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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

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Research of algorithm and analysis of performance for DC surge impedance relay

Research of algorithm and analysis of performance for DC sur...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Lei, Aoyu Dong, Xinzhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China

Surge Impedance Relay(SIR) is applied to DC system. Characteristics of SIR in DC line are analysed. A DC SIR algorithm implementing wavelet transform applied to HVDC line protection is proposed. The feasibility of DC ... 详细信息

ISBN: (纸本)9781849198349

关键词： Wavelet transforms

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Modeling and Analysis of Unit Commitment Considering RCAES System 33

Modeling and Analysis of Unit Commitment Considering RCAES S...

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第三十三届中国控制会议

作者： LIU Bin CHEN Laijun ZHANG Yu FANG Chen MEI Shengwei ZHOU Yuan State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University Electric Power Research Institute State Grid Shanghai Municipal Electric Power Company Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of Sciences

ISBN: (纸本)9781479947249

Regenerative compressed air energy storage(RCAES) system is a practical and efficient solution to large-scale integration of renewable energy problems faced by power systems currently. Appropriately modeling of RCAES system is critical to its practical application, whereas research in this area has been very limited. According to the energy storage and transformation process, a concise model of RCAES system applicable to power scheduling field is proposed. Then, a unit commitment model with RCAES system is formulated as a MILP problem which can be accurately solved with high computation efficiency by CPLEX. A modified IEEE 39 bus system is used to study the impacts of parameters of RCAES system on unit commitment and the effectiveness of the proposed model is then validated. Furthermore, the proposed model can also be employed to optimize key parameters of RCAES system, e.g. efficiency and capacity of each part in an integrated way.

关键词： unit commitment,regenerative,CAES,efficiency analysis,schedule

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Travelling wave sampling data sharing solution in distribution substation based on IEC61850

Travelling wave sampling data sharing solution in distributi...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Ni, Jiang Wang, Bin Dong, Xinzhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781849198349

The signal of travelling wave has the merit of immunity to system oscillation, transition resistance, CT saturation and the neutral point operation modes;it has been widely applied in field of fault detection and protection. Especially in isolated neutral grounded wind farm distribution network, the algorithm using multiple-bay travelling wave's information can exclusively achieve the fast fault feeder selection and tripping. However, travelling wave sampling frequency tends to reach 500 to 1000 times of that in algorithms with power frequency signal. The direct of travelling wave sampling data sharing in process bus would produce the communication block, and weaken the security of whole substation automation. To solve this problem, the performance of communication in process bus is theoretically analyzed and simulated in this paper, the communication requirement of travelling waves is quantified, and then a feasible scheme is proposed with data pre-processing and fault characteristic abstraction moving forward into the merging unit. simulations prove its validity. The work in paper can promote the wide application of travelling waves in substation based on IEC61850.

关键词： Merging

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The bandwidth of instrument current transformer for fault detection in distribution networks

The bandwidth of instrument current transformer for fault de...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Jiang, Bo Dong, Xinzhou Shi, Shenxing Wang, Bin Bak, Dominik State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781849198349

The distribution network detection devices are generally using two kinds of instrument current transformer (ICT), of which one is used to transform the travelling wave and transient signals, while the other is used to transform the power frequency signals. Such scheme is neither necessary nor economical. This paper analyses the influences of sampling resistance, stray capacitance and magnetizing inductance on the frequency characteristic of ICT. Considering that fault zero sequence transient current has big transient component and small power frequency component, an ICT with wide band frequency accuracy has been chosen. Practical experiments have been done. The technical parameters given by the instrument factory are only within 20-20kHz. The characteristics in higher frequency are seldom reported due to the lack of test means. The experiments in this paper is based on the transient tester instrument and current amplifiers developed by our laboratory, which can output wide frequency band current within 20Hz-100kHz up to 50A. Experiment shows that, the predicted results were in good agreement with the measured ones.

关键词： Electric instrument transformers

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A novel protection scheme for two-phase faults in power distribution system with neutral ungrounded

A novel protection scheme for two-phase faults in power dist...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Shi, Shengxing Lei, Aoyu Li, Xin Dong, Xinzhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Shibei Power Supply Company Shanghai Municipal Electric Power Company Shanghai China

ISBN: (纸本)9781849198349

A novel protection scheme for two-phase faults in power distribution system with neutral ungrounded is presented. The feasibility of tripping single-phase circuit when a phase-tophase or two-phase-to-ground fault occurs is studied with induction motor loads as the focus. The paper at first analyses the effect of a induction motor runs with one phase cut off theoretically. And then a real power distribution system model with 110kV, 35kV and 6kV voltage levels is built in PSCAD/EMTDC. Three feasibility criteria are proposed for motors in continuous operation with single-phase opened. At last, the novel protection scheme is testified in simulation with protection time and reclosing time as variables respectively. The results verify that the scheme is feasible and power supply reliability is improved.

关键词： Induction motors

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Characteristics calculation and pattern recognition for partial discharge of cable joint

Characteristics calculation and pattern recognition for part...

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2014 International Conference on Communication Technology and Application, CTA 2014

作者： Xia, Y.F. Gui, J.F. Chen, X.Y. Gao, S.Y. Huang, J.H. Lin, J.H. Dongguan Power Breuse of Guangdong Grid China School of Electrical Engineering Beijing Jiaotong University China Department of Electrical Engineering Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments China

ISBN: (纸本)9781845649302

For PD pattern recognition, six kinds of typical cable fault models are made and tested. Characteristics are calculated from test data. Multiple statistical characteristics of PD distribution map are calculated and pattern vectors are formed. Artificial neural network is trained for recognition. Through the selection and adjustment of characteristics and network parameters, recognition effect with satisfactory result is obtained. © 2014 WIT Press.

关键词： Partial discharges

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Travelling wave based single phase grounding protection for distribution system

Travelling wave based single phase grounding protection for ...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Dong, Xinzhou Wang, Jun Shi, Shenxing Wang, Bin Dominik, Bak Kirby, Brian Yang, Xia State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Alstom Grid Stafford ST174LX United Kingdom

ISBN: (纸本)9781849198349

It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.

关键词： Wavelet transforms

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Probabilistic substation fault diagnosis considering instrumentation channels and heterogeneous information: A unified Bayesian network model

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Qinghua Daxue Xuebao/Journal of tsinghua university 2014年第10期54卷 1384-1390页

作者： Mu, Jianan Sun, Hongbin Wu, Wenchuan Guo, Qinglai Zhang, Boming State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China

Fault diagnosis plays an important role in improving power network troubleshooting capability. Conducting local fault diagnosis in substations can make full and quick use of abundant local information. A substation fault diagnosis method was presented based on Bayesian network to adapt to a wealth of information and distributed autonomy under smart grid environment. The method is effective in dealing with uncertainties induced by malfunctions of protection relays and circuit breakers as well as instrumentation channel errors. Heterogeneous information available in substations, such as sequence of events (SOEs), wave records and blocking signals, was also integrated into the method, with the junction tree algorithm used to conduct probabilistic reasoning. The results show that breaker SOEs can be better utilized when considering instrumentation channels. Furthermore, introduction of wave records and blocking signals can significantly improve diagnosis accuracies. ©, 2014, Press of tsinghua university. All right reserved.

关键词： Bayesian networks

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Summary of health index theory and application of state maintenance equipment 5

Summary of health index theory and application of state main...

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5th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2014

作者： Cheng, Lin Manjun, L.I.U. Peng, Feijin Dept. of Elec. Eng. Tsinghua University State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Beijing100084 China Guangdong Power Grid Company Foshan Power Supply Bureau Foshan528010 China

ISBN: (纸本)9789881532329

This paper describes several methods for condition-based maintenance, introduced CBM, RCM development process, the main theoretical logic, techniques and practices. Focuses on the health index based on equipment maintenance strategies, namely CBRM. Focused on the development of narrative context, theoretical foundation, model healthy index. And for its application in power transformers were introduced.

关键词： Condition based maintenance

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