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IEEE General Meeting power& Energy Society

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

Voltage fluctuation and flicker is an important aspect of power quality. The core of flicker analysis is to track the envelope of voltage signals and then calculate the short-term flicker severity P st , which is the premise of flicker source location. This paper firstly derives the formulas of extracting flicker envelope of signals containing harmonics using Teager energy operator and Hilbert transform. Then the measuring performance of Teager energy operator, Hilbert transform and square demodulation of flicker with one frequency, multi-frequencies and with harmonics are analyzed. After extracting the flicker envelope, the flicker frequency and amplitude error, and short-term flicker severity P st error are calculated. Besides the relationships between amplitude error and frequency, P st error and frequency with respect to these three methods are illustrated respectively. At last it is proved that Hilbert transform has the highest accuracy and stability than TEO and square demodulation with the increase of frequency.

关键词： Performance analysis Voltage fluctuations Demodulation power quality Signal analysis Position measurement Energy measurement Frequency measurement Harmonic analysis Stability

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New Topological Structure of Combination Switch Based Reactive power Compensation Installation

New Topological Structure of Combination Switch Based Reacti...

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

作者： Fei Wang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China

A new topological structure of combination switch based reactive power compensation installation is presented in this paper. The new topological structure overcomes those shortcomings of traditional product satisfactorily by take advantage of the features of new system topological structure: concise structure, flexible configuration, high speed communication and powerful capacity of resisting disturbance. The new system topological structure and software program design features of this new installation are described in detail, contrastive analysis and practical test between the new installation and the traditional product are discussed. The results show that the new installation not only has the virtue of: structural standard, simply connection, intelligent identification, easy to extend, high reliability and high power density, but also improves the performance index by means of integrated intelligent control principle and compensation capacity dynamic modification.

关键词： Switches Reactive power ISO standards Reactive power control power system dynamics Control systems Communication system control power system reliability Low voltage Access protocols

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Feedback Linearization Based Nonlinear Control Strategy of VSC-HVDC

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IFAC Proceedings Volumes 2009年第9期42卷 308-313页

作者： Gengyin Li Ming Yin Ming Zhou Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 P.R. China (Tel: +86 10 80798551) State Power Economic Research Institute Beijing 100761 P.R. China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 P.R. China

The model of Voltage Source Converter (VSC) based HVDC in the synchronous dq reference frame is presented in this paper. The model includes the DC link model and the VSC models. The feedback linearization principle for Multi-input Multi-output plants is analyzed. Based on the analysis, nonlinear decoupling control strategies for the two VSCs are proposed. For one VSC, the proposed nonlinear control strategy enables it to decouple DC voltage and reactive power control, and for the other one, the strategy guarantees the control of active power and that of reactive power independently. Simulation was conducted with MATLAB/Simulink software to verify the proposed control strategies. The simulation results prove that the nonlinear decoupling control strategies are able to provide good performance.

关键词： Feedback linearization HVDC nonlinear control strategy voltage source converter (VSC)

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Simulation Research on the Multiple Objective Voltage Quality Regulator

Simulation Research on the Multiple Objective Voltage Qualit...

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

作者： Yajing Di Zhongdong Yin Xiangning Xiao Zhi Zhang Key Laboratory of Power System Protection and Dynamic Monitoring and Control under Ministry of Education Beijing China

Due to the complexity of power systems combined with other factors such as increasing susceptibility of equipment, power quality (PQ) is apt to waver. With electricity in growing demand, low PQ is on the rise, the method of resolve those problem about power quality must be considered. In accordance with the familiar PQ problem, such as voltage sag, voltage swell, short interruption of supply voltage, harmonic suppression and short circuit fault. Basing on the H bridge cascade connection method, this paper design a new type regulator for the multiple objective control. Through the simulation software of PSCAD/EMTDC, the device can resume the voltage and restrain the harmonic dynamically and effectively, when there are voltage disturbances in the power system side. This device also could confine the short circuit current to a supportable level, when there is short circuit fault in the load side.

关键词： Regulators power system simulation PSCAD Voltage fluctuations power quality Circuit faults power system harmonics Harmonics suppression Bridge circuits Design methodology

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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 fault location scheme based on spectrum characteristic of fault-generated high-frequency transient signals

A fault location scheme based on spectrum characteristic of ...

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IEEE General Meeting power& Energy Society

作者： S. F. Huang X. G. Wang Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

When a fault occurs on a transmission line, fault-generated high-frequency signals contains a lot of information about fault. This paper proposes a fault location scheme for transmission lines based on spectrum characteristic of high-frequency components, the difference of adjacent two natural frequencies in one ends of transmission line is used to compute fault distance. This method need not identify arriving time of first traveling wave and traveling wave from fault point, it is insensitive to swings, fault type, fault resistance and system source parameters. The scheme performance was proven using power system computer aided design (PSCAD) simulations in 500-kV power system considering critical fault cases.

关键词： Fault location power transmission lines PSCAD power system simulation power system transients Frequency Fault diagnosis Computational modeling Computer simulation power system faults

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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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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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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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