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International Conference on Industrial and Information systems, IIS

作者： Chengcheng Zhang Fei Wang Foreign Language Teaching & Researching Department Hebei University Baoding China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding China

This article has been retracted by the publisher.

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Measurement of micro-scale two-phase flow in a pulsating heat pipe using electrical capacitance tomography

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第17期29卷 103-107页

作者： Li, Jing-Tao Xiao, Hai-Ping Dong, Xiang-Yuan Liu, Shi Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Changping District Beijing 102206 China School of Energy and Environmental Engineering Zhongyuan Institute of Technology Zhengzhou 450007 Henan Province China

The electrical capacitance tomography (ECT) system was used to the visualization of the two-phase flow as well as the measurement of the film thickness in a pulsating heat pipe (PHP). The new-developed micro-sensor was also applied as a part of the flow channel, with the characteristics of heat transfer and hydrodynamics similar to the measured tube. The measurement accuracy and the image resolving power were improved as compared with the conventional sensors. So the applied area of the ECT technology was widened. The experimental results indicate that there might exist three flow patterns, i.e. bubble-liquid slug flow, semi-annular flow and annular flow, corresponding to different operating conditions. The measurement results of the film thickness compare well with the actual conditions, and the trend of the film thickness can realize the identification of the flow patterns.

关键词： Two phase flow

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A variable step maximum power point tracking algorithm based on gradient descent method

A variable step maximum power point tracking algorithm based...

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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Jianpo Zhang Tao Wang Huijuan Ran Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China School of Electric Engineering North China Electric Power University Baoding China

ISBN: (纸本)9781424449347

Solar energy is considered as one of the most effective, less expensive, harmless and less environment pollution effect of renewable energy sources. The problem of using solar power including varying weather condition brings different output power of the photovoltaic (PV) array, which may cause a serious waste of solar power. For solving this problem, a Maximum power point tracking (MPPT) strategy is always required to make PV array keep giving maximum power under different environment condition. In this paper, a variable step MPPT based on gradient descent method is proposed for faster and more precise tracking process. A model based on matlab/simulink was established to analysis the performance of the proposed MPPT strategy. Simulation proves that this MPPT method is practical with a better performance than the traditional strategies.

关键词： Equations Solar energy Mathematical model Temperature power generation Diodes Radio access networks Voltage Circuit simulation Equivalent circuits

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Reliability analysis of Wide Area Measurement system based on the Centralized Distributed model

Reliability analysis of Wide Area Measurement System based o...

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IEEE PES power systems Conference and Exposition, PSCE

作者： Wen-xia Liu Nian Liu Yong-feng Fan Li-xin Zhang xin Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Under Ministry of Education North China Electric Power University Beijing 102206 China College of Electric and Electronic Engineering in North China Electric Power University China

In this paper, based on Centralized Distributed model, a study method of reliability of WAMS is presented. The whole WAMS system is divided into two sub-systems: Monitor Center system and Data Acquisition system. The Communication system is also modeled as an auxiliary evaluation system. According to the Markov condition, the Monitor Center system establishes the Kolomogorov equation, sets the invalidation function based on the GO software model, and obtains the evaluation methods of its availability. The analysis of data acquisition system takes the phasor measurement unit and Phasor Data Concentrator (PDC), which installed in various protection areas, as the study objects, and gets the reliability evaluation of data acquisition system by the series system model, the parallel system model and k/n judgment system model of those facility units. The study method is used in the reliability evaluation of a real WAMS system of IEEE 14 Node. As the result shows that this reliability evolution method has a guiding significance in the practical application of WAMS system.

关键词： Wide area measurements power system reliability monitoring power grids power system dynamics power system security Phasor measurement units power system protection power system modeling Data acquisition

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Multi-objective evaluation for distribution network reconstruction basing on hierarchical data envelopment analysis

Multi-objective evaluation for distribution network reconstr...

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IEEE PES power systems Conference and Exposition, PSCE

作者： Wen-xia Liu Li-xin Zhang Jian-hua Zhang Yong-feng Fan Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Under Ministry of Education North China Electric Power University Beijing 102206 China College of Electric and Electronic Engineering in North China Electric Power University China

Studying the optimal subsection of distribution networks feeders, a subsection scheme synthesizing load and the length of subsections is presented. Hierarchical data envelopment analysis (DEA) method is proposed for multi-objective evaluation of subsection schemes. First, the scientific assessment system is established by using the analytic hierarchy process (AHP) and the weights of assessment criteria are derived from the judgment matrix. Secondly, the actual index data is used to structure DEA model, the schemes are evaluated quantificational with regard to different assessment criteria. Finally, each scheme is evaluated comprehensively. Using this method and the evaluation system to evaluate the subsection schemes, the evaluation results show that the assessment method is scientific and effective; the subsection method presented in this paper can better meet the economic and reliability requirements and is simple and practical.

关键词： Data envelopment analysis power supplies power system reliability Switches power generation economics Maintenance Investments Costs power system economics power system planning

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A maximum power point tracking algorithm based on gradient descent method

A maximum power point tracking algorithm based on gradient d...

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IEEE General Meeting power& Energy Society

Solar energy is considered as one of the most effective, less expensive, harmless and less environment pollution effect of renewable energy sources, the problem of using solar power including varying weather condition brings different output power of the photovoltaic (PV) array, which may cause a serious waste of solar power, for solving this problem, a Maximum power Point Tracking (MPPT) strategy is always required to make PV array keep giving maximum power under different environment condition. In this paper, a variable step MPPT based on gradient descent method is proposed for faster and more precise tracking process, a model based on matlab/simulink was established to analysis the performance of the proposed MPPT strategy, simulation results prove that this MPPT method is practical with a better performance than the traditional strategies.

关键词： Solar energy Mathematical model power generation Analytical models Voltage Radio access networks Pollution Renewable energy resources Solar power generation Character generation

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Notice of Retraction: Anti-islanding Detection and protection for Grid Connected PV system Using Instantaneous power Theory

Notice of Retraction: Anti-islanding Detection and Protectio...

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International Conference on Industrial and Information systems, IIS

作者： Fei Wang Chengcheng Zhang Zengqiang Mi Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China Foreign Language Teaching & Researching Department Hebei University Baoding Hebei China

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protection and control for Grid Connected Photovoltaic power Generation system Based on Instantaneous power Theory

Protection and Control for Grid Connected Photovoltaic Power...

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Pacific-Asia Conference on Circuits, Communications and systems, PACCS

作者： Fei Wang Chengcheng Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Under Ministry of Education North China Electric Power University Baoding Hebei China Foreign Language Teaching & Researching Department Hebei University Baoding Hebei China

Reliable protection and reasonable control run an important role in grid connected PV power generation system. The detection and calculation of real and reactive power are the bases of many inverter resident passive and active islanding detection method (IDM). As well as the detection and calculation of real and reactive power also concern with the inverter control of grid connected PV power generation system. In this paper, considering instantaneous voltage and instantaneous current are periodic function about time, think of it in terms of periodic function space to define the inner product and norm, Hilbert space based power theory is proposed. Real power, reactive power and apparent power in Hilbert space based theory are defined. This proposed Hilbert space based power theory provide a novel view for the protection, islanding detection and control of grid connected PV power generation system.

关键词： Photovoltaic systems power system protection control systems Solar power generation Hilbert space power system reliability Reactive power Inverters Reactive power control Voltage

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Comparison of pitch angle control models of wind farm for power system analysis

Comparison of pitch angle control models of wind farm for po...

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IEEE General Meeting power& Energy Society

作者： Li. Lin Jing. Zhang Yihan. Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China North China Grid Corporation Beijing China

With rapid development of wind power generation, the large capacity wind farms are built up and integrated into transmission network. The effect of wind farms on the grid becomes more serious and more extensive. In order to investigate the dynamic performances of the grid-connected wind farm and the interaction of the wind farms, it is necessary to present the appropriate models of wind farms, which can present the wind power characteristics completely and are not too complicated. In this paper, based on the detailed model of the pitch angle control system, two kinds of simplified pitch angle control models are deduced by mathematics equivalence method. Then the three models are adopted respectively, the relatively dynamic characteristics of the wind farm and the grid are compared. Later, the wind farm with different pitch angle control model is connected to the CIGRE B4-39 grid, and the simplified models are verified by simulation. Finally, the methods how to choice pitch angle control models are present.

关键词： power system modeling Wind farms power system analysis computing power system control power systems power system dynamics Mathematical model Wind power generation Wind energy control system synthesis

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Comparison of reactive power compensation strategy of wind farm based on optislip wind turbines

Comparison of reactive power compensation strategy of wind f...

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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Li Lin Feng Sun Yihan Yang Qunju Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China North China Electric Power Science Institute Beijing China

The paper studies reactive power compensation strategy of wind farm based on optislip wound rotor induction generators (WRIGs). The WRIGs wind farm shares high market occupancy in China, but academic researches on this grid-connected wind generation are few. Due to the WRIGs wind turbines not allowing the control of the reactive power, so it is necessary that reactive power compensation device is adopted in the large scale grid-connected wind farm. In the paper, from the perspective of system study, the compensation effects of three kind of static var compensation (SVC) are compared, and the influence of different ratings SVC on the voltage stability of the optislip wind farm is investigated. Finally, reactive power compensation strategy of the wind farm is proposed.

关键词： Reactive power Wind farms Wind turbines Induction generators Reactive power control Static VAr compensators Wounds Rotors Mesh generation Wind energy generation

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