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Mitigation of electrical treeing at high temperature in nano-SiO_(2) doped epoxy resin

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High Voltage 2023年第3期8卷 640-649页

作者： Yuanyuan Li Yang Yang Shuangshuang Yan Zhipeng Lei Meiqing Guo shanxi key laboratory of mining electrical equipment and intelligent control College of Electrical and Power EngineeringTaiyuan University of TechnologyTaiyuanShanxiChina Simpson Querrey Institute for BioNanotechnology Northwestern UniversityEvanstonIllinoisUSA State Grid shanxi Electric Power Company Jinzhong Power Supply Company JinzhongShanxiChina College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuanShanxiChina

In this work,electrical tree inception and ageing experiments were conducted to investigate the initiation,growth characteristics and structural characteristics of electrical trees of nano-SiO_(2) doped epoxy resin at different *** tree inception and ageing experiments were conducted using power frequency voltage of 15 kV at 20,40,60,80 and 100℃.electrical breakdown properties of epoxy resin were investigated by applying AC and DC voltages at 20,40,80 and 120℃.There are two major observations based on the experimental *** the increase of temperature,the morphological structure of the electrical trees changes from dendritic to plexiform,the tree inception voltage decreases and the growth rate of the electrical trees increases *** under DC or AC voltage,the breakdown strength of the nano-SiO_(2) doped epoxy resin decreases as the temperature ***,based on the space charge and the trap level measurement,the mechanism of the electrical tree propagation and breakdown in nano-SiO_(2) doped epoxy resin was analysed.

关键词： resin electrical strength

Effects of ambient humidity and thermal aging on properties of Nomex insulation in mining dry‐type transformer

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High Voltage 2021年第1期6卷 71-81页

作者： Lu Li Jiancheng Song Zhipeng Lei Ailiang Kang Zhengyu Wang Rujia Men Yun Ma shanxi key laboratory of mining electrical equipment and intelligent control College of Electrical and Power EngineeringTaiyuan University of TechnologyTaiyuan ShanxiChina Zhengzhou Power Supply Company State Grid Henan Electric Power CompanyZhengzhou HenanChina Jinzhong Power Supply Company State Grid Shanxi Electric Power CompanyJinzhong ShanxiChina

Temperature and humidity are the main factors that cause the decomposition of Nomex paper widely used as turn‐to‐turn insulation material of mining dry‐type transformers. In this study, for understanding the effect of ambient humidity and thermal aging on the properties of Nomex paper, specimens with the initial moisture content of 7% were aged in the oven for 168, 504, 672 h at 180°C, respectively. After thermal aging, corona discharge experiments of unaged and aged specimens with different aging degrees were carried out at different relative humidity (RH) levels from 10 to 70%. The characteristic parameters of corona discharge, such as the average discharge amplitude and the number of discharges, were measured. Then, the surface conductivity and the surface potential decay rate were measured. The morphology and attenuated total internal reflectance Fourier transform infrared spectroscopy were also analysed for explaining the difference of properties be-tween unaged and aged specimens. The experiment results indicate that the average discharge amplitude decreases with the increase of RH or the deepening of the aging degree of specimens, but the number of discharges shows the reversal tendency. The changes in the physical structure and chemical composition, which is induced by the hydrolysis reaction of Nomex paper, accelerate the surface potential decay and increase the surface conductivity.

关键词： aging thermal humidity

Development and pattern identification of end-winding discharge under effect of relative humidity and temperature for HV motors

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High Voltage 2020年第4期5卷 434-443页

作者： Ailiang Kang Muqin Tian Chuanyang Li Jiancheng Song Simone Vincenzo Suraci Wei Li Lingyan Lin Zhipeng Lei Davide Fabiani shanxi key laboratory of mining electrical equipment and intelligent control College of Electrical and Power EngineeringTaiyuan University of TechnologyTaiyuan 030024People's Republic of China Department of electrical Electronicand Information Engineering‘Guglielmo Marconi’University of BolognaViale Risorgimento 2Bologna 40136Italy

During operation of high voltage(HV)motors,different types of discharges,*** discharge,corona discharge and bar-to-bar discharge can occur at the same time,increasing the difficulty of partial discharge(PD)sources determination and PDs pattern *** this study,the end-winding of a 10 kV motor coil was artificially aged and the related PD was *** initiation and variation of different PDs under multi-factor stresses were *** localised fingerprints coexisting with multiple PDs were identified and *** results confirm that the end-winding discharge process was significantly influenced by the experiment relative humidity(RH)and *** bar-to-bar discharge was easily recognised at a lower voltage since the identification of bar-to-bar discharge pattern would be affected by the corona discharge pattern at a higher *** is shown that it is more difficult for the corona discharge to be detected when RH exceeded 80%,while the surface discharge dominated at the higher *** addition,the PDs were more easily identified with the rise of the *** study can provide a reference in PD identification test and be useful for the PD online monitoring of HV motors.

关键词： temperature difficulty effect

3D velocity field reconstruction of gas-liquid two-phase flow based on space-time multi-scale binocular-PIV technology

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Optoelectronics Letters 2022年第10期18卷 613-617页

作者： WANG Hongyi DOU Gongcheng ZHANG Hao ZHU Xinjun SONG Limei Tianjin key laboratory of intelligent control of electrical equipment School of Artificial IntelligenceTiangong UniversityTianjin300387China Tianjin key laboratory of intelligent control of electrical equipment School of Control Science and EngineeringTiangong UniversityTianjin300387China

For particle image velocimetry(PIV) technique, the two-dimensional(2D) PIV by one camera can only obtain 2D velocity field, while three-dimensional(3D) PIV based on tomography by three or four cameras is always complex and expensive. In this work, a binocular-PIV technology based on two cameras was proposed to reconstruct the 3D velocity field of gas-liquid two-phase flow, which is a combination of the binocular stereo vision and cross-correlation based on fast Fourier transform(CC-FFT). The depth of particle was calculated by binocular stereo vision on space scale, and the plane displacement of particles was acquired by CC-FFT on time scale. Experimental results have proved the effectiveness of the proposed method in 3D reconstruction of velocity field for gas-liquid two-phase flow.

关键词： flow flow phase

Radar false alarm plots elimination based on multi-feature extraction and classification

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The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 83-92页

作者： Cheng Yi Zhao Yan Yin Peiwen School of control Science and Engineering Tiangong UniversityTianjin 300387China Tianjin key laboratory of intelligent control of electrical equipment Tianjin 300387China

Caused by the environment clutter,the radar false alarm plots are *** false alarm points has always been a key issue in Radar plots *** this paper,a radar false alarm plots elimination method based on multi-feature extraction and classification is proposed to effectively eliminate false alarm ***,the density based spatial clustering of applications with noise(DBSCAN)algorithm is used to cluster the radar echo data processed by constant false-alarm rate(CFAR).The multi-features including the scale features,time domain features and transform domain features are ***,a feature evaluation method combining pearson correlation coefficient(PCC)and entropy weight method(EWM)is proposed to evaluate interrelation among features,effective feature combination sets are selected as inputs of the ***,False alarm plots classified as clutters are *** experimental results show that proposed method can eliminate about 90%false alarm plots with less target loss rate.

关键词： radar plots elimination density based spatial clustering of applications with noise multi-feature extraction classifier

Significant enhancement in the electrical conductance properties of ethylene propylene diene monomer using the nano‐SiO_(2) particles

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High Voltage 2021年第3期6卷 487-494页

作者： Chunyu Xu Ruixue Zhao Chuanyang Li Yuanyuan Li Guodong Zhang Tohid Shahsavarian Mengqiang Yuan Zhipeng Lei shanxi key laboratory of mining electrical equipment and intelligent control College of Electrical and Power EngineeringTaiyuan University of TechnologyTaiyuanChina electrical and Computer Engineering University of ConnecticutStorrsConnecticutUSA State Grid Jincheng Power Supply Company JinchengChina shanxi Jincheng Anthracite mining Group Co. LtdJinchengChina School of electrical Engineering Shandong UniversityJinanChina

To study the effect of nano‐silica particles on the conductivity characteristics of ethylene propylene diene monomer(EPDM)insulation,EPDM nanocomposites with different mass fractions of nano silica were prepared via the melt‐blending *** electron microscopy was used to analyze the dispersion of nanoparticles in *** on the Fourier‐transform infrared spectrum,the bonding properties between the nanoparticles and EPDM were *** steady‐state current at 30-100°C and 1-20 kV/mm was ***,the conductivity characteristic was *** experimental results show that as the content of nano‐silica increases,the electrical conductivity of EPDM nanocomposite as well as the threshold field strength gradually *** with a small number of nanoparticles will increase the activation energy of the carrier conductivity,and the interface region effect introduced by nanoparticles will reduce the carrier mobility and concentration,resulting in a lower *** the calculated value of the dielectric constant with the measured value can conclude that the high‐field conductance process is a combination of the electrode effect and the body effect,which in this case,Schottky effect dominates.

关键词： propylene conductivity conductance

Integrated generation–consumption dispatch based on compensation mechanism considering demand response behavior

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Journal of Modern Power Systems and Clean Energy 2018年第5期6卷 1025-1041页

作者： Yumin ZHANG Xueshan HAN Li ZHANG Bo XU Mingqiang WANG Ming YANG key laboratory of Power System intelligent Dispatch and control of Ministry of Education Shandong University State key laboratory of control and Simulation of Power Systems and Generation equipment Department of Electrical Engineering Tsinghua University

Demand response(DR) is important to account for behaviors of the demand side to yield an optimal dispatch result. However, it is difficult for energy suppliers to collect customers' private information unless there is an incentive mechanism for customers to do so. Therefore,this paper proposes a new integrated generation–consumption dispatch based on compensation mechanism considering DR behavior. Firstly, in light of the dayahead load forecast data, we deduce the utility function model of different customers. By subtracting generating units' operation cost from consumers' total utility, the dispatch model has a decentralized demand participant structure based on this utility function. The utility function is used to describe consumers' preferences and energy consumption behaviors. Secondly, an effective compensation mechanism is designed to ensure customers to select the level of compensation appropriate to their willingness to curtail load. Finally, a new dispatch model is proposed that incorporates the DR compensation mechanism into the generation–consumption dispatch model. The new model can improve the interaction of generation and consumption,and benefit both the energy supplier and its customers. The proposed model is piecewise linearized and solved by a mixed-integer linear programming method. It is tested on a six-bus system and the IEEE 118-bus system. Simulation results show that the proposed model can realize both maximum social welfare and Pareto optimal results.

关键词： Compensation mechanism Demand response Demand utility function Integrated generation– consumption dispatch

Free-matrix-based time-dependent discontinuous Lyapunov functional for synchronization of delayed neural networks with sampled-data control

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Chinese Physics B 2017年第11期26卷 127-134页

作者：王炜曾红兵 Kok-Lay Teo School of electrical and Information Engineering Hunan University of Technology key laboratory for Electric Drive control and intelligent equipment of Hunan Province Department of Mathematics and Statistics Curtin University

This paper is concerned with the synchronization of delayed neural networks via sampled-data control. A new technique, namely, the free-matrix-based time-dependent discontinuous Lyapunov functional approach, is adopted in constructing the Lyapunov functional, which takes advantage of the sampling characteristic of sawtooth input delay. Based on this discontinuous Lyapunov functional, some less conservative synchronization criteria are established to ensure that the slave system is synchronous with the master system. The desired sampled-data controller can be obtained through the use of the linear matrix inequality（LMI） technique. Finally, two numerical examples are provided to demonstrate the effectiveness and the improvements of the proposed methods.

关键词： neural networks synchronization sampled-data control free-matrix-based inequality

Stability Analysis of Systems With Time-varying Delay via a Novel Lyapunov Functional

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IEEE/CAA Journal of Automatica Sinica 2019年第4期6卷 1068-1073页

作者： Yun Chen Gang Chen the School of electrical and Information Engineering Hunan University of TechnologyZhuzhou 412007 the key laboratory for Electric Drive control and intelligent equipment of Hunan Province Zhuzhou 412007China

This paper investigates the stability problem for time-varying delay *** obtain a larger delay bound,this paper uses the second-order canonical Bessel-Legendre(BL)***,using four couples of integral terms in the augmented Lyapunov-Krasovskii function(LKF)to enhance the relationship between integral functionals and other ***,unlike the construction of the traditional LKF,a novel augmented LKF is constructed with two new delayproduct-type terms,which adds more state information and leads to less conservative ***,two numerical examples are provided to demonstrate the effectiveness and the significant improvement of the proposed stability criteria.

关键词： Integral inequality Lyapunov theorem stability time-delay systems