analysis Based on Experiment in Underground Distribution Power Cables

This paper describes the simulation and experiment for partial discharge (PD) pulse propagation in 22.9kV CNCV power cables. To investigate the propagation characteristics of PD, experiments are carried out by injecting the PD pulse in 100m-long 60 mm² CNCV cable in the laboratory. The characteristics of PD are also simulated using EMTP to investigate and analyze PD in the same cable. By comparing the simulation and test results, parameter permittivity is recalculated by considering semiconducting screen in the process of simulation and analysis of PD. After it is proved that simulation results and test results are almost similar in the laboratory, extensive simulations are performed to analyse various PD characteristics such as propagation velocity, attenuation, etc. in 60 mm² and 325 mm² CNCV cables. Authors are confident that results obtained in this paper will be used as important technical materials to detect and investigate PD generated in transmission and distribution power cables.

Lateral Distribution of Critical Current Density in Coated Conductors Slit by Different Cutting Methods

We have investigated the lateral distributions of critical current densities in narrow coated conductors slit by different cutting methods. The objective was to find an optimal slitting process to make a narrow conductor that should be effective for ac loss reduction of assembled conductors such as power transmission cables. In-plane 2-D distribution of critical current density was characterized by means of scanning Hall-probe microscopy. From an analysis along the width direction, we could estimate the degradation in critical current density by a slitting process at both tape edges. We determined an equivalent width for the slit tapes in order to discuss such degradation with a high spatial resolution. Furthermore, the 2-D scanning allows us to evaluate the effective tape width as a function of longitudinal coordinate. In other words, we could evaluate the equivalent width of a slit conductor together with its statistics along the longitudinal direction. As a result, it was found that coated conductors slit by laser cutting processes were clearly better than those by mechanical ones from the viewpoint of less degradation at their edges. In addition, an optimal condition among laser slitting processes was also presented.

Superconducting Levitation Using Coated Conductors

The second-generation (2G) YBCO wire has been used for several applications, such as electric power transmission and distribution cables, fault current limiters, MagLev vehicles, electric machines, high field magnets, superconducting magnetic energy storage, etc. The main advantages of 2G wires are: high critical current density values, large scale production, lower manufacturing cost than first generation, and superior performance under high magnetic fields. This work presents a preliminary study of superconducting magnetic bearings (SMB) using 2G wires as passive levitators. A superconducting block using stacked 2G wires was built to evaluate the behavior of coated conductors in the SMB application. The levitation and lateral force between the 2G block and a permanent magnet guideway was measured and compared with the results for an YBCO bulk with approximately the same dimensions. The results indicate that 2G wires have potential for applications with superconducting levitation, but its economic feasibility still depends on the coated conductors price decreasing.

Analytical Methods and Formulas for Modeling High Temperature Superconductors

The electrodynamics of type-II superconductors is considered in the quasi-static limit when the concept of the so-called critical state is well applicable to the superconductors. We review analytical techniques and formulas used to describe the critical states in the superconductors of the various shapes characteristic of high-temperature superconducting materials. In particular, it is explained how 3-D critical-state problems for thin planar superconductors can be reduced to more simple 2-D problems. Within this approach, the critical states in a thin infinitely long superconducting strip are analytically described not only in the simplest case of a constant critical current density jc but also in the case of anisotropic flux-line pinning and for simple model dependence of jc on the magnetic-field magnitude. We also present the analytical solutions of the critical-state problem for superconducting strips with ferromagnetic substrates and for various arrays of superconducting strips with a transport current or in an external magnetic field. In particular, one of the discussed configurations of the strips can model superconducting power transmission cables. We also describe some analytical solutions of the electrodynamic equations for type-II superconductors with power-law voltage-current characteristics.

Development of a finite differential model for the analysis of environmental effects on transmission lines for down-hole applications

Coaxial cables are often used for data-transmission between top-side and down-hole tools over long distances. In term of cost, it is advantageous to use the same cables for power transmission when feasible. However, environmental effects can degrade the performance of cables, which are exposed to hostile conditions. This paper examines the environmental effects on transmission efficiency of coaxial cables when used for the transmission of power to down-hole tools and data acquisition systems. The performance of the cables was analysed using a finite differential model. A special feature of the model is that it implicitly introduces the effects of temperature differentials to which the cable may be exposed, through the primary cable constants. The model can be used to predict the optimum condition for maximum power transfer in the low-to-medium frequency range.

A model of hoarfrost formation on a cable

Abstract A time-dependent numerical model of hoarfrost formation on an overhead cable is presented. The model is aimed at calculating the thickness of a hoarfrost layer using routinely measured meteorological data as input. The growth rate and density of hoarfrost are simulated. This requires continuous calculation of the surface temperature around the cable. The model also simulates the disappearance of hoarfrost by sublimation, melting and dropping off. The feasibility of explaining the occurrence of corona losses on overhead power transmission cables by the modeled hoarfrost thickness is demonstrated by field data.

Design and Test of Saturable Reactor

With the expansion of the grid, continuous reactive power compensation is vital for efficient operation of long transmission power lines or cables. Yunnan Electric Power Grid is planning to development saturable reactors for 500 kV long distance AC transmission lines. As the first stage of the development plan, the appropriate saturable reactor structure should be presented and verified by experiment. In this paper, different ferromagnetic materials, core structures and winding arrangements of saturable reactors are analyzed. Then, appropriate saturable reactor structure is determined by simulating calculation. Based on that, a small-scale prototype is designed and fabricated. The experimental results show that it can obtain a continuous controllable reactive power output.

Ac loss analyses of superconducting power transmission cables considering their three-dimensional geometries

Numerical electromagnetic field analyses of superconducting power transmission cables consisting of coated conductors were made considering their three-dimensional spiraled structures. Thin strips of superconductor were wound spirally around a round former to represent a layer in a cable. The analyses were made for two-layer cables where the spiral pitch of the inner layer and that of the outer layer are different. A non-uniform lateral critical current density distribution, a trapezoidal distribution with shoulders, was assumed across each coated conductor. The calculated ac losses were compared with measured ones. The influence of the relative positions between the inner-layer coated conductors and the outer-layer coated conductors on the current distribution across each coated conductor as well as ac losses was discussed. The influence of the current distribution between layers, determined by the spiral pitches, on the ac losses was also studied.

AC loss reduction of outer-diameter-fixed superconducting power transmission cables using narrow coated conductors

AC loss reduction of superconducting power transmission cables is of great importance to promote their application in power grids. To meet certain installation conditions, cables are required to be designed with fixed outer diameters. This paper focuses on outer-diameter-fixed monolayer and multilayer (2-layer and 4-layer) superconducting power transmission cables constructed with coated conductors. Detailed numerical analysis of their AC loss reduction by replacing generally used 4-mm wide coated conductors with 2-mm wide narrow ones are presented. A 2-D FEM numerical model was developed to calculate AC losses of the cables. For detailed and comprehensive analysis, a series of variable parameters, such as number of layers, critical current density (Jc) distributions of coated conductors and load rate, are varied at well selected values to study their influences on the AC loss reduction. It is obtained and testified that 2-mm wide narrow coated conductors can effectively reduce AC losses in both monolayer and multilayer cables, even though more gaps are introduced. The knowledge presented is helpful for designing and fabricating practical cables.

Simulation of Snow Adhesion on Real-Scale Lines

Wet snow shedding from overhead power transmission cables due to periodically repeated impacts was simulated using the finite element software ADINA. It was simulated by point loads whose mass depended on the snow load on the cable. The adhesion between snow and cable was modeled by vertical springs whose stiffness was determined so that the spring force simulates tensile adhesion. Failure criterion for snow detachment from the cable was defined based on the acceleration of the snow-covered cable. This model was applied on a real scale cable with span length of 470 m. Time history of displacement at the excitation point was the input to the model, where varying impacts lead to different accelerations of the cable. The results showed the effects of increasing impact loads on cable jump and, consequently, on the rate of shedding.

Recent Progress in Electrical Insulation Techniques for HTS Power Apparatus

This paper describes the electrical insulation techniques at cryogenic temperatures, i.e. Cryodielectrics, for HTS power apparatus, e.g. HTS power transmission cables, transformers, fault current limiters and SMES. Breakdown and partial discharge characteristics are discussed for different electrical insulation configurations of LN2, sub-cooled LN2, solid, vacuum and their composite insulation systems. Dynamic and static insulation performances with and without taking account of quench in HTS materials are also introduced.

Experiment of the 200-Meter Superconducting DC Transmission Power Cable in Chubu University

Abstract After we constructed the 200-meter superconducting DC power cable in spring of 2010, three experiments have been done until March, 2011. We changed and improved the experimental devices, especially to reduce the heat leak. We describe the experimental results and the data analysis for the pressure drop of liquid nitrogen circulation. We summarized the experimental results briefly, and estimate the pressure drop of the circulation for a longer cable system (∼2 km) depending on the experimental conditions. We also mentioned the performance of the system as compared with the copper cable.

Assessment of alternative design schemes to reduce the edge losses in HTS powertransmission cables made of coated conductors

In this paper, we investigate the effectiveness of alternative designs to reduce the AC lossesof high temperature superconducting (HTS) power transmission cables. The idea behindthese designs is to undermine the edge effect, which is one of the main factorscontributing to AC losses in HTS power cables made of coated tapes. The edgeeffect, which arises from the presence of gaps between the tapes, results in largenormal components of magnetic field near the edges of the tapes and in turnsleads to a current distribution with higher density near the edges. To perform ourinvestigation we use a numerical technique developed in our previous work whichallows us to consider the helical configuration of the tapes. Through numericalsimulations we assess the effectiveness of two overlapped designs, i.e. a cyclic overlappeddesign and an anticyclic overlapped design, in reduction of AC losses in singlelayer HTS power cables made of coated tapes. Simulation results show that AClosses can be reduced by about 70% as compared with a typical single layer cable.

A Bi-2223 Layer-Winding Coil Using 540 m Tape Including a Joint Inside the Winding

High Temperature Superconductors (HTS) are now widely used in many applications such as power transmission cables, motors, etc. Recent (Bi,Pb) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Ca <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> (Bi-2223) conductors have been much improved in transport and mechanical properties, and their application as insert coils for high field generation is expected. In order to demonstrate the feasibility and the potential of Bi-2223/Ag tapes for magnet applications, we fabricated a layer-wound coil using Bi-2223/Ag/Cu-alloy tapes. We used two tapes, 330 m- and 210 m-pieces, in order to examine the possibility of extension of conductor length through a lap-joint inside the coil. These two tapes were soldered without removing Cu-alloy laminations. The winding has the dimensions: inner dia. 57.1 mm, outer dia. 88.9 mm, coil height: 153.9 mm, 44 layers (2,355 turns). We tested this coil at 4.2 K in 0 ~ 12 T. The test coil carried 193.3 A (0.1 μV/cm criterion) and generated 3.3 T in the axial direction of the coil in external 12 T (15.3 T in total). The critical current is close to the short sample performance in the perpendicular fields. Splice resistance at the joint stayed about 1 μΩ at 4.2 K, 10 T.

Investigation of Power Dissipation Mechanisms in Coated Conductors at High Current Densities Based on Ultra-Fast Pulsed Current Measurements

In this contribution, we report and discuss the physical meaning of pulse current measurements carried out on coated conductors (CCs) consisting of a superconducting YBCO film deposited on a Hastelloy substrate and coated with a thin metallic layer. The high current (up to 1000 A) and short duration pulses (from 10 μs to 1 ms) have allowed us to determine the current-voltage characteristics of two different samples in a situation near that of zero injected energy, and therefore remove the bias resulting from the temperature rise during the measurement. The characteristics obtained show a flux creep region and two linear regimes. The first linear regime is the flux flow regime. In this regime, we show that the vortex velocity is a constant that depends on the metal film resistivity. The second linear regime is ohmic and his origin is less clear. We propose models describing both linear regimes, that are in agreement with the measurements. Finally, we discuss the consequences of these results for the applications of the coated conductors in devices for power systems, especially fault current limiters and power transmission cables.

Alternative Design Concepts for Multi-Circuit HTS Link Systems

Superconducting cables for power transmission usually contain two conductors for DC application, or three conductors for AC, with high voltage insulation. In contrast, for some applications related to accelerators it is convenient to transfer high currents via superconducting links feeding a number of circuits at relatively low voltage, of the order of a kilovolt, over distances of up to a few hundred meters. For power transmission applications based on cooling via sub-cooled liquid nitrogen, suitable HTS conductors are only available in the form of tape, and a multi-layer variant can be envisaged for the multi-circuit links. However, where cooling to temperatures of the order of 20 K is feasible, MgB2 conductor, available in the form of both tape and wire, can also be envisaged and in the latter case used to assemble round cables. There are, therefore, two distinct topologies-based on the use of wires or tapes-that can be envisaged for use in applications to multi-circuit link systems. In this paper the merits of the two approaches are compared, and case studies related to applications to the LHC are presented.

Critical Current and Its Magnetic Field Effect Measurement of HTS Tapes Forming DC Superconducting Cable

We constructed a test stand of 20 m-class DC superconducting power transmission cable in Chubu University, in 2006. The cable consisted of thirty-nine Bi-2223 HTS tapes in two layers; nineteen tapes were used in the first layer and twenty tapes were used in the second layer. One of the features of the cable is that each HTS tape in the first layer is electrically isolated. Therefore, we can apply the current to the individual HTS tapes in the first layer. We measured critical current of the one HTS tape in the first layer when current was applied to the other HTS tapes, and compared the result with the magnetic field calculation due to the applied current. The critical current increased by 2 ~ 4% when the current was applied to all other eighteen HTS tapes in the same layer. From the magnetic field calculation, we concluded that the self magnetic field of the measured HTS tape was eliminated at the tape edge by the applied magnetic field from the neighbor HTS tapes, and then the critical current increased.