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2012 International Conference on High Voltage Engineering and Application, ICHVE 2012

作者： Bao, Lianwei Li, Jian Lv, Jinzhuang He, Zhiman Wang, Yan State Key Laboratory of Power Transmission Equipment and System and New Technology Chongqing University Chongqing 400044 China HVDC Technology Research Department Electric Power Research Institute China Southern Power Grid Guangzhou 510623 China

ISBN: (纸本)9781467347464

With the improvement of voltage level of HVDC transmission, the insulation of converter transformer has become increasingly prominent. Different from the general power transformer, valve side windings on converter transformer withstand pulsating voltages, which makes insulation problem get more serious. In this paper, experiments were carried out under pulsating voltage over a wide range of the pulsating coefficients defined as p=Eac/Edc, which can obtain the relationship between p and breakdown voltage of oil-paper insulation. Experiment results showed that the breakdown voltages were regularly decreased by the increases of p, and the breakdown voltage value of pre-stressed DC-voltage is higher than that of pre-stressed AC-voltage, also the scatter of the pre-stressed DC-voltage is better. Moreover, the short-time breakdown tests of oil-paper insulation specimens were also carried out at different levels of temperature. The results showed that when the temperature exceeds a certain threshold, the temperature will show a significant impact on the breakdown strength. A great influence of temperature on the DC component of the breakdown voltage was observed, while the effect on AC component is relatively small. At last, this paper presents an expression which relates the breakdown strength to the temperature. © 2012 IEEE.

关键词： Electric breakdown

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Research on large-area fire monitoring and warning system for power grid

Research on large-area fire monitoring and warning system fo...

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2012 International Conference on Systems and Informatics, ICSAI 2012

作者： Lu, Jiazheng Yang, Li Zhang, Hong Xian Li, Bo Lin, Hai Hunan Electric Power Corporation Research Institute State Grid Corporation Power Transmission and Transformation Equipment anti Icing Disaster Technology Key Laboratory Changsha China Hunan Bureau of Meteorology Changsha China

ISBN: (纸本)9781467301992

The bushfire may seriously effected the neighboring transmission line. Every year a large number of transmission lines tripping accidents happened due to fire. As the transmission line distributed throughout the areas, and the range is wide, and in most areas it's given priority to the hill terrain, seriously affecting the efficiency of the traditional inspection method for transmission line, and is difficult to detect the neighboring fires. Through the establishment of satellite receiving system, it can make use of satellite remote sensing image to accurately monitor the fire situation of transmission line corridor and its surrounding in time Through the development of fire identification method, distance measurement algorithm, 3D fire spread model based on weather information, spatial database and a series of key technology, the large-area fire monitoring and early warning system for transmission line can effective monitor the fire plot real time, release the warning information, and improve the transmission line to fight fires disasters. © 2012 IEEE.

关键词： Electric lines

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Investigation of heat dissipation of power cable laid in the tunnel with ventilation

Investigation of heat dissipation of power cable laid in the...

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2012 Asia-Pacific power and Energy Engineering Conference, APPEEC 2012

作者： Yang, Fan Cheng, Peng Yang, Yongming Chen, Jun Chen, Tao State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing 400040 China Chongqing Power Grid Maintenance Company Chongqing China Chongqing Electric Power Research Institute Chongqing 401123 China

ISBN: (纸本)9781457705472

To increase the current carrying capacity of the power cable, more and more power tunnel are installed with ventilation. Hence in the paper the heat dissipation of power cable is investigated. Firstly the model to calculate the thermal field of power cable with natural ventilation is presented based on the fluid mechanics and heat transfer, and the governing equations and boundary conditions are inferred. Then the thermal field for six-loop cables in power tunnel was calculated, which verified the accuracy of the model. In addition, the factors influencing the thermal field with ventilation is investigated, including the size of the power tunnel, the distance between the cable. Finally the current carrying capacity of the power cable is calculated and the economic benefit of the operation mode of power cable is analyzed. © 2012 IEEE.

关键词： Ventilation

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The properties of space charge in oil-paper insulation during electrical-thermal aging

The properties of space charge in oil-paper insulation durin...

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2012 International Conference on High Voltage Engineering and Application, ICHVE 2012

作者： Wu, Sicheng Li, Jian Zhao, Linjie Wang, Yan He, Zhiman Bao, Lianwei State Key Laboratory of Power Transmission Equipment and System Security and New Technology College of Electrical Engineering Chongqing University Chongqing 400044 China HVDC Technology Research Department Electric Power Research Institute China Southern Power Grid Guangzhou 510623 China

ISBN: (纸本)9781467347464

Valve windings of converter transformer withstand pulsating voltages. In order to reveal the relationship between the properties of space charge and electrical-thermal aging of oil-paper insulation in converter transformer, this paper did the electrical-thermal aging test at 70°C under 7.6kV pulsating DC voltage and obtained the samples of different aging time. The internal space charge injection and accumulation properties of aged samples under 20kV/mm and 30kV/mm DC electric field was measured and analyzed by the Pulsed Electro-Acoustic (PEA) method. The results showed that homo-charges injection still occurs at both electrodes in the electrical-thermal aging samples. Aged oil-paper insulation was dominated by negative charge injection as the stressing time increases, which directly cause hetero-charge accumulation in the vicinity of the anode, and homo-charge accumulation near the cathode. It could help explain the reason of the electrical-thermal aging lifetime of oil-paper in sulation is obviously shorter than the electrical or thermal aging. In addition, the longer the aging time, the more the total charge accumulated in the samples. © 2012 IEEE.

关键词： Electric space charge

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Investigation on the propagation characteristic of electromagnetic waves in converter transformers

Investigation on the propagation characteristic of electroma...

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2012 International Conference on High Voltage Engineering and Application, ICHVE 2012

作者： Wang, Peng Li, Jian Zhao, Linjie Jiang, Tianyan He, Zhiman State Key Laboratory of Power Transmission Equipment and System Security and New Technology College of Electrical Engineering Chongqing University Chongqing 400044 China HVDC Technology Research Department Electric Power Research Institute China Southern Power Grid Guangzhou 510623 China

ISBN: (纸本)9781467347464

Ultra-high-frequency (UHF) approaches, when used to detect partial discharge in converter transformers, can avoid the impulse interference generated by converter valve, thus contributing to high sensitivity. The electromagnetic waves (EM-waves) propagation in transformer could be affected by transformer components and other factors. In this paper, a simulation model of converter transformer was built up based on a reasonable simplification of transformer components. And then the EM-waves propagation characteristics in transformer was simulated and studied with Finite Difference Time Domain (FDTD) method. The simulation results explained the propagation characteristics of EM-waves between the core and windings, the attenuation and distortion of EM-waves caused by the core, windings and bushings. © 2012 IEEE.

关键词： Electromagnetic waves

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Failure evaluation model of oil-paper insulation under AC-DC combined voltages

Failure evaluation model of oil-paper insulation under AC-DC...

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2012 International Conference on High Voltage Engineering and Application, ICHVE 2012

作者： Wang, Yan Li, Jian Zhao, Yuming He, Zhiman Wu, Sicheng Bao, Lianwei State Key Laboratory of Power Transmission Equipment and System Security and New Technology College of Electrical Engineering Chongqing University Chongqing 400044 China HVDC Technology Research Department Electric Power Research Institute China Southern Power Grid Guangzhou 510623 China

ISBN: (纸本)9781467347464

The insulation of windings connected with converter valves have to withstand AC, DC and repetitive impulse combined voltages in converter transformers. This paper presented the failure evaluation model by experimental research on electrical breakdown characteristics of oil-paper insulation under AC, DC and AC-DC combined voltages. Both short-time tests and constant-stress tests were carried out when the insulation system was subjected to different applied voltages. The breakdown strength and times-to-breakdown of oil-paper specimens have been investigated by tests. The inverse power model was presented by the weibull parameters which were estimated by the times-to-breakdown of specimens. Using the parameters of weibull model and inverse power model, the functions of failure evaluation model were calculated. It could establish the relationship between times, voltages and failure probability of insulation. And final evaluation results showed it was more effective than tradition failure model and weibull model. The DC component behavior in the insulation system has been analyzed and the influence of AC-DC combined voltages on insulation system was discussed. © 2012 IEEE.

关键词： Insulation

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Time-varying waveform analysis for power transformer protection using frequency shift empirical mode decomposition

Time-varying waveform analysis for power transformer protect...

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11th IET International Conference on Developments in power Systems Protection, DPSP 2012

作者： Bazargan, Masoud Liang, Wuxing Li, Chengxin Liu, Junyong Yang, Jiashi Yao, Liangzhong Alstom Research and Technology Centre Alstom Grid St Leornd Avenue Stafford ST 17 4LX United Kingdom Provvincial-Level Key Laboratory of Smart Grid Sichuan University Chengdu 610065 China Sichuan Electric Power Company Chengdu 610061 China State Grid Electric Power Research Institute Nanjing 210003 China

ISBN: (纸本)9781849196208

Empirical mode decomposition (EMD) method is a novel time-frequency analysis tool to analyse non-stationary signals, which decomposes the signal concerned into intrinsic mode functions (IMFs) modulated in terms of both amplitude and frequency. The original version of EMD, however, suffers from an algorithm difficulty to separate two individual components, frequencies of which are within an octave. To improve the frequency resolution, a signal pre-processing method is used to shift the frequencies apart based on signal communication theory. This proposed frequency shift EMD has been successfully applied to extract modal parameters of low frequency oscillations for power systems. In this paper, this method is used to analyse the transient signals (inrush current) in the field of power transformer protection. Comparing with low frequency oscillation signals, these signals include more frequency components with faster dynamics. Numerical simulations are conducted to verify the frequency shift EMD. The results show that this method is adequate for time-varying waveform analysis for power transformer protection, and with the information provided by this frequency shift EMD, more robust protection schemes for power transformer could be proposed.

关键词： Empirical mode decomposition

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Study on evaluation index system of equipment utilization on distribution network 2012

Study on evaluation index system of equipment utilization on...

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2012 IEEE Innovative smart grid Technologies - Asia, ISGT Asia

作者： Yang, Wei-Hong Liu, Hong Wang, Zhe Cui, Wen-Ting Cao, Lei State Power Economic Research Institute Beijing 100052 China Key Laboratory of Smart Grid Tianjin University Ministry of Education Nankai District Tianjin 300072 China Tianjin Tianda Qiushi Electic Power High Technology Co. Ltd. Tianjin 300384 China

ISBN: (纸本)9781467312219

For the current inefficient use of distribution network equipment and the lack of effective evaluation means, a set of comprehensive evaluation index system is built, which could accurately evaluate utilization level of equipment and find weakness. First, use fish bone diagram to find out influencing factors of distribution network equipment utilization;then build evaluation index system of distribution network equipment utilization;finally, based on association analysis of influencing factors and evaluation indexes, the reasonable values of evaluation indexes of distribution network equipment utilization are proposed, so as to improve the economy of planning, construction and operation of distribution network in our country. © 2012 IEEE.

关键词： Construction equipment

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Effects of Macroparticle Sizes on Two-phase Mixture Discharge Under DC Voltage

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中国电机工程学报 2012年第13期32卷 I0020-I0020,203页

作者： YAO Wenjun HE Zhenghao DENG Heming WANG Guoli ZHANG Man MA Jun LI Jin YE Qizheng HU Hui State Key Laboratory of Advanced Electromagnetic Engineering and Technology （Huazhong University of Science and Technology） Research Institute of China Southern Power Grid Co. Ltd. Guangzhou Branch EHV Power Transmission Company China Southern Power Grid

随着放电等离子体在各个领域应用的不断扩大，两相体放电问题越来越重要，需要解决的基础问题之一即是两相体中放电发生、发展的特点和规律及影响因素。采用21种不同的介质材料研究直流电压下两相体放电的效应，由实验结果可知介质的介... 详细信息

随着放电等离子体在各个领域应用的不断扩大，两相体放电问题越来越重要，需要解决的基础问题之一即是两相体中放电发生、发展的特点和规律及影响因素。采用21种不同的介质材料研究直流电压下两相体放电的效应，由实验结果可知介质的介电常数对放电路径基本无影响，而介质颗粒的粒径大小对两相体放电路径的选择起决定作用，即粒径效应。此外，对颗粒介电常数、电场畸变、光电离作用和颗粒荷电等几个方面进行研究，可知两相体放电的粒径效应与颗粒粒径大小紧密相关。

关键词：两相混合物粒子大小直流电压宏观放电高压输电线路排放法规外部绝缘

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DISCHARGE CHARACTERISTIC TESTS UNDER SALTY AND ACIDITY HAZE SIMULATING CONDITIONS

DISCHARGE CHARACTERISTIC TESTS UNDER SALTY AND ACIDITY HAZE ...

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The ⅪⅩ International Conference on Gas Discharges and Their Applications

作者： CHEN WEIMIN HE ZHENGHAO WANG GUOLI MA JUN ZHANG XIAOFEI XU TAISHENG ZHAO HUAN LIU QINGYING State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science and Technology) Research Institute of China Southern Power Grid Co.Ltd.

ISBN: (纸本)9771003651221

The research on electric discharge characteristic in haze is *** may be conducive to improve the high voltage transmission line insulation design and *** paper presents recent research work of discharge characteristic tests under the haze conditions simulated in salty or *** rode-plane gap breakdown and flashover along insulator string surface are involved in the *** show that the discharge voltage is different while the concentration in salty or acidity is *** discharge has its own performance when the condition is in salty and in acidity respectively. Another important phenomenon deduce from the results is that the lowest discharge voltage in simulating haze is no obviously difference between rode-gap and insulator string while the equivalent distance are *** implies that the worst haze may cause discharge directly in space path and not along the surface of the insulator *** may lead to trip the line and the system. Some more research work is expected to do further.

关键词： DISCHARGE CHARACTERISTIC TESTS UNDER SALTY AND ACIDITY HAZE SIMULATING CONDITIONS

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