短路试验电流光纤测量技术研究

针对交、直流开关电器短路试验电流校准问题,提出光纤短路电流测量方法。建立了光纤电流传感器低频动态模型,通过时域、频域特性仿真确定了闭环检测系统的参数,并计算了传感器对直流和工频短路电流的响应,结果表明传感器的动态性能能够满足跟踪被测短路电流的要求。搭建了光纤电流传感器校准装置,校准结果表明:在直流5～300 kA、工频5～50 kA范围内,传感器样机的测量准确度优于0.2%。利用光纤电流传感器进行短路电流实验测试,并与目前普遍使用的分流器和罗氏线圈比较,结果表明:对于6～100 kA的直流短路电流,分流器与光纤电流传感器之间的相对误差小于0.3%;对于10～130 kA的工频短路电流,罗氏线圈与光纤电流传感器之间的相对误差不超过0.2%。研究工作为短路试验电流的测量提供了新的解决途径。     

微秒级脉冲电流幅度校准用罗氏线圈的研制及定值

针对微秒级时间尺度、千安级电流幅度的脉冲大电流的校准需求,建立了自积分式罗氏线圈的数学模型,分析了线圈的幅频特性,研究了磁芯材料、结构参数、电磁参数对罗氏线圈性能的影响规律,研制了可测量幅值达2kA的微秒级脉冲大电流的罗氏线圈。建立了罗氏线圈关键性能参数的校准平台,对罗氏线圈的上升时间、刻度因数等性能参数进行了校准,结果表明:罗氏线圈刻度因数为498. 6A/V,上升时间优于2. 6μs,可测量脉冲电流幅值达2kA。     

一种工频大电流罗氏线圈的校准方法及不确定度分析

提出一种用电流比例标准配合标准电阻的方法来校准工频大电流罗氏线圈,克服了传统标准源校准方法测量工频大电流的量程局限性,解决了工频扩大至20 kA电流量程罗氏线圈的校准问题,并对该方法下典型值的测量结果不确定度进行了分析和评定。     

变压器工频短路电流测量技术研究

针对变压器工频短路电流测量需求,研究了外积分式罗氏线圈技术和光纤电流传感技术。建立了2种传感器的低频数学模型,基于MATLAB/Simulink仿真计算传感器对工频短路电流的响应特性,结果表明:罗氏线圈对工频短路电流的测量精度受其下截止频率影响,下截止频率越低,测量精度越高;光纤电流传感器理论上可以精确复现工频短路电流。采用多种电流传感器进行变压器工频短路电流现场对比测试,结果表明:电流比较仪、光纤电流传感器及下截止频率为0.02Hz的罗氏线圈测得的电流波形吻合较好,而下截止频率为0.2Hz的罗氏线圈测量结果出现了明显的偏移,且无法归零,与仿真分析结论基本一致。对于外积分式罗氏线圈,为保证高精度测量,建议下截止频率应低于0.1Hz;光纤电流传感器具有极好的直流及低频响应特性,是工频短路电流高精度测量的理想方案。     

光纤电焊电流测量技术研究

针对直流逆变电阻焊机焊接电流精确测量的需求,提出基于光纤电流传感技术的焊接电流测量方法。建立了光纤电流传感器闭环检测系统动态模型,通过优化系统的前向增益,提升了传感器响应速度和带宽。仿真和实验结果表明:传感器的上升时间约为4.1 μs,在DC~30kHz范围内幅频特性衰减小于0.3%。基于该动态模型计算传感器对焊接电流纹波分量的响应,仿真结果表明:系统的动态跟踪能力可满足对纹波电流的测量需求。利用等安匝法对光纤电流传感器进行校准,在直流5~50kA范围内,传感器的测量误差优于±0.05%。现场实验结果证明了光纤电流传感器用于直流逆变焊接电流测量及电焊电流测试仪现场校准的可行性。     

宽带脉冲大电流测量及大数据分析技术

多磁路调压变压器的脉冲电流具有频带宽、幅度大的特点,其测量与大数据分析易受到噪声等影响。本文研究了多磁路调压变压器宽带脉冲大电流测量与大数据分析技术,设计了基于法拉第磁光效应和光纤电流传感器的宽带脉冲大电流测量系统方案,采用卷积神经网络对测量得到的海量数据进行处理,消除测量过程中干扰对测量结果的影响。通过与罗氏线圈的测量结果比对,本文研究的方法测量结果的脉冲波形一致性好、脉冲峰值检测准确度较高,脉冲幅值误差符合测试要求。     

光纤直流大电流传感器非线性机理及校准技术

非线性误差是干涉型数字闭环光纤电流传感器超大电流测量的主要误差源之一。借助琼斯矩阵方法,推导了光纤1/4波片不理想条件下传感器输出与被测电流的理论关系,确定了1/4波片的方位角和相位延迟误差是造成光纤电流传感器超大电流测量非线性的主要原因之一。仿真结果表明:在5~300kA范围内,方位角误差小于4.53°,相位延迟误差小于9.05°,可保证传感器的测量误差小于0.2%。搭建了光纤直流大电流传感器校准系统,提出了分段线性插值补偿方法校准光纤电流传感器的非线性误差。测试结果表明:非线性补偿后传感器的测量误差由最大的0.6%降低到0.1%以内,证明了非线性补偿方法的有效性。     

柔性电流探头校准方法及不确定度评定

柔性电流探头是一种基于罗氏线圈(Rogowski Coil)原理制作的空芯型交流电流传感器,一般用来测量交流大电流,罗氏线圈和载流导线间的互感系数为柔性探头的电流变换系数。文章介绍了一种柔性电流探头的电流变换系数的校准方法,给出了其测量不确定的评定,并给出了电流变换系数线性度和输出频率响应的测试及结果分析。     

Rogowski线圈在高压脉冲大电流测量中的应用

利用Matlab软件的Simulink仿真环境,创建了高压脉冲大电流测量系统的仿真模型,实现对罗氏线圈结构参数的确立和积分器积分常数的优化.给出了一种适合于高压脉冲大电流测量的罗氏线圈的结构设计及其积分电路的设计方法,并将这种测量装置成功应用到脉冲成形网络(PFN)放电系统中.通过在积分电路中加入滤波抗干扰设计,实现了对高压脉冲大电流的测量,克服了冲击电流测量中常规用分流器存在的问题和不足.     

高精度CT测试与校验系统实验与分析

电流互感器是国防、制造等领域大电流准确测量的重要设备.本文采用光纤宽带大电流测量仪对交直流电流互感器进行测试校准,并与"高精度CT测试与校验系统"、高精度罗氏线圈(仅测交流信号)进行比对测试试验,有利于确保电参数设置与执行的准确可靠与一致性.     

Rogowski Sensor for Plasma Current Measurement in J-TEXT

Rogowski coil is very useful in transient current measurement. Rogowski sensor consisting of Rogowski coil and integrator is one of the most important diagnostic instrumentations in Tokamak. In recent years, new structures of Rogowski coil based on printed circuit board (PCB) are developed to replace traditional handmade Rogowski coil for more excellent accuracy, better temperature stability, more accordant mutual-inductance, more symmetrical windings, and other advantages. However, the existing structures of Rogowski coil based on PCB are useless in Tokamak because the required Rogowski coil installed on the vacuum vessel should have long diameter and little space. This presentation provides a new twin-loops Rogowski coil (TRC) consisting of several PCB strips. TRC has all the advantages of existing PCB Rogowski coils and can meet the limited space requirement in Tokamak at the same time. A special experiment is carried out to prove that the mutual-inductance of TRC is immune to the variation of center position of plasma current. Moreover, a differential long-term integrator is designed to cooperate with the TRC. Two switches are used in the integrator to release the remaining electric charges on integrating capacitors once the measurement is over. Then, the error accumulation of integrator is canceled in repetitious measurements. The designed new Rogowski sensor can be used to measure long pulse current below 1 s.      

A novel electro-optic hybrid current measurement instrument forhigh-voltage power lines

Details of an electro-optic, hybrid current-sensing instrument, and its application to high-voltage power line current measurement, are presented. The current is first detected via a Rogowski coil, followed by conversion of the detected current into a frequency-modulated optical pulse signal in the high-voltage area. Subsequently, the optical pulse signal is transmitted to the ground through an optical fiber cable. Finally, the measured current is recovered from the optical pulse signal by a ground-located signal-processing module. Compared with conventional current transformers, widely used for high-voltage line current measurement, this instrument provides a significant reduction in size, weight, and cost, together with features of convenient installation, secure operation, and high accuracy. Furthermore, it can be configured to be compatible with conventional secondary meters widely used in today's power plants and substations. In 1996, a prototype of this instrument was demonstrated online at a power substation and has shown good accuracy, stability, and safety for more than two years     

Current measurement by Faraday effect on GEPOPU

The design of an optical current sensor to be used in a pulsed power generator is presented. The current sensor is based on the polarization rotation by the Faraday effect. GEPOPU is a pulsed power generator, 110 kA, 120 ns double transit time, 1.5 Ω coaxial geometry, and current rise time of 50 ns. Two different optical geometries surrounding the conductor were tried, using Amici roof prism and pentaprism to go around the current once, as a way to preserve the state of polarization along the optical path by means of complementary reflections within the sensing element. We believe this to be the first time that such large and rapidly varying currents have been measured with this configuration. The values obtained for both geometries agree with the values obtained with a Rogowski coil. The traces obtained are completely noise-free and no significant time lag has been observed between the current determined from the Faraday rotation and the current measured using a Rogowski coil.     

基于数字图像识别和光纤传感器的直流大电流在线校准装置

在电解冶金和电化学工业领域,大量霍尔直流超大电流传感器无预留校准接口。针对这一实际问题,设计了一种基于数字图像识别和光纤电流传感器的直流大电流在线校准装置。该在线校准装置以光纤电流传感器为标准,利用图像传感器实时采集霍尔电流传感器二次显示仪表的示数图像,对采集到的图像进行灰度化、中值滤波、二值化、闭运算、字符分割等预处理,并采用穿线法进行图像识别,获取霍尔电流传感器的采样值,并与光纤电流传感器的标准测量值进行实时比较,计算被校霍尔电流传感器的测量误差。现场校准的实验结果验证了校准方法及装置的可行性。     

High Accuracy On-Line Calibration System for Current Transformers Based on Clamp-Shape Rogowski Coil and Improved Digital Integrator

To solve the problems of the existing on-site calibration methods, for instance, the methods need power off, and the standard transformers have large volume, heavy weight and small dynamic range, this paper proposes a high accuracy on-line calibration method for current transformers. By using a clamp-shape Rogowski coil as the standard current transformer, instead of traditional electromagnetic transformer, the volume and weight are reduced greatly, and the power of the line needn’t to be interrupted. The output signal of the clamp-shape Rogowski coil needs to be integrated, and to overcome the problems of analog integrator, which have temperature and zero drift, a high accuracy digital integrator is proposed in the paper to improve the accuracy and stability of the signal processing circuit. Test results indicate that the accuracy of the whole calibration system can reach up to 0.05 accuracy class. The on-line calibration system can calibrate the traditional and electronic current transformers when the line is energized.     

Self-Integrating Rogowski Coil for High-Impulse Current Measurement

This paper presents the operating principle, the performance under impulse condition, and the design of a self-integrating Rogowski coil for measuring high-impulse currents. Oscillatory and overdamped unidirectional impulse currents are generated up to 10 kA and measured by different methods, namely, two commercial impulse current transformers, a resistive shunt, and the newly designed self-integrating Rogowski coil. For the resistive method, the voltage drop across the shunt affects the total voltage measured across the test object and causes distortion in the case of simultaneous measurement by an impulse current transformer having a small aperture. The Rogowski coil theory under impulse current conditions is presented. The concept of transmission lines is used, and the line parameters are optimized to achieve a self-integrating mode and avoid spurious effects of reflections and stray capacitances. The output voltage linearity of the designed self-integrating Rogowski coil is checked using different linear and nonlinear loads and coil termination resistances. It is found that at a termination resistance of 1 $Omega$, satisfactory impulse current waveforms are measured by taking the commercial impulse current transformer as a reference signal. Results reveal that the measurement errors for the current peak and front and tail times are $pm$2%, $leq$6%, and $leq$ 12%, respectively. Overdamped impulse currents are generated by different generator capacitances, where comparisons between the measured and calculated current waveform parameters have shown good agreement.