检索结果-内蒙古大学图书馆

作者： Yu, Zhanqing Li, Qian Zeng, Rong He, Jinliang Zhang, Yong Li, Zhizhao Zhuang, Chijie Liao, Yongli State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Department of Mathematical Sciences Tsinghua University Beijing 100084 China Electric Power Research Institute China Southern Power Grid Guangzhou China

Lightning is the major cause of interruptions in power transmission lines. Ultra-high voltage (UHV) AC transmission line has been put into operation in China. Due to the large tower height up to 90 m and the high operation voltage up to 1000 kV, the shielding failure probability increase obviously. Nowadays the leader progression model is an advanced method to evaluate the shielding failure probability of transmission lines. The surface electric field is the key issue for lightning failure analyzing, because the upward leader inception mainly depends on the surface electric field. In this paper, the lightning leader model is introduced. A charge simulation method based piecewise linear function is adopted to analyze the surface electric field on phase conductors and ground wires. The influence factors, such as operation voltage, lightning peak current, lightning down leader position, protection angle, on surface electric field were analyzed. © 2012 Elsevier B.V. All rights reserved.

关键词： Electric lines

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Ultra-short-term solar power forecasting based on a modified clear sky model

Ultra-short-term solar power forecasting based on a modified...

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Chinese control Conference (CCC)

作者： Yuan Ma Xuemin Zhang Shengwei Mei Zhao Zhen Rui Gao Zijie Zhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9789881563903

ISBN: (纸本)9781728165233

The ultra-short-term prediction of photovoltaic power system is of great significance to the safe operation of power system. However, the daily and annual periodicity of solar radiation brings strong non-stationary to the photovoltaic power series, which makes it difficult to predict the photovoltaic power series. In order to overcome the problem that the detailed clear sky model relies on a large number of plant parameters, this paper proposes a prediction algorithm based on a modified clear sky model. Firstly, historical data and geographical location of a certain site are utilized to build a modified clear sky model, then the theoretical clear sky power curve fitted by the modified clear sky model are divided by the actual historical power output to get a stabilized time series, finally the method of "online update" is adopted to forecast PV plant power output in the ultra-short-term time horizon (0-4 h). The test results of a photovoltaic power station in Ningxia show that the proposed model can reduce the prediction error of the 4th hour to about 3%.

关键词： Photovoltaic systems Predictive models Data models Mathematical model Forecasting

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Numerical Analysis of Space Charge Characteristics in Low-density Polyethylene Nanocomposite under External DC Electric Field

Numerical Analysis of Space Charge Characteristics in Low-de...

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中国物理学会第十八届全国静电学术会议

作者： ZHOU Yuanxiang ZHANG Ling SHA Yanchao TIAN Jihuan State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University ABB (China) Limited Universal

In this work, we are interested in space charge dynamics characteristics in the low-density polyethylene(LDPE) nanocomposite mixed with some mass fraction of inorganic nanofillers. Different with all previous qualitatively theoretical works, numerical simulation based on the bipolar charge transport model was performed to systematically investigate the influence of trap depth, trap concentration, and injection barrier height on the space charge and electric field distributions under DC external electric field of 100 k V/mm. Our simulation results showed that increasing the trap depth would severely distort the electric field distribution at the balanced status with the highest and lowest electric field of 119 k V/mm and 47 k V/mm, respectively. Due to the introduction of nanofillers, more deep traps were created and blocked the space charge movement, capturing most of space charge in the vicinity of the electrode and largely declining the local electric field further. In addition, our theoretical analysis also showed both the high permittivity and low local electric field contributed to the increase of injection barrier height. Once the injection barrier height surpassed 1.25 e V, there was almost no charge that could overcome the injection barrier. At last, a mechanism of space charge suppression in the LDPE nanocomposite was presented.

关键词： LDPE nanocomposite space charge bipolar charge transport model trap depth Schottkyinjection barrier height

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Optimal power and energy sizing of compressed air energy storage in distribution network using multiparametric programming 5

Optimal power and energy sizing of compressed air energy sto...

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5th International Conference on Energy Engineering and Environmental Protection, EEEP 2020

作者： Chen, Fan Guo, Zhongjie Lin, Qiyou Xue, Xiaodai Xie, Yuguang Mei, Shengwei State Grid Anhui Electric Power Research Institute Hefei230601 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China State Grid Wuhu Electric Power Supply Company Wuhu241027 China

As a new type of mechanical energy storage, compressed air energy storage (CAES) has attracted wide attention in recent years. This paper studies the optimal sizing problem of CAES in power distribution network (PDN). CAES plays a role in shaving the peak and filling the valley at demand side and thus reduces the operation cost of PDN to purchase electricity from the main grid. A multi-parametric linear programming (MP-LP) model is formulated where the power and energy capacities of CAES are regarded as parameters;the parameterized optimal value function (OVF) provides a graphical tool to describe the impact on operation cost of CAES configuration, which helps determine the planning strategy in a visual manner. The visualized results reveal not only the optimal solution, but also some useful information, like the sensitivity of operation cost to parameters. Case studies conducted on the IEEE 33-bus distribution system verifies the effectiveness of the proposed method. © Published under licence by IOP Publishing Ltd.

关键词： Linear programming

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Study on High Impedance Grounding Fault Protection for Personal Safety Guard in Distribution Grid

Study on High Impedance Grounding Fault Protection for Perso...

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International Conference on Advanced power system Automation and Protection (APAP)

作者： Kun Liu Xin Cui Bin Wang Xinzhou Dong Dispatching and Controlling Center of Guangdong Power Grid Key Lab for Power System Protective Relaying Real Time Digital Simulation of Guangdong Power Grid Guangzhou China Tsinghua University Key Lab of Control and Simulation of Power Systems and Generation Equipment Beijing China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

In recent years, human electric shock accident caused by line fault of distribution system has happened all over the world. This kind of problem of high resistance grounding fault safety is becoming more and more the attention of the researchers. In this paper, typical arc high resistance grounding fault model is established to simulate the human electric shock accident and the line fell to the ground condition. The transient- state and steady-state fault characteristics of high resistance grounding fault are analyzed in the neutral point grounded through a small resistance grounding system and the resonant grounding system. The above analysis has laid a good foundation for the establishment of an effective fault detection method for high resistance grounding and the realization of human electric shock protection.

关键词： Grounding Immune system Resistance Harmonic analysis Transient analysis Electric shock Steady-state

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Optimal Allocation Strategy of Frequency Modulation power for Multiple Energy Storage systems Considering Dual Constraints of Frequency Modulation Cost and Frequency Modulation Capability

Optimal Allocation Strategy of Frequency Modulation Power fo...

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power Science and Technology (ICPST), IEEE International Conference on

作者： Yongming Peng Wenbo Si Haiji Zhao Changlin Lv Chengzhe Liu Fei Xu Ling Hao Junhui Li Northeast Branch of State Grid Corporation of China Shenyang China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education (Northeast Electric Power University) Jilin China State Key Laboratory of Power System and Power Generation Equipment Control and Simulation (Tsinghua University) Beijing China

Aiming at the power allocation problem of multiple energy storage power stations distributed at different locations in the regional power grid participating in frequency modulation services, a frequency modulation power optimization allocation strategy for multiple energy storage systems considering the dual constraints of frequency modulation cost and frequency modulation capability is proposed. Firstly, a multi-objective optimization allocation model for frequency modulation power is constructed with the minimum frequency modulation cost and minimum deviation of the state of charge (SOC) for energy storage power plants. Secondly, using Pareto based multi-objective genetic algorithm (MOGA) to solve the model, introduce adaptive weight coefficients and fuzzy membership functions for each objective function regarding the frequency regulation demand of the power grid and the deviation of the SOC of energy storage stations, construct a comprehensive satisfaction function to make decisions on the most advantageous points on the Pareto frontier, in order to obtain the optimal output of each energy storage station that can adapt to the frequency regulation requirements of the power grid. Finally, simulation analysis was conducted on the proposed strategy in this article, and the results showed that: The proposed strategy not only enhances the frequency regulation economy of the regional power grid, but also helps to restore the SOC of the energy storage power station.

关键词：

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Switching Current Imbalance Mitigation for Paralleled SiC MOSFETs Using Common-mode Choke in Gate Loop

Switching Current Imbalance Mitigation for Paralleled SiC MO...

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IEEE Energy Conversion Congress and Exposition

作者： Jiye Liu Zedong Zheng State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9781728158266

ISBN: (纸本)9781728158273

Paralleling SiC MOSFETs is a popular way to increase the current capacity. However, due to asymmetric layout, device parameter mismatch and other factors, imbalanced switching or dynamic current is observed among the paralleled switches in multi-device paralleling application which results in unequal switching loss, challenging the security and reliability of the system. In this paper, a common-mode choke in the gate loop is proposed and analyzed to suppress the imbalanced switching current induced by asymmetric layout in a half-bridge configuration with a Kelvin-source connection. The mechanism of the proposed method is comprehensively investigated to show that though the common-mode choke is placed in the gate loop, it can also mitigate the imbalanced current caused by asymmetric power loop. And it also shows that only the leakage inductance of the choke is seen in the gate loop and thus the switching speed is not expected to be influenced. The proposed method can be easily extended to multi-device paralleling application and the switching transients is hardly influenced by the common-mode choke. simulation and experimental results are presented to verify the proposed method.

关键词： Inductance MOSFET Silicon carbide Switches Logic gates Inductors Transient analysis

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Resistance Characteristics of Arc in Long Air Gap

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高电压技术 2013年第8期39卷 1881-1885页

作者： YU Zhanqing YU Junjie ZENG Rong CHEN He PENG Xiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Maintenance and Test Center of EHV Power Transmission Company China Southem Power Grid Co. Ltd. Guangzhou 510663 China

Arc resistance is an important parameter for characterizing long arcs in air, and its laboratory testing is of importance for accurate arc modeling of electromagnetic transient caused by short circuit fault. Therefore, we constructed an experimental system to study the cha- racteristics of long AC arc in air. Driven by currents of 10 kA or 40 kA (root mean square value), the system produces arcs with different initial lengths of 1 m, 2 m and 4 m, and the movement of the arcs are captured by a high-speed camera. After performing experiments using the system, we carried out analysis and comparisons of the arc resistance of arcs with different lengths and different currents, as well as a study of the relationship between the macro-morphology and the resistance of the arcs. Conclusions were drawn from the experimental re- sults: the arc voltage had obvious saturation characteristics; the arc resistance increased with the increase of arc length and the decrease of current; the arcs bended or extended significantly in time and the peak arc voltage within a single cycle increased correspondingly; the arcs had voltage and current in the same phase. In the end, a formula of arc resistance based on the experiment results is derived.

关键词：耐电弧性电阻特性空气间隙实验室测试电流驱动实验系统初始长度电弧电压

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Influence of annealing method on the space charge properties in polyethylene

Influence of annealing method on the space charge properties...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Ninghua Wang Yuanxiang Zhou Hongbin Liu Bin Gao Xidong Liang Zhicheng Guan T. Takada State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Electronic Measurement Laboratory Musashi Institute of Technology Tokyo Japan

In this paper, high-density polyethylene (HDPE) films were prepared by three kinds of annealing methods which were different in cooling speed. The crystallinity of those HDPE samples were measured and compared. A high DC voltage was applied to the samples and the space charge formed was measured. Homo-charges were found in samples that were applied with a negative high voltage. The space charge properties were discussed, based on crystallinity. From these results, it is found that the space charge formed in samples cooled at high speed is more than that of the samples cooled at normal and low speed.

关键词： Annealing Space charge Polyethylene Voltage Current measurement Charge measurement Conducting materials Crystallization Morphology laboratories

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Implementation of non-communication protection of double circuit line systems based on integrated protection platform

Implementation of non-communication protection of double cir...

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2011 International Conference on Advanced power system Automation and Protection, APAP 2011

作者： Hu, Xi Dong, Xinzhou Wang, Bin Shi, Shenxing Liu, Kun Li, Youyi State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Research Ltd. Chaoyang District Beijing 100016 China

ISBN: (纸本)9781424496198

The implementation of non-communication protection of double circuit line systems based on two independent relays has disadvantages like information shareless,complex connection and lack of economic. This paper researched the implementation of non-communication protection of double circuit line systems based on one relay - the integrated protection platform. Hardware structure of the integrated protection platform is described, and software flow of non-communication protection of double circuit line systems which implemented on the integrated protection platform is also described. Large number of RTDS experiments proved that, according to various asymmetrical fault and symmetrical fault, this protection scheme has reliable and sensitive action performance. It is proved that the implement non-communication protection of double circuit line systems based on the intergrated protection platform is feasible. © 2011 IEEE.

关键词： Timing circuits

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