Cable Layout Research Articles

Wind Farm Cable Connection Layout Optimization Using a Genetic Algorithm and Integer Linear Programming

This work addresses the wind farm (WF) optimization layout considering several substations. It is given a set of wind turbines jointly with a set of substations, and the goal is to obtain the optimal design to minimize the infrastructure cost and the cost of electrical energy losses during the wind farm lifetime. The turbine set is partitioned into subsets to assign to each substation. The cable type and the connections to collect wind turbine-produced energy, forwarding to the corresponding substation, are selected in each subset. The technique proposed uses a genetic algorithm (GA) and an integer linear programming (ILP) model simultaneously. The GA creates a partition in the turbine set and assigns each of the obtained subsets to a substation to optimize a fitness function that corresponds to the minimum total cost of the WF layout. The fitness function evaluation requires solving an ILP model for each substation to determine the optimal cable connection layout. This methodology is applied to four onshore WFs. The obtained results show that the solution performance of the proposed approach reaches up to 0.17% of economic savings when compared to the clustering with ILP approach (an exact approach).

Optimization of Cable Layout With Consideration of Environmental Impact

Optimization of Cable Layout With Consideration of Environmental Impact

Comprehensive layout optimization of the transmission system in a deepwater wind farm cluster

Compared to nearshore wind farms, deepwater offshore wind farms have better wind resources and broader development space and will be the main trend of wind power development in the future. Due to the long distance from the shore, the investment and operation costs of the transmission system in a deepwater wind farm cluster are high and the electricity generated by the cluster is commonly transmitted by high-voltage direct current transmission technology to decrease power losses. For a given converter station, the comprehensive optimization of the layouts of the substations, AC export cables from the substation to the converter station, and cable arrays within each wind farm are complex and have not been well studied. This paper proposes a multi-level nested optimization strategy to minimize the total cost of the collection cables for a deepwater offshore wind farm cluster. The proposed method applies the Informed-RRT* method to optimize the layout of AC export cables while the cable arrays are arranged by Prim’s algorithm. During the optimization process, the gradient descent algorithm is used to optimize the positions of the substations, obtaining the transmission system scheme with the minimum cable investment. For a certain deepwater wind farm cluster, the total cable cost after optimization is reduced by 3.58%, which indicates the effectiveness of this method.

Cable net generation of a deployable offset parabolic reflector using quasi-geodesic curves

Designing an offset cable net in parabolic reflectors introduces several complexities compared to prime focus configurations. This study aims to develop a versatile cable net generation algorithm capable of adapting to the reflector’s dimensions and the curvature of the paraboloid surface. In this regard, we propose a methodology that leverages specific paraboloid surface curves known as quasi-geodesic curves. Similar to geodesic curves on a sphere, quasi-geodesic curves visually resemble proper geodesic shapes but may follow distinct mathematical principles. We introduce two types of quasi-geodesic curves: primary curves that intersect the center point of the cable net and secondary curves that pass through any two points on the net. We present various solutions accommodating different cable net layouts and introduce a quality index based on an equilateral triangle cable net. Finally, we compare the quasi-geodesic-type cable net with the isogrid-type cable net to highlight tension distribution and surface accuracy improvements.

Study on the safety assessment and protection design of human exposure to low-frequency magnetic fields in electric vehicles.

As the power performance of electric vehicles continues to improve, the human body may be exposed to electromagnetic threats in the cabin. This study tested an electric vehicle to analyze the low-frequency magnetic field distribution in the cabin and to assess the safety of human low-frequency magnetic field exposure. A simulation analysis of human electromagnetic exposure was carried out to obtain the magnetic flux density, induced electric field strength and induced current density, and the test results were much lower than the limits specified in GB8702-2014 and the International Commission on Non-Ionizing Radiation Protection, and the relative error between the simulation results and the test results was <15%. This paper investigates the frequency, driving current, vehicle body material and cable layout to explore the law of human body induced electromagnetic field changing with power cable current, and provides theoretical reference for the design of human body low-frequency magnetic field protection.

Rapid Analysis of Bent Cable Crosstalk Based on Numerical Calculation

In this paper, a fast prediction method of cable crosstalk is introduced, which can simulate the crosstalk problem more accurately in the actual cable situation. The traditional flexible cable model considers few factors to truly reflect the spatial pose of the cable. In this paper, constraints of the assembly space are considered to truly reflect the structural characteristics of the cable, providing a theoretical basis for cable bundle layout in the virtual environment. Based on the element method and the theory of multi-conductor transmission lines, the crosstalk coupling model of curved cable is established. In this model, the traditional multi-conductor transmission line theory is improved, and the bending cable bundle model is divided into several equivalent subsegments by using the element method. In the subsegment, the multi-conductor transmission line theory is used for modeling, and the chain parameter method is used for crosstalk coupling analysis. The accuracy of the model introduced in this paper is verified by MATLAB and CST Studio simulation.

Experimental study on fire spread behavior of single 110 kV cable under different layout conditions

High-voltage cable fire accidents can cause large-scale power outages. In particular, the 110 kV large-section (diameter 10 cm) cable has complex cable structures. Therefore, based on the actual cable laying scenarios, three cable layout conditions are set, including the horizontal cable above horizontal floor structure (HCAHFS), the inclined cable above horizontal floor structure (ICAHFS), and the inclined cable above inclined floor structure (ICAIFS). The combustion behaviors and flame spread characteristics of 110 kV large-section cable are experimentally studied. It is found that the flame cannot spread on the surface of the flame-retardant outer sheath of the cable. However, when the cable-floor distance (lcf) is between 0.75 d and 2 d (d is the cable diameter) in HCAHFS, i.e. there is a floor under the cable that can catch cable melt, and the flame spread characteristics is different. After the cable is ignited, the cable fire can be divided into two parts, outer sheath flame and melt flame, and the cable fire can spread under the joint action of two flames. When lcf ≤ 0.75 d, the space under the cable is narrow. With the accumulation of melt on the floor, air entrainment is limited during cable combustion, resulting in the cable flame unsustainable. When lcf ≥ 2 d, the thermal radiation and convection from the melt and outer sheath flame to the cable preheat zone are weakened, resulting in cable flame extinction as well. In ICAHFS, the cable flame spread rate is first increased and then decreased with the increasing lcf at the fixed inclination angle; In ICAIFS, the upward spread rate of cable flame is faster than the downward spread rate at the fixed inclined angle. Moreover, the cable flame spread rate (FSR) in HCAHFS is the slowest compared to that in ICAIFS with different inclined angles. The preheating length for ICAIFS increases under both upper and lower ignition modes, while it is obviously at upper ignition, due to the melt flow. Finally, a correlation of FSR was proposed for various ignition positions and inclined angles. This study provides a reference for fire protection design and numerical simulation parameter setting of 110 kV cable fire.

Pile defect assessment using distributed temperature sensing: fundamental questions examined

Thermal integrity testing has been successfully used to assess the quality of cast-in-place piles for the past decade. It employs temperature data measured during concrete curing to identify defects along the piles’ length. However, the uptake of this technology has been rather limited in the piling industry. The main concerns are that the method is not standardised and its reliability is not well understood. In order to address these, there are a number of fundamental questions that need to be explored in more detail, including (a) the optimum time to conduct the assessment, (b) the defect thermal impact, (c) the zone of influence on temperature sensors, (d) the minimum detectable size of a defect and (e) the associated optimum sensor location required. In this paper, experimental and numerical studies were conducted to examine these questions. Fibre optic sensors were employed on model concrete piles in laboratory tests to provide fully distributed temperature data throughout the curing process. The test results showed that the optimum time to assess the defects is approximately at 60% of the time to reach peak temperature and the minimal detectable defect size, using the currently available optical fibre sensor technology, is 4% of the cross-sectional area. In addition, the thermal influence of different defect sizes is presented. Following this, it is shown in the paper that the minimum numbers of sensor cables required to identify defects with cross-sectional areas of 4%, 5% and 8% are eight, six and four cables, respectively. The optimum layout of these sensor cables within a pile cross-section has also been discussed. When specifying pile instrumentation for integrity assessment, the findings of this paper enable practising engineers to make informed judgements in relation to the size of defects they would like to detect (and hence the associated risk this entails) together with the corresponding instrumentation layout required.

WebGripper: Bioinspired Cobweb Soft Gripper for Adaptable and Stable Grasping

Web structure is a flexible structure widely used in animal predation behavior and human hunting work, which exhibits an excellent capability of gripping objects stably and securely. Inspired by the predation behavior of spiders, in this article, we present a bioinspired cobweb soft gripper, named WebGripper, which takes on a form like a spider web before grasping an object and presents an entangling state like a snake after grasping the object. These characteristics result in broad adaptability to various objects and enhanced grasping stability. The design concept, grasping principle, and fabrication process of the WebGripper are presented in this work, and the influences of cable layout and soft finger installation angle are analyzed to provide a reference for the design of the WebGripper. To evaluate the performance of the WebGripper, we carried out experiments on grasping objects with different shapes and sizes. Experimental results illustrated the universal adaptable grasping ability of the WebGripper, which exhibits excellent application prospects in many fields, such as goods sorting, fruit picking, and underwater fishing. This work is expected to promote the development of a high-performance soft gripper that may be used in a number of applications based on the understanding of the bionic web structure.

Application of modular mathematical modeling in intelligent design of 3D digital substation

Abstract The construction of modular digital smart grid, as a result, the complexity of the power grid is increasing and new technologies and schemes are emerging, more sophisticated design means are needed. Therefore, the author puts forward the research on the intelligent design of three-dimensional digital substation. The emergence of 3D design has changed the status quo of difficult collaboration among multiple disciplines under the traditional design mode, and improved the level of substation design from the perspective of life-cycle management. Firstly, the characteristics of digital collaborative design are analyzed, the construction of 3D model library of equipment is explained, and the intelligent auxiliary control system of substation is described, taking a project as an example, after checking the electrification distance, it can be found that the electrification distance between the camera arranged in the 220kV power distribution unit area and the lightning arrester of the outgoing line does not meet the requirements, and the number of equipment is 3, the application of three-dimensional design is described from the aspects of video monitoring system, automatic fire extinguishing system, etc, its application in the front end equipment layout, model retrieval, collision inspection between safety distance and foundation, buried pipe design, material statistics and other dimensions of these systems were shown in detail, the method of 3D design is deeply studied and applied to the practical engineering design of high voltage substation. The space characteristics of 3D design can be used to realize complex underground pipeline layout, cable optimal layout, collision inspection, construction simulation, visual display, etc.

Особенности моделирования воздушных и кабельных участков линий электропередачи 110–750 кВ при использовании фазного координатного базиса

Power system steady state and transient analysis require correct modeling of overhead transmission lines and cables operating at 110–750 kV. The key difficulties to model sections of overhead and cable lines are caused by complex conductor geometry, their transposition, as well as grounding schemes of ground wires of overhead lines and screens of underground cables. The paper covers various aspects of 110–750 overhead line and cable modeling that must be taken into consideration to obtain a reliable mathematical model in a phase domain. Modern software does not provide a universal solution to determine line parameters. The 110–500 kV cable line modeling issues have not been worked out properly and require careful analysis of specialized foreign literature. Thus, the task to develop the algorithms of calculating the parameters of overhead and cable power lines is relevant, taking into account the various configuration options of these lines which are possible in operational practice. To derive overhead transmission line and cable line models, electric circuit theory and matrix algebra methods have been used. The ATP/ATPDraw and MATLAB/Simulink software environment has been used to investigate what tools are available to determine line parameters, as well as to verify some of the calculation results. Analysis has been carried out to reveal the options available in the ATP/ATPDraw and MATLAB/Simulink software to compute line parameters in a phase domain. An algorithm has been developed and verified to calculate overhead line parameters regardless of the number of parallel circuits. The key features of the calculation of the matrix of linear resistances of overhead power transmission lines are outlined. The main features of modern cable lines operating at 110–500 kV are also described. The paper presents various cable layouts possible in real-field conditions, as well as provides expressions that allow obtaining correct impedances and admittances for a system of cable line conductors. Study of the options of various software tools dedicated to overhead line parameter calculation in a phase domain has revealed that these tools cannot be deemed universal to represent an overhead line of whatever configuration. However, the developed algorithm is universal as it allows computing line parameters regardless the ground wire grounding approach. The expressions presented in this paper consider various layouts of 110–500 kV cable lines that could be encountered in the Russian power system.

Effect of cable layout on hydrodynamic response of submerged floating tunnel under wave action

A submerged floating tunnel (SFT) is a new type of traffic-crossing scheme in relatively deep waters that realizes suspension fixation through gravity, buoyancy, and cable force. The cable mainly constrains the SFT, and its layout has a critical impact on the dynamic characteristics of the SFT. In this study, hydrodynamic experiments are conducted on a reduced-scale model of the SFT under regular waves. The acceleration of the SFT tunnel, cable force, wave height, and other data are collected. The dynamic response of the SFT with three cable layouts (parallel, inclined, and mixed) is analyzed. Results show that the dynamic response of the SFT with a parallel cable layout is considerably less than that of the other two cable layouts under the action of regular waves. The amplitude of cable force at the upstream side is generally less than that at the downstream side for the inclined cable of the SFT with inclined and mixed cable layouts. The cable slack phenomenon reduces the overall constraint stiffness of the SFT, and the dynamic response considerably exceeds that under non-slack conditions. Resonance zone and long-period waves are the main excitations causing the motion of SFTs when the submerged depth is at safe level.

Techno-economic study of very dense optical wireless access using visible or infrared light

Future wireless networks need to serve a high density of end-user devices with a high quality of service. The density of wireless access points and the infrastructure behind them lead to substantial cost. We study this cost impact for the particular case of optical wireless communication [also denoted as light fidelity (LiFi)] in a large manufacturing hall. We compare different LiFi network topologies using visible or infrared light. Considering aspects such as the fronthaul cabling layout, equipment investments, and installation and operational costs for energy and maintenance, different LiFi solutions are analyzed for greenfield and brownfield scenarios. The techno-economic analysis is performed in terms of total cost of ownership as well as the impact of each cost category to the final cost. Furthermore, the cost per delivered Mbps is compared to take into account the expected densification (more bits/s/m2) and satisfy the demand for future wireless traffic. Both delivered capacity and power consumption have been identified as the two most critical parameters.

Synergetic concrete shape and cable layout optimization of pre-stressed concrete beams

Synergetic concrete shape and cable layout optimization of pre-stressed concrete beams

High voltage consolidation of the temperature measurement channels of the LHC superconducting current leads

Recurrent dielectric breakdowns on the cryogenics instrumentation during the CERN LHC Electrical Quality Assurance (ELQA) campaigns led to an investigation of their root causes. During the CERN Long Shutdown 2 (LS2), several weaknesses were identified like floating wires or cable screens, cabling non-conformities, connector assembly issues, and weakness of the electronic conditioning cards. The paper presents the cabling layout from the sensor till the acquisition cards and the actions undertaken to increase the robustness against dielectric ruptures. These actions include rebuild of the cabling and connectors using a laser stripping machine, new wiring patterns and upgrades on the electronic cards.

Optimizing wind farm cable layout considering ditch sharing

AbstractWind power is becoming an important source of electrical energy production. In an onshore wind farm (WF), the electrical energy is collected at a substation from different wind turbines through electrical cables deployed over ground ditches. This work considers the WF layout design assuming that the substation location and all wind turbine locations are given, and a set of electrical cable types is available. The WF layout problem, taking into account its lifetime and technical constraints, involves selecting the cables to interconnect all wind turbines to the substation and the supporting ditches to minimize the initial investment cost plus the cost of the electrical energy that is lost on the cables over the lifetime of the WF. It is assumed that each ditch can deploy multiple cables, turning this problem into a more complex variant of previously addressed WF layout problems. This variant turns the problem best fitting to the real case and leads to substantial gains in the total cost of the solutions. The problem is defined as an integer linear programming model, which is then strengthened with different sets of valid inequalities. The models are tested with four WFs with up to 115 wind turbines. The computational experiments show that the optimal solutions can be computed with the proposed models for almost all cases. The largest WF was not solved to optimality, but the final relative gaps are small.

Internal resonance of generalized suspension bridge model considering torsional-vertical vibration

Non-linear vibration is a crucial issue for suspension bridge due to its slenderness and low damping. This study proposes a fully mathematical model of a suspension bridge considering arbitrary inclined angle of main cables by using principle of Hamilton. This is the first mathematical model that is capable of analyzing the nonlinear coupled vertical-torsional vibration of generalized bridge configurations with independently considering the motion of main cables and girder. Galerkin method is adopted for the discretization of the model, and the multi-scale method is employed to acquire modulation equations. The accuracy of the non-linear vibration obtained from proposed mathematical model are validated by a FE model. The internal resonance analysis for such a suspension bridge with spatial layout of main cables between vertical and torsional modes with frequency ratio of 2:1, and between two torsional modes respectively dominated by deck and main cables with frequency ratio of 1:1 are successively investigated in the first time within a narrow detuning frequency domain. The phenomenon of nonlinear resonance was discussed with different inclination angle of main cables and detuning parameters. Some novel and practical conclusions were obtained. Results show that 2:1 internal resonance between vertical and torsional modes may be induced only when two forces with frequencies corresponding to involved modes are applied simultaneously. In addition, significant 1:1 internal resonance is observed, with inducing Hopf bifurcation. Understanding such possible situations is favorable to the design of bridge structure.

A simple algorithm for optimal design in distributed fibre-optic sensing

SUMMARY We present a basic algorithm for optimal experimental design in distributed fibre-optic sensing. It is based on the fast random generation of fibre-optic cable layouts that can be tested for their cost-benefit ratio. The algorithm accounts for the maximum available cable length, lets the cable pass through pre-defined points of interest, avoids obstacles that the cable must not traverse, permits the adaptation of geometric complexity of different cable segments and allows for the incorporation of topography. Furthermore, the algorithm can be combined with arbitrary measures of the cost-benefit ratio, and its simplicity enables easy adaptations to the needs of specific applications. In addition to a description of the basic concept, we provide examples that illustrate the circumnavigation of obstacles, the steering of geometric complexity and the cable layout optimization in the presence of topographic variations.

Sectional Model Wind Tunnel Test and Research on the Wind-Induced Vibration Response of a Curved Beam Unilateral Stayed Bridge

The linear curve distribution of the beam and the asymmetrical layout of the stay cables may have beneficial or adverse influences on cable-stayed bridges. Sectional model wind tunnel tests and numerical simulations were used to analyze the influence of these two factors on the wind-induced vibration characteristics of a curved beam unilateral stayed bridges (CBUSB) and the interaction between its stay cables and curved beams. According to the basic similarity law, the sectional models of a CBUSB example were designed and manufactured. The aerodynamic force and wind-induced vibration of the models were measured in an atmospheric boundary wind tunnel laboratory to obtain the aerodynamic coefficient and displacement, respectively. Based on the wind tunnel test results, the verified finite element model was used to determine the displacement, acceleration, and cable tension of the CBUSB excited by the buffeting force under 5 curvature cases and 4 cable layout cases. Then, band-pass filter technology and fast Fourier transform technology were used to analyze the influence of these two parameters on the wind-induced vibration characteristics of the CBUSB. Results show that the CBUSB had good aerodynamic stability in the wind tunnel at low and high wind speeds. With increasing curvature, the high-order modal vibration and modal coupling vibration of the CBUSB may be generated. The frequency, the proportion of wind-induced vibration response components, and the distribution characteristics of spectrum energy of CBUSB will be affected by 4 cable layout schemes. Cables arranged on both sides of the bridge and near the center of curvature can improve pedestrian comfort and reduce wind-induced vibration, respectively. Affected by the interaction between cable and bridge, the cable and bridge transmit their own vibration to each other, both of which contain the response components of each other.

Improvement and Performance Evaluation of a Dual-Probe Heat Pulse Distributed Temperature Sensing Method Used for Soil Moisture Estimation.

Large-scale measurements of soil moisture play a critical role in many fields, such as agriculture, hydrology, and engineering. The distributed temperature sensing (DTS) technology, based on a dual-probe heat pulse (DPHP), is a novel approach to realizing large-scale soil moisture estimation. However, the application of the method is limited by the complex optical cable layout, calculation algorithm, and lack of standardized heating strategy. In this paper, an improved DPHP-DTS method considering the soil bulk density was proposed. The measurement accuracy of the DPHP-DTS method under different heating strategies was studied in laboratory experiments, and its long-term stability in regard to the monitoring of soil moisture during natural evaporation in different soils was tested. The results show that the improved DPHP-DTS method can accurately measure the soil moisture, and the fitting algorithm can reduce the error caused by the accuracy of the DTS temperature measurement under the low-power heating strategy. Its measurement accuracy increases with the increase in the heating strength and duration. In addition, the improved DPHP-DTS method can describe soil evaporation in both sand and loess with good reliability and stability.