Performance comparison of 1X versus 4X HTS tapes toward the design a 10‐MW direct drive HTS generator for wind turbine applications

With current developments underway at the University of Houston, 4× high‐temperature superconducting (HTS) yttrium barium copper oxide (YBCO) tapes are expected to reach a fourfold critical current density improvement at 30 K and 3 T as part of an Advanced Research Projects Agency‐Energy (ARPA‐E)‐sponsored project. The impetus for this project is to develop and deploy cost‐effective direct drive HTS generators for large offshore wind turbine generators. The improved conductor performance of 4× tapes over 1× tapes is projected to allow for a significant reduction in the amount of HTS tapes required to generate the excitation field and, thus, lead to a reduction of the overall generator cost. It was, however, deduced from simulation results that conventional methods of rotor field enhancement using rotor iron makes 1× conductor competitive enough compared with 4× conductors; hence, commercially available YBCO tapes can provide all the energy density requirements to make wind turbines a competitive energy resource based on energy forecasts. This paper is a presentation of design and optimization work to find the best generator topology from the point of view of both machine design and electricity supply. The generators are numerically modeled and simulated using 1× and 4× YBCO HTS conductors on either or of both the rotor and stator side of the generators.     

Evaporating system for cryogenic support of long length HTS power cables

The paper deals with an analysis of the results of theoretical and experimental research on an evaporating system for cryogenic support as supplied to long length thermostatting channels of high-temperature superconducting (HTS) cables and hybrid power transmission lines as well as thermal control systems for cryogenic components in aircraft fuel tanks during long-term spaceflights. Experimental evidence for nitrogen and hydrogen are presented here. The importance of such research for practical application in developing modern cryostatting systems has been highlighted.The design of an experimental hybrid power transmission line for studying thermostatting of superconducting power cables has been considered in the paper. The transmission line contains three sections with different types of thermal insulation and current leads providing high current supply to superconducting threads with minimum external heat inflow. The unique experimental data on heat inflows from the outer surface of the transmission line in different sections has been obtained by the authors. It is shown that it may be possible to compensate fully for external heat inflow to a cryogenic line as well as to lower the temperature of a cryogenic coolant in the section with an evaporating system for cryogenic support. In order to determine the possible length of the cryostatting work field of a long length superconducting cable, estimates of using liquid nitrogen and liquid hydrogen as a working fluid for various mass flow rates of the coolant feed have been made via the mathematical model describing physical processes in a thermostatting channel using an evaporating system for cryogenic support. Calculation data on changes in the length of the long length temperature cryostat, pressure and cooling capacity of the evaporating cryostat system has been obtained.     

35kV三相统包冷绝缘高温超导电缆磁场数值计算

针对传统地下输电电缆已不能满足大城市未来发展的用电需求,以35kV三相统包冷绝缘高温超导电缆为例,首先对其超导电缆结构参数进行分析,计算出每层自感和互感,进而得出层电流分布;然后基于电磁物理学结合微分法推导超导电缆本体磁场逐点计算公式,根据三相超导电缆结构建立数值仿真计算三维模型;分别使用解析法、数值法对其超导电缆内部、外部磁场进行计算。计算结果表明,内部磁场分布并不均匀,最大磁感应强度位于载流层最外层;外部磁场呈负指数分布且护套层外部磁场最大值远远低于国际非电离辐射防护委员会给出的磁场强度限值100μT。     

Economics of cryocables

This paper examines the technical and economic feasibilities of: (1) using cryogenic hydrogen to cool a.c. cryoresistive or a.c. superconducting power transmission cables and, (2) delivering liquid hydrogen concurrently with cryoresistive or superconducting electrical power through a common cable. Cryogenic hydrogen coolant options considered are subcooled liquid and slush. Cryogenic nitrogen and helium coolants are also considered for cryoresistive and superconducting cables, respectively, to provide reference data for comparison with our H₂-coolant calculations. Thermodynamic analyses are performed to optimize the coolant flow rate and refrigerator spacing for each specific coolant, coolant fluid state, cable design, cable insulation quality and energy delivery option. The use of hydrogen as a coolant in electrical cables is discussed from a safety viewpoint.Helium-cooled and hydrogen-cooled superconducting power transmission lines are shown to be economically competitive and offer lower unit·transmission costs than conventional underground power lines. The hybrid hydrogen-superconducting cable concurrently transmits liquid hydrogen and electricity at the lowest unit cost of all cryocable energy systems examined. Hydrogen-cooled power lines and hybrid hydrogenelectric energy cables appear to be technically and economically feasible; however, they do not currently provide sufficient economic incentive to warrant the increased hazard of operation.     

Magnetohydrodynamics approach for active decay heat removal system in future generation IV reactor

In this work, a helical‐type magnetohydrodynamics transportation system for active decay‐heat‐removal system in a prototype fourth‐generation sodium fast reactor was numerically analysed considering operational conditions of atmospheric pressure, for liquid sodium transportation in a loop. The prototype fourth‐generation sodium fast reactor is a reactor with high uranium utilisation and an electric power output of 150 MWe, subjected to a developed pressure of 10 kPa and flowrate of 0.005 m³/s under a temperature condition of 468.75 K for the active decay‐heat‐removal system. A helical‐type magnetohydrodynamics transportation system was used to develop pressure in such a loop to reduce the current compared with that in a rectangular‐type one; this could overcome the principal limitation of the requirement of a high current in a magnetohydrodynamics transportation system. The main parameters of the considered helical‐type magnetohydrodynamics transportation system were the inner diameter, silver brazing, number of turns, and radius of pump, which affect the current, magnetic‐flux density, and its velocity. The parameters were analysed in relation to the minimisation of the pump current while maximising the pressure. The specifications of the optimised helical‐type magnetohydrodynamics transportation system—current of 352 A and magnetic‐flux density of 0.466 T—were derived to satisfy the conditions of the active decay‐heat‐removal system.     

Design, performance, and cost characteristics of high temperaturesuperconducting magnetic energy storage

A conceptual design for superconducting magnetic energy storage (SMES) using oxide superconductors with higher critical temperature than metallic superconductors has been analyzed for design features, refrigeration requirements, and estimated costs of major components. The study covered the energy storage range from 2 to 200 MWh at power levels from 4 to 400 MW. A SMES that uses high temperature superconductors (HTS) and operates at high magnetic field (e.g. 10 T), can be more compact than a comparable, conventional low-temperature device at lower field. The refrigeration power required for a higher temperature unit (20 to 77 K) will be less by 60% to 90%. The improvement in energy efficiency is significant for small units, but less important for large ones. The material cost for HTS units is dominated by the cost of superconductor, so that the total cost of an HTS system will be comparable to a low temperature system only if the superconductor price in $/ampere-meter is made comparable by increasing current density or decreasing wire cost     

Superconductive magnetic energy storage

Technical and economic aspects of large scale superconductive magnetic energy storage are discussed. This paper is a review of a program which has been under way at the University of Wisconsin since 1970. Early work between 1970 and 1976 was primarily involved in proving economic and technical feasibility of the concept The present program deals with component development and detailed design ultimately leading to construction of a large superconducting magnet capable of storing 1000–10,000 MWh. The magnet is a single-layered segmented solenoid of approx. 100 m radius. Energy containment is achieved economically by burying the magnet underground in bedrock tunnels. Magnetic loads are transmitted from the conductor to bedrock through glass fiber reinforced composite struts. The conductor consists of a composite of aluminum and NbTi and is designed for full cryogenic stability in 1.8 K superfluid helium. The dewar-conductor assembly will be rippled in a l m radius of curvature to reduce the hoop stress tension. A Graetz bridge is required to convert the d.c. superconducting current into a.c. current in the three-phase power system. Economic analysis indicates that superconductive magnetic energy storage is competitive with alternative large scale storage schemes for units greater than 1000 MWh size.     

Wave‐current interaction effects on structural responses of floating offshore wind turbines

This paper proposes a model considering the wave‐current interactions in dynamic analyses of floating offshore wind turbines (FOWTs) and investigates the interaction effects on the FOWT responses. Waves when traveling on current are affected by the current, leading to frequency shift and shape modification. To include such interactions in FOWT analysis, which has not been considered by the researchers till date, a nonlinear hydrodynamic model for multicable mooring systems is presented that is able to consider the cable geometric nonlinearity, seabed contact, and the current effect. The mooring model is then coupled with a spar‐type FOWT model that handles the structural dynamics of turbine blades and tower, aerodynamics of the wind‐blade interaction, and wave‐current effects on the spar. The analytical wave‐current interaction model based on Airy theory considering the current effect is used in the computation of flow velocity and acceleration. Numerical studies are then carried out based on the NREL offshore 5‐MW baseline wind turbine supported on top of the OC3‐Hywind spar buoy. Two cases, (1) when the currents are favorable and (2) when the currents are adverse, are examined. Differences of up to 15% have been observed by comparing the cable fairlead tension obtained excluding and including the wave‐current interactions. In particular, when irregular waves interact with adverse current, a simple superposition treatment of the wave and the current effects seems to underestimate the spar motion and the cable fairlead tension. This indicates that the wave‐current interaction is an important aspect and is needed to be considered in FOWT analysis.     

A porous medium analogy for the helium flow in CICCs

Cable-in-Conduits are superconducting conductors that consist of a bundle of cabled strands enclosed in a leak-tight pipe, the jacket. Helium flows inside the jacket, in a meandrous flow path defined by the intersticial space among the cabled strands, or in specific passages introduced by design to reduce pressure drop. The main advantage of this design is to bring the coolant in close thermal contact with the superconductor, thus enhancing the heat removal as well as its thermal stability. To date, however, the details of the flow and heat transfer mechanism in this complex geometry are not well understood. We propose to use an analogy between the bundle of strands in the cable and a porous media. The analogy provides simple correlations for pressure drop and heat transfer prediction that contain explicitly permeability, drag factor and thermal dispersion. We use published pressure drop data to show that the range of permeability of a CICC is within the expected values for a porous medium with the same equivalent particle diameter, while the drag factor is consistently lower than what expected from the theory of particle beds, which will require further work to produce a satisfactory explanation. Experimental data for the internal heat transfer obtained from a short ITER conductor sample are in good agreement with the expected contribution of thermal dispersion, which supports or proposal.     

500 kV充油海底电缆导体温度分布式光纤传感监测及应用

依据海南联网系统500 kV海底电缆捆绑特殊海底光缆的实际情况,通过分布式光纤传感技术结合经有限元仿真模型优化的IEC60287热路模型的方法可以监测海底电缆内部的温度分布.在实验室中搭建岸上模拟实验平台,利用中压电缆捆绑光纤的结构进行捆绑电缆岸上模拟实验.同时,将经验证的温度监测方法应用于海南联网系统500 kV海底...     

DEFORMATION OF AN INFINITELY LONG,DC CABLE WITH TEMPERATURE-DEPENDENT ELECTRIC CONDUCTIVITY OF THE INSULATION

We investigate the deformation of an infinitely long, circular cylindrical electric conductor carrying a uniform axial current, for the case when the electric conductivity of the coating is temperature dependent. This model conforms with the real situation for many of the existing modern dc cables with polyethylene coating. The distributions of temperature, magnetic field, stresses, and displacements in the cable are obtained and discussed under a thermal radiation condition at the boundary of the cable. In particular, it appears that there is a critical temperature for the ambient medium to the cable, above which no solution for the steady heat problem can exist and the thermal equilibrium of the cable is no longer fulfilled. A formula for the calculation of this critical value is given, which may turn out to be of practical importance for a reliable design of the cable. The obtained results also show that the electric conductivity of the coating strictly decreases as one moves from the core to the boundary of the cable in conformity with the behavior of temperature. Some numerical results are presented.     

基于电流波形差异性的超导电缆失超保护策略

针对高温超导电缆失超运行工况难以准确快速检测,失超过程中发生轻微故障差动保护难于及时反应的问题,提出了失超综合保护策略。利用超导电缆简化数据模型推导出超导态运行时屏蔽层电流相对于超导层的补偿系数,计算出电缆失超时电流波形的差异度,提出基于电流波形差异性和非电气量的失超综合保护策略,并利用PSCAD建立反应超导态、失超态连续变化的超导电缆失超模型,对提出的保护策略进行了仿真研究,仿真验证了失超综合保护策略的可行性。     

Anhydrous proton conductivity of a lamella-structured inorganic–organic zirconium–monododecyl phosphate crystalline hybrid

A lamella-structured inorganic–organic zirconium–monododecyl phosphate crystalline hybrid was investigated as an anhydrous proton conductor. Inorganic zirconium ions were coordinated by OH groups of a phosphate moiety from organic monododecyl phosphate. The inorganic–organic zirconium–monododecyl phosphate hybrid showed a lamella structure with crystalline ZrP, and the thermal stability increased up to 230 °C. A maximum proton conductivity of 2 × 10⁻³ S cm⁻¹ was obtained at 150 °C under anhydrous conditions. The high proton conductivity under high temperature and anhydrous conditions could be explained by considering the interaction between Zr ions and the phosphate group, and the phosphate concentration in the lamella-structured inorganic–organic zirconium–monododecyl phosphate hybrid.     

Thermal performance of a packed bed reactor for a high‐temperature chemical heat pump

The thermal performance of a chemical heat pump that uses the reaction system of calcium oxide/lead oxide/carbon dioxide, which is developed for utilization of high‐temperature heat above 800°C, is studied experimentally. The thermal performance of a packed‐bed reactor of a calcium oxide/carbon dioxide reaction system, which stores and transforms a high‐temperature heat source in the heat pump operation, is examined under various heat pump operation conditions. The energy analysis based on the experiment shows that it is possible to utilize high‐temperature heat with this heat pump. This heat pump can store heat above 850°C and then transform it into a heat above 900°C under an approximate atmospheric pressure. An applied system that combines the heat pump and a high‐temperature process is proposed for high‐efficiency heat utilization. The scale of the heat pump in the combined system is estimated from the experimental results. Copyright © 2001 John Wiley & Sons, Ltd.     

Understanding the origin of half‐metallicity and thermophysical properties of ductile La2CuMnO6 double perovskite

For first time, the magneto‐electronic structure with thermoelectric and mechanical properties of lanthanum‐based double perovskite La₂CuMnO₆ are investigated, using first‐principle methods. Generalized gradient approximation and modified Becke‐Jhonson potentials are integrated to figure out exchange‐correlation potential. The alloy stabilizes in cubic structure with ferromagnetic nature and determined structural parameters are consistent with experimental results. The band profile reveals the half‐metallic character, which is further confirmed by calculated electronic conductivities of up and down spin channels. The effect of pressure on the structural and electronic profile is demonstrated here. The analysis of the transport properties portrays that the highest value of 0.39 is achieved for figure of merit at higher temperatures. The mechanical stability of La₂CuMnO₆ is established, by determination of elastic constants. The calculated elastic parameters specify the ductile behavior of alloy with high melting temperature. The efficient thermoelectric parameters with half‐metallic and ductile character suggest the likelihood of applications of alloy to design hard spintronic devices or potential thermoelectric materials.     

Photon energy amplification for the design of a micro PV panel

To design a micro PV panel, thousands of photons have been produced from a single photon by breaking down its photonic structure using Higgs‐Boson BR (H → γγ¯) quantum field under high temperature conditions. Because the Higgs‐Boson BR (H → γγ¯) Quantum can be excited under high temperature conditions which forms extremely short‐range week force by the photon‐photon collusion of the bare ions; thus, a pair photon (e⁺e^?) is created from a single photon. This pair of photon can be dissociated by 2 surface semiconductors of the photovoltaic panel and further dispersed by the 3 diodes superconducting silicon surface to form multiple photons, here named as Hossain Multiple Photons (HmP¯). A mathematical test has been performed by applying MATLAB software, which revealed that production of HmP¯ [1_photon = (1 + 1 = 2_photons) = (2_photons + 2_photons)^2surface = 16_photon = (16_photons)^3diode = ∑4,096_photons] from a single phone is doable through photon‐photon collusion, photon dissociation, and photon scattering process into the Higgs‐Boson BR (H → γγ¯) quantum field under high temperature condition. These multiple photons can be converted from direct current into alternating current for commercial use. Calculation revealed that 1590.9 MW/h clean energy can be produced by merely 1 cm² PV panel which indeed would be a new field of science that will substantially satisfy the total global energy demand.     

Thermal analysis of underground power cable system

The paper presents the application of Finite Element Method in thermal analysis of underground power cable system.The computations were performed for power cables buffed in-line in the ground at a depth of 2 meters.The developed mathematical model allows determining the two-dimensional temperature distribution in the soil,thermal backfill and power cables.The simulations studied the effect of soil and cable backfill thermal conductivity on the maximum temperature of the cable conductor.Also,the effect of cable diameter on the temperature of cable core was studied.Numerical analyses were performed based on a program written in MATLAB.     

高温超导电缆终端预制式应力锥气隙缺陷仿真及改善措施

高温超导电缆终端预制式应力锥可有效改善终端电场分布从而降低终端电场强度,但预制式应力锥在制造过程中可能会出现一些气隙缺陷,使电缆终端电场畸变、集中,引起局部放电甚至发生击穿致使高温超导电缆损坏。基于球型和长型两种气隙缺陷类型,建立了7种缺陷模型,通过有限元软件仿真得到各缺陷模型终端电场的分布和最大值,并根据仿真结果给出了改善措施。     

Hybrid polymer electrolyte membrane fuel cell–lithium‐ion battery powertrain testing platform – hybrid fuel cell electric vehicle emulator

A testing and validation platform for hybrid fuel cell (FC)–lithium‐ion battery (LIB) powertrain systems is investigated. The hybrid FC electric vehicle emulator enables testing of hybrid system components and complete hybrid power modules up to 25 kW for application in electric light‐duty vehicles, light electric vehicles and so forth. A hybrid system comprising a 10‐kW_el low‐temperature polymer electrolyte membrane FC stack and an 11.5‐kWh LIB pack is installed. The system supplies power to a 20‐kW permanent magnet synchronous motor and a 25‐kW alternating current asynchronous, electrically programmable dynamometer is used to simulate the vehicle load during testing at dynamic drive cycle. The steady‐state performance tests of the direct current (DC) motor, DC/DC converter, low‐temperature polymer electrolyte membrane FC stack and LIB are performed as well as dynamic tests of the complete hybrid system. The Economic Commission for Europe driving cycle is selected as a reference cycle to validate the investigated hybrid FC–LIB powertrain. An efficiency of 83% and 95% is measured for electric motor and DC/DC converter, respectively. An average stack efficiency of 50% is achieved. An average hydrogen consumption of 3.9 g * km^?1 is reached during the Economic Commission for Europe driving cycle test. Copyright © 2017 John Wiley & Sons, Ltd.