750kV CVT电容量及介质损耗角正切值测量试验分析

通过介绍750 kV电容式电压互感器(CVT)的原理及基本结构,对电容量和介质损耗角正切值测量方法以及误差影响因素进行了分析,并将现场测试结果与出厂试验值作了对比分析,得出该测量方法产生的误差很小,完全可以满足实际运行需要的结论,对于准确判断现场设备状态,提高高电压等级CVT参数测量精度和效率具有积极的指导意义。     

CVT高频特性的测量及影响因素

对CVT高频特性进行了试验研究,分析了影响高频特性的一些因素。着重对高频电容、等值串联电阻、低压端杂散电容、杂散电导进行了试验分析,总结了减小测量误差的方法,并通过试验总结了在产品结构上应采取的必要措施,指出了控制高频电容及等值串联电阻的有效方法。     

CVT高频特性的测量及影响因素

对CVT高频特性进行了试验研究,分析了影响高频特性的一些因素。着重对高频电容、等值串联电阻、低压端杂散电容、杂散电导进行了试验分析,总结了减小测量误差的方法,并通过试验总结了在产品结构上应采取的必要措施,指出了控制高频电容及等值串联电阻的有效方法。     

特快速暂态过电压光学测量系统的设计

提出一种应用Pockles效应的特快速暂态过电压(VFTO)光学测量方法。通过光学敏感头感应一次VFTO信号,并将电压的变化信息通过光缆传输至电气单元进行解析,最终得到实际电压。该传感器采用光学测量方式,具有可靠性高、抗干扰能力强、测量精度高、测量频带宽的优点。设计制作的新型光学传感器的低频截止频率低于10 Hz,高频截止频率高于1 GHz。对隔离开关操作所引发的VFTO进行了测量试验,通过同步触发装置同时采集两侧安装的光学传感头和电容式传感头信号,对比验证了VFTO光学测量方法的可行性。试验结果表明:光学测量方式与电容式测量方式均反映了刀闸分合闸的过程,2种方式的分合闸持续时间测量结果吻合较好;电容式测量方式测得的VFTO振荡幅度明显小于光学方式的测量结果,光学测量方式在高频段性能要优于电容式测量方式。     

Retention Characteristics of (Bi,La)4Ti3O12 Films on Si(100) Substrates Using LaAlO3 Buffer Layers

We demonstrate the ferroelectric behavior of (Bi,La)₄Ti₃O₁₂ (BLT) films deposited on Si(100) substrates by using LaAlO₃ buffer layers. LaAlO₃ films were prepared by molecular beam deposition method. Then, they were subjected to ex situ dry N₂ annealing in a rapid thermal annealing furnace. From the capacitance-voltage measurement, the dielectric constant of LaAlO₃ was estimated to be 20 to 26. On these structures, BLT films were deposited by sol-gel method and they were characterized by X-ray diffraction analysis. It was found from capacitance-voltage measurements that the characteristics showed a hysteresis loop and the memory window was about 0.5 V for the voltage sweep of ±9 V. It was also found from the retention measurement that the higher and lower capacitance values in the hysterisis loop could be distinguished at least for 3 days. It is concluded from these results that the BLT/LaAlO₃/Si(100) structure is one of the most promising structures for realizing MFISFETs (metal-ferroelectric-insulator-semiconductor field effect transistors).     

油／气绝缘套管出线变压器现场试验方法

通过油／气套管和GIS连接的电力变压器是一种新型结构电力设备。对其进行介质损耗和电容测量试验,需要将SF6气室打开才能进行试验接线,现场处理难度大,并且容易在处理过程引起新的设备缺陷。文中介绍不打开SF6气室,对变压器进行介质损耗和电容测量的试验方法。理论分析和现场试验证明,该试验方法简单,测试数据可靠。     

一种新型配电网电容测量系统的设计

为了确定配电网络的对地分布电容,设计了一种基于3个频率信号注入法的配电网电容测量系统,给出了系统测量原理及硬件系统的构成,介绍了用集中电容来模拟配电网电容的测量实验,提出了用扫频法测得的模拟实验结果结合MATLAB仿真技术确定最佳注入信号频率的方法,探讨了注入信号的频率对测量精度的影响。注入特定的3个频率恒流信号,测试模拟实验中的集中电容,测量结果的相对误差在2%之内。测量过程不涉及高压侧,操作方便,有很好的应用前景。     

Simplified parasitic capacitance extraction of shield in HVDC converter system with boundary element method

It is critical to build a wide-band circuit model to conduct research on the characteristics of the electromagnetic disturbance source during the localization of high voltage direct current (HVDC) technology. Parasitic capacitance is most essential for modeling the equivalent circuit, so a fast and accurate computation of capacitance parameters plays a vital role. Because of the large size and complex structure of the converter equipment, it is impossible to obtain capacitance parameters by means of measurement or simulating calculation with finite element software. In this paper, a simplified method of capacitance extraction based on boundary element method is proposed, which can provide an efficient means of establishing simulation models. In the method presented, simulation model of the shield may not be chamfered. Consequently, the edge and corner of the shield do not need to be handled with a sphere, cylinder and other curved surface model. The availability of this method is demonstrated by comparing the capacitance parameters of chamfered shield with that of non-chamfered shield.     

一种提高CVT绝缘介质损耗及电容量测量准确度的有效方法

章针对江西新余发电有限责任公司CVT的特殊结构，采用具有CVT功能的测量仪器，并结合一系列的现场反干扰措施，测试准确度大大提高，取得了良好的测试效果，能够反映CVT的真实绝缘状态。     

以选频平衡法测量局部放电的原理

传统的局部放电平衡测量法以电阻电容为输入电路,存在许多缺点,难以在高压和超高压领域推广使用,文中以电感电容为输入电路,全面分析了用选频平衡法测量局部放电的原理,模拟实验的结果表明,在选定的测量中心频率下,在调谐电容的调节范围内,存在着无数组平衡点。选频平衡法测量局部放电抑制干扰的关键是使用选频放大吕。实际高压实验表明,在存在于强烈干扰信号时,采用本测试法的测试电路在试样为２５５ｐＦ时,最小可测放电     

一种小型集中式电容分压器的研制

对于对地杂散电容较小的试品 ,若用普通的电容分压器进行其电压分布的测试 ,会因分压器电容的引入而造成较大的测量误差。本文对适用于此类试品交流电压分布测试的小型集中电容分压器进行了研究 ,介绍了这种电容分压器的设计思路 ,并给出了实物模型及其试验结果     

微小电容检测系统的设计及应用

针对在微小电容的检测中,传统模拟电路存在设计复杂,电容测量范围小等诸多局限性这一问题,设计了一种微小电容检测系统。该系统硬件主要由电容测量芯片Pcap01、单片机STM32F103C8T6最小系统、供电电路以及LCD液晶显示屏构成。系统软件包括下位机的C程序,实现了电容数据采集、Pcap01 AD与单片机之间的通信以及数据转换。实验结果表明,该系统结构简单,精度高,误差小,稳定性好,抗干扰能力强。能方便的应用于需要微小电容检测的场合,如电容式液位传感器等。     

高性能MOS结构高频C-V特性测试仪

MOS结构高频C-V(电容-电压)特性测量是检测MOS器件制作工艺的重要手段。本阐述了用高频检测法测量MOS电容的原理,介绍了用变频技术和集成芯片设计MOS结构高频C-V特性测试仪的方法。该测试仪电路简单,成本低,分辨率高,测量准确,稳定性好。     

基于移相和平衡测量原理的介质损耗在线测量方法

基于目前的微电流传感器设计和制造技术,利用信号移相和小电流平衡测量原理,采用单匝无源微电流传感器作为检流计,通过微型控制单元(Micro-Controlller Unit,MCU)实现了低成本高准确度的介质损耗因数在线测量方法.介绍了该方法的测量原理和实现方式,分析了该方法的理论测量精度:设计了通过电阻电容改变介质损耗角的简单实用的模拟试验电路.理论分析和试验结果表明,该介质损耗测量方法具有较高的测量准确度及稳定性.     

基于CVT电容电流的谐波电压测量方法

准确有效地进行谐波电压测量是掌握电网谐波状况、开展谐波治理、提升电能质量水平的重要前提和依据。为解决目前大量在运CVT无法准确测量谐波的问题,提出基于CVT电容电流的谐波电压测量方法。该方法测量流过高压电容和中压电容支路的电流并进行谐波分析,根据电容参数即可方便准确地计算得到高压侧谐波电压。该方法只需对CVT二次回路进行简单改造,在不影响设备运行安全的前提下,实现谐波电压测量。首先给出该方法的基本原理,然后结合仿真计算分析电流测量精度和电容值变化对谐波测量误差的影响,对实际CVT完成了物理试验验证。试验表明：该方法的2~50次谐波电压测量误差均小于2%,满足谐波国家标准的相关要求。     

Polarization Switching and Dielectric Properties of PZT Structures

We have taken an extensive investigation of ferroelectric structures based on Pt/PbZr 0.53 Ti 0.47 O 3 /Pt/Ti/SiO 2 /Si (PZT) thin films. Such characteristics as D-E hysteresis loops, C-V and V-I curves, polarization pulse switching, and pyroelectric coefficient were examined in the temperature range between 20 200C. The effects of interface layers and of the process of charge transfer on the dielectric behavior of the ferroelectric thin films were studied as well. Appreciable asymmetric capacitance-voltage curves and hysteresis loops behavior have been observed for some specimens. These results provide an explanation for the model, which describes the PZT structure as a series circuit of three depletion layer capacitors. Following this method for the high field voltage, one can obtain the values of associated parameters, such as the depletion layer capacitance, bulk permittivity, and space-charge density.     

Characterization of charge accumulation and detrapping processesrelated to latent failure in CMOS integrated circuits

A series of measurements were performed on a variety of custom fabricated CMOS test structures to investigate the latent mode of failure due to ESD. Devices were stressed using the current injection test method and measurement of the quiescent current state was used to detect the failure thresholds. The fault sites were further isolated and the failure mechanisms studied by measuring the electrical characteristics before and after exposure to thermal stimulation and light excitation. An analysis of the oxide trapped charge was performed using measured capacitance-voltage profiles. The measurement procedure is useful in the study of electrostatic phenomena in semiconductor devices. The results further support a charge injection/trapping model for latent failures     

700MW水轮发电机定子绕组介质损耗测量研究

本文结合某水力发电厂发电机定子绕组介损测量实际情况,就定子绕组介损测量的有关问题迚行了研究,提出了应用串联谐振试验装置和介损测试仪迚行水轮发电机介损和电容测量方法,在该厂13F发电机上验证了该方法的可行性与准确性,幵用相关标准对试验结果迚行了分析研究,试验结果满足要求。     

MEMS接触电容式高温压力传感器的温度效应

介绍了一种基于SOI／硅片键合技术制作的接触电容式高温压力传感器结构,并对传感器的测试装置、测试方法进行详细的介绍后,对传感器进行压力测试和温度特性测试。压力测试结果表明,传感器线性工作区压力为110～280kPa,灵敏度约为0．14pF／kPa;温度特性测试结果表明,传感器具有正温度效应,在30～300％,传感器输出误差约为0．5％。文中还分析了热胀冷缩及介电常数温度系数对传感器温度效应的影响,以及设计了参考电容及运算放大器式传感器测量电路来消除温度效应。     

An impedance measurement of a small‐capacitance circuit using transient responses for lightning surge analysis

A method to measure a small capacitance with its loss resistance using a set of transient current waveforms is proposed in this paper. The parameters are obtained from the time constants in the time domain. The method has high resistance to extraneous noise, because a time‐to‐frequency transformation, which is sensitive to noise, is not required. The transient current waveforms are obtained by a voltage or current source, a current transformer, and a waveform recorder. The measured capacitance by the proposed method is not affected by the capacitance of the voltage probe, because it is obtained without any voltage information. The sheath surge impedance of the current injection cable, which is indispensable for the transient measurement, is corrected. The application of the method has the advantage in that it allows the modeling of a fast transient of a power apparatus, comparing it with the steady‐state measurement using an impedance measuring instrument. The proposed method is applied to create an equivalent circuit between electrodes implanted into a piece of wood, and its reliability is confirmed by comparison between the measured and calculated results. Stray capacitances of a miniature circuit breaker are also measured, and the results show that the proposed method is applicable to equipment in power systems. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.