35 kJ高温超导磁储能(SMES)的热输运实验研究

研制了中国首台高温超导磁储能直接冷却系统,该系统不使用低温液体(液氦、液氮).在10-3Pa的真空度下,高温超导磁体线圈由1台单级GM制冷机从室温293 K冷却到19 K,Bi2223电流引线由另一台制冷机冷却到77 K以下.整个系统在通140 A直流电流的时候产生了4.5 T的磁场.系统连续运行480 h(20 d),磁体和低温系统各参数动态特性良好.实验研究表明,控制系统的漏热,优化磁体内部导冷结构,有效减少热传导部件的接触界面热阻是制冷机直接冷却高温超导磁体的关键技术.     

Design and test of a simplified and reliable cryogenic system for high speed superconducting generator applications

Under the contract with Air Force Research Lab (AFRL), General Electric has successfully tested a high speed, superconducting generator for a Multimegawatt Electric Power System (MEPS). As the first successful full-power test of a superconducting generator for the Air Force, the demonstration tested the generator’s load up to 1.3 MW and over 10,000 rpm. A key component of the generator system is a closed loop cryo-refrigeration system to cool the field excitation coil at liquid neon temperature. This paper reports the design and tests of the cryogenic system, including the liquid neon dewar, cryogenic cooling loop for the high temperature superconducting (HTS) field coil and the cryostat. Performance data during both short-term load run and long-term non-load run were presented. Also, some key issues to design a reliable cryogenic system for a superconducting generator were discussed.     

Detecting and describing the inhomogeneity of critical current in practical long HTS tapes using contact-free method

The nondestructive and contact-free apparatus for measuring local critical current of long high temperature superconducting (HTS) tapes is presented. The local critical current of tape is acquired by using Hall probe array sensor to measure the remanent field after exposed to dc external magnetic field since the critical current is proportional to remanent field based on Bean critical state model. A detailed experiment on multifilamentary Bi2223/Ag tape is made to validate reproducibility, reliability, resolution, nondestructiveness and usefulness for manufacturer and user of tapes. The parameter COV (coefficient of critical current variation) is suggested for quantitatively describing the inhomogeneity and quality of practical long HTS tape based on Gaussian statistical analysis. The developed apparatus can detect HTS tape at velocity of 100 m/h with resolution smaller than 3 mm in liquid nitrogen.     

移动通信用高性能高温超导滤波器的研制

研制了用于移动通信系统的高性能高温超导滤波器。设计了一个由12节H形谐振器组成的超导滤波器,采用LaAlO3基片,厚度为0.518mm,介电常数为23.75,尺寸为38.6mm×25.8mm。滤波器制备采用了光刻技术和氩离子束刻蚀工艺,经封装检测后得到了优异的微波性能,其中心频率是830.5MHz,带宽11MHz,插入损耗<0.2dB,反射损耗>15.6dB,带外抑制>75dB,与设计结果符合得很好,优于实际应用的要求。     

高温超导磁体的一种失超判别方法

高温超导同步电动机转子上的Bi2223／Ag带高温超导磁体,其结构特殊,且工作在旋转状态,必然给其失超信号的检测提出新的问题。试验表明,为快速、准确检测到失超信号,仅用经验失超判据Ec=1μV／cm是不够的。为此,通过对试验数据的分析提出dv／dt失超判别方法。此方法从磁体的电压一电流特性入手,根据每个励磁阶段的电压变化情况,设置相应的电压变化率的阈值。     

A modified circuit topology for inductive pulsed power supply based on HTSPPTs

High temperature superconducting pulsed power transformer (HTSPPT) provides an efficient method for inductive energy storage and current multiplication. The primary inductor of HTSPPT used for energy storage is made of high temperature superconducting coils, and the secondary inductor used for current pulse generation is made of normal conductor coils. In the initial circuit, the secondary inductor generates current pulse by switching out the coupled primary superconducting inductor. However, during the switching period, the leakage flux caused by imperfect coupling and the sudden change in primary current induce a voltage across the opening switch which exceeds the affordability of modern solid-state switches. In previous studies, a half-cycle oscillatory discharge circuit is proposed to mitigate these problems by using a capacitor to recapture the energy in the leakage flux and to slow down the turnoff of current in the primary. However, there are still some problems should be settled. For example, the output pulse cannot be adjusted, the residual energy cannot be recovered and the capacitor branch circuit may have an impact on the charging process. In the paper, a modified discharge circuit topology is introduced to solve these problems. A multi-module system comprising of several HTSPPTs charging in series connection and discharging in parallel is also designed and simulated. This system can be used to power an electromagnetic emission device.     

舰船电力系统用1 MJ高温超导储能磁体设计研究

介绍了舰船电力系统用的1MJ螺管型高温超导储能磁体的设计优化步骤，给出了用Bi-2223超导带进行1 MJ磁体线圈的设计和优化结果，分析了高温超导体的各向异性对磁体临界电流的影响，讨论了储能容量一定的多螺管磁体系统在漏磁、储能密度和所需超导线材方面的变化。     

Cryogenic system with the sub-cooled liquid nitrogen for cooling HTS power cable

A 10 m long, three-phase AC high-temperature superconducting (HTS) power cable had been fabricated and tested in China August 2003. The sub-cooled liquid nitrogen (LN₂) was used to cool the HTS cable. The sub-cooled LN₂ circulation was built by means of a centrifugal pump through a heat exchanger in the sub-cooler, the three-phase HTS cable cryostats and a LN₂ gas-liquid separator. The LN₂ was cooled down to 65 K by means of decompressing, and the maximum cooling capacity was about 3.3 kW and the amount of consumed LN₂ was about 72 L/h at 1500 A. Cryogenic system design, test and some experimental results would be presented in this paper.     

Development of a single-phase 30 m HTS power cable

HTS power transmission cables appear to be the replacement and retrofitting of underground cables in urban areas and HTS power transmission cable offers a number of technical and economic merits compared to the normal conductor cable system. A 30 m long, single-phase 22.9 kV class HTS power transmission cable system has been developed by Korea Electrotechnology Research Institute (KERI), LS Cable Ltd., and Korea Institute of Machinery and Materials (KIMM), which is one of the 21st century frontier project in Korea since 2001. The HTS power cable has been developed, cooled down and tested to obtain realistic thermal and electrical data on HTS power cable system. The evaluation results clarified such good performance of HTS cable that DC critical current of the HTS cable was 3.6 kA and AC loss was 0.98 W/m at 1260 Arms and shield current was 1000 Arms. These results proved the basic properties for 22.9 kV HTS power cable. As a next step, we have been developing a 30 m, three-phase 22.9 kV, 50 MV A HTS power cable system and long term evaluation is in progress now.     

Maintenance schedule optimisation for a railway power supply system

High reliability is the crucial requirement in railway operation and a power supply system is one of the key components of electrified railways. The cost-effectiveness of the maintenance works is also the concern of the railway operators while the time window on trackside maintenance is often limited. Maintenance scheduling is thus essential to uphold reliability and to reduce operation cost. It is however difficult to formulate the optimal schedule to meet both reliability and maintenance cost for a railway power supply system as a whole because of its functional complexity and demanding operation conditions. Maintenance scheduling models to achieve reliability and maintenance cost are proposed in this study. Optimisation algorithms are then developed to attain the solutions of the model. The applicability of the models and efficiency of the solution algorithms are demonstrated in an example. The proposed methods are vitally important for the railway engineers and operators to assure the service quality in the increasing demands of the modern electrified railways.     

Design of an energy storage flywheel system using permanent magnet bearing (PMB) and superconducting magnetic bearing (SMB)

We propose a new energy storage flywheel system using a superconducting magnetic bearing (SMB) and a permanent magnet bearing (PMB). The superconducting magnetic bearing (SMB) suppresses the vibrations of the flywheel rotor. And the permanent magnet bearing (PMB) passively controls the rotor position. The energy storage flywheel system is characterized by using the two different type magnetic bearings of permanent magnet bearing (PMB) and superconducting magnetic bearing (SMB). This paper, discusses the design of the permanent magnet bearing (PMB) and the dynamics of the new energy storage flywheel system.     

Design of high-efficiency Joule-Thomson cycles for high-temperature superconductor power cable cooling

Liquid nitrogen (LN₂) is commonly used as the coolant of a high temperature superconductor (HTS) power cable. The LN₂ is continuously cooled by a subcooler to maintain an appropriate operating temperature of the cable. This paper proposes two Joule-Thomson (JT) refrigeration cycles for subcooling the LN₂ coolant by using nitrogen itself as the working fluid. Additionally, an innovative HTS cooling cycle, of which the cable coolant and the refrigerant are unified and supplied from the same source, is suggested and analyzed in detail. Among these cycles, the highest COP is obtained in the JT cycle with a vacuum pump (Cycle A) which is 0.115 at 78 K, and the Carnot efficiency is 32.8%. The integrated HTS cooling cycle (Cycle C) can reach the maximum COP of 0.087, and the Carnot efficiency of 24.8%. Although Cycle C has a relatively low cycle efficiency when compared to that of the separated refrigeration cycle, it can be a good alternative in engineering applications, because the assembled hardware has few machinery components in a more compact configuration than the other cycles.     

Simple measurement of the AC transport current loss for HTS conductors using an active power detection method

Reducing AC loss in a superconducting apparatus is one of the most important issues, and the precise measurement and estimation of AC losses are essential to reduce them. The four-terminal method is universally used as an electric measurement method of AC losses for superconducting tapes and wires. In this method, noise and inductive voltage superposed on the terminal voltage of the superconductor are eliminated by a lock-in amplifier and cancel coil, respectively, and then measurement of very small resistive voltage is achieved. However, using this conventional method, a plurality of measuring instruments and apparatuses are needed, and therefore the measuring system becomes complicated and much time is consumed in the calibration process. In this paper, we present a simple and precise measurement system based on an active power detection method, which is proposed as a quench detection method. The proposed system consists of a small number of instruments and apparatus and is less susceptible to noise. Its usefulness is verified by comparing the proposed method and the conventional four-terminal method in measuring the AC transport current loss of a Bi2223/Ag tape.     

随钻高效电源的管理系统优化设计

根据随钻仪器的工作特点,提供了一种对随钻电源进行管理的高效且易于实现的解决方案,该方案从工作方式上采用间歇供电,使得仪器在非工作状态时电能的消耗降到最低;在工作原理上,采用Buck型开关电源,使得电能的转化效率达到最大。而根据不同电源的需求指标,数字电源与模拟电源采用不同的芯片。对于数字电源,利用了TPS40200芯片设计简单的特点,并且在高温下可实现较大功率;对于模拟电源,利用了UC3842芯片适用性广泛的特点,在其后添加合适变压器,同时输出正负两路模拟电源。经过实际验证,该方式很大程度上提高了电能的利用效率和电池的工作时间,符合随钻高效电源的设计要求。     

大功率半导体激光器全固态风冷散热系统

设计并制作了一种全固态大功率半导体激光阵列恒温散热系统。它利用半导体制冷器对大功率半导体激光阵列吸热,然后经由风冷散热。经测试,单bar激光阵列连续输出功率达到15.28W,双 bar 阵列输出达 27.8W 时,全部达到风冷散热控温精度±0.1 ;当环境温度达到 45 时,仍然能够保证激光阵列的正常使用。     

Operating characteristics and cooling cost evaluation for HTS receiver arrays of wireless power charging system in superconducting MAGLEV train

Since conventional power supply unit should be attached to HTS magnet in the MAGLEV, a large thermal loss is indispensably caused by power transfer wires and joints, those have been one of essential obstacles in the superconducting MAGLEV train. As the wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air, there are advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power during movement. Above all, the WPT technology in the MAGLEV can reduce the cost of tunnel construction since the space of conventional power line doesn’t required. From these merits, the WPT systems have been started to be applied to the wireless charging for various power applications such as transportations (train, underwater ship, electric vehicle). In this study, as a practical approach, authors investigate transfer efficiency and cooling cost for multi-Tx and multi-sized single Tx coils under different size of Rx coils arrays, respectively. Additionally, authors investigated transfer ratio at HTS Rx with helix and spiral Tx coils under different interval. As well as, authors evaluate cooling cost of different sizes of HTS receiver under long single and multi-copper antenna arrays based on nitrogen evaporation method.     

上海港岸基船用供电系统研究与实践

描述的一种移动式岸基船用变频变压供电系统利用集装箱码头前沿为桥吊运行配备10 kV/50 Hz/2 000 kV ·A的高压电源,经过变压和变频为靠港船舶提供450 V/60 Hz电源。该方案灵活性强,节能减排效果明显,且无需对码头进行土木改造,为我国作业繁忙的集装箱码头实现岸基供电提供新方案。     

Development and parametric study of the convection-type stationary adiabatic demagnetization refrigerator (ADR) for hydrogen re-condensation

The adiabatic demagnetization refrigerator (ADR) system in this paper is composed of a conduction-cooled current cycling high-temperature superconducting (HTS) magnet system, a magnetic bed assembly, its heat exchange parts and an auxiliary precooling stage (a commercial GM cryocooler and a liquid nitrogen vessel). The whole magnetic refrigeration system including the conduction-cooled HTS magnet is cooled by the precooling stage to absorb the rejection heat of the ADR cycle. The packed bed type magnetic bed consists of tiny irregular powders of Dy_0.9Gd_0.1Ni₂ enclosed in a thin walled stainless steel container (22.2 mm in O.D., 0.3 mm in thickness and 40.0 mm in height). The precooled heat transfer fluid (helium) travels through the magnetic material when heat rejection is required; otherwise the helium stagnates within its pores (pseudo-adiabatic process). Flow of the heat transfer fluid substitutes for the function of a traditional heat switch, creating, essentially, a forced-convection type heat switch. The magnetic bed assembly is periodically magnetized and demagnetized at the center of the conduction-cooled HTS magnet which can stably generate both strong and alternating magnetic field from 0 T to 3.0 T (0–130 A) with an average ramp rate of 0.24 T s⁻¹. The cooling capacities of the ADR system at 20 K which is the normal boiling point (NBP) of hydrogen, are 11.1 J cycle⁻¹, 6.3 J cycle⁻¹ and 1.9 J cycle⁻¹ when the temperature spans are 1 K, 2 K and 3 K, respectively. We describe the detailed construction of the ADR system and discuss the test results with the operational parameters (the entrained helium pressure, the mass flow rate of helium and the operating temperature span) in the 20 K region.     

Integration of SPC and performance maintenance for supply chain system

In this paper, a supply chain system is viewed as a maintainable system, and the economic-statistical design of a likelihood ratio control chart with a maintenance application is considered for this system. The supply chain system is described by a three-state: normal state, warning state and failure state. A likelihood ratio control chart is used to monitor the system given that only categorical observations can be obtained. When the chart signals, a full inspection is performed to determine the actual system state (normal or warning), and preventive maintenance is immediately performed in the warning state. In addition, the supply chain system must be corrected upon failure (i.e. corrective maintenance), and should be maintained in a scheduled time (i.e. planned maintenance). A mathematical model is developed for the joint optimisation of the control chart parameters and planned maintenance time based on renewal theory. An example is presented to illustrate how to determine the optimal design parameters. We also investigate the effect of coefficients and statistical constraints on the decision variables and the expected cost.     

Thermal anchoring of conduction-cooled current leads for superconductivity applications near liquid nitrogen temperature

As the YBa₂Cu₃O_7-δ, or YBCO, superconductor is commercially developed and utilized for various HTS (high temperature superconductor) applications such as motor, generator, and fault current limiter, the cryocooling for 50 or 60 K range is more demanded than ever. In this case, non-superconducting current leads instead of HTS ones need to be used for energization from room temperature all the way to the cryogenic operating temperature. This technical note describes a simple method of reducing cooling load requirement for those HTS applications. Non-superconducting current leads are to be thermally anchored at an appropriate intermediate cryogenic temperature before they are connected to the application target temperature. The optimum thermal-anchoring temperature and its configuration have been obtained to minimize the required cryocooler’s cooling capacity for practical as well as ideal cases.