自平衡式交直流电流比较仪研究

为满足日益提高的宽频电流测量需求,文章设计研制了一种自平衡式交直流电流比较仪。该交直流电流比较仪在磁调制式直流电流比较仪的基础上引入闭环交流测量通道,不仅极大地拓展了其测量的频带宽度,而且利用反馈技术实现了电流比较仪的自动平衡。详细介绍了电流比较仪的研制过程,并搭建虚拟仪器自动测试系统对所研制电流比较仪的性能进行考察。测量结果表明,该交直流电流比较仪在直流测量时的线性误差小于2×10-4,交流测量带宽不低于100k Hz,测量标准不确定度为2×10-5。     

直流电流比较仪比例误差的测量方法及理论分析

本文对直流比较仪比例误差的测量问题进行了探讨和分析,介绍了4种测量方法及误差理论分析,结果表明换位式电压比对法适用于测量精度低于1×10~(-5)的直流匝比仪器,电流对按法适用于测量精度低于1×10~(-6)的直流匝比仪器。而小电流测差法、调制电压法适用于测量精度低于1×10~(-7)的直流比较仪,其中调制电压法是一种很有应用前景的测量方法。     

交流电流比较仪在四端钮阻抗测量中的应用

交流电流比较仪能提供精确的电流比例,本征地适合四端钮阻抗的测量.本文概述交流电流比较仪的发展状况及其基本原理,介绍交流电流比较仪电桥在四端钮阻抗测量中的应用,指出音频电流比较仪电桥将成为未来研究的主要方向,并重点讨论音频交流电流比较仪电桥在容性误差补偿、灵敏度以及比例校验等几方面的关键问题.     

介绍一种新型高压电桥QS32型

本文叙述了一种基于电流比较仪原理构成的能十分方便在10千伏下测量一端接地试样(反接法)的介质损失角(tgδ)和电容量(c)的高压电桥。由于它具有比传统使用的西林电桥有更大的优越性,在八十年代中它将有可能替代高压西林电桥为电力系统广大的用户服务。     

一种电流比较仪校验的新方法

为了解决现有电流比较仪校验方法繁琐的问题,本文提供了一种电流比较仪校验的新方法及其校验装置,并给出了该方法的计算公式和校准数据.采用本文的技术方案,仅依靠一台参考电流互感器即可进行一台电流比较仪误差的自校准,从而实现了比例(k:n)(k为小于n的自然数)的自耦式电流比较仪自校验.     

一种高准确度电子补偿式电流比较仪

电流互感器(CT)被广泛应用于电流的比例变换,但其准确度一般难以优于0.01%。具有更高准确度的电流比例变换装置,例如双级电流互感器或补偿式电流比较仪,由于使用上的限制,一般只用于工频电流比例的量值溯源或量值传递。针对于此,研发出一种利用电子线路补偿铁心励磁电流的即所谓电子补偿式电流比较仪(ECCC)。文中阐述这种电流比较仪的基本原理,理论分析其误差性能,并进行了误差校准试验。试验结果表明,该ECCC的准确度满足0.000 5级要求,既可作为一种高准确度的电流比例标准,也可用于工频电流的高准确度测量。     

全光纤电流传感器的原理及应用

全光纤电流传感器在高压电网中常用作监测保护和计量,具有重要的实际工程价值,且容易解决高压绝缘和高频电流的测量难题.详细介绍全光纤电流互感器的原理、结构和技术性能.     

电力设备直流电阻测量用恒流源研究

介绍了一种用于测量大型电力设备(如电力变压器)支流电阻的高稳定度10A恒流源的工作原理、设计方法和重要性能指标，并提出了利用直流比较仪对大电流恒流源(测量微小电阻时)进行校验的新颖方法。     

一种双惠斯通桥磁阻传感器大电流检测系统

提出了一种双惠斯通桥差模电路的磁阻传感器电流测量新方法。本方法采用通用低成本磁阻传感器,相对于目前主流的电流检测技术具有抗干扰能力强、可靠、易于实现二次封装与板级应用、性价比高、测量范围广、温度漂移低的优点。本文详细介绍了系统的设计思想与结构,分析了系统工作原理,并通过实验数据验证了该方法的可靠性和稳定性。     

用于电晕电流测量的高电位数据采集系统开发和应用

电晕是高压输电线路设计中必须考虑的问题。电晕电流是导线周围带电粒子的复杂运动引起的,具有环境电压高、频谱宽、变化剧烈等特点。针对高压试验线路,采用屏蔽箱、电流探头和高速采集卡设计了电晕电流测量系统,采用光电技术和计算机控制技术,解决了高压绝缘、信号干扰和电晕信号高频采样记录的测量困难,实现高压试验线段电晕电流的地面安全可靠测量。在实验室搭建模拟线路,利用该系统进行了测量,测量现象和结果符合预期的分析,验证了方案的可行性。     

The Application of the Current Comparator in Instrumentation for High Voltage Power Measurements at Very Low Power Factors

A current-comparator technique is applied to several auxiliary instruments which enables accurate high voltage power measurements to be made at very low power factors using precision wattmeters and precision bridges. The instruments include a high-voltage active-divider with a nominal output voltage of 100 V, a high-voltage inductive-quadrature-current reference source with current output ranges of 1 mA, 2 mA, and 10 mA, and a high-voltage high-capacitive-quadrature-current reference source with current output ranges of 0.1 A, 0.5 A, and 1 A. The current comparator is used in a feedback loop to correct the magnitude and phase of the associated outputs of these instruments to an accuracy of better than ±10 ppm (parts per million) and ±10 ?rad respectively.     

A current-comparator-based load loss standard for in-situcalibration of transformer loss measuring systems

A current-comparator technique for obtaining a load-loss standard with adjustable loss tangent (or power factor) for in-situ calibration of transformer loss-measuring systems is described. The standard, driven by the test voltage through a low-loss, high voltage compressed-gas-dielectric reference capacitor, simulates an inductive load that can be operated with load currents of up to 1000 A. The equivalent rating of the load is determined by the voltage of the high-voltage reference capacitor. Adjustment of the loss tangent (or power factor) is achieved by comparing the load current, using the current comparator, with in-phase and quadrature reference currents derived from the test voltage. The standard features three current ranges of 10 A, 100 A, and 1000 A. The maximum current of each range is available at five different voltage levels which are determined by the voltage rating of the high-voltage reference capacitor. The standard also features a direct-reading loss tangent (tan δ) adjustment in the range from 0 to 0.1 with five-digit resolution and an accuracy of better than 20 parts per million     

A Current-Comparator-Based Wattmeter for High Voltage Power Measurements at Very Low Power Factors

A current-comparator technique for obtaining a wattmeter for accurate high voltage power measurements at very low power factors is described. The quadrature component of the load cturrent is automatically balanced in the current comparator against a quadrature current obtained from a slave supply, thereby reducing the stringent high accuracy requirement of the wattmeter when used for measuring power at very low power factors. The current-comparator-based wattmeter has an estimated accuracy with respect to its readings of better than 3 percent at 0.001 power Factor, 1 percent at 0.005 power factor, and 0.5 percent at 0.01 power factor and higher. It features an internal high-voltage active-divider and displays to indicate source voltage, current, power factor, and reactance of the load, in addition to the power.     

A microprocessor-controlled high-voltage current-comparator-basedcapacitance bridge

A microprocessor-controlled high-voltage current-comparator-based capacitance bridge is described. The bridge has a capacitance ratio and a dissipation factor (loss tangent) measurement range of 1/1 to 100/1 and 0 to 10%, respectively, with a resolution of 1 PPM (part per million). To accommodate capacitance ratios larger than 100/1 (up to 100000/1) and load currents of up to 1000 A, an additional range-extending two-stage current transformer is employed. The overall accuracy of the bridge including the ratio extender is better than 5 PPM in both magnitude and phase. The automatic balancing feature facilitates the use of the bridge for accurate load loss measurements of large high-voltage inductive loads, such as shunt reactors and power transformers. It allows tracking of the changes in the inductive and loss tangent balance due to power frequency fluctuations and heating effects, respectively     

高频高压变极性矩形波发生电路设计

高频高压电路在科学仪器中应用广泛。利用MOS管、半桥驱动芯片LM27222、栅极驱动变压器等器件,设计了变极性矩形波发生电路。基本原理是使用高频低压逆变器,经变压器隔离驱动高压逆变器,来实现直流高压的高速开关。驱动电路具有低内阻,工作速度快,抗干扰能力强的优点。电路只需一路控制信号,矩形波频率和幅值均可调,最高工作频率可达2 MHz,幅值取决于所加直流电压。介绍了电路设计过程,给出了实验结果。实验证明电路运行稳定,具有实用价值。     

在武汉市城区采用随桥梁敷设高压电缆的探索

文章介绍了国内外随桥梁敷设高压电缆现状以及国内相关规程规范,对在武汉市城区随桥敷设高压电缆进行了主要技术因素分析、利弊分析以及工作设想。     

正确测量电力电容器的电容和tanδ

详细说明了利用高压西林电桥和高压标准电容器测量电力电容器的电容和介质损耗角正切(Tanδ)的原理;扩大量程的途径及注意事项;引起测量误差的因素以及如何消除或减小测量误差,提高测量精度的方法。同时还简要介绍了通过测量全膜介质电力电容器的损耗功率求得全膜介质电力电容器的Tanδ值的方法。     

The application of the current-comparator technique ininstrumentation and measurement equipment for the calibration ofnon-conventional instrument transformers with non-standard rated outputs

An overview of the development of instrumentation and measurement techniques at the National Research Council of Canada, based on current comparator technology, for calibration of nonconventional instrument transformers with nonstandard rated outputs, is presented. The instruments include: (1) a wide-dynamic-range transimpedance amplifier for operation of input currents from 1 A to 1000 A with means for modifying the in-phase and quadrature components of the output voltage (rated 10 V) within a ±10% range; (2) a high-voltage high-current transconductance amplifier with output current ranges of 10 A, 100 A, and 1000 A; and (3) a voltage ratio standard also with means for modifying the in-phase and quadrature components of the output voltage (rated 100 V) within a ±10% range. The current comparator technique is used to obtain accuracies of better than 20 parts per million in both magnitude and phase of the associated outputs of these instruments     

一种适合宽范围输出的三电平DC/DC变换器

提出了一种宽电压范围输出的三电平DC/DC变换器,其包含两组并联的主桥臂和辅助桥臂以及级联形式连接的主变压器和辅助变压器。该变换器具有低压低功率和高压高功率两种工作模式,其中低压模式下辅助桥臂不开通以降低电路损耗,高压模式下辅助桥臂开通以提高输出电压。与传统电路相比,变压器具有更低的变比,分析了传统拓扑的损耗,并比较了新拓扑与传统拓扑在不同输出模式下的效率,得出新拓扑在低压模式下具有更高效率的结论。研制了一台2 000 W的原理样机,实验数据表明,在低压模式下新拓扑的效率仍可高达94%,较传统拓扑提升了3%,验证了理论分析的正确性。     

多路输出高压隔离驱动电源的研究

研究了一种具有高压隔离性能的多路输出驱动电源。利用全桥串联谐振在桥臂间形成电流型交流母线,配合高压电缆线、光纤传输实现高压隔离性能。利用磁环数目的增减可以灵活控制驱动电源输出路数。分析了该电源的适用环境、结构及其特点,分析了部分参数对驱动电源输出电压的影响并进行了仿真,验证了该驱动电源配合IGBT运用在轻型高压直流输电中的可行性。最后,制作了一台125 W/2.5 A的样机,进行了实验验证。实验证明,该驱动电源结构、控制简单,可以实现软开关,符合多路输出以及高压隔离中驱动的要求。