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2nd IEEE International Electrical and Energy Conference, CIEEC 2018

作者： Cheng, Zixia Shi, Jinxing Zhang, Ling Zhou, Yuanxiang Lu, Zekai Guo, Shaowei School of Electrical Engineering Zhengzhou University Zhengzhou450001 China State Key Lab of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing100084 China School of Electrical Engineering Xinjiang University Urumqi830047 China Electric Power Research Institute State Grid Jibei Electric Power Company Beijing100045 China

ISBN: (纸本)9781538653913

In order to study the effect of AC aging on space charge characteristics of low-density polyethylene (LDPE) films, an AC electric field of 50 kV/mm (peak value) was adopted for the accelerated aging test and space charge measurements of AC aged LDPE films were carried out subsequently. The results show that no significant space charge accumulation in the LDPE samples aged under a 50 kV/mm AC electric field. It can be seen that a significant positive space charge accumulation occurs inside the sample, when DC electric fields were applied to the AC aged LDPE samples. The long-term AC aging also causes more and deeper cracks on the surface of LDPE samples. Moreover, AC aging promotes the oxidation reaction of LDPE. The longer the aging time, the higher the degree of oxidation. On this basis, the probable relationship between space charge characteristics and material physicochemical properties of LDPE during AC electrical aging is clarified. © 2018 IEEE.

关键词： Electric space charge

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Effect of UV Radiation Aging on Creepage Discharge Characteristics of High Temperature Vulcanized Silicon Rubber at High Altitude

Effect of UV Radiation Aging on Creepage Discharge Character...

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中国物理学会第二十二届全国静电学术年会

作者： JIN Fu-bao LIANG Bin ZHOU Yuang-xiang ZHONG Liu ZHANG Ling School Of Water Resources and Electric Power Qinghai University Xining80016China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Ele

Aiming at the special working environment of composite insulators at high altitude area,we investigate the creepage discharge characteristics of aged HTV(High Temperature Vulcanized,HTV)silicone rubber materials by UV(ultraviolet radiation,UV)aging method in this *** results show that the creepage discharge flashover voltage first increased,then decreased as aging time increasing,whereas the creepage discharge initial voltage was not significantly affected by aging *** aging time has little effect on creepage discharge *** aging time contributed to shorter endurance time and higher creepage discharge development *** magnitude of discharges increase rapidly in a short time after *** partial discharge detection system was used to detect the whole creepage discharge development *** to the partial discharge characteristics parameters of creepage discharge,we divided the development process of creepage discharge into initial stage,developmental stage,accelerating stage,and critical breakdown *** with characteristic parameters of unaged HTV silicone rubber,the characteristic parameters for the aged HTV silicone rubber exhibited less fluctuation and clear *** aging not only has an effect on the physicochemical and hydrophobic properties of the materials,but also accelerates the development process of creepage discharge under AC *** should be given enough attention in engineering practice,especially at high altitude area.

关键词： High temperature vulcanized silicone rubber creepage discharge UV aging creepage discharge inception voltage creepage discharge flashover voltage high altitude characteristic parameters

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Effects of Temperature on Creepage Discharge Characteristics in Oil-Impregnated Pressboard Insulation under Combined AC-DC Voltage

Effects of Temperature on Creepage Discharge Characteristics...

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中国物理学会第二十二届全国静电学术年会

The characteristics of oil-impregnated pressboard(OIP)insulation in converter transformer are different with that in traditional AC transformers due to the complication of voltage applied on valve side windings of converter *** is a serious lack of empirical research on effect of temperature on creepage discharge characteristics in OIP under combined AC-DC ***,this study investigates the characteristics spectrum of creepage discharge in OIP under combined AC-DC voltage,and explores the effect of temperature on creepage discharge characteristics under different temperature from 70 to 110℃.The experimental results show that the partial discharge inception voltage and flashover voltage decrease as temperature *** times of low amplitude discharge(LAD)decrease and amplitude of LAD *** temperature had an accelerating effect on the development of creepage discharge in the OIP under combined AC-DC voltage Meanwhile,the times of high amplitude discharge(HAD)gradually increase at each stage of creepage discharge with higher *** analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of *** residual charge carriers are more easily dissipated after ***'hump'region of LAD moves to the direction of higher discharge *** interval time between two consecutive discharges drastically *** HAD intensively appear,result in accelerating the development of creepage discharge in OIP insulation.

关键词： Oil-impregnated pressboard insulation temperature combined AC-DC voltage creepage discharge inception voltage flashover voltage

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Skin Effect and Eddy Current Loss in Electrical Steel Sheets under Applied Excitation Fields.

Skin Effect and Eddy Current Loss in Electrical Steel Sheets...

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International Conference on Magnetics (INTERMAG)

作者： J. Li Q. Yang S. Wang Y. Li State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

Body: By applying electromagnetic diffusion equation, skin effect in electrical steel sheets in the condition of alternating excitation is analyzed based on Maxwell electromagnetic field theory. Due to skin effect is more significant mainly at high frequency, non-dimensionalized treatment for the diffusion equation is produced and eddy current loss is calculated by considering or not skin effect, respectively. Meanwhile, broadband magnetic losses and separation of typical electrical steel are obtained by using a 3-D magnetic properties testing system to bring to light the emergence of skin effect under rotational excitation. The simplification of magnetic constitutive equation is proposed and introduced into the diffusion equation, which is solved by employing finite elements coupled to Fredholm's equation. An approximate expression for the rotational eddy current loss component with skin effect is eventually written. The simulations show that due to the influence of skin effect, non-uniform distribution of induction flux density within electrical steel sheets will become more and more significant, the fl ux density and fi eld intensity nearby the surface are larger than that in the centre of the sheets [1, 2]. And with increasing of alternating excitation frequency, the inhomogeneity of induction flux density will be extended and growing more inhomogeneous, due to the smaller skin depth and a small increase of anomalous loss in the total core losses, as shown in Fig. 1.2. Therefore, alternating eddy current loss P as functions of the peak mean alternating flux density B mamean and the alternating excitation frequency f a can be deduced as follows: limv→∞P ae (B ma_mean f a )=[2ω a (B ma_mean ) 2 /3ρμν 2 =(σπ 2 d 2 /3ρ)(f a ) 2 (B ma_mean ) (no skin effect)[W/kg] (1) limν→0 P ae (B ma_mean f a )=[4ω a (B ma_mean ) 2 /ρμν=(4σ 1/2 π 3/2 d/ρμ 1/2 )(f a ) 3/2 (Bma_mean) 2 (considering significant skin effect) [W/kg] (2) where, ω a is the angular frequency; v = 2δ

关键词： Magnetics Conferences

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Losses Modeling Based on Domain Wall Processes and Valida-tion Considering Rotational Excitation of Electrical Steel Sheets.

Losses Modeling Based on Domain Wall Processes and Valida-ti...

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International Conference on Magnetics (INTERMAG)

On the basis of damping principle of vibration, the domain wall processes is investigated and modeled at low-to-medium frequencies in electrical steel sheets. Due to the energy dissipation chiefly descends from a micro-vortex current caused by domain wall motion, the coupled Landau-Lifshitz-Gilbert (LLG) and Maxwell electromagnetic diffusion equations are thus considered to describe the high-frequency characteristics. The overall core losses are eventually deduced in terms of separate contributions by domain wall processes and classical eddy current. Moreover, the calculation model can be extended to rotational excitation pattern. Hence, taking the typical electrical steel sheets as example, the novel core losses calculation model is analysed and compared with the total alternating core losses supplied by electrical steel sheets manufacturers and the 3-D rotating experimental core losses of sheets specimens which are carried out by using a 3-D magnetic properties testing system.

关键词： Magnetics Conferences

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A Novel Structure Design of Iron Core for power Transformers Considering Joints Forms and Magnetostriction.

A Novel Structure Design of Iron Core for Power Transformers...

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International Conference on Magnetics (INTERMAG)

作者： J. Li S. Wang H. Gao M. Liu J. Hong State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a

关键词： Magnetics Conferences

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Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

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Plasma Science and Technology 2017年第6期19卷 74-81页

作者： Yuanji CAI Yonggang GUAN Weidong LIU State Key Lab of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 People＇s Republic of China

Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary *** is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）*** this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike *** TEV waveforms during disconnector operations are recorded by a self-developed measurement system ***,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are *** transmission line theory is introduced to analyze the TEV and is validated by the experimental ***,the relationship between the TEV and the repeated strike process is *** proves that the pulse voltage of the TEV is proportional to the corresponding breakdown *** results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

关键词： transient enclosure voltage （TEV） gas-insulated switchgear （GIS） ultra-high-voltage （UHV） repeated strike process disconnector

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Effect of Vinyl Content on Mechanical Property and Electrical Tree Initiation in Silicone Rubber 2

Effect of Vinyl Content on Mechanical Property and Electrica...

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2nd IEEE International Electrical and Energy Conference, CIEEC 2018

作者： Sui, Jiangyuan Zhang, Ling Zhou, Yuanxiang Zhang, Xinyan Cheng, Zixia Guo, Shaowei School of Electrical Engineering Xinjiang University Urumqi830047 China State Key Lab of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing100084 China State Key Lab of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an710049 China School of Electrical Engineering Zhengzhou University Zhengzhou450001 China Electric Power Research Institute State Grid Jibei Electric Power Company Beijing100045 China

ISBN: (纸本)9781538653913

The vinyl content in methyl vinyl silicone oil has a significant impact on the mechanical and electrical properties of reinforced silicone rubber. In this study, mechanical property and electrical tree initiation of silicone rubber were studied by comparing different vinyl contents. The results show that shore hardness, tensile strength, elongation at break, and tear strength of insulating silicone rubber material increase first and then decrease with the of vinyl content increasing from 1% to 5%. The breakdown strength and the initiation voltage of electrical tree are basically consistent with the variation of tensile strength and tear strength. Detailed discussion are presented. This work could provide data support for the practical preparation of engineering silicone rubber. © 2018 IEEE.

关键词： Tensile strength

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An Improved Master-Slave control for Three-port Converter Based Distributed DC Grid-connected PV system 8

An Improved Master-Slave Control for Three-port Converter Ba...

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8th International power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

作者： Jiang, Siyue Sun, Kai Wu, Hongfei Shi, Haixu Dong, Xiaofeng Raza Kazmi, Syed Muhammad State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Jiangsu Key-Laboratory of New Energy Generation and Power Conversion Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu Province China United States Pakistan Center for Advanced Studies in Energy National University of Sciences and Technology Islamabad Pakistan

ISBN: (纸本)9784886864055

With the development of DC grid technology, it has become a trend to introduce photovoltaic(PV) as a power source to the DC power distribution network. In this paper, an improved master-slave control strategy is proposed to realize power splitting and voltage sharing in a modular system with PV connected. Each module is a three-port converter: Input port connects distributed PV, output port connects to DC grid, and intermediate port is connected in parallel with other modules as a bus to realize the power splitting. For a single module, input voltage, intermediate bus voltage and output voltage should all be controlled to reference but only duty ratio and phase-shifting angel can be regulated hence it may occur the multi-objective variables control problem. While using the proposed strategy, this problem can be solved effectively and the system stability is ensured during the voltage sharing process. This control strategy is verified by simulation and experiment. © 2018 IEEJ Industry Application Society.

关键词： system stability

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On engineering game theory with its application in power systems

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control Theory and Technology 2017年第1期15卷 1-12页

作者： Shengwei MEI Wei WEI Feng LIU Department of Electrical Engineering and Applied Electronics Technology Tsinghua Universily Beijing 100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China

Due to its capability of solving decision-making problems involving multiple entities and objectives, as well as complex action sequences, game theory has been a basic mathematical tool of economists, politicians, and sociologists for decades. It helps them understand how strategic interactions impact rational decisions of individual players in competitive and uncertain environment, if each player aims to get the best payoff. This situation is ubiquitous in engineering practices. This paper streamlines the foundations of engineering game theory, which uses concepts, theories and methodologies to guide the resolution of engineering design, operation, and control problems in a more canonical and systematic way. An overview of its application in smart grid technologies and power systems related topics is presented, and intriguing research directions are also envisioned.

关键词： Decision making engineering game theory power system smart grid technology

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