磁阀式可控电抗器设计与性能分析

介绍了磁阀式可控电抗器的设计原理及其性能分析。考虑铁心的导磁能力、制作工艺,绕组的补偿容量、额定电压等因素,根据铁磁非线性规律,提出一套切实可行的设计原理,考虑到现有条件和成本问题,运用该原理设计出一台工频小容量磁阀式可控电抗器。运用Saber磁性元件分析工具对电抗器进行仿真,验证了设计原理的正确性。制作出一台10 k VA的可控电抗器样机。仿真和实验结果对比表明,运用该原理设计出的磁阀式可控电抗器具有损耗低、调节平滑、可行性好等优点。理论分析、仿真分析和实验结果相吻合,研究结果为磁阀式可控电抗器的大容量化工业设计提供了一定的理论依据。     

Analysis and Performance of a Fixed Filter-Thyristor Controlled Reactor (FF-TCR) Compensator

A fixed Filter-Thyristor Controlled Reactor (FF-TCR) type of compensator is proposed to improve the power factor of a single phase thyristor-controlled inductive load and it is shown that this compensator gives better power factor improvement than the more generally used FC-TCR type of compensator. Analysis is carried out for the exact equivalent circuit of an FF-TCR compensator containing two filter branches tuned to the third and the fifth harmonics respectively. It is shown that with an FF-TCR compensator the power factor improvement is much better when the source impedance is large. However, even with a small source impedance, a reasonable improvement in power factor is realised. It is further shown that even when the source impedance is large the distortion in the terminal voltage waveform is kept within reasonable limits. The analytical results are verified experimentally.     

静止无功补偿器对电力系统性能改善的综述

随着电力电子技术、微处理技术和控制技术的发展,柔性交流输电系统FACTS(Flexible AC Transmission System)的出现,为电力系统急待解决问题提供了新的手段或策略。静止无功补偿器(SVC)作为FACTS家族的成员之一,对电力系统性能的改善也已取得了可喜的成绩。因此,从静止无功补偿器提高稳态输送容量、提高暂态稳定性、增强系统阻尼抑制低频振荡、缓解次同步谐振、预防电压不稳定或控制电压的波动、改善直流输电系统的性能等六个方面进行综述。     

静止无功补偿器对电力系统性能改善的综述

随着电力电子技术、微处理技术和控制技术的发展,柔性交流输电系统FACTS(Flexible AC Transmission System)的出现,为电力系统急待解决问题提供了新的手段或策略.静止无功补偿器(SVC)作为FACTS家族的成员之一,对电力系统性能的改善也已取得了可喜的成绩.因此,从静止无功补偿器提高稳态输送容量、提高暂态稳定性、增强系统阻尼抑制低频振荡、缓解次同步谐振、预防电压不稳定或控制电压的波动、改善直流输电系统的性能等六个方面进行综述.     

压控恒流源的动态性能研究

研究了一种常用的恒流源电路的输出动态特性。研究发现：在负载及输出电流值不变的情况下,影响恒流源动态性能的主要因素是误差放大器积分电容的容值、反馈放大器的放大倍数等;在电路参数固定的情况下,在一定的输出电流范围内,影响系统动态性能的主要因素是负载阻值,而电流值影响很小。最后,根据实际电路设计指标,提出了改善系统动态性能的解决方案,仿真及实际电路测试证明了结论的正确性。     

基于分岔理论的磁阀式可控电抗器匝数比研究

匝数比取值对磁阀式可控电抗器(MVCR)的工作性能有较大影响.匝数比取值合理.能够保证MVCR的端电压瞬间变化时,其工作电流迅速稳定在某一个当前值;若匝数比取值不当.会使MVCR在运行过程中表现出很强的非线性特性,对系统的运行特性造成极大的影响.甚至无法工作.利用非线性动力学的分岔理论,阐述了一种固定周期离散映射的建模方法.首先建立MVCR的离散模型.然后利用该模型计算得到匝数比不同取值时等效工作电流的稳态值.在分析稳态值分岔现象的基础上,给出了匝数比的合理取值范围.仿真结果验证了所提方法的有效性和合理性.     

三相磁阀式可控电抗器的特性仿真分析

提出了一种能根据电力系统变化而平滑调节自身容量的三相磁阀式可控电抗器(MCR).简单介绍了其在电力系统中的应用、结构、工作原理及电磁特性,并采用Ansoft Maxwell 3D有限元分析软件进行了电磁仿真分析.仿真分析证实了改变可控硅导通角能改变控制电流大小,从而平滑调节MCR自身容量的可行性.     

系统阻抗对竞比型低励限制控制励磁系统的稳定性影响研究

推导了单机-无穷大系统在竞比型低励限制(UEL)动作后的扩展菲利普斯模型,并基于阻尼转矩法分析了发电机励磁系统阻尼转矩系数及同步转矩系数随系统阻抗的变化特性;采用小干扰稳定性分析法,从特征根分布、阻尼比大小以及参与因子等方面研究了竞比型UEL动作后系统阻抗对系统稳定性的影响。研究结果表明:当竞比型UEL代替励磁主环控制励磁系统时,系统阻抗的增加能够提高系统阻尼,增强系统稳定性,但同时会对无功功率的稳定性产生不利的影响,增加无功功率的波动次数;基于某实际励磁调节器厂家UEL模型详细分析了其与励磁主环发生反复切换的机理,验证了无功功率波动的死区范围配合不当时会引发系统振荡的结论。     

Characterization of a thyristor controlled reactor

This paper characterizes the operation of a thyristor controlled reactor (TCR) which consists of an inductance and a bi-directional thyristor switch connected in parallel. Firing angle control of the thyristor switches regulates the time for which the inductance is included in the circuit. This controls the average value of the inductance. The continuously regulated inductance can be used for line flow regulation and short circuit current reduction. It can also be used for series compensation when the TCR is connected in series with a fixed capacitor and when the combination is inserted in series with transmission lines. This paper analysis the operation of the TCR using equations and EMTP simulations.The analysis shows that a series compensator using TCR regulates the level of compensation from inductive to capacitive and the system response is faster than the recently commercialized ‘Advanced Series Compensation’ (ASC) scheme. Also, the problems of resonance and harmonic instability associated with the ASC are eliminated. The TCR can control short circuit current within half cycle.     

锂源过量对固相合成Li_4Ti_5O_(12)电化学性能的影响

以Li_2CO_3和TiO_2为原料,固相法合成了不同Li_2CO_3过量的Li_4Ti_5O_(12)(简称LTO),通过X射线衍射法(XRD)对LTO相和残余TiO_2相的定量分析计算了合成纯的LTO所需Li_2CO_3原料过量程度.Li_2CO_3过量起到两方面的作用:(1)补充高温合成LTO过程中所挥发的锂,从而减少TiO_2含量;(2)造成一些Li+进入LTO晶格取代部分Ti~(4+),使得LTO的电导率增加,过多的取代量会降低LTO的比容量.这两种作用决定了Li_2CO_3过量对LTO的充放电性能具有显著影响,综合结果表明,Li_2CO_3过量5%所制备LITO具有最佳电化学储锂性能.     

新型混合型磁控电抗器的特性研究

针对传统磁控电抗器功率损耗大,谐波电流含量高的特点,设计了一种新型混合型磁控电抗器,该混合型磁控电抗器采用磁阀式可控电抗器与不饱和铁芯电抗器线圈串联技术,中间柱不饱和铁芯上流过的交流磁通为两个边柱铁芯交流磁通之和,磁阀式可控电抗器的直流磁通不流过中间柱铁芯.该结构可以大大减小磁阀式电抗器的线圈匝数,从而减小磁控电抗器的...     

Convertible static compensator performance studies on the NY state transmission system

New York Power Authority is installing a new flexible AC transmission system (FACTS) controller, known as the convertible static compensator (CSC), at Marcy 345 kV substation. Two 100 MVA converters are installed. Through one 200 MVA shunt and two 100 MVA series transformers, the converters may be connected to each other and to the system in 11 different configurations. This arrangement of the converters allows STATCOM, SSSC, UPFC, or IPFC deployment at the bus and two of the lines exiting the substation, namely, Marcy-Coopers Corners and Marcy-New Scotland 345 kV lines. Voltage, small signal, and transient stability simulations are conducted using the developed models of these configurations within the user-defined capability of the EPRI's power system analysis package. The focus of the studies is on finding out which configuration of the CSC provides the highest performance improvement from all stability points of view. Modulation controls are designed to improve inter-area oscillation damping. In general, all CSC configurations improve voltage, small signal, and transient stability margins of the system. The performance of the individual devices resulting from CSC configurations and their capabilities in the studied cases is presented. It is shown that the CSC in conjunction with three fixed capacitor banks at three other substations can increase the system power transfer limit by up to 310 MW.     

定(变)负荷对冰箱制冷系统性能影响的模拟分析

通文采用MATLAB软件对传统的ON-OFF控制冰箱进行了建模,对它们在恒温闭门定负荷条件下和实际工作环境的变负荷下控制系统的效果进行了模拟和比较分析。模拟的结果显示,这两种条件下的耗电量与冰箱温度控制效果均存在不同程度的差异。     

磁饱和式可控电抗器在无功补偿中的应用

介绍了磁饱和式可控电抗器的基本结构和工作原理,以此为补偿元件、晶闸管为执行元件的无功补偿设备可以快速、准确、平滑、合理地调节系统的无功功率,满足超高压、长距离输电和冲击性负荷的供电要求。     

流型对固体氧化物燃料电池性能的影响

固体氧化物燃料电池(SOFC)是一个伴随流动、传热和电化学反应的复杂系统,它的性能在很大程度上取决于电池的系统结构.基于容阻特性建模和分布集总参数方法,在已建立的一维内重整固体氧化物燃料电池数学模型的基础上,分别建立了顺流型和逆流型固体氧化物燃料电池的仿真模型,并比较和分析了燃料电池的稳态分布特性和动态特性.仿真结果表明顺流型固体氧化物燃料电池能更好地满足动力系统性能和安全方面的需求.     

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.     

Improving the energy performance of an ac electric locomotive using a new compensator control structure

A device for improving the power factor for ac electric locomotives that are based on an adjustable passive reactive-power compensator is described. This compensator configuration allows an increase in the power factor of an electric locomotive in all its operating modes. The control of the compensator unit is based on the method of extremal voltage control at the output of an autonomous voltage inverter (AVI). The voltage is chosen on the basis of the numerical differentiation of the dependence of the power factor on the AVI voltage. The mathematical simulation of the operation of the compensator with an extremal regulator, which was performed in the MATLAB package, showed that the proposed device is highly efficient.     

镍粉对Ni(OH)2电极电化学行为的影响

利用恒电流充放电、循环伏安法研究了过量镍粉对Ni（OH）2电极电化学行为的影响,并用X射线衍射分析了放电后镍粉结构的变化。结果表明：电极中的镍粉在碱性电解液中会氧化成活性物质β—Ni（OH）2,从而对放电容量作出贡献,同时因氧化使导电性降低而影响Ni（OH）2的放电效率。利用镍粉作空白试验对照,将电极在第4～6周期的放电容量扣除镍粉的贡献可尽量准确地测定Ni（OH）2的放电容量。     

能量回馈型超声波电机定子振动特性有限元分析与特性测试

提出一种集精密驱动和振动能量采集于一体的新型多功能压电振动电机——能量回馈型超声波电机,设计了电机夹心式内锥面压电定子,建立了电机压电定子的有限元模型,仿真分析定子振动特性和能量采集输出特性;研制电机原理样机,并对电机进行阻抗和能量采集特性测试与分析。研究结果为工作在极端封闭环境中的微型机器人系统提供一种集驱动与供电一体化的机电器件。     

Minimization of high harmonics in the current of a biasing controlled arc suppressing reactor

Compensation of single-phase earth fault currents in 6- to 35-kV networks is one of the purposes of using arc suppressing reactors (ASRs). Nonlinear distortion current of the reactor contributes to the residual fault current, for which reason its minimization is a critical task during ASR design. Operation under the technical saturation mode of electrotechnical steel is a characteristic feature of biasing controlled ASRs. Moreover, the biasing current of the device contains the high harmonics components; the share of these components depends on the structure of the magnetic system and on the properties of the electrotechnical steel. This paper proposes an approach to optimization of the magnetic system of a biasing controlled ASR based on adjustment of the biasing characteristics of the magnetic core according to the results of experimental measurements of the harmonic composition of reactor currents within a wide biasing range. Analysis of the influence of the parameters of the combined shell–core magnetic system on the reactor distortion current is carried out. Results of experiments for obtaining a biasing characteristic aiming at calculation of the harmonic composition of the reactor current with minimum 10% error are given. An optimization calculation of the parameters of the RUOM reactor magnetic system sections was carried out that allowed reducing the distortion current to 4% within the whole control range (10–120%) of the reactor nominal power and to 1% within the range of 60–100% of the reactor nominal power.