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arXiv 2017年

作者： Peng, Shuitao Wang, Lu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan Hubei430074 China

Intrinsic flow in plasma physics is a long-standing puzzle, since it is difficult to understand its origin without contradiction to momentum conservation in conventional wisdom. It is proved that the electromagnetic turbulent acceleration as a candidate for intrinsic parallel flow generation driven by pressure gradient along the total magnetic field line does not contradict momentum conservation. The conserved quantity corresponding to axial symmetry is the total gyrocenter parallel canonical momentum carried by both species or the total gyrocenter parallel momentum including the ion gyrocenter kinematic momentum and electromagnetic fields momentum, but not the ion kinematic momentum, or even the ion parallel flow. A conservation equation of total parallel momentum including the ion particles' kinematic momentum and electromagnetic fields momentum is also presented. Copyright © 2017, The Authors. All rights reserved.

关键词： Momentum

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Research progresses of cathodic hydrogen evolution in advanced lead–acid batteries

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Science Bulletin 2016年第6期61卷 451-458页

作者： Feng Wang Chen Hu Min Zhou Kangli Wang Jiali Lian Jie Yan Shijie Cheng Kai Jiang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074 China China Electric Power Research Institute Beijing 100192 China

Integrating high content carbon into the negative electrodes of advanced lead–acid batteries effectively eliminates the sulfation and improves the cycle life,but brings the problem of hydrogen evolution,which increases inner pressure and accelerates the water *** this review,the mechanism of hydrogen evolution reaction in advanced lead–acid batteries,including lead–carbon battery and ultrabattery,is briefly *** strategies on suppression hydrogen evolution via structure modifications of carbon materials and adding hydrogen evolution inhibitors are summarized as *** review points out effective ways to inhibit hydrogen evolution and prolong the cycling life of advanced lead–acid battery,especially in high-rate partial-state-of-charge applications.

关键词： Lead–carbon battery Ultrabattery Hydrogen evolution reaction Hydrogen inhibition

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Short-Circuit Current of Grid-Connected Voltage Source Converters: Multi-Timescale Analysis Method

Short-Circuit Current of Grid-Connected Voltage Source Conve...

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IEEE Power and Energy Society General Meeting

作者： Wangqianyun Tang Jiabing Hu Yuanzhu Chang Xiangping Kong State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Jiangsu Electric Power Company Research Institute

ISBN: (纸本)9781538622131;9781538622124

Grid-connected voltage-source converters (VSCs) exhibit very different short-circuit behaviors from synchronous generators (SGs). This paper analyzes the short-circuit current (SCC) of VSC, especially considering the typical vector control strategy and the transient control scheme during grid fault. The SCC characteristics are obtained in multi-timescale, including both AC current control and DC voltage control timescales. Further, a simple SCC expression is obtained similar to the sub-transient and transient processes of traditional SG. In addition, the influences of different controllers' parameters and fault degree on the SCC characteristics are discussed. The analytical results are helpful to understand the stress distribution of power electronics devices and design of relay protection in power systems with high penetration of wind/solar power generations that are integrated into grid via VSCs.

关键词： Voltage control Transient analysis Power conversion Circuit faults Current control

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Anisotropy on electrical insulation performance of 3D printed nylon 12

Anisotropy on electrical insulation performance of 3D printe...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Zijian Li Hua Li Jiandong Rao Chunze Yan Li Li Fuchang Lin Yi Liu Yuan Pan State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan P. R. China

ISBN: (纸本)9781538611951

3D printing (3DP) is developing rapidly and has been highly technology maturation, which has broad application prospects in making complex insulation structures which require special pre-designed electric field in uniform or uneven distribution. But the properties of the 3DP material are dependent with the anisotropic intrinsic, which is caused by the lamination manufacturing process. In this paper, the influences of traditional injection molding process (TIMP) and 3DP technology on physical and electrical properties are investigated by using 1mm Nylon12. In the 3DP process, the thickness of the individual laminated layer is 0.1mm. And in order to study the anisotropy of 3DP process, the printing direction is set to be in perpendicular (90°) and parallel (0°) to the electric field direction (thickness direction). The physical and electrical insulation performance, such as density, dc and ac breakdown strength and volume resistivity are studied by using Nylon 12 made by TIMP and 3DP of 0°and 90°. Experimental results indicate that the breakdown electric field and volume resistivity of TIMP is much higher than 3DP materials; under high frequency, the permittivity of 3DP and TIMP is similar, however, under low frequency, the permittivity of 3DP materials is higher than TIMP. Under different printing angles, the volume resistivity and breakdown electric field in the direction of 90° is higher than that in the direction of 0°. The reason for the difference between 3DP and TIMP samples is that there is a gap between layers which results in the decrease of performance. Meanwhile, the equivalent parameters of different direction samples change, resulting in anisotropy of electrical properties.

关键词： Shape Permittivity Three-dimensional printing Laser sintering Three-dimensional displays Dielectrics Topology

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PV-based virtual synchronous generator with variable inertia to enhance power system transient stability utilizing the energy storage system

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Protection and Control of Modern Power Systems 2017年第1期2卷 428-435页

作者： Ju Liu Dongjun Yang Wei Yao Rengcun Fang Hongsheng Zhao Bo Wang State Grid Hubei Economic Research Institute WuhanChina State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhanChina.

The Photovoltaic(PV)plants are significantly different from the conventional synchronous generators in terms of physical and electrical characteristics,as it connects to the power grid through the voltage-source *** penetration PV in power system will bring several critical challenges to the safe operation of power grid including transient *** address this problem,the paper proposes a control strategy to help the PVs work like a synchronous generator with variable inertia by energy storage system(ESS).First,the overall control strategy of the PV-based virtual synchronous generator(PV-VSG)is *** the control strategies for the variable inertia of the PV-VSG are designed to attenuate the transient energy of the power system after the *** results of a simple power system show that the PV-VSG could utilize the energy preserved in the ESS to balance the transient energy variation of power grid after fault and improve the transient stability of the power system.

关键词： Energy storage system Virtual synchronous generator Variable inertia Transient stability Photovoltaic power

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Observation of non-local effects in ion transport channel in J-TEXT plasmas

arXiv

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arXiv 2018年

作者： Shi, Yuejiang Yang, Zhoujun Chen, Zhongyong Cheng, Zhifeng Zhang, Xiaoyi Yan, Wei Wen, Jie Cai, Qinxue Zhao, Kaijun Hong, Seulchan Kwon, JaeMin Diamond, Partick H. Shi, Peng Zhou, Hao Pan, Xiaoming Chen, Zhipeng Yang, SeongMoo Dong, Yunbo Wang, Lu Ding, YongHua Liang, Yunfeng Shi, Zhongbin Na, Yong-Su Department of Nuclear Engineering Seoul National University Seoul Korea Republic of International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China College of Nuclear Science and Engineer East China University of Technology Nanchang China National Fusion Research Institute Daejeon Korea Republic of Southwestern Institute of Physics Chengdu China CMTFO and CASS University of California San Diego United States Jülich Germany

In cold pulse experiments in J-TEXT, the ion transport shows similar non-local response as the electron transport channel. Very fast ion temperatures decreases are observed in the edge, while the ion temperature in core promptly begin to rise after the injection of cold pulse. Moreover, the cutoff density is also found for the ion non-local effect. The experimental observed density fluctuation in a high frequency ranging from 500 kHz to 2 MHz is obviously reduced in the whole plasma region during non-local transport (NLT) phase. Copyright © 2018, The Authors. All rights reserved.

关键词： Electron transport properties

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Accuracy improvement of remaining capacity estimation for energy storage batteries

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The Journal of engineering 2017年第13期2017卷 1833-1837页

作者： Cheng Xu Guo'an Liu Kangli Wang School of Electrical and Electronic Engineering State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan Hubei Province People's Republic of China

Scheduling lithium-ion batteries for energy storage applications in power systems requires accurate estimation of their remaining capacity. Due to the varying discharge rate during a cycle caused by complex operating conditions, conventional estimation methods suffer greatly from poor estimation accuracy. Therefore, this study proposes an improved Ah-counting method for remaining capacity estimation, in which a neural network-based model is introduced to consider the rate capability of batteries. Moreover, to avoid the inherent error caused by Ah-counting, a straightforward method is applied to the estimation. Simulations show that the estimation accuracy can be effectively improved by the proposed method.

关键词： secondary cells lithium compounds power engineering computing neural nets accuracy improvement capacity estimation energy storage batteries energy storage applications power systems complex operating conditions Ah-counting method discharge rate neural network-based model Li

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The Reliability Evaluation Method of Generation System Based on the Importance Sampling Method and States Clustering

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Energy Procedia 2017年 118卷 128-135页

作者： Sheng Zhong Tianmeng Yang Yaowu Wu Suhua Lou Taijun Li Central Southern China Electric Power Design Institute Wuhan 430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China

To improve the reliability evaluation efficiency of large scale power system, an efficient reliability evaluation method of generation system is proposed in this paper. It can improve the calculation efficiency both in the sampling method and states evaluation. Firstly, the importance sampling method is used to replace the conventional Monte Carlo sampling method, which can accelerate the convergence speed of iteration calculation. Secondly, the states clustering method is proposed to get several typical generating states to replace all sampling states, which can improve the calculation speed. Finally, the simulations based on the IEEE RTS-79 generating system and the actual power system are carried out, and the efficiency and accuracy of this evaluation method in this paper are verified.

关键词： Monte Carlo simulation importance sampling method reliability evaluation method states clustering

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Low-Voltage Analysis of Distribution Network Software Design and Application

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Energy and Power engineering 2017年第4期9卷 183-188页

作者： Mingqiu Du Yan Li Chunfang Liu Tangjie Liang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Foshan Electric Power Design Institute Co. Ltd. Foshan China

With the rapid development of urban economy, distribution network construction of city is lagging behind the increment of load, and low-voltage problem has become the main complaints of the power users. Based on Python [1] scripting language, this paper develops a piece of software which can provide a friendly human-machine experience for the user, calculate the voltage of the power distribution area and propose corresponding control measures, then the paper takes the actual power distribution area to verify its effectiveness.

关键词： Low-Voltage Analysis Distribution Network Python

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Generation method for the PV power time series combining the decomposition technique and Markov chain theory

Generation method for the PV power time series combining the...

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6th International Conference on Renewable Power Generation

作者： Xu, Shenzhi Ai, Xiaomeng Fang, Jiakun Wen, Jinyu Li, Pai Huang, Yuehui State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan Hubei Province430074 China Department of Energy Technology Aalborg University AalborgDK-9220 Denmark China Electric Power Research Institute State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems Beijing100192 China

Photovoltaic (PV) power generation has made considerable developments in recent years. However, its intermittent and volatility of its output have seriously affected the security operation of the power system. In order to better understand the PV generation and provide sufficient data support for analysis the impacts, a novel generation method for PV power time series combining decomposition technique and Markov chain theory is presented here. It digs important factors from historical data from existing PV plants and then reproduce new data with similar patterns. In detail, the proposed method first decomposes the PV power time series into ideal output curve, amplitude parameter series, and random fluctuating component three parts. Then generating daily ideal output curve by the extraction of typical daily data, amplitude parameter series based on the Markov chain Monte Carlo (MCMC) method, and random component based on random sampling, respectively. Finally, the generated three parts are recombined into new PV power time series by the decomposition formula. Data obtained from real-world PV plants in Gansu, China, validates the effectiveness of the proposed method. The generated series can simulate the basic statistical, distribution, and fluctuation characteristics of the measured series. © 2017 Institution of engineering and technology. All rights reserved.

关键词： Time series

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