提出基于正弦波波形的工频电压在线监测方法.这是一种时域测量方法,能同时监测由于工频电压幅值、频率、相位的变化或外来干扰产生的实时工频电压畸变.该方法适用于捕获工频电压的暂态或短时电压畸变,并能对电压畸变的时间点进行定位.同时本文还提出一个关于实时电压监测的新概念——有效监测时间,这是一个关于各类监测仪或监测方法是否能真正实现全面有效监测的性能参数.

According to the characteristics of hybrid electric field under the parallel AC/DC transmission lines, the mutual influences between AC and DC electric field is analyzed and the experiment research is undertaken for the hybrid electric field formed by single phase AC and monopolar DC conductors. Using a calculation method based on the Deutcsh assumption, the ground-level hybrid electric field of the experimental reduced model is calculated. The calculation is in good agreement with the experiment results, thus the calculation method is demonstrated in validity. Moreover, the ground-level hybrid electric field of the parallel UHVAC and UHVDC transmission lines is calculated. The calculation results are compared with the corresponding calculation results when mutual influences between AC and DC electric field are neglected and the conclusion is obtained that the magnitude of ground-level DC ion flow field under AC line is reduced owing to an intensified AC line shielding effect resulted from the AC corona.

This paper analyses the insulation characteristics of c-C4F8/N2 gas mixtures using the improved Monte Carlo method with the null-collision technique and studies the possibility of applying that in the gas insulation of power equipment. The densitynormalized effective ionization coefficient ( ) / N    for c-C4F8/N2 gas mixtures has been calculated using a sample of a pulsed Townsend discharge. The overall density-reduced electric field strength / E N could be varied between 160 and 480 Td (1Td = 10 V m), while the c-C4F8 content in the gas mixtures is varied over the range 0–100%. From the variation curve of ( ) / N    with the cC4F8 mixture ratio k , the limiting field lim ( / ) E N of the gas mixture at different gas contents is determined. The required gas pressure ratios comparable to the insulation property of SF6 and the global warming potential (GWP) at this gas pressure were also investigated. It is found that the dielectric strength of c-C4F8/N2 mixtures is less than that of the SF6/N2 gas mixture at k below 60%, and is larger at k above 60%, and the GWP of the former is significantly lower than that of the latter.

Thyristor valve is the core device of UHVDC transmission project. In order to ensure the operation reliability of valves and to meet the research needs of its test methods, it is necessary to study the operation performance and failures mechanism of UHVDC valves. In this paper, each of the operation conditions of valves is analyzed, and the characteristics of different operation conditions and the simulation waveforms are illustrated. Then the operation status of valves in different duty cycles (turn-on, on-state, turn-off and off-state) is discussed and the equivalent turn-on/off model is established. Finally, combined with the internal physical characteristics of the device, the development process of the valve failure is analyzed and the failure mechanism is demonstrated.

在正弦电压激励下,由于金属氧化物避雷器(metal oxide arrester,MOA)泄漏电流中的阻性电流是非正弦稳态(非线性),MOA泄漏电流也是非正弦稳态.因此,将正弦稳态分析工具——相量法用于MOA泄漏电流测量的研究时就必须要注意适用性问题.通过分析LCD-4 MOA泄漏电流测量仪测量阻性电流的基本原理,给出了典型补偿法测量MOA泄漏电流中阻性电流的基本原理:基于MOA泄漏电流中工频正弦分量超前MOA电压90°.通过三相工频电场的分析,给出了绝大多数变电站中在三相运行电压下MOA泄漏电流中的工频正弦分量并不是正好超前MOA电压90°.

For the situation that the electric corona happens on UHVDC transmission lines,a measure experiment to study the effect of ion flow on the ground electric field under the DC-wire after the electric corona appearing is proposed.By the experiment,the linear relation between the total electric field strength,the nominal electric field strength,the electric field strength of space charges and wire potential separately under the DC-wire after the electric corona appearing,the differences between corona discharge of positive and negative wire,the proportion of nominal electric field strength changing in total field strength with its height are obtained.

For the real situation that HVAC transmission line and HVDC transmission line are in the same corridor or even same tower,a simulation experiment of HVAC and HVDC transmission lines was carried out in laboratory to study the infection between AC electric field and DC electric field under the hybrid lines.Experiment results showed that the additional line and its voltage change,the line safety spacing change and other factors can affect the ground AC and DC electric field greatly.And the conclusion that the additional line shunting or shielding would decrease the electric field strength of the other lines was also obtained.

The rectifier transformer of high-frequency high power-rating switching power supplies has a drawback of low power density due to the rigorous requirements of high voltage insulation. With some tests of a model transformer, the potential distribution of the high power transformers was analyzed and the unfavorable factors affecting their potential distribution were investigated in this paper. Meanwhile, the distribution of the leakage magnetic field of the transformer is also investigated which shows that the insulation distance has a significant impact on leakage. Finally, some improvement measures are proposed based on the results above.

From the view of physical chemistry, gas discharge is complicated chemical process caused by collision, which produces plasma including electrons, ions, molecules, and atoms. Moreover, ion or electron concentration should vary with the course of gas discharge. This study sets up a general chemical reaction model and formula of computation in gas discharge, mainly analyzes first-order reactions of electronegative gas Such as SF(6), especially electron concentration, and gives rate constants decided by quantum chemistry theory. This study provides a novel researching method about gas insulation because gas insulation properties are dependent on the ability to reduce electrons.

Based on the energy conservation equation, mathematics simulation program to obtain the arc dynamic process. We can calculate the arc extinction properties of various gases by using thermodynamic properties, radiation, and transport coefficients of gas to set up the arc model. We can bring out that the most efficient gas for arc extinction performance is SF6, and the order is SF6 > CF3I > CO2 >N-2.

The development of UHV GIS in China and other countries and the important value of gas discharge properties in the design,manufacture and operation of GIS in UHV power grid were introduced.The research of discharge characteristic under high field and long gap should be started as early as possible in order to provide important references and standards for UHV utilities and GIS manufacture.Research on discharge characteristic of SF6/N2 mixture under long gap,various pressures,various voltages,and various fields should be accelerated.The nonlinear scale of gas discharge,the relation of gas discharge properties and temperature,especially the mechanism of long gap discharge properties were described.When the gap discharge voltage excesses 1800kV,the lightning impulse tolerate electrical strength and switching over voltage tolerate electrical strength will be nonlinear,especially switching over voltage tolerate electrical strength,the nonlinearity will be more obvious while the gap discharge voltage excesses 2000kV.When the content of SF6 in the SF6/N2 mixture is small,the liquefaction temperature will decrease,so it is suitable for using high gas pressures in cold region.The SF6/N2 mixture can also decrease the sensitivity of discharge of SF6 on the nonlinearity of electrical field,the metal particle and the surface roughness of electrode.

In electrical power industry,optical sensors are inherently advantageous over conventional measurement techniques.In this paper,the research and developments of some high voltage optical current and optical voltage transducers were reported in detail.The application prospect of optical transducers in UHV power grid was described.The key application technology of optical transducer in UHV power grid was analyzed,the scheme of high electrical potential of electrical source and matching technology on input side were also discussed.An equalizer ring was proposed to be used to get the electric source of high potential side.On the transient supply interruption,a cluster of super capacitor was designed for power supply in 0.5~1 hours.It is also suggested to revise the interface of relay protection to meet the input requirements of optical transducers.The optical fiber technology used in power system in the future for optical sensing,optical monitoring,optical communication,optical relay protection and optical local area network were introduced.

This paper presented a new method,capacitance-bridge method,to measure the resistive leakage current of MOA.Using capacitance current as the compensation reference signal was the highlight of capacitance-bridge method.Experimental results show that the advantages of the method lie in,reduce the measuring influence caused by the harmonics greatly,simplify the measure of resistive leakage current,and make it possible to display the waveform on the oscillograph for observing and comparing.

提出了利用数字化示波器的测量功能快速确定冲击试验电压波形参数的方法.讨论和评估了该方法对实际测量结果的影响,肯定了该方法可行.

The paper puts forward a method for automatic detecting and suppressing periodic pulse shaped interference in PD signal by comparing several recorded cycles. The algorithm is based on calculating the correlation of signal’s envelopes. The laboratory test shows the ability of this method.

分析了变压器局部放电在线监测中的各种干扰,提出了分层式抑制干扰的处理模型,采用不同的数字信号处理方法分层处理各种干扰,具有结构灵活、易于扩充等特点.现场实验结果表明,该模型可有效、快速地抑制干扰,具有良好的应用前景.

MOA在线监测的主要对象是它的泄漏电流和其中的非线性阻性电流。本文以传统的指数函数为数学模型，研究了该数学模型应用于MOA阻性电流时的相关问题。还研究该数学模型与DT/L987-2005给出的标准波形和实际MOA泄漏电流波形的关系。在此基础上文章最后讨论了现行各种MOA泄漏电流检测技术、检测装置的标定和检测数据与MOA状态的判别。

在正弦电压激励下，MOA泄漏电流中的阻性电流是非正弦稳态（非线性），所以MOA泄漏电流也是非正弦稳态。将正弦稳态分析工具-相量法用于MOA泄漏电流测量研究时就必须要注意适用性问题。通过分析LCD-4 MOA泄漏电流测量仪测量阻性电流的基本原理，文章给出了经典补偿法测量MOA泄漏电流中阻性电流的基本原理是：基于MOA泄漏电流中工频正弦分量超前MOA电压90度。通过三相工频电场的分析，文章最后给出了绝大多数变电站中在三相运行电压下的MOA的泄漏电流中的工频正弦分量并不是正好超前MOA电压90度。

本文继续讨论有关MOA泄漏电流测量的一些问题。它们是：最可靠的MOA阻性电流测量方法-电容电桥法；符合MOA泄漏电流测量特点的MOA泄漏电流标准波和标准波发生器；MOA阻性电流测量仪的测量性能试验的问题以及在线MOA泄漏电流监视器的标定和检验的问题。最后还讨论了智能在线MOA泄漏电流监视器的一些问题。

本文根据气体放电理论详细描述了特高压直流输电线在运行电压作用下，空间离子（电荷）的产生和发展；空间离子在直流电场作用下的迁徙、离子流的形成和离子的消失。根据电路理论和相关文献的内容讨论了有关在直流离子流电场下地面测量离子流的技术方案，测量装置和测量仪器。在比较了各种方案后，提出了新的测量地面离子流的技术方案、测量装置和测量仪器。