直流SMC铁心高温超导故障限流器的研究

分析了直流电力系统保护的发展现状,设计了一种铁心型高温超导故障限流器。为了尽量延长限流的时间,限流器的铁心采用软磁复合材料(SMC)。限流器在系统正常工作时对电力系统影响很小,当短路故障发生时,它会很快表现为大阻抗以限制短路电流。基于磁场有限元与电路耦合的计算方法,首先对限流线圈在短路过程中的非线性电感进行精确计算,然后结合计算结果,在电路仿真程序中计算短路电流。通过对比SMC与硅钢铁心材料限流器的限流情况,可以看出SMC铁心限流器对于直流电力系统短路故障的限流效果更好。在短路故障发生后8 ms时,该限流器能将短路电流限制到最大值的12%。     

Design guidelines of a flux‐lock superconducting fault current limiter with ac magnetic field coil for a 6.6‐kV distribution system

We have proposed a new type of fault current limiter, which consists of a flux‐lock reactor with high‐Tc superconducting (HTS) elements and an ac magnetic field coil (Flux‐Lock‐Type Fault Current Limiter: FLT‐FCL). The FLT‐FCL can increase both the current capacity and the limiting impedance by means of a transformer action and an ac magnetic field application mechanism. This paper reports the conceptual design of an FLT‐FCL for application to a 6.6‐kV/200‐A distribution system. Theoretical expressions for the current limiting behavior are derived and the new concept of “quench power” is proposed in order to estimate the required number of HTS elements for two types of FLT‐FCL and for a basic FCL type consisting only of HTS elements. Design guidelines for the FLT‐FCL are derived from the calculation results. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 17–25, 2001     

Operating characteristics of a superconducting fault current limiting transformer (SFCLT) and enhancement of electric power system stability

We have been investigating the feasibility of a superconducting fault current limiting transformer (SFCLT) with the functions of fault current suppression and system stability improvement. This paper discusses these functions with consideration of overvoltage and thermal characteristics of SFCLT, and their dependence on recovery time into superconducting state after the quench of SFCLT. Simulation results using EMTP suggested that SFCLT would be coordinated with the background power system under the appropriate superconducting recovery time. The operating parameters of SFCLT were also optimized in a simplified power transmission model system. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 40–47, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10070     

Increase of inductance ratio of flat type fault current limiter with high‐Tc superconducting disk

Fault current limiters (FCLs) are expected to reduce fault current and improve stability of power systems. A flat type fault current limiter consisting of the pancake primary winding and a high‐T_c superconducting (HTS) disk was proposed as a modified version of a conventional magnetic shield type of the FCL with the superconducting cylinder. The flat type FCL has the advantage of being manufactured smaller than the cylinder type FCL. It is pointed out, from a magnetic field analysis, that the volume of the flat type FCL is smaller than that of the cylinder type FCL with same magnitude of the limiting inductance. Further, the magnetic field analysis suggests that a high inductance ratio can be realized by radially enlarging both the primary winding and the HTS disk, stacking the FCL modules in layers and sandwiching the primary winding with superconducting disks. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Proposal of flux‐lock‐type fault current limiter with high‐TC superconducting element

This paper proposes a new type of fault current limiter (FCL), which consists of a high‐T_C superconducting (HTS) element and two coils wound on the same core without any leakage magnetic flux. In this FCL, either the limiting impedance or the initial limiting current level can be controlled by adjusting the inductances and the winding direction of the coils. Therefore, this FCL could relax the material restrictions on high‐T_C superconducting FCL. A current‐limiting experiment by a model FCL was carried out, and the limiting performance was observed. The initial limiting current level of the model FCL was 1.7 times higher than the critical current of the HTS element, and the fault current is suppressed to 52% immediately after the short‐circuit in the test. Considering voltage–current characteristics of a high‐T_C superconductor in a computer simulation, the calculated results almost agreed with the experimental results. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 31–38, 1999     

Fault current limiting system for 500‐kV power systems

Recently, expansion in the scale of power systems and development of localized power sources are leading to an increase in fault current of 500‐kV systems. In the future, it is quite likely that the fault current at the interconnection of such power systems may exceed the rated short‐time current of existing electric power facilities. As one of the solutions of this problem, a thyristor‐controlled series‐resonant‐type fault current limiter (FCL) is proposed to restrain the fault current. This paper deals with the FCL system configuration, the placement method of the FCL in power systems, the outline of the FCL's specification, and the operation method of the protective relay in the multimachine system. Finally, the effectiveness of the FCL is evaluated from the viewpoints of limiting the fault current by simulation analysis. The FCL is shown to be a useful protection device for large, high‐capacity power systems. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 11–22, 1999     

桥式超导故障限流器的数字仿真研究

桥式超导故障限流器,它由超导磁体、二极管桥路和直流偏压源组成。超导故障限流器与常规限流电抗器不同之处是:将其接入电网,当电力系统正常运行时,超导体电阻几乎为零,对电力系统运行无影响;当电网发生短路故障时,超导线圈可以无时延地被自动串入线路,从而限制了短路故障电流,使得轻型断路器可以正常动作。通过PSCAD软件对超导故障限流器的运行特性进行仿真分析,证明超导故障限流器在电力系统中应用的意义与前景。     

故障限流装置的发展和应用

在综合大量文献的基础上综述了国内外各种故障限流装置的研究现状、发展应用,特别对广泛应用的电力电子类故障限流器FCL(Fault Current Limiter)和前景广阔的超导类故障限流器SFCL(Superconducting Fault Current Limiter)进行了比较深入的分析,对各类限流装置的技术水平做了比较,提出了实用化过程中存在的应用问题,并对限流装置的发展趋势做出了预测.     

基于MgB2的新型电阻型超导故障限流器的研制和性能分析

超导故障限流器对限制短路电流和短路容量具有重要的研究意义。文中基于MgB2的特性,采用先变形后退火的方法,并利用特制高温玻璃纤维进行绝缘,在退火处理后再通过环氧树脂胶黏剂固化,研制了一台小体积电阻型超导故障限流器样机。同时通过液氦和氦气冷却,对其性能进行测试;通过建立电阻型超导故障限流器的一维热传导模型和电路方程,对其动作特性进行仿真。测试和仿真结果表明该样机限流效果明显,限流百分比可达44%以上,然而限流器的失超长度、超导线材温度和失超电阻随着时间呈非线性变化且限流器的线材并未全部失超。失超恢复时间约为1.5s,可通过交替连接方式满足重合闸需求。最后针对10kV电力系统,提出了MgB2的小体积电阻型超导故障限流器工程设计原理,并分析了其在工程应用中的可行性。     

新型磁控开关型故障限流器拓扑及试验研究

基于饱和铁心型高温超导故障限流器的拓扑,提出了一种适用于中高压电网的磁控开关型故障限流器拓扑结构,在偏置回路中串联了一个限流电感,通过故障前后交流电流的变化自动实现限流电感的退出和接入,从而实现对短路电流的限制,并研制了一台220 V/50 A试验样机。对限流器样机的试验结果表明,磁控开关型故障限流器在正常工作时电压损耗很小,对线路几乎没有影响;故障发生后,限流电感立即自动插入故障回路进行限流,基本不产生谐波,运行控制灵活且简单可靠,对短路电流具有快速、有效的限制作用。     

高压及超高压故障电流限制技术分析

220kV和500kV高压及超高压故障电流限制技术被认为是保障大电网安全稳定运行、提高供电可靠性和灵活性的有效途径。本文结合国内外高压及超高压领域的几个限流器工程示范项目,对比分析串联电抗限流技术、串联谐振限流技术、分裂电抗开断技术、超导限流技术以及其他混合限流技术的原理、设计和制造关键技术、可靠性和造价,并对各种限流技术的优缺点进行了评述。     

Influence of output power out of a synchronous generator installed in a customer system on current limiting effects due to a fault current limiter

In this paper, it was assumed that a synchronous generator in a customer system was connected to a distribution system via the fault current limiter (FCL). We theoretically investigated the influence of the output power of the generator on the limiting effect of the fault current when a three‐phase short‐circuit fault occurs. It was shown that the fault current out of the customer system, limited by the FCL, rises with the output power of the generator. It was found that the larger the output, the higher the fault current at the fault point is when the limiting resistance is less than 15 Ω in the case of the resistive‐type FCL. On the other hand, the fault current at the fault point decreases with an increase in the output power for a limiting resistance more than 15 Ω. In contrast, it was found that the suppressing effect on the fault current at the fault point due to the inductive‐type FCL hardly depends on the output power. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 15–24, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10357     

Experimental studies of the improvement of power system stability by superconducting fault current limiters

With increasing demands for electric power, the electric power system is becoming more and more complicated, and the stable, highly reliable delivery of electric power is encountering two major problems, namely, large fault currents and power system instability. In particular, the fault currents occurring in power systems are tending to increase. To solve this problem, superconducting fault current limiters (SCFCLs) have been developed, and it is hoped that they will also solve the problem of power system stability. This paper describes the results of experiments on the improvement of power system stability and the suppression of fault currents with SCFCLs, performed with power transmission simulators. An experiment using an R‐type SCFCL in a power system was performed. An R‐type SCFCL was simulated by using a resistor and an electromagnetic contactor with thyristors. It was found that the inclusion of an SCFCL in the electric power system gives improved suppression of fault currents and improved power system transient stability. © 2000 Scripta Technica, Electr Eng Jpn, 133(4): 41–52, 2000     

Study of Superconductor Recovery Time Characteristics and High‐Speed Reclosing of Electromagnetic Repulsion Switch

Using a high‐temperature superconductor, we constructed and tested a model superconducting fault current limiter (SFCL). The superconductor and a vacuum interrupter serving as the commutation switch were connected in parallel using a bypass coil. When the fault current flows in this equipment, the superconductor is quenched and the current is then transferred to the parallel coil due to the voltage drop in the superconductor. This large current in the parallel coil actuates the magnetic repulsion mechanism of the vacuum interrupter and the current in the superconductor is interrupted. Using this equipment, the current flow time in the superconductor can easily be minimized. On the other hand, the fault current is also easily limited by the large reactance of the parallel coil. This system has many advantages. Thus, we introduced an electromagnetic repulsion switch. High‐speed reclosing after interrupting the fault current in the electrical power system is essential. Thus, the SFCL should recover to the superconducting state before high‐speed reclosing. But the superconductor generates heat at the time of quenching, and it takes time to recover to the superconducting state. Therefore, the recovery time is an issue. In this paper, we study the superconductor recovery time. We also propose an electromagnetic repulsion switch with a reclosing system. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(3): 12–19, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21072     

磁偏置超导故障限流器限流响应模型与并网运行研究

针对电网短路故障限流问题,提出一种新型磁偏置超导故障限流器(SFCL),采用超导无感组件、双分裂电抗器支路两级限流的运行方式,具有自触发、分级故障限流、快速自我恢复等优点.应用MATLAB/Simulink软件,搭建了含磁偏置SFCL的10 kV电网线路仿真模型,提出超导限流组件磁热耦合特性的物理建模方法,并对0°和90°短路故障角下的SFCL并网限流效果进行瞬态仿真和比较.仿真结果表明,在电网0°和90°不同故障短路角电流冲击下,SFCL在首半波中的限流率分别为36.45％和45.89％,随后第2个半波的最大限流率达到78.58％,限流电阻在90°短路故障角下的变化率是0°短路故障角下的1.75倍,实现了较快的限流动作响应和显著的分级限流效果.最后实验验证了磁偏置超导限流技术的可行性.     

超导限流器基本概念和发展趋势

超导限流器是多年以来人们在超导电力技术领域的研究焦点之一,也是被认为最有可能率先实现工业化应用的超导电力设备。本文在介绍超导限流器的基本概念、组成要素和功能特点的基础上,讨论了超导限流器设计和应用相关的一些重要技术参数和性能指标。文章还较系统地分析了电阻型和饱和铁心型两种目前发展水平较高的超导限流器的工作原理和应用情况,并比较了两者的优缺点。随着性能的进一步完善,可靠性和可用性的进一步提高,超导限流器有可能成为理想的电网短路故障限流装置。作者期待在不远的将来超导限流器会在各种电网中得到广泛的应用,并由此推动电网的深刻技术革命。     

空心超导变压器参数设计对可控阻抗型限流器性能的影响

介绍了可控阻抗型超导限流器的电路结构和工作原理,该限流器由空心超导变压器及PWM变流器组成.故障发生后,通过变流器控制变压器二次侧注入电流的相位和幅值,进而调节限流器的等效阻抗,从而实现抑制短路电流的目的.针对空心超导变压器参数设计对限流器工作性能的影响,以初始补偿电流、不同工作模式下的限流阻抗以及变流器的功率传输为指标,进行了理论研究;以该型限流器在一个三相接地系统的应用为例,利用Matlab建立仿真模型,分析了不同变压器参数下限流器工作性能的差别.仿真结果与理论分析相符,得出如下结论:增大变压器一次侧自感有利于加强限流能力;增加变比会导致初始补偿电流的上升;提高耦合系数有助于降低变流器的无功功率输出.     

改进的双桥混合式桥路型高温超导故障限流器

针对现有断路器开断容量不能满足超高压系统故障短路电流要求的现状,介绍了两种单相桥型高温超导限流器的基本工作原理;针对整流桥中直流偏压的引入问题,提出了一种改进的双桥混合式桥路型高温超导故障限流器,深入讨论了新型限流器的工作原理,限流器的参数变化对其限流特性的影响,包括临界电流、动作电流和超导线圈电感.仿真与实验表明该类型限流器具有良好的限流作用,从工程的角度解决了直流偏压引入困难的问题.     

Performance evaluation of 6000‐A‐class superconducting field windings for 600‐MW‐class superconducting generators

Superconducting generators have many advantages such as increasing generator efficiency and improving power system stability. In Japan, a national project has been conducted since 2000 which is aimed at the development of fundamental technologies required for high‐output‐density and large‐capacity superconducting generators. This paper describes the results of this project, focusing on 6000‐A‐class field winding development. Copyright © 2004 Wiley Periodicals, Inc. A superconducting generator with a high output density and a large capacity has inherent factors that decrease superconducting stability. These are: (1) increase in the magnetic field in the winding which is caused by the increase in winding current density and (2) difficulty in fabricating windings which increases as a conductor diameter becomes larger. To secure the stability, we adopted a higher‐copper‐content conductor and a design that increases winding fixing pressure, along with devising a winding method that accommodates larger conductor diameter. These improvements were applied to a partial model of a 600‐MW field winding. Test results of the model showed good stability, indicating that design and fabrication technique for a 6000‐A‐class superconducting field winding has been successfully evaluated. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 7– 18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20332     

Operation of superconducting fault current limiter using vacuum interrupter driven by electromagnetic repulsion force for commutating switch

Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315