检索结果-内蒙古大学图书馆

International Conference on Renewable power generation (RPG 2015)

作者： Yujing Sun Fei Wang Zengqiang Mi Hongbin Sun Chun Liu Bo Wang Jing Lu Zhao Zhen Kangping Li State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources North China Electric Power University Baoding Hebei China State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources Tsinghua University Beijing Haidian China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing Haidian China China Electric PowerResearch Institute Beijing Haidian China

ISBN: (纸本)9781510821415

To improve the prediction accuracy of photovoltaic (PV) power generation, the temperature of PV modules and its prediction is very important. A short-term step-wise temperature prediction model for PV module based on Support Vector Machine ( SVM) is proposed in this paper. Firstly, the primary impact factors of PV module temperature are determined in terms of the PV module physical characteristics and the correlation coefficient between each factor and module temperature. Secondly, two kinds of prediction models, direct and step-wise models, are built to predict module temperature respectively. For direct model, the prediction model is based on SVM using the historical data. For step-wise one, the prediction models of the primary impact factors are built at the first step and then the mapping models between module temperature and the impact factors are established. In the end, the deviations of two different kinds of prediction models are analy%ed and discussed based on actual operation data. The results indicate that the stepwise prediction model has better accuracy than the direct prediction model if other things are equal.

关键词： impact factor module temperature photovoltaic power forecasting step-wise prediction support vector machine

来源：评论

学校读者我要写书评

暂无评论

Reducing the impact of source internal resistance by source coil in resonant wireless power transfer

Reducing the impact of source internal resistance by source ...

引用

作者： Zhang, Yiming Lu, Ting Zhao, Zhengming State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781479956982

Wireless power transfer (WPT) is the state-of-the-art research interest. In the WPT system efficiency is an important figure of merit. In order to reduce the impact of the source internal resistance and improve the system efficiency of the conventional two-coil structure, a source coil is added to the two-coil structure, forming a three-coil structure. Both the two-coil structure and the three-coil structure are modeled and analyzed with the circuit theory. The system efficiencies of both structures with optimal loads and a fixed load are deduced. The system efficiency of the three-coil structure is proved to be higher than that of the two-coil structure. An experimental apparatus is implemented and the experimental results match well with the theoretical calculations. The larger the source internal resistance, the more significantly the addition of the source coil improves the system efficiency. © 2014 IEEE.

关键词： Energy transfer

来源：评论

学校读者我要写书评

暂无评论

power transmission mode to promote low-carbon development of load center

引用

Dianwang Jishu/power system Technology 2015年第3期39卷 663-668页

作者： Tian, Xin Sun, Yanlong Niu, Xinsheng Zhu, Xiubo Zhao, Guangfeng Shandong Power Economic Research Institute Shandong Electric Power Company Ji'nanShandong Province250001 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 Shandong Electric Power Company Ji'nanShandong Province250021 China

Regarding the power transmission mode from energy base to load center as the heart of the matter, a joint optimal operating model for both sending- and receiving- end power grids is established. In this model, the carbon emission is taken into the total system operation cost in the form of economic costs and taking the minimized total system operation cost as the objective the operation of the tie line and the generating unit in the receiving end power grid is scheduled. Based on the planning parameters for the power transmission from XilinGol League to Shandong, the case study on the application of the proposed model is performed and the results show that through reasonable power transmission mode the wind power accommodation space of the receiving end power grid can be fully utilized to accommodate the wind power generated in the sending power grid, thus the system operating cost is reduced while the low carbon development of power grid can be promoted effectively. ©, 2015, power system Technology Press. All right reserved.

关键词： Wind power

来源：评论

学校读者我要写书评

暂无评论

Electrical properties of oil-paper insulation affected by water conductivity during paper-making process

Electrical properties of oil-paper insulation affected by wa...

引用

32nd Electrical Insulation Conference, EIC 2014

作者： Huang, Jianwen Zhou, Yuanxiang Jin, Fubao Sha, Yanchao Zhang, Ling Le, Trung Hieu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781479927876

Developments of ultra-high voltage grid in China require better insulation materials, and that forces the transformer presspaper and pressboard manufactures to pay more attention to the papermaking process to enhance their product qualities. In this study, pure water and three kinds of sodium chloride solutions with conductivities of 100 μS/cm, 500 μS/cm and 1000 μS/cm were respectively used to prepare presspaper samples. By vacuum impregnation, four kinds of oil-paper samples were acquired. Test results showed that relative permittivity and tand of oil-paper specimens first varied little then increased a lot with the increasing of water conductivity;DC breakdown field decreased while AC breakdown field changed little. To confirm the differences were due to water conductivity, ion chromatography was used to determine the sodium and chloride ion contents of the presspaper samples, we found that the ion contents increased with electrical conductivity. This indicates that water conductivity does have effects on most electrical properties of oil-paper insulation and lower conductivity can bring better insulation performances. © 2014 IEEE.

关键词： Ion chromatography

来源：评论

学校读者我要写书评

暂无评论

Phase-shift control of isolated bidirectional DC-DC converters for unidirectional power flow

Phase-shift control of isolated bidirectional DC-DC converte...

引用

作者： Ge, Junjie Zhao, Zhengming Ma, Junchao He, Fanbo Yuan, Liqiang Lu, Ting State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781479956982

In the conventional phase-shift control of isolated bidirectional DC-DC converters, the phenomenon of power backflow is quite obvious. General improved phase-shift control methods can reduce the power backflow of the input. However, they do not take the power backflow of the output into consideration. In this paper, a novel phase-shift control of isolated bidirectional DC-DC converters for unidirectional power flow is proposed. It can eliminate the power backflows of both the input and the output at the same time. Furthermore, the converters in the proposed phase-shift control can achieve the zero-current switching in the whole power rang. Experimental results from a prototype verify the feasibility and validity of the proposed control method, and show superior performance. © 2014 IEEE.

关键词： Zero current switching

来源：评论

学校读者我要写书评

暂无评论

Series-connected HV-IGBTs using active voltage control with status feedback circuit

Series-connected HV-IGBTs using active voltage control with ...

引用

作者： Ji, Shiqi Lu, Ting Zhao, Zhengming Yu, Hualong Yuan, Liqiang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781479956982

The transient voltage unbalance is the major problem that limits the application of series-connected IGBTs in high voltage and high power converters. The asynchronous gate delay which causes that series-connected IGBTs do not turn-on and turn-off at the same time results in the most serious unbalanced voltage sharing. The active voltage control technique is proposed in this paper to solve the asynchronous gate delay problem. By sampling the feedback signal caused by unbalanced voltage, the microcontroller generates a time delay for gate driver to compensate the asynchronous gate delay. The most vital part of active voltage control is the status feedback circuit which is also given in detail in this paper. The function of the status feedback circuit and the effect of active voltage control are verified in a two series-connected HV-IGBTs platform in rated operation (5kV bus voltage and 600A load current). © 2014 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

来源：评论

学校读者我要写书评

暂无评论

Photovoltaic plant operating statuses identification model based on support vector machine using loss quantity of electricity feature parameters

Photovoltaic plant operating statuses identification model b...

引用

International Conference on Renewable power generation (RPG 2015)

作者： Kangping Li Fei Wang Zhao Zhen Yujing Sun Zengqiang Mi Hongbin Sun Chun Liu Bo Wang Jing Lu State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources (North China Electric Power University) Baoding 071003 Hebei Province China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment (Department of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 China China Electric Power Research Institute Haidian District Beijing 100192 China)

ISBN: (纸本)9781510821415

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： Feature Extraction Loss quantity of electricity Operating Statuses Identification Support Vector Machine

来源：评论

学校读者我要写书评

暂无评论

Cloud identification model for sky images based on Otsu

Cloud identification model for sky images based on Otsu

引用

International Conference on Renewable power generation (RPG 2015)

作者： Hongping Li Fei Wang Hui Ren Hongbin Sun Chun Liu Bo Wang Jing Lu Zhao Zhen Xiaoli Liu State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources (North China Electric Power University) Baoding 071003 Hebei Province China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment (Department of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 China China ElectricPowerResearch Institute HaidianDistrict Beijing 100192 China

Irradiance changes caused by clouds movement are the main 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： Otsu cloud identification texture threshold Clouds sky images texture textures pixel

来源：评论

学校读者我要写书评

暂无评论

An Improved OPA Model in power system Considering Planning 33

An Improved OPA Model in Power System Considering Planning

引用

第三十三届中国控制会议

作者： GONG Yuan MEI Shengwei PENG Dong LONG Wangcheng GUO Mingxing Power Systems and Power Generation Equipment Control and Simulation National Key Laboratory Department of Electrical Engineering Tsinghua University State Power Economic Research Institute

ISBN: (纸本)9781479947249

The power system now is a typical complex system, which has inherent characteristics of SOC. Studying on cascading failures are necessary and meaningful to insure the grid's safety, national security and economic development. This paper firstly establishes the indices of power system development diagnosis, which are closely relevant to the trigger of power system evolution. Then a cascading failure model is proposed, considering planning and evolution of the power system. This model is based on OPA model, including both fast dynamics and slow dynamics. The slow dynamic process simulates the evolution of power system, which represents the functions of the planning department, while the fast dynamic process simulates power flow and cascading failures, which takes the effects of dispatch, relay protection and automation into consideration. Moreover, simulations are tested on the case of Kaifeng-Shangqiu power system in Henan Province of China, and evolution results are presented.

关键词： power system evolution,cascading failure,power system diagnosis,power grid complexity,OPA model

来源：评论

学校读者我要写书评

暂无评论

Experimental investigation and analysis of some common faults for wind turbine 68

Experimental investigation and analysis of some common fault...

引用

68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

作者： Yang, Wenguang Li, Shaohua Jiang, Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

This paper focus on the fault characteristic by experimental research. A test rig is built for the direct driving stall fix-pitch horizontal axis wind turbine. 8 signals are collected by the experiment system, including wind speed, rotor rotational speed, shaft torque, the output electric power, vertical and horizontal vibration displacement of main shaft, vibration acceleration of the front bearing pedestal and the back bearing pedestal. 11 common wind turbine faults are researched by experiment. These faults are rotor mass imbalance, pneumatic asymmetry, airfoil changed, yaw fault, shaft horizontal misalignment, shaft vertical misalignment, front bearing pedestal looseness, rear bearing pedestal looseness, front bearing outer ring fault, front bearing inner ring fault, and front bearing roller fault. Several signal analysis methods, which are waveform analysis, orbit analysis, amplitude domain analysis, frequency domain analysis and envelope spectrum analysis, are adopted to extract characteristics from vibration signals. The influence on output power and vibration characteristics of these faults is presented by comparing with normal operation. The findings can be used to guide wind turbine fault diagnosis in engineering applications.

关键词： Wind

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：