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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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A novel active islanding detection method based on current-disturbing

A novel active islanding detection method based on current-d...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Peng Li Yinbo Sheng Ling Zhang Xilei Yang Yishu Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding China Shandong Electric Power Research Institute Jinan China

Desired islanding detection method not only can detect islanding within acceptable duration, but also require it has less adverse impact on power quality. This paper presents an active islanding detection method for a distributed resource (DG) unit which is coupled to a utility grid through grid-connected converter. With the proposed method which is based on adding periodical disturbing current through current controller of the interface voltage-sourced inverter, islanding can be effectively detected. But when the disturbing current remains unchanged, this method still has some shortages, so this article improved it and used a changed time-varying disturbing current ending with faster detecting time and less disturbing. The studies reported in this paper are based on time-domain simulations in the PSCAD/EMTDC environment. And the results show that the proposed islanding detection method always meets the two-second UL detection requirement.

关键词： Voltage control Inverters control systems power systems power conversion Frequency Condition monitoring Laboratories power system protection power system dynamics

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Method for PD location in oil combining ultrasonic phased array with wideband array signal processing

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第28期29卷 13-17页

作者： Xie, Qing Li, Yan-Qing Lü, Fang-Cheng Li, Cheng-Rong Wang, Nan Ding, Yu-Jian Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Changping District Beijing 102206 China Beijing Key Laboratory of High Voltage and EMC North China Electric Power University Changping District Beijing 102206 China China Electric Power Research Institute Haidian District Beijing 100192 China

A new method for partial discharge (PD) location in oil is presented based on ultrasonic phased array and wideband array signal processing. Firstly, the wideband ultrasonic signal of PD is measured directly by the ultrasonic phased array sensor and the array signal model is formed. Secondly, according to the frequency characteristic of the ultrasonic signal between 50 kHz to 300 kHz, the method of rotational signal subspace (RSS) is used to focus processing, which can convert the signal direction matrix under different frequencies to the same center frequency by focusing matrix. RSS can reserve the information maximally to realize the direction information accumulation of wideband signals. Finally estimation and location of the PD source signal's direction of arrival (DOA) are realized by means of the multiple signal classification (MUSIC) and crossover locating principle. The method is validated by the results of the experimental research. © 2009 Chin. Sco. for Elec. Eng.

关键词： Location

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Simulation and comparison of transient stability of power system including DFIGs wind farm based on detailed model

Simulation and comparison of transient stability of power sy...

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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Li Lin Hongjing Hou Wenxia Li Sheng Jing Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China Production & Technology Department Zhumadian Electric Power Company Henan China

This article is concerned with the impact of large-scale wind farms utilizing double fed induction generator (DFIG) on the transient stability to a general power system. In the first instance, the synthetical dynamic model of the wind turbine generators (WTGs) is introduced, including pitch angle control model and the generator protective model. And then, the simulation is made to the CIGRE B4-39 standard grid through the comparison between synchronous generator integration and wind farm based DFIG integration with the same power capacity. The simulation is also contained after the load and the topological structure changed. The conclusion shows that the transient stability of the power system including DFIGs wind farm is more robust than conventional synchronous generator connected.

关键词： power system simulation power system transients power system stability power system modeling Wind farms power system dynamics Induction generators power system protection Wind energy generation Synchronous generators

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Design of PV Array Model Based On EMTDC/PSCAD

Design of PV Array Model Based On EMTDC/PSCAD

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Jinhui Xue Zhongdong Yin Bingbing Wu Jun Peng Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China North China Electric Power University Beijing Beijing CN

Along with consuming of fossil energy step by step, crisis of energy has been appeared. The solar energy, which is endless, is a kind of renewable energy. Radiation of sun coming to earth in a day is equal to the energy, which is released by trillion buckets of oil. The research of solar energy generation has stepped into a very activity period. This paper analyses the physics characteristic of photovoltaic array firstly, then researches the mathematical model applying in engineering, and designs the total simulation model based on power electronic circuit in the end. In order to validate the correctness and validity, this paper makes a simulation as an example. The scheme can express the V-I characteristic of photovoltaic array very well.

关键词： EMTDC PSCAD Solar power generation Solar energy Photovoltaic systems Mathematical model Circuit simulation Renewable energy resources Sun Earth

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A method of tracking voltage flicker envelope real-time

A method of tracking voltage flicker envelope real-time

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IEEE General Meeting power& Energy Society

作者： Xiufang Jia Qing Chen Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China North China Electric Power University Baoding Hebei China

Fast and accurate tracking of voltage flicker envelope is significant to the performance of flicker meter, flicker source location and the mitigation of voltage flicker. Using the energy of a signal and its shifted signals to track the envelope of voltage flicker is presented in this paper. It is assumed that the signal is shifted, once by a lead angle equal to beta, and at another time by a lag angle equal to beta, which generates two new signals u + (t) and u - (t). According to the energy differences, the relationship between the flicker amplitude and u(t), u + (t), u - (t) can be obtained, so the voltage flicker envelope is successfully tracked. How to obtain the shifted signals u + (t), u - (t) is analyzed in the paper. The frequency error e f (%), amplitude error e m (%) and waveform standard deviation sigma(%) are used as the weighing index of the accuracy of tracking flicker envelope. The theoretical analyzing and RTDS simulation test verify that the suggested method is accurate, fast and anti-noise.

关键词： Voltage fluctuations Frequency Signal analysis Envelope detectors power quality Wavelet transforms Narrowband Filters Blind source separation Noise reduction

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Vulnerability assessment for communication network of Substation Automation systems to cyber attack

Vulnerability assessment for communication network of Substa...

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IEEE PES power systems Conference and Exposition, PSCE

作者： Nian Liu Jianhua Zhang Hao Zhang Wenxia Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Under Ministry of Education North China Electric Power University Beijing China Automation and information security North China Electric Power University China

The Substation Automation system (SAS) is a crucial element of power system control. The devices of SAS with remote-control functions are one of the main target of cyber attack. The vulnerability assessment for communication network of SASs that supporting the analysis of control process, is an unsolved problem. Combined with the characteristics of SAS and the vulnerability assessment of the distributed systems, a vulnerability assessment method for communication nework of SASs to cyber attack is proposed. The substation communication system has been classified into six basic models used to construct vulnerability state graph (VSG). The vulnerability of single action is defined based on exponential distribution function including parameters called vulnerability factor and equivalent attacking cost, and then the vulnerability value of target systems are calculated by four connection types of VSG. Furthermore, a vulnerability factor quantity method based on AHP-TOPSIS is designed. An evaluation instance is constructed from IEC 61850 standard, the proposed method is applicable to evaluate the vulnerability of communication network of SASs.

关键词： Communication networks Substation automation Synthetic aperture sonar IEC standards power system control Automatic control Process control Communication system control Exponential distribution Cost function

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A study on VSC-HVDC based black start compared with traditional black start

A study on VSC-HVDC based black start compared with traditio...

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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Sheng Li Mingxia Zhou Zongqi Liu Jianhua Zhang Yinhui Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing China Department of Electrical Engineering School of Electrical and Electronic Engineering North China Electric Power University Beijing China

ISBN: (纸本)9781424449347

A good black-start scheme is important and necessary to resume power supply fast and efficiently after black out, and how to choose black-start power is the first thing to consider in the scheme. In this paper, the advantages of VSC-HVDC as black start power are analyzed with contrast to traditional black start power. The ability of VSC-HVDC to soft energize major power system equipment is proved through simulation by software PSCAD/EMTDC. Simulation waveforms during soft energization are illustrated. These plots have described the good voltage and frequency characteristics of VSC-HVDC. The transition from one control mode of VSC to another is also discussed. Simulation results indicate that by using soft energization, VSC-HVDC is an ideal black start power.

关键词： Converters power conversion PSCAD power system harmonics power system simulation power system restoration Voltage control power system transients Frequency Transformers

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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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Notice of Retraction: Research on Cross Cultural Communication and Cultural Instruction of College English Language Teaching

Notice of Retraction: Research on Cross Cultural Communicati...

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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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