Characterization of coupled finlines by generalized transverse resonance method

The conventional transverse resonance method, which has been widely used for the approximate characterization of a number of guiding structures and leaky wave antennas, is formulated in a generalized form. The transverse resonance viewpoint combined with the generalized matrix representation of discontinuities yields a rigorous transverse equivalent circuit of the guiding structure. This technique is used to compute the characteristics of both symmetrical and asymmetrical double slot unilateral finlines in terms of phase constant and characteristic impedance of the dominant as well as higher-order modes. Numerical aspects of this method are discussed. In a double-slot finline structure, a coupled-mode regime is established with the onset of the first higher-order mode in addition to the dominant quasi-TEM mode. Symmetrical structures are simply modelled in terms of even and odd mode characteristics, but a more general coupled-line model, in terms of the C-mode and the II-mode must be applied to asymmetrical coupled finlines.     

磁耦合谐振式无线能量传输的阻抗匹配特性

针对无线电能传输过程中传输效率随匹配阻抗大小变化的特点,提出两种阻抗匹配的方法:一种是基于步进电动机通过检测网络反馈信号,控制网络通过GA神经网络算法控制步进电动机,改变电容实现阻抗匹配;另一种是基于直直变换器中Cuk电路的占空比大小来匹配阻抗的方法.在负载和线圈之间嵌入单相桥式整流电路和Cuk升降压变压器实现匹配.根据最大传输功率理论,定量分析了改变电路的阻抗值大小,使系统的传输功率及效率最大.在MATLAB/Simulink平台验证了两种阻抗匹配设计方案的有效性.结果 表明,利用基于步进电动机和Cuk电路的阻抗匹配方法可以实现最佳阻抗值匹配,使无线电能传输效率最大化.     

Stochastic assessment of distribution system resonance frequencies with capacitors or shunt filters

The paper explores the statistical harmonic response of power systems due to manufacturing tolerances of capacitor and shunt filter banks. Expressions to deterministically locate the resonance frequencies of power systems with capacitors and shunt filters are provided. From these expressions, the stochastic behavior of resonance frequencies due to random variations of system and equipment parameters is studied, and analytical expressions of probability density functions of these frequencies are obtained. Finally, the results are compared with Monte Carlo simulations to check their validity and their practical application is discussed.     

一种音频功率测量的新方法

介绍了一种单频范围内功率测量的新方法。这种方法是以有效值转换电路实现模拟运算,以程序数据处理实现数字计算,同时利用了新的算法,克服了热电式、时分割式、采样计算式等方法测量音频功率的不足之处。文中定量地给出了这种功率测量方法对测量误差的影响,为单频范围功率的准则测量提供了新途径。     

The evolution of power-line frequencies 133 1/3 to 25 Hz

It is generally understood that 60 Hz as frequency of AC power, has not always been that number. 60 Hz resulted after several trials of values for AC frequency, each determined by different criteria. This article presents a brief overview of the various frequencies beginning with 133 1/3 Hz and traveling through 125, 83 1/3, 66 2/3, 60, 50, 40, 30, and 25 Hz. They did not appear in the chronological order listed here, and their selection was influenced, to a great degree, by the types of applications made of electrical power during the early period of electrical technology     

矩型渡槽槽-水耦合体高阶共振特性研究

建立在小幅晃动假设上的槽水耦合体响应理论解显示,当外加激励为简谐荷载且激振频率为水体奇数阶晃动频率时,槽内水体出现共振现象,响应幅值趋于无穷大.如果此理论解确能代表现实中响应特性,则渡槽减隔震设计中存在槽.水耦合体高阶共振问题.这不但给渡槽减隔震设计增加了难度,也给实际工程带来潜在的风险.因此,通过槽-水耦合体高阶共振特性的CFD仿真分析,对槽-水耦合体高阶共振特性进行概念修正,并得出在渡槽减隔震设计中,几乎不存在槽.水耦合体高阶共振影响,在选择隔震周期时,只需避开一阶水体晃动频率的结论.     

Simplified impedance broadband matching by the image parameter method: The RC case

The image parameter theory is now considered as outdated for filter design owing to the existence of very efficient optimization procedures for the effective behaviour of filters. Nevertheless, it allows one to exhibit very simple relations between the bandwidth and the values of the components. Hence it is ideally suited for the problem of impedance broiband matching where the bandwidth and some components are specified data. It is shown that it allows to make a straightforward distinction between well- and ill-conditioned problems. In the first case the problem is reduced to a one-dimensional optimization and an image parameter design provides very easily an equalizer optimal for all practical purposes. In the second case the values of the image parameter design provides excellent initial values for an optimization process. The method is applied here to the simplest problem, the RC load. In a separate paper it will be shown that it is easily extended to more complicated loads and the double-matching problem.     

Measurement of harmonics/inter-harmonics of time-varying frequencies

A novel method of extraction and measurement of individual harmonics of a signal with time-varying frequency is presented. The proposed method is based on a nonlinear, adaptive mechanism. Compared with the well-established techniques such as DFT, the proposed method offers (i) higher degree of accuracy, (ii) structural/performance robustness, and (iii) frequency-adaptivity. The structural simplicity of the algorithm renders it suitable for both software and hardware implementations. The limitation of the proposed method as compared with DFT-based methods is its slower transient response. Based on simulation studies, performance of the method is presented and its accuracy and response time are compared with a DFT-based method.     

机炉耦合余热利用系统节煤效益计算匹配体系研究

以某600 MW机组含广义回热机制的空气预热器旁路余热利用系统一体化试验数据为依托,参照欧盟标准和国标这2类锅炉计算规范,对机炉耦合系统的锅炉效率/热耗/煤耗计算匹配体系进行了比较,分析了对发电厂标准煤耗计算的影响。基于热量输入-输出守恒原理与反平衡相结合的方法,结合案例验证了现行锅炉计算规范的可行性和不足之处。所推导得到的锅炉效率/机组热耗/燃煤量计算匹配体系的新模式,在机炉耦合余热利用系统中可以更加直观地反映锅炉效率及汽轮机侧得益的变化,并可据以评估热风温度的变化。同时,探讨了有热量输入-输出过程的余热利用系统中,在锅炉效率、燃煤量、管道效率、厂用电率及标准煤耗率计算中需要研究澄清的一些理论和实践问题。     

Automated frequency and quality‐factor matching method for frequency modulated / rate integrating gyroscope

This paper reports an automated tuning method for a frequency modulated / rate integrating gyroscope (FM/RIG). The frequency and quality factor mismatches in a MEMS resonator cause the mode‐coupling, thus degrade the accuracy of the gyroscope. The X‐Y phase difference and amplitude ratio of driving signals are used as the tuning parameters for the mismatch compensation. An automated tuning method based on the relationship between those tuning parameters and mode‐coupling terms were developed. Using the proposed method, the mode‐coupling effect, which comes from the frequency and quality factor mismatch, could be 3 orders of magnitude smaller than the noncompensated one.     

科氏流量计一次仪表与变送器匹配方法研究

针对科氏质量流量计一次仪表和变送器匹配不佳时所带来的无法启振、测量精度不高以及驱动效率较低等问题,提出基于模拟驱动电路的稳态幅值图解分析方法,以国内某型号的一次仪表和自身研制的变送器为对象,分析启振、稳态振荡和高温情况下的匹配过程。给出一些最佳匹配的措施,使得启振时间缩短为3s,驱动效率提高20%,保证流量计在高温60℃环境下仍能正常运行。实验结果表明,匹配方法简单、可行和有效。     

基于模板匹配的电能表液晶屏检测新方法

为实现自动化检定中对智能电能表液晶屏质量的在线检测,并解决误判率高的难题,文中提出了一种基于快速模板匹配的电能表在线液晶屏检测新方法。该方法采用基于阈值自适应序贯相似性算法的自学习型模板快速匹配算法,将多幅模板图像的特征综合为一个标准模板,建立实时调整的自学习型模板库,并改进传统的序贯相似性算法,将其阈值自适应。实验结果表明文中提出的方法不仅具有较高的检测效率和匹配精度,还有效降低误判率,具有较高的工程应用价值。     

The mortar edge element method on non‐matching grids for eddy current calculations in moving structures

The subject presented in this paper concerns the approximation of the eddy current problem in non‐stationary geometries with sliding interfaces. The physical system is supposed to be composed of two solid parts: a fixed one (stator) and a moving one (rotor) which slides in contact with the stator. We consider a two‐dimensional mathematical model based on the transverse electric formulation of the eddy currents problem in the time domain and the primary unknown is the electric field vector. The first‐order approximation of the problem that we propose here is based on the mortar element method combined with the edge element discretization in space and an implicit Euler scheme in time. Numerical results illustrate the accuracy of the method and allow to understand the influence of the rotor movement on the currents distribution. Copyright © 2001 John Wiley & Sons, Ltd.     

一种配电网层间供电能力匹配度评价方法

传统配电网供电能力评价的对象一般是单一电压等级下的配电网,由于配电系统涵盖多电压等级,所以其并不能很全面的评价整个配电系统。为了改善传统方法对整体配电网供电能力裕度评估的局限性,基于配电网具有多电压等级这一前提,提出一种配电网层间供电能力匹配度评价方法与指标,其意义在于评价不同电压等级配电网上级与下级间的匹配程度,能够充分考虑上级配电网对下级配电网的限制情况以及下级配电网对上级配电网的制约情况,进而全方位评定配电网供电能力。并结合供电裕度、负载能力裕度等单一电压等级下的指标,运用线性规划算法建立模型,从而对配电网整体的供电能力有较为直观的判断。最终利用算例分析证明模型可行性,从而完善评估配电网最大供电能力的指标体系。     

逆变电源对风火/光火打捆送端电网低频振荡影响及其惯量匹配方法

为研究逆变电源(Inv)对“风火/光火”打捆送端电网稳定运行的影响,提出了一种计及系统参数的控制模型及不同类型电源的惯量匹配方法。首先,构建Inv所有控制环节的数学模型,进而形成整个研究系统的小信号模型,并通过Matlab仿真验证。其次,基于小信号模型利用根轨迹法,分析系统参数对送端电网内部低频振荡的影响。研究表明送端电网内部线路越短,阻感比越大,Inv出力越多,越有利于系统稳定。最后,利用等效电源原理,推导出送端电网中两种类型电源的惯量匹配方法。RT-LAB半实物仿真验证了所提惯量匹配公式能更好分配功率,提高送端电网稳定性。     

基于行波固有频率的特高压直流输电线路纵联保护方法

故障后行波在故障点与线路终端间来回反射,形成的固有频率与故障距离有明确的数学关系。特高压直流(Ultra High Voltage Direct Current, UHVDC)输电线路的边界由平波电抗器和直流滤波器构成,与交流线路相比,线路故障后形成的行波固有频率更加清晰。基于此,提出了一种利用线路两端固有频率主成分特征的特高压直流输电线路纵联保护方案。根据电流变化率构造故障启动判据;用MUSIC方法对故障后的暂态电流数据进行频谱分析,利用区内外故障时线路两端固有频率特征差异构造保护判据;利用原始行波信号和解耦后行波信号提取的固有频率主成分构造选极判据,形成完整的基于行波固有频率的特高压直流输电线路纵联保护方案。在PSCAD/EMTDC中建立特高压直流输电系统模型,并在不同故障工况下对该保护方案的适应性进行仿真。大量仿真结果表明,该保护方法在不同故障工况下均能可靠、快速动作,具有较好的适应性和实用价值。     

The dielectric response of ferroelectric films AT intermediate frequencies

Abstract

A technique is described for evaluating dielectric data on ferroelectric films using a Cole-Cole distribution function to separate film and electrode capacitance and resistance. The nature of the information obtained, and methods for validating the conclusions are discussed. The method is applied to lead zirconate titanate films on platinum and ruthenium oxide. Electrode capacitances are generally of the same order of magnitude as the film capacitance.