基于宽频特性测量的电气设备局部放电检测

为了提高电气设备运行的稳定性与安全性,降低局部放电危险事故的发生概率,提出了基于宽频特性测量的电气设备局部放电检测。首先分析宽频特性测量以及电气设备局部放电检测基本原理,得到电磁波主要输出过程;通过分析结果建立检测系统框架以及动态检测模型,并计算反馈延时、获取驱动电路函数,为后续输出准确电量结果提供有效保障,结合电气设备工作流程完成最终的系统结构设计,实现基于宽频特性测量的电气设备局部放电在线检测。使用不同方法对四种不同类型局部放电进行检测实验,验证了所提方法的有效程度以及高准确性,可为后续的故障处理工作提供便利条件。

本安电源电容性电路放电特性研究

本质安全电路理论及检测是与电气放电密切相关的,由于开关电源输出端存在较大的电容,它对电源的本质安全输出有较大影响,因此有必要对电容性电路的放电特性进行进一步研究。

防爆设备的设计要点

防爆设备,目前被广泛大量地应用在石油和化工行业等爆炸性危险场所,它的防爆安全性能对安全生产作业起着至关重要的作用,防爆设备的保护方式和设计要点是本文重点要讨论的。

Runaway Electrons Pre-ionized Diffuse Discharges in SF6, Air, Argon and Nitrogen

The formation of runaway electron pre-ionized diffuse discharges at the pressures 0.05-0.7 MPa of in air, argon, nitrogen, and SF6 in an inhomogeneous electric field was investigated. Dynamics of intensity of the discharge plasma radiation from the different discharge gap regions in the gas pressure range （0.05-0.7 MPa） was established. It was shown that, the breakdown is occurred owing to the ionization wave, which starts from the electrode with small radius of curvature at both polarity of high voltage pulses. It is seen that formation of bright spots on the fiat electrode at the negative polarity of the electrode with small radius of curvature are observed during the changing of the discharge current polarity. It was shown that, at positive polarity of electrode with a small radius of curvature, the bright spots on the flat electrode arise due to the participation of the dynamic displacement current in the gap conductance.

Effect of yttrium and calcium additions on electrochemical behaviors and discharge performance of AZ80 anodes for Mg-air battery

The effects of yttrium(Y)and yttrium+calcium(Y+Ca)additions on the electrochemical properties and discharge performance of the as-extruded Mg−8Al−0.5Zn−0.2Mn(AZ80)anodes for Mg−air batteries were investigated.The results show that the addition of 0.2 wt.%Y increased the corrosion resistance and discharge activity of AZ80 anode.This was attributed to the fine and sphericalβ-Mg_17)Al_(12) phases dispersing evenly in AZ80+0.2Y alloy,which suppressed the localized corrosion and severe“chunk effect”,and facilitated the rapid activation ofα-Mg.Combinative addition of 0.2 wt.%Y and 0.15 wt.%Ca generated grain refinement and a reduction of theβ-Mg_17)Al_(12) phase,resulting in a further enhancement in discharge voltage.However,the incorporation of Ca in Mg_17)Al_(12) and Al_(2)Y compounds compromised the corrosion resistance and anodic efficiency of AZ80+0.2Y+0.15Ca anode.Consequently,AZ80+0.2Y anode exhibited excellent overall discharge performance,with the peak discharge capacity and anodic efficiency of 1525 mA·h·g^(−1) and 67%at 80 mA/cm^(2),13%and 14%higher than those of AZ80 anode,respectively.

Noise properties in breaking and loose contacts and their effect on quality degradation of digital signal

Electric contact discharge is subject closely related to digital information transmission, and integrity of digital signals for realizing high reliablility transmission. This kind of problem is a part of EMC (electromagnetic compatibility). From such a viewpoint, contact noise problems will be mentioned which disturb and degrade digital signals. The induction noise and radiation noise from discharge, electrostatic discharge (ESD), and connector related fundamental subject will be mentioned.

A novel current-sharing scheme based on magamp

The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica-tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.

Partial Discharge Measurement of OCP-Tapes in Rotating Electrical Machines

Nowadays, PD （partial discharge） measurements are a crucial part of the preventive maintenance of electrical equipment within high voltage engineering. Especially for electrical machines, both the supplier and the user are interested in the results of PD measurements. However, PDs hardly represent the cause of the failure, more likely they are claimed as the outcome of a failure. This paper deals with the insulation of a 6 kV electrical machine, whereas PD measurements were carried out at a single stator from wound coils. During manufacturing, these coils were equipped with different materials for the OCP （outer corona protection）. Using different PD measurement systems and different bandwidths, investigations of the PD behavior of the coils were carried out. Additionally, the surface resistivity of the corona protection was determined. As a result, conclusions for the correlations between the resistance of the OCP as well as the PD behavior are stated. Furthermore, the influence of using different measurement systems, different measuring circuits, and different bandwidths is shown.

Natural Ionizing System of Electrical Protection and Energies against Atmospheric Discharges （Lightning）

This is the new highest technology, 100% Venezuelan and unique in the world, technological innovation, world patent for maximum protection, security and zero risk （0） to all electrical and power generation systems： hydroelectric and thermoelectric power plants, wind, nuclear and solar power plants, etc.; it is the only technology around the world that has the potential to disperse and propagate to land mass the enormous energies associated to the atmospheric discharges （lightning）, which are in the order： 200,000 to 500,000 Amperes; 1,000 million kilowatts and high-level transient voltage of 100 million volts. This new high technology is the solution to the paradigm of Benjamin Franklin and it is the mechanism to end ＂blackouts＂ that produces so many damages and losses of billions of dollars to both generators and users of electrical service, throughout the world.

Changes in Low Energy Neutron Counts Rate near Ground Level Associated to Steady Rain

Measurements of neutron count rate （0.025 eV to 10 MeV） at ground level were performed with a single free （He-3） tube detectorthat is located near ground level in Aeronautical Institute of Technology （ITA） Silo Jos6 dos Campos, SP, Brazil. The data were collected uninterruptedly since February 28, 2016 to March 11, 2016. Based on the analysis of data obtained in this period, was possible to observe the occurrence of events, backscattering for example,with significant increases in the neutron count rate during about 3 days of steady rain for all nearby regions. These events seem to be correlated with changes in local weather conditions such as cloud coverage or rain-precipitation of weak intensity. It was reported that the non-observation of a single event seems to be an indicative of the production of a burst of neutrons by a lightning discharge near the detector. Some explanations about the increasing of low energy neutrons are suggested in this article.

Spectroscopic Diagnostic of Spark Discharge Plasma at Atmospheric Pressure

The emission of CuInSe2-based spark discharge plasma at atmospheric pressure in air has been investigated by optical emission spectroscopy method. The plasma was formed by action of the high voltage pulse generator （with nanosecond pulse） on the corresponding electrodes （CulnSe2 compound）. The emission characteristics have been obtained for the spark discharge plasma at 3 mm interelectrode distance. It was established that the spark discharge plasma radiation was determined by decay products of the compound from which electrodes were made. The most suitable spectral lines for plasma diagnostics is atomic copper lines in the visible spectrum and atomic indium lines in UV （ultraviolet） and visible spectrum.

Non-local Consciousness Influence to Physical Sensors： Experimental Data

Experimental approach to investigation of NLCI （Non-local Consciousness Influence） effects is based on sensors of different design, and most of it based on transitional effects in gas-discharge plasma with several quasi-stable states is also presented. Computerized device for detecting NLCI is based on commercially available Gas Discharge Camera （www.ktispb.ru） and allows following time dynamics of several sensors in NLCI conditions. The typical sensors are： water, air, earth, and wood, this instrument was named ＂The 5th Element＂. Readings are taken continuously by special software every five or ten seconds in automatic mode. Sensitivity of the device was tested by detecting the influence of total sun eclipse in Siberia in 2008 and by detecting sunrise and sunset. Several experimental modalities have been developed： （1） directed NLCI of a person; （2） directed NLCI of a group of people; and （3） non-directed NLCI of a group of people. Experiments during many years demonstrated efficiency of the developed approach.

Using Biomass in Power Generation for Supplying Electrical and Thermal Energy in Iran and Evaluation of Environmental Pollution Spread

The main objective of this study is estimating environmental pollution of hybrid biomass and co-generation power plants. Efficiency of direct tapping of biomass is about 15%-20%. Consequently, about 80% of energy would be waste in this method. While in co-generation power plant, this number could improve to more than 50%. Therefore, to achieve higher efficiency in utilizing biomass energy, co-generation power plants is proposed by using biogas as fuel instead of natural gas. Proposed system would be supplied thermal and electrical energy for non-urban areas of Iran. In this regard, process of fermentation and gas production from biomass in a vertical digester is studied and simulated using analytic methods. Various factors affecting the fermentation, such as temperature, humidity, PH and optimal conditions for the extraction of gas from waste agriculture and animal are also determined. Comparing between the pollution emission from fossil fuel power plants and power plants fed by biomass shows about 88% reduction in greenhouse emission which significant number.

Development of Numerical Model for Radio Frequency Atmospheric Pressure Glow Discharges in Argon

A one-dimensional,self-consistent fluid model is developed for a computational investigation on discharge characteristics and dynamics of radio frequency(RF) glow discharges in atmospheric argon,which are demonstrated through the spatial and temporal profiles of plasma species,electric field,and mean electron energy.Furthermore,in the discharge current density range from 7.1 mA/cm2 to 119.5 mA/cm2,different discharge operation modes of α and γ are indicated by changing differential conductivity of voltage-current characteristics and sheath dynamics in terms of sheath voltage and sheath thickness.

General Economic Analysis about the Wind Farms Repowering in Spain

Environmental pollution and emissions from greenhouse gases caused by fossil fuel use are a threat to sustainable development. With renewable energy sources, no polluting emissions are released into the atmosphere. Therefore, using these sources on a large-scale is a key to reducing emissions and meeting the commitments established by Kyoto Protocol. Moreover, EU wants that the 20% of energy consumption is renewable in 2020. This study describes economic aspects, such as net present value and internal profitability rate, of the repowering process for the wind farms. Repowering can generate considerably more power with fewer facilities. This process was the result of a growing demand for renewable energies, facilitated by the great potential of wind energy in the north of Spain. The wind farms studied in this work were set up before 1998 and they had obsolete machinery with low power. There are strong indications that repowering is a profitable endeavour.

氦、氢、氮空心阴极放电的真空紫外辐射特性

介绍了一种水冷、陶瓷封接结构的空心阴极放电装置.研究了He、H_2、N_2在120nm～20Onm范围内该装置的真空紫外辐射特性,获得了100～600mA电流范围内的辐射强度与放电电流的关系,以及充气气压变化对它的影响.实验表明:在实验条件下,主要发射谱线为氮的原子线和氦的离子线;辐射谱线强度在0.03～0.72mW·cm^(-2);气压改变时,N_2、H_2辐射强度有一极大值,而He的离子线辐射强度则出现二个极大;在He/H_2混合气体放电时,随着He的加入,氢分子带光谱有明显下降.

Dielectric barrier plasma dynamics for active aerodynamic flow control

The paper investigates the dynamics of a new multiple bipolar multiple Dielectric Barrier Discharges(DBD)actuator using in large-scale flow control.Particle image velocimetry experiments are performed to characteristic the effectiveness of the multiple bipolar DBD plasma actuator.The results show that the mutual interaction between the electrodes,one major disadvantage of traditional DBD characterized by reverse discharge can be entirely avoided,and a constantly accelerating electric wind velocity can be obtained by using the new multiple bipolar DBD plasma actuator.

An easy synthesis of Ni-Co doped hollow C-N tubular nanocomposites as excellent cathodic catalysts of alkaline and neutral zinc-air batteries

Exploring high-activity electrocatalyst for oxygen reduction reaction (ORR) is of great significance for a variety of renewable energy conversion and storage technologies. Herein, we fabricated novel ORR electrocatalysts derived from Ni-Co nanoparticles encapsulated in hollow tubular C-N composites (ht-CN) through an easy and scalable pyrolysis route utilizing nickel acetate and cobalt acetate as metal precursors, 2-cyanoguanidine as the nitrogen source, and sucrose as the carbon source. Among the prepared nanocomposite catalysts with different molar ratios ofNi/Co, the catalyst Ni2Co3@ht-CN exhibits an outstanding ORR electroactivity comparable to Pt/C catalyst both in alkaline and neutral media. Home-made zinc-air battery with the Ni2Co3@ht-CN as cathode electrocatalyst presents excellent performance and superior durability either in neutral or alkaline medium. The Ni2Co3@ht-CN battery delivers an open circuit voltage of 1.08 V and a maximum power density of 47 mW cm^-2 in 0.5 mol L^-1 KNO3 solution, while 1.51 V and 314 mW cm^-2 in 6 mol L-^1 KOH solution. In addition, whether in neutral or alkaline solution, the constant current discharge curves of the Ni2Co3@ht-CN battery at different current densities exhibit higher voltage plateau and stability than the Pt/C battery. Results demonstrate the potential application of the catalysts of the present investigation to Zn-air batteries both in alkaline and neutral media.

Review on Partial Discharge Detection Techniques Related to High Voltage Power Equipment Using Different Sensors

When operating an equipment or a power system at the high voltage, problems associated with partial discharge （PD） can be tracked down to electromagnetic emission, acoustic emission or chemical reactions such as the formation of ozone and nitrous oxide gases. The high voltage equipment and high voltage installation owners have come to terms with the need for conditions monitoring the^process of PD in the equipments such as power transformers, gas insulated substations （GIS）, and cable installations. This paper reviews the available PD detection methods （involving high voltage equipment） such as electrical detection, chemical detection, acoustic detection, and optical detection. Advantages and disadvantages of each method have been explored and compared. The review suggests that optical detection techniques provide many advantages in the consideration of accuracy and suitability for the applications when compared to other techniques.

Cubic imidazolate frameworks-derived CoFe alloy nanoparticles-embedded N-doped graphitic carbon for discharging reaction of Zn-air battery

The construction of transition metal-based catalysts with high activity and stability has been widely regarded as a promising method to replace the precious metal Pt for oxygen reduction reaction(ORR).Herein,we synthesized CoFe alloy nanoparticle-embedded N-doped graphitic carbon(CoFe/NC)nanostructures as ORR electrocatalysts.The ZIF-67(zeolitic imidazolate framework,ZIF)nanocubes were first synthesized,followed by an introduction of Fe2+ions to form CoFe-ZIF precursors via a simple ion-exchange route.Subsequently,the CoFe/NC composites were synthesized through a facile pyrolysis strategy.The ORR activity and the contents of cobalt and iron could be effectively adjusted by controlling the solution concentration of Fe2+ions used for the ion exchange and the pyrolysis temperature.The CoFe/NC-0.2-900 composite(synthesized with 0.2 mmol of FeSO4·7H2O at a pyrolysis temperature of 900℃)exhibited ORR activity that was superior to the other samples owing to a synergistic effect of the bimetal,especially considering the extremely high limiting current density of 6.4 mA cm^-2 compared with that of Pt/C(5.1 mA cm^-2).Rechargeable Zn-air batteries were assembled employing CoFe/NC-0.2-900 and NiFeP/NF(NiFeP supported on nickel foam(NF))as the catalysts for the discharging and charging processes,respectively,The above materials achieved reduced discharging and charging platforms,high power density,and prolonged cycling stability compared with conventional Pt/C+RuO2/C catalysts.