紫外电晕检测仪在电晕放电检测中的应用

首先阐述一种新型紫外电晕检测仪的原理,介绍该仪器目前在国外的应用情况,然后分析该类仪器在系统应用中技术特点和存在的一些问题,最后结合电力系统快速发展的展望了应用的前景。     

Effects of an electric field shield on the neutralizing characteristics of a corona discharge air ionizer

The effects of an electric field shield on the electric field noise and neutralizing current of a corona discharge air ionizer were investigated as a means to prevent soft errors during quality control inspections. The neutralizing current and noise voltage were measured for shielded and nonshielded air ionizers using a charged plate monitor. The use of an electric field shield decreased both the neutralizing current and the noise voltage. Therefore, neutralizing current to noise voltage ratio was calculated to evaluate the effect of the shield on the neutralization performance, and this ratio was several times higher for the shielded air ionizer than for the nonshielded air ionizer. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Simulation of corona discharge. Negative corona in SF6

Negative coronas in SF₆ under three voltage levels are investigated by Monte Carlo simulation. For the purpose of simulation, the gap between a hyperboloidal needle and a plane is divided into two regions: region I where the electric field is very steep and most electrons and ions are accumulated, and region II the rest of the gap. In region I electron motion is simulated by dividing the region into a number of cells and a small cell size improves the accuracy. The magnitude of current pulse increases with increasing voltage and there appears to be more than one peak in each pulse as observed by experiment. The development of electron avalanches is due to ionization and photoionization in the high field region, while the quenching of the avalanches is due to the space charge field suppression. Also the accumulation of positive and negative ions are displayed in detail. The space charge field distortion is studied and found to increase with increasing applied voltage     

Simulation of corona discharge. Positive corona in SF6

Positive coronas in SF₆ under three voltage levels, 3.0, 3.5 and 4.0 kV, are studied for a 0.5 cm gap between a hyperboloid needle and a plane electrode at a gas number density N=2.12×10¹⁸ cm³. The current in the form of a burst of pulses is found to increase with increasing voltage. The initiation and development of successive avalanches are traced as function of time after voltage increases. The development of electron avalanches and streamers are due to ionization and photoionization and quenching of avalanches is due to space charge. The simulation provides a detailed structure of avalanches from which essential differences between positive and negative corona with regard to total field distribution, propagation of successive avalanches and ion distribution can be discerned     

半导体三极管静电放电敏感端对实验研究

针对典型的硅微波低噪声三极管进行静电放电电磁脉冲效应实验,主要研究静电放电沿着三极管的哪个管脚组合(端对)注入时最容易造成三极管的损伤.三极管的那个部位对静电放电最为敏感.实验采用静电放电模拟器对三极管的所有管脚组合(端对)进行静电放电,每次静电放电后测量三极管主要电参数的变化情况,根据有关规定判断三极管是否损伤.实验发现,国产三极管3DG120D和日本产三极管2SC3331沿着各个管脚组合(端对)注入静电放电电磁脉冲时的损伤电压不同,沿着CB端对注入静电放电电磁脉冲时的损伤电压最小,CB端对对静电放电最为敏感.硅微波低噪声三极管对静电放电电磁脉冲最敏感的部位是集电结(CB结).     

Pulsed corona discharge for hydrogen sulfide decomposition

The results of the use of a wire-in-tube corona reactor, energized by short voltage spikes, to decompose small concentrations of hydrogen sulfide contained in hydrogen are presented. Parameters investigated include the reactor geometry, hydrogen sulfide concentration, corona power, and the nature of the product. Electronic-molecular interactions are considered, and a mathematical model is formulated that accurately predicts experimental results     

Triangle-shaped DC corona discharge device for moleculardecomposition

An earlier point-to-plane geometry corona device with a rectangular cross section demonstrated low decomposition efficiencies. The numerical simulation of this device suggested that three were zones of low electron density and electric field significant decrease in resulting in electrical sneakage which caused a significant decrease in the kinetic rate coefficients in the chemical reaction process. A triangle-shaped DC corona discharge device was developed to improve the electrical sneakage problem, and a semiempirical mathematical model was developed to describe the detailed electrical characteristics and to refine estimates on the optimum shape of the device. The preliminary experimental results indicated that the decomposition efficiency was much improved     

Nonlinear boundary-value problem for cylindrical corona discharge

Contents Closed-form (one-dimensional) solutions are derived for the electric fieldE(r) and potentialV(r) in a positive ion discharge between a stressed wire anode atr=a and a coaxial cylinder cathode atr=b. It is shown that this system sustains two different corona discharge modes, namely with radially (i) decreasing (k<1) and (ii) increasing (k>1) electric field strengthE(r), wherek=E _I /E _a is the crucial discharge number. E_I = (I/2₀)^1/2 [V/m] is given in terms of the discharge currentI [A/m], whereas the electric fieldE _a [V/m] at the anode depends on currentI and ion temperatureT _i at the cathode. The physical properties of these discharge modes are discussed analytically.

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Nichtlineares Randwertproblem der zylindrischen Korona-Entladung

Übersicht Geschlossene (eindimensionale) Lösungen werden abgeleitet für das elektrische FeldE(r) und PotentialV(r) in einer positiven Ionen-Entladung zwischen einer Hochspannungsanode mit Radiusr=a und einer koaxialen Zylinderkathode mit Radiusr=b. Es wird gezeigt, daß in diesem System zwei verschiedene Typen von Korona-Entladungen existieren können, nämlich mit radial (i) abnehmender (k<1) und (ii) zunehmender (k>1) elektrischer Feldstärke, wobeik=E _I /E _a der kritische Entladungsparameter ist. E_I = (I/2₀)^1/2 [V/m] ist durch den EntladungsstromI [A/m], während das elektrische FeldE _a [V/m] an der Anode durch StromI und IonentemperaturT _i an der Kathode bestimmt ist. Die physikalischen Eigenschaften dieser Entladungstypen werden analytisch diskutiert.

     

Agglomeration of particles by ac corona discharge

Improving the collection efficiency for particles smaller than 1 μm on every precipitator is important. We sought to improve the collection of these particles on an ESP due to particle agglomeration. Particles are charged by ac corona discharge in a precharger and agglomerated by a dc electric field in an agglomerator downstream of the precharger. Diesel exhaust particles were used as particulate matter for the experiments. The distribution of particle size was measured using a particle counter and a scanning electron microscope. By these methods, particles as small as 0.01 μm could be counted. Results showed the agglomeration between particles at ac corona discharge operating mode. The concentration of particles smaller than approximately 0.35 μm decreases, and that of particles larger than approximately 0.35 μm increases in the agglomerator. The agglomeration rate increases with increasing applied voltage, then saturates. These results may be due to the size distribution and to decrease of concentration by agglomeration. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 30–37, 2000     

整浸高压电机用防晕结构设计及防晕材料的研究

通过理论计算和有关的优化理论，设计出合理的防晕结构，并对10kV整浸电机的防晕结构进行了设计，经实验检验该设计方法有效可行且十分准确。将国内外材料进行各项性能考核、比较，最终选定了10kV级VPI电机用防晕材料。     

Monte Carlo simulation of electrical corona discharge in air

Electrical discharges play a key role in technologies; there are many industrial applications where the corona discharge is used. Air as insulator is probably the best compromise solution for many applications. All of this reflects on the great importance of the evaluation of the corona performance characteristics. Numerical simulation of the corona discharge helps to better understand the involved phenomena and optimize the corona devices. This paper is aimed at calculating the corona discharge in negative point-plane air gaps. To describe the non-equilibrium behavior of the electronic avalanches and to simulate the development of corona discharge the method of Monte Carlo has been used. This model provides the spatial-temporal local field and particles charged densities variations as well as the ionization front velocity.     

变压器高压线圈表面发生电晕放电现象的分析探讨

对变压器高压线圈表面发生电晕放电现象进行了分析和探讨,并提出了处理及防范措施。     

Partial discharge, dissipation factor, and corona aspects for high voltage electric generator stator bars and windings

High voltage stator windings in modern electric generators are subject to high electrical, mechanical, and thermal stress. Operation of these machines in both air and high pressure hydrogen results in different considerations. Operation in the air environment does not offer the dielectric advantages of operating in high-pressure hydrogen. The two major design factors that are significant for the design of high voltage stator bars to be operated in air, are corona activity and PD activity. These of course are closely related. With the movement to increasing the power density of generators, which means operation at higher voltages and higher insulation stress levels, it has become more critical to be sure the design constraints are met in the stator bar design to minimize both partial discharge activity and corona activity involving the stator bars. The stator bar insulation system must be designed for minimum partial discharge activity and ideally is corona free at the stator winding operating stress levels, and at the operating conditions (temperature and pressure) the generator is subject to. This paper will present the findings associated with the development work in designing, testing and implementing a PD reduced and corona free design.     

高压外部电晕放电及其检测

从电晕放电现象出发,简单介绍了电晕放电的形成机制,分析了高压输变电系统中高压外部电晕放电的基本特征及危害;介绍了传统电晕放电检测方法(红外成像和超声波测量)及其不足,详细阐述了紫外成像检测新技术的原理、技术特点、应用领域,展望了紫外成像检测技术在高压输变电系统中的应用前景。     

一种新型电力系统蓄电池放电装置的设计

在电力系统发电厂和变电所内,蓄电池组性能好坏,很大程度决定了直流操作电源的可靠性,合理使用和维护蓄电池,使之保持在良好的运行状态,这是延长蓄电池寿命和提高直流操作电源可靠性的关键。在分析了电力系统蓄电池放电重要性和当前蓄电池放电装置现状的基础上,结合蓄电池放电的基本要求,设计出了一种新型的正弦波逆变蓄电池回馈放电装置,该装置包括DC/DC变换电路、PWM整流逆变电路、控制电路、保护电路等,同时也对放电装置的工作原理进行了详细的阐述。     

一种新型电力系统蓄电池放电装置的设计

在电力系统发电厂和变电所内,蓄电池组性能好坏,很大程度决定了直流操作电源的可靠性,合理使用和维护蓄电池,使之保持在良好的运行状态,这是延长蓄电池寿命和提高直流操作电源可靠性的关键.在分析了电力系统蓄电池放电重要性和当前蓄电池放电装置现状的基础上,结合蓄电池放电的基本要求,设计出了一种新型的正弦波逆变蓄电池回馈放电装置,该装置包括DC/DC变换电路、PWM整流逆变电路、控制电路、保护电路等,同时也对放电装置的工作原理进行了详细的阐述.     

空气局部放电衍生物气体生成规律的研究

分解气体分析法通过检测故障产生的气体组分诊断设备故障,是检测电力设备故障的重要方法,在一些应用场合具有不可替代的作用。然而目前该方法只在绝缘油、SF6等绝缘介质的场合有应用,对于空气这一最重要的绝缘介质少有应用。本文搭建空气局部放电过程模拟实验平台及气体产物检测系统,研究放电衍生物气体生成规律。分别采用两种检测方式对气体产物进行检测,结果显示O_3、NO、NO_2为空气放电的主要产物;在放电强度较低时,空气放电主要分解产物为O_3,放电强度进一步增大可以检测到氮氧化物NO和NO_2的产生,且臭氧O_3浓度远大于氮氧化物气体浓度;对于封闭空间,随着放电时间增长分解产物浓度增加,但趋向饱和,且随着施加电压增大,气体产物浓度增加;而在相同放电电压下,空气相对湿度变化对气体产物含量有明显影响,O_3、NO_2的浓度在相对湿度为18%时高于相对湿度为25%和44%时的值;而NO的浓度在相对湿度为44%时高于相对湿度为18%和25%时的值,同时差异较小。     

Bipolar DC corona discharge from a floating filamentary metalparticle

The motion of a filamentary particle and also the discharge from a particle have been extensively investigated for the development of a prevention and protection method against breakdown in gas-insulated switchgear. The particle showed several different patterns of motion, e.g., "standing," precession motion, oscillating up and down, etc. Each of these types of motion depends on corona discharge from the particle itself. Since this motion cannot be explained only by monopolar discharge from one end of a particle, bipolar discharge from both ends of a particle occurring simultaneously has been investigated by applying the floating particle method. The particle length and the gap between the particle and electrode were chosen as parameters. From experimental results, several interesting features were obtained. The curve of bipolar corona. current lies between negative and positive corona currents of monopolar curves. There is a sudden current increase at the threshold voltage that seems to be a new feature of the corona current from a filamentary particle. So far, the experimental results indicate that this threshold voltage is not a function of particle length, but it could depend slightly on length. Flashover voltage is a function of particle length and the gap. It decreases with length and increases with the gap     

Electrostatic discharge issues in electric vehicles

Electrostatic discharge (ESD) is an important issue in any motor vehicle. Anecdotal reports abound of cars with spark ignition hazards because of fuel tank designs, and even toll collectors reluctant to collect money by hand from certain late model cars. As electric vehicles move from the laboratory and test track to the production floor and showroom, ESD concerns take on a new context and become more critical. In this paper, the attributes of electric vehicles that give rise to concerns about ESD are introduced. When the concerns are taken into account, certain basic design constraints become evident. A candidate design is analyzed for its ESD properties. Some common design practices, especially the practice of isolating the battery bus, can create reliability problems because of ESD