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International Conference on Renewable power Generation, RPG 2015

作者： Li, Kangping Wang, Fei Zhen, Zhao Sun, Yujing Mi, Zengqiang Sun, Hongbin Liu, Chun Wang, Bo Lu, Jing State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Baoding Hebei Province071003 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China China Electric Power Research Institute Haidian District Beijing100192 China

ISBN: (纸本)9781785610400

Operating Statuses Identification (OSI) can help operators to find fault timely and minimize the loss. So it is of great significance for optimal operation of photovoltaic (PV) plants. The loss quantity of electricity (LQOE) is defined as that should have been generated but actually not, which is caused by inverter fault, PV modules fault, dust stratification or combinations of them. Firstly, mathematical models of PV cells are proposed to figure out the LQOE of each PV module. Secondly, after analysing the relation between LQOE and operating statuses, an index set of LQOE describing the distinction of different operating statuses are defined including four statistical feature parameters and a user-defined index. Thirdly, Support Vector Classification models for OSI (OSI-SVC) are built with input features extracted from the index set. Lastly, simulations are carried out to verify the effectiveness and evaluate the performance of the OSI-SVC models. The results indicated that the operating statuses can be effectively recognized by the proposed model.

关键词： Support vector machines

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Cloud identification model for sky images based on Otsu

Cloud identification model for sky images based on Otsu

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International Conference on Renewable power Generation, RPG 2015

作者： Li, Hongping Wang, Fei Ren, Hui Sun, Hongbin Liu, Chun Wang, Bo Lu, Jing Zhen, Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Baoding Hebei Province071003 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China China Electric Power Research Institute Haidian District Beijing100192 China

ISBN: (纸本)9781785610400

Irradiance changes caused by clouds movement are the mam factors, which lead to mutation of photovoltaic power. In order to increase the accuracy of the ultra-short-term photovoltaic power prediction, based on of clouds images, the cloud identification for sky images is one of the primary aspects for improving photovoltaic power accuracy. A cloud identification model for sky images is established based on Otsu. Firstly, a series of sky images are collected by Total Sky Imager (TSI) with the regions of clouds and sky are distinguished. Secondly, the color features (based on RGB values) of pixels in sample images and the spectral and texture features of the whole image are extracted;Finally, we established a cloud identification model for sky images based on Otsu according to the clouds' and sky areas' division and the general characteristics featured by pixels and images. The simulated results show that the model in this paper can identify the clouds in a sky images effectively.

关键词： Pixels

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Communication-less harmonic compensation in a multi-bus microgrid through autonomous control of distributed generation grid-interfacing converters

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Journal of Modern power systems and Clean Energy 2015年第4期3卷 597-609页

作者： Guangqian DING Ran WEI Ke ZHOU Feng GAO Yi TANG Key Laboratory of Power System Intelligent Dispatch and Control(Shandong University) Ministry of EducationJinan 250061China State Grid Jining Electric Power Supply Company Jining 272000China School of Electrical and Electronic Engineering Nanyang Technological University50 Nanyang AveSingapore 639798Singapore

This paper proposes a novel approach to compensate buses voltage and current harmonics through distributed generation(DG)interfacing converter in a multibus *** control approach of each individual DG unit was designed to use only feedback variables of the converter itself that can be measured *** the proposed approach,the adjacent bus voltage is indirectly derived from the measured DG converter output voltage,DG line current and line impedance.A voltage closed-loop controller and a current closed-loop controller are designed to achieve both functions of DG real power generation and harmonics ***,the traditional harmonic measurement devices installed at the bus as well as the long distance communication between the bus and the DG converter are not *** proposed approach can compensate the current harmonics,mitigate the buses voltage distortion and enable the customer devices to be operated in normal conditions within the multi-bus microgrid,and meanwhile relieve the burden of power quality regulator installed at the point of common *** simulations and experimental results are presented to show the operational effectiveness of the proposed approach.

关键词： Multi-bus microgrid Distributed generation Grid-tied converter Harmonic compensation control

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Analysis of Ant Colony Algorithm for Finding the Optimal Circuitous Route in the Communication Network of power system

Analysis of Ant Colony Algorithm for Finding the Optimal Cir...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Xin Chen Zhiqian Bo Xinzhou Dong Shenxing Shi State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781467371070

The communication network of power system is often damaged after a disaster. To solve this problem, this paper uses ant colony algorithm to find the optimal circuitous route. simulation results show that the method is fast, which can accelerate the recovery of the communication network. Besides, this paper does some research on the dead end problem, and analyses relationship between degree of adjacency and ratio of coming to a dead end. The result shows that the efficiency of ant colony algorithm can be improved only if it tries to avoid coming to dead ends.

关键词： ant colony algorithm circuitous route degree of adjacency dead end

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A novel method to improve low voltage ride-through capability of DFIG

A novel method to improve low voltage ride-through capabilit...

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International Conference on Renewable power Generation, RPG 2015

作者： Wang, Y. Guo, P. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources School of Control and Computer Engineering North China Electric Power University Beijing102206 China

ISBN: (纸本)9781785610400

In order to prevent wind turbines departing from the grid when the grid fault occurs, the Crowbar circuit of the doubly-fed induction generator (DFIG) is often used to improve low voltage ride-through (LVRT) capability. Based on the analysis of the traditional Crowbar protection circuit, a modified Crowbar protection circuit with resistance in series with the capacitor was proposed. The double-fed induction wind power generator (DFIG) with the modified Crowbar protection circuit was simulated on MATLAB/Simulink platform. Compared with the traditional Crowbar protection circuit with the resistance, the modified Crowbar protection circuit not only restrains the rotor over current, but also shortens the transition process of the rotor over current. The simulation results show that the modified Crowbar protection circuit is reasonable and improves the low voltage ride-through capacity of DFIG effectively.

关键词： Wind turbines

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Molecular dynamics simulations of coating process: Influences of thermostat methods

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Journal of Computational and Theoretical Nanoscience 2016年第7期13卷 4629-4633页

作者： Li, Qibin Peng, Xianghe Peng, Tiefeng Tang, Qizhong Liu, Chao Shi, Xiaoyang College of Aerospace Engineering Chongqing Key Laboratory of Heterogeneous Material Mechanics Chongqing University Chongqing400044 China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Chongqing400044 China Key Laboratory of Low-Grade Energy Utilization Technology and System Ministry of Education College of Power Engineering Chongqing University Chongqing400044 China Department of Earth and Environmental Engineering Columbia University New YorkNY10027 United States

Several thermostat methods, including Nose-Hoover method, Berendsen method, Langevin method and Velocity rescaling method are employed to investigate the coating process using molecular dynamics simulations. The coating system consists of Au atoms depositing onto Cu substrate. The temperature profiles of the particles indicate Nose-Hoover thermostat and Velocity rescaling method every 10,000 steps are not appropriate for constraining the temperature of the simulation system. The thermostat methods show little difference on the particles in the coherent layers. In addition, by the end of the simulation, the surface is found to be rougher in the simulations with Nose-Hoover method and Velocity rescaling method every 10,000 steps. © 2016 American Scientific Publishers All rights reserved.

关键词： Molecular dynamics

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Wind Turbine Fault Diagnosis system Based on A Fuzzy Expert system

Wind Turbine Fault Diagnosis System Based on A Fuzzy Expert ...

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2015 International power,Electronics and Materials Engineering Conference(IPEMEC 2015)

作者： Wenguang Yang Dongxiang Jiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal EngineeringTsinghua University

ISBN: (纸本)9781510806474

A fuzzy expert system which can simultaneously support many kinds of rules including fuzzy production rule,fault tree and decision tree in a unified framework are *** rete algorithm is adopted to speed up the fuzzy reasoning chain.A wind turbine diagnosis expert system is developed based on the fuzzy expert *** data is employed to verify the feasibility of the inference engine,and the results show that with proper knowledge imported the misdiagnosis rate is low,the inference process can be exported and the match degree of the health rule can be used as a health state indicator.

关键词： Wind turbine Fault diagnosis system Fuzzy expert system Fuzzy Rete algorithm

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Trends of Extreme Precipitation in Eastern China and Their Possible Causes

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Advances in Atmospheric Sciences 2015年第8期32卷 1027-1037页

作者： LIU Run LIU Shaw Chen Ralph J.CICERONE SHIU Chein-Jung LI Jun WANG Jingli ZHANG Yuanhang State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Research Center for Environmental Changes Academia Sinica Department of Atmospheric Science NCU National Academy of Sciences Earth System Science University of California Institute of Urban Meteorology of China Meteorological Administration

Significant increases of heavy precipitation and decreases of light precipitation have been reported over widespread regions of the globe. Global warming and effects of anthropogenic aerosols have both been proposed as possible causes of these changes. We examine data from urban and rural meteorological stations in eastern China （1955-2011） and compare them with Global Precipitation Climatology Project （GPCP） data （1979-2007） and reanalysis data in various latitude zones to study changes in precipitation extremes. Significant decreases in light precipitation and increases in heavy precipitation are found at both rural and urban stations, as well as low latitudes over the ocean, while total precipitation shows little change. Characteristics of these changes and changes in the equatorial zone and other latitudes suggest that global warming rather than aerosol effects is the primary cause of the changes. In eastern China, increases of annual total dry days （28 days） and ） 10 consecutive dry days （36%） are due to the decrease in light precipitation days, thereby establishing a causal link among global warming, changes in precipitation extremes, and higher meteorological risk of floods and droughts. Further, results derived from the GPCP data and reanalysis data suggest that the causal link exists over widespread regions of the globe.

关键词： extreme precipitation global warming aerosols meteorological risk of floods and droughts

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Stackelberg Game Model of Wind Farm and Electric Vehicle Battery Switch Station

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IOP Conference Series: Materials Science and Engineering 2017年第1期199卷

作者： Zhe Jiang Zhimin Li Wenbo Li Mingqiang Wang Mengxia Wang Department of Electrical Engineering Harbin Institute of Technology Harbin 150001 China. Electric Power Research Institute State Grid Shandong Electric Power Company Jinan 250003 China. Key Laboratory of Power System Intelligent Dispatch and Control Shandong University Jinan 250061 China. Collaborative Innovation Center for Global Energy Interconnection (Shandong) Jinan 250061 China.

In this paper, a cooperation method between wind farm and Electric vehicle battery switch station (EVBSS) was proposed. In the pursuit of maximizing their own benefits, the cooperation between wind farm and EVBSS was formulated as a Stackelberg game model by treating them as decision makers in different status. As the leader, wind farm will determine the charging/discharging price to induce the charging and discharging behavior of EVBSS reasonably. Through peak load shifting, wind farm could increase its profits by selling more wind power to the power grid during time interval with a higher purchase price. As the follower, EVBSS will charge or discharge according to the price determined by wind farm. Through optimizing the charging /discharging strategy, EVBSS will try to charge with a lower price and discharge with a higher price in order to increase its profits. Since the possible charging /discharging strategy of EVBSS is known, the wind farm will take the strategy into consideration while deciding the charging /discharging price, and will adjust the price accordingly to increase its profits. The case study proved that the proposed cooperation method and model were feasible and effective.

关键词：

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Fault analysis of VSC-HVDC system with saturated iron-core superconductive fault current limiter

Fault analysis of VSC-HVDC system with saturated iron-core s...

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International Conference on Applied Superconductivity and Electromagnetic Devices, ASEMD

作者： Bo Tong Li Jian Fei Jia Bin Li Yun Ke Zhang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

ISBN: (纸本)9781467381086

VSC-HVDC is one of the important development directions in smart grid. However, VSCs are vulnerable to dc-cable short-circuit faults due to the high discharge current from the dc-link capacitance. The huge current is a great threat to the capacitors and diodes. In order to limit the fault current to a relatively low level, the superconductive fault current limiter is introduced into the VSC-HVDC network and becomes an effective solution. The cardinal principle and electrical properties of SFCL are presented first. The transient process of the inter-pole short circuit fault in VSC-HVDC network with SFCL is analyzed. The effectiveness of SFCL is demonstrated through the comparison of fault current and voltage on network with and without SFCL. The correctness of the theoretical analysis is testified by simulation results in PSCAD/EMTDC.

关键词： Circuit faults Fault currents Inductance power conversion Fault current limiters Rails

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