Experiments on a tokamak device with force‐balanced coils

High field is very favorable for magnetically confined fusion devices such as a tokamak, but the electromagnetic force derived from the field becomes a fatal problem. In particular, the largest in‐plane centering force hinders toroidal field coils from operating at higher fields. Although variable‐pitch multihelical coils, which we term force‐balanced coils (FBCs), by which this force is drastically reduced, were proposed for the coil system of tokamaks, there had been no actual tokamak device with FBCs. Therefore, Todoroki‐1, a small tokamak device with FBCs has been manufactured and experiments started. In this paper, the structure of Todoroki‐1 is indicated, and the stray magnetic field and centering force on FBCs are investigated. The plasmas have been generated in the device, and attempts at better plasmas are beginning. © 1999 Scripta Technica, Electr Eng Jpn, 130(3): 19–29, 2000     

Application of a force‐balanced coil to a tokamak device

High field is very favorable for magnetically confined fusion devices such as a tokamak, but electromagnetic force derived from the field becomes a fatal problem. In particular, the largest in‐plane centering force hinders toroidal field coils from operating at higher fields. Variable pitch multihelical coils, which we term force‐balanced coils (FBCs), by which this force is drastically reduced, are proposed for the coil system of tokamaks. FBCs can also provide poloidal flux swing for plasma breakdown and current induction during the ramp‐up phase of the coil current. In this paper, we indicate how to design FBCs for tokamaks. The fusion reactor‐size FBCs are designed and compared with that of the conventional toroidal field coil system. © 1999 Scripta Technica, Electr Eng Jpn, 130(3): 39–48, 2000     

Interconnected power systems with superconducting magnetic energy storage

The objective of this work is to discuss the concept of back‐to‐back interconnection systems with energy storage, especially with a Superconducting Magnetic Energy Storage (SMES) incorporated into a back‐to‐back DC link. In this case, each converter of the back‐to‐back system is used as a power conditioning system for the SMES coils. Since the AC–DC converter can be designed independently of the frequency of the power system, a two‐way switch is connected to the AC side of each converter. This two‐way switch can select the interconnected power systems. By using the two‐way switches, this system can provide the stored energy in the SMES system to each interconnected power system through two AC–DC converters. For instance, lower‐cost power of each power network can be stored through two converters during the off‐peak hours and made available for dispatch to each power network during periods of demand peak. Then this system increases the reliability of electric power networks and enables the economical operations depending on the power demand. This paper describes the unique operations of the back‐to‐back interconnection with SMES and discuses the optimal SMES configuration for a 300‐MW‐class back‐to‐back interconnection. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 37–43, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20482     

Neural-network-controlled superconducting magnetic energy storage for power system stabilization

It has been clarified that a superconducting magnetic energy storage (SMES) is very effective for power system stabilization. The control methods proposed for power system stabilization by SMES are the pole assignment, the optimal control, and so on, each of which, however, has its drawbacks. This paper is concerned with the power system stabilization by neural network control of the active power of SMES. First, the optimal stabilizing control of the SMES power for the model power system is calculated for various power system operating conditions and fault conditions. Then these optimal controls are used as training data for the neural network. The neural network used is a multilayer type with a feedback from the output layer to the input layer. The trained neural network is examined by untrained operating conditions and faults.     

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     

大储能容量超导磁储能系统的拓扑结构及控制策略

随着可再生能源规模化发展,电网对大功率等级储能系统的需求日益增长,因此研究应用于大功率等级场合的超导磁储能(SMES)系统拓扑结构及运行控制策略具有重要的理论意义.提出了一种基于模块化多电平换流器(MMC)的SMES系统拓扑结构,设计了允许多个超导磁体同时接入以成倍数提升系统整体储能容量的新型斩波器.该新型斩波器采用模块化设计,由多个子模块串联构成,可随MMC扩展至多种电压等级和功率等级,且能够均衡各子模块的电容电压和磁体电流.针对新型斩波器的旁路子模块数量难以确定的问题,提出了新型斩波器旁路子模块数量的计算方法.基于线性自抗扰控制设计了MMC双闭环控制器和新型斩波器的直流电压控制器,利用复频域分析法整定了线性自抗扰控制器参数.通过仿真验证了所提拓扑结构和控制策略的正确性和有效性.     

基于超导磁储能和变流器重构的DFIG连续故障穿越方案

由高压直流输电系统换相失败引起的送端风电场母线低高电压连续故障,会对双馈感应发电机(DFIG)产生严重的暂态冲击,现有单一的风机低压、高压故障穿越方案难以完全适应此类连续故障穿越的要求。为此,提出了一种结合重构式网侧变流器与超导磁储能装置的软硬件协同穿越方案,以提升DFIG的连续故障穿越能力。在故障期间,网侧变流器由并联运行模式切换至串联运行模式,以维持定子端电压不变为目标,并控制转子侧变流器根据并网点电压自适应发出动态感性/容性无功电流。仿真结果表明,所提方案既可以维持DFIG的机端电压,又可以为电网提供无功支撑,有效地实现DFIG的低高电压连续故障穿越。     

Optimization of the electric power leveling system by using superconducting magnetic energy storage with genetic algorithm

A new optimization method of the electric power leveling system using an SMES is proposed. The SMES is parallelly connected with rolling mills in steel works. The leveling control is based on fuzzy reasoning. The SMES capacity and the scaling factors of the fuzzy controller will be optimized so that the power leveling control can be achieved and then the total cost of the added SMES cost and reduced contract electricity rate becomes lower. The optimization is carried out using a genetic algorithm and a cost reduction of 7.76 billion yen can be achieved. Power leveling simulation confirms that the proposed optimization method is very effective for designing the power leveling system. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(3): 62–69, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20049     

基于反馈线性化的超导磁储能装置控制器研究

以含超导磁储能SMES(SuperconductingMagneticEnergyStorage)装置的单机无穷大电力系统为研究对象,建立了其非线性数学模型。在此模型基础上,提出了一种基于反馈线性化方法和线性最优控制理论的SMES控制规律的简便设计方法。一个重要的特点是:在所构成的线性系统中,通过坐标变换引入了发电机机端电压,因此,可以方便地实现使用SMES同时对系统的功角和电压稳定进行控制。仿真结果表明该控制器对改善系统的阻尼特性和提高系统的电压稳定性都具有良好的控制效果,同时也验证了该控制器的可行性。     

基于超导磁储能装置的MMC-HVDC系统直流振荡抑制方法

基于模块化多电平换流器的柔性直流输电(MMC-HVDC)系统中的功率控制换流站对外呈现负阻性,降低了系统阻尼,使系统产生直流振荡甚至导致系统失稳。通过直流侧并联超导磁储能装置抑制系统功率振荡,以解决MMC-HVDC系统向恒定功率负载供电所导致的弱阻尼问题。建立了双端MMC-HVDC系统的小信号模型,通过小信号稳定性分析方法研究了影响MMC-HVDC系统稳定性的主要因素,并且验证了所提直流振荡抑制方法的有效性。在MATLAB/Simulink中搭建了双端MMC-HVDC系统模型,并与改变控制器的功率阻尼控制策略进行时域仿真对比,结果证明了所提控制策略能有效抑制系统振荡,提高系统稳定性。     

电压型高温超导储能系统变流器设计与试验

为提高电力系统动态稳定性,实现高温超导储能系统对电网电压跌落的有效补偿,采用三单相H桥型拓扑结构,搭建了一个电压型高温超导储能系统功率变换器.对控制系统、信号调理系统、功率和驱动保护电路进行了设计;基于SPWM脉冲触发方式,应用TMS320F2812型DSP实现了动态电压瞬时跌落补偿的全数字闭环控制,给出了相关的软件程...     

超导磁储能系统抑制风力发电功率波动的研究

建立含超导磁储能装置(SMES)的单机无穷大系统的Phillips-Heffron模型,导出含SMES电力系统总的电磁转矩表达式,从理论上分析SMES对增强系统阻尼的作用.并设计了SMES非线性比例积分微分控制器,数字仿真结果验证了SMES阻尼系统功率振荡的特性,同时表明该控制器具有较好的鲁棒性.     

储能技术在分布式发电中的应用

简要介绍了分布式发电的发展现状,分析了储能技术在分布式发电中的作用。重点介绍了飞轮储能、超导储能、蓄电池储能和超级电容器储能在其中的应用,分析了各种蓄能系统的优缺点和发展前景。     

电力系统稳定控制用高温超导磁储能装置及实验研究

超导磁储能稳定控制装置是将超导电力技术、大功率电力电子技术和控制理论相结合的一种新型电力系统稳定控制装置。它从及时补偿系统中由于各种原因产生的不平衡功率这一个新的角度出发考虑提高电力系统稳定性的问题，可望为解决由于功率不平衡产生的电力系统失稳问题提供一条新的途径。理论研究结果表明，这是一种非常有效的电力系统稳定控制措施。为了促进这一成果的广泛应用，同时进一步研究这种装置在实现过程中可能产生的问题，该作者在实验室环境中研制了一套基于直接冷却技术的高温超导磁储能控制装置样机，并在电力系统动态模拟实验室环境下，对该样机的性能进行了实验，得到了满意的结果。该文在简述利用超导磁储能控制装置进行电力系统稳定控制原理和特点的基础上，详细介绍了研制的高温超导磁储能稳定控制装置实验样机的构成和功率调节特性实验结果，以及将它用于电力系统动态模拟系统进行稳定控制的实验结果。     

混合储能脉冲电源中电容重复利用方案设计及仿真

在基于超导电感-电容混合储能脉冲电源中,两个储能电感比值较大时转换电容的容量要求也较大,降低了超导储能的体积优势。针对这一问题,本文分析了转换电容对单模块电路工作特性的影响,提出了多模块超导电感-电容混合储能脉冲电源电路共用一个转换电容支路的设计思路,并以三模块为例对同时放电和延时放电模式进行了仿真验证。仿真结果表明:多模块超导电感-电容混合储能脉冲电源电路可以共用一个转换电容支路,两种放电模式对负载电流脉冲都进行了改进,但同时放电模式进一步降低了超导储能的优势,而延时放电模式可大幅提高超导储能的优势。     

Consideration of multi‐coil type magnetization system for magnetic particle testing of omnidirectional crack in all surfaces of 3D shape test object

Mechanical parts, plants, and cross‐linkages inspected with magnetic‐particle testing (MT) are typically complex 3D shapes. In complex 3D shape portions, because a magnetizer often cannot be configured to inspection portions and the test object cannot be appropriately magnetized, there is a possibility of overlooking a crack in such an instance. Thus, MT system development that was successfully able to detect omnidirectional cracks in 3D shape portions was considered in this study's trials. Two multi‐coil type magnetizers were hence arranged face‐to‐face, and the magnetization of omnidirectional scenarios for all surfaces of 3D shape test object was evaluated.     

Design of a coil geometry for generating magnetic field to evaluate biological effects at 85 kHz

In recent years, the use of induction‐heating systems has increased and wireless power transmission (WPT) systems have been discussed. These applications are installed close to a human body. Therefore, it is important to discuss the effects of alternating magnetic fields and to evaluate electromagnetic interference. This paper discusses the design procedure of a magnetic field generator to evaluate the electromagnetic interference at 85 kHz that is being studied in WPT systems for EV and HEV. The magnetic field generator presented in this paper consists of a single‐phase inverter circuit that uses SiC‐MOSFETs and an air–core inductor that is used as the coil for generating a magnetic field. In particular, this paper shows that the coil used for generating magnetic field needs to reduce the winding voltage to generate higher magnetic flux. In addition, this paper presents the design procedure of the proposed coil structure that can satisfy some limited conditions. The experimental results of the proposed system rated at 82 kHz and 100 A are presented.     

电感式磨粒传感器线圈参数对磁场均匀性影响研究

磁场均匀性是影响电感式磨粒传感器检测精度的重要因素,为了提高传感器磁场均匀性,研究线圈参数对传感器磁场分布规律,根据磁场叠加原理,建立了电感式磨粒传感器三线圈数学模型,推导出传感器磁场计算公式,提出磁场均匀性评价系数K。对电感式磨粒传感器磁场进行仿真,分析了线圈内径、线圈宽度、线圈间距以及线圈匝数对传感器磁场分布的影响。通过极差分析和方差分析分别得到磁场均匀性最优线圈参数组合和线圈参数对磁场均匀性影响的显著性。实验结果表明:当线圈为最优参数时,传感器对70～200μm的磨粒有良好的监测能力,磨粒在不同径向的监测结果偏差小于5%,为传感器线圈的设计提供了参考。     

储能技术在电力系统中的应用

储能技术在电力系统中具有削峰填谷、一次调频、提高电网稳定性、改善电能质量、提高电网利用率、提高可再生能源利用率等重要作用.对此,介绍了中国电力系统建设对储能技术的迫切要求,并阐述了电池储能、电磁储能和机械储能等储能技术的发展现状.对电池储能、超级电容器与蓄电池混合储能和飞轮储能在电网中的应用分别作了说明,最后展望了储能技术未来的发展方向.