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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Li Lin Liangliang Song 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 Henan Electric Power Technical Institute Management of Production & Technology Department Zhumadian Electric Power Company China

The paper deals with the impact of wind power integration on power system small signal stability. The DFIG wind turbine consisting of a back-to-back PWM converter is introduced. Generator model is given first, ignoring the transient of stator. The converter control, shaft and pitch angle control diagrams are picked out for a detailed study subsequently. A case study is performed in part three, eigen-analysis of a modified IEEE 14 system is conducted considering the PF and VT control modes of wind farm. The pole map gives an intuitionistic view that DFIG introduces two oscillation modes related to the shaft and VAR controller model respectively. Eigen-structure depicts the electromechanical oscillation modes, and comparison of DFIG and SG case was studied which gives an overall conclusion that DFIG can have a favorable performance. Also the influence of increased penetration of wind power is examined.

关键词： Modal analysis Induction generators power system modeling Wind energy power system stability power system transients Shafts power system analysis computing Wind turbines Pulse width modulation converters

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Graph-based optimal solution for siting and sizing of grid-connected distributed generation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第4期29卷 91-96页

作者： Li, Peng Lian, Chao Li, Bo-Tao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Baoding 071003 China

Besides the conventional benefit of improving power flow, distributed generation (DG) can also be used to mitigate voltage sag and reduce line loss. In this paper, a graph and gene based algorithm was proposed to address the optimal location and capability for grid-connected DG, under the assumption of the radial distribution network and static constant power load model, meanwhile taking the characteristic of DG and its effect on network losses and voltage into consideration. This algorithm used graphic methods to solve a large number of equations. This effectively simplified the complicated process and numerous assumptions in the traditional method. Genetic algorithm with voltage boundary violation constraints was utilized to effectively prevent the bus voltage from reaching its upper boundary. Simulation of the benchmark examples and the comparsion with traditional methods show the correctness and feasibility of the proposed method. © 2009 Chin. Soc. for Elec. Eng.

关键词： Distributed power generation

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Wave-front arrival time analysis using wide-area frequency measurements

Wave-front arrival time analysis using wide-area frequency m...

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IEEE General Meeting power& Energy Society

作者： Jing Ma Jinlong Li Zengping Wang Jie Wu Tao Xia Lang Chen Yilu Liu School of Electrical and Electronic Engineering North China Electric Power University Beijing China Bradley Department of Electrical and Computer Engineering Virginia Polytechnic Institute Blacksburg VA USA Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Zhejiang Electric Power Design Institute Hangzhou China

Due to the influence of the local noise at the distribution level, the frequency curve obtained from the frequency disturbance recorder (FDR) unit is too non-stationary to observe its wave-front directly, which causes some problems in the event location estimation method. In this paper, a morphological filter (MF) is employed to extract the wave-front arrival time and the trend of the frequency curve. With the help of the MF, the accuracy of the event location method is greatly improved.

关键词： Frequency measurement Frequency estimation power system measurements Network servers Wide area measurements Filters Web server Global Positioning system Frequency synchronization power system dynamics

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Transformer Partial Discharge Sources Number Estimation Based on Ultrasonic Array Sensors and Modified CCT

Transformer Partial Discharge Sources Number Estimation Base...

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第九届电介质材料性能与应用国际会议(The 9th International Conference on Properties and Applications of Dielectric Materials)

作者： Qing XIE Xin XIANG Nan WANG Fang-cheng L(U) Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control(North China Electric Power University) Ministry of Education Baoding 071003

ISBN: (纸本)9781424443673

Correctly estimated the number of partial discharge (PD) source is the premise of the power transformer PD location based on ultrasonic array sensors. Therefore, estimation of the number of power transformer PD source is a very necessary research work. In this paper, we proposed the modified Canonical Correlation Technique (CCT) to estimate the number of transformer PD source. The simulation experiment results confirm the validity of the method.

关键词： Transformer Partial discharge Sub-band averaging CCT number estimation

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Simulation of PD Location in power Transformer Based on Root Multiple Signal Classification Method

Simulation of PD Location in Power Transformer Based on Root...

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第九届电介质材料性能与应用国际会议(The 9th International Conference on Properties and Applications of Dielectric Materials)

作者： Yan-qing LI Qing XIE Nan WANG Xin XIANG Fang-cheng L(U) Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control(North China Electric Power University) Ministry of Education Baoding 071003

ISBN: (纸本)9781424443673

Due to the heavy calculation and low estimation precision with little signal-to-noise (SNR) of MUSIC (Multiple Signal Classification) algorithm in partial discharge location used ultrasonic phased array, in this paper, a new location method is proposed based on Root-Multiple Signal Classification(Root-MUSIC). Firstly, Root-MUSIC algorithm is used for direction of arrival estimating of PD source. Secondly, space location of PD source is realized by crossover location principle. Finally, the result of simulation based on 7×7 plane phased array model vertifies the correctness of the new method.

关键词： partial discharge root-MUSIC crossover location

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The optimal control policies of three-phase current source rectifier based on over-modulation technique

The optimal control policies of three-phase current source r...

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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Chunyu Zhang Yabin Li Qi Wang Chengrong Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China Key Laboratory of High Voltage & EMC North China Electric Power University Baoding China East China Electric Power Design Institute Shanghai China Department of Electrical Engineering North China Electric Power University Beijing China

ISBN: (纸本)9781424449347

This paper introduces an over-modulation technique, a continuous extension of space vector PWM (SVPWM) linear control scheme for the three-phase current source rectifier (CSR). The over-modulation range is divided into two modes depending on the modulation index (MI). In mode I, the reference angles are derived from the Fourier series expansion of the reference voltage which corresponds to the MI. In mode II, the holding angles are also derived in the same way. The strategy, which is easier to understand graphically, produces a linear relationship between the output voltage and the MI up to six-step operation. The relationship between those angles and the MI can be written in lookup tables or, for real-time implementation, can be piecewise linearized. In addition, harmonic components and total harmonic distortion (THD) of the output voltage are analyzed. When the method is applied to the V/f control of the induction motor, a smooth operation during transition from the linear control range to the six-step mode is demonstrated through experimental results.

关键词： Optimal control Rectifiers Space vector pulse width modulation Frequency synchronization Voltage Pulse width modulation inverters Pulse width modulation Switching frequency Synchronous generators power harmonic filters

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A spatial information-based self-adaptive differential evolution for distribution substations location and sizing

A spatial information-based self-adaptive differential evolu...

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2008 Pacific-Asia Workshop on Computational Intelligence and Industrial Application, PACIIA 2008

作者： Nian, Liu Jianhua, Zhang Wenxia, Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Changping Beijing 102206 China

ISBN: (纸本)9780769534909

The location and sizing of distribution substations integrated with urban spatial information is a optimization problem which primary characteristics are the existence of many suboptimal cost peaks and the solution space is on a discrete floating-point variables rage with some unfeasible area constraints. To solve this problem, a spatial information based parameter selfadaptive schema of DE (ISADE) is proposed The populations are formulated by spatial coordinates of candidate substation locations which chosen randomly and attempt to cover the entire planning area. A randomized self-adaptive scheme for DE mutation weighting factor F is used to increase the ability of searching out the global solution. The effectiveness of the proposed method is then tested on two practical substation planning areas of Beijing Electric power Corporation and the results are compared with PSO and standard DE. © 2008 IEEE.

关键词： Location

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Wide area measurements-based model validation and its application

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IET Generation, Transmission and Distribution 2008年第6期2卷 906-916页

作者： Ma, J. Han, D. Sheng, W.-J. He, R.-M. Yue, C.-Y. Zhang, J. Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing 102206 China Limited CNCRC Universal Plaza Chaoyang District Beijing 100016 China

Simulation veracity is very important to the plan and operation of a power system. Too optimistic a simulation will put the system at risk whereas too pessimistic a simulation will waste investments. Wide area measurements (WAMs), one of the fast developing technologies in recent years, could record the synchronized phasors in the whole power grid, which provides the possibility for simulation validation work. Recent contingency reproduction work worldwide has shown the inaccuracy of current digital simulation. Therefore simulation validation and model calibration are necessary to enhance simulation veracity. However, because of the complexity of the power system, it is difficult to find the erroneous ones among a large amount of components, which makes the simulation validation a very challenging problem. A new approach for WAMs-based simulation validation work is proposed. The proposed method is very simple and easy to be implemented in the available power system simulation software. Then, the trajectory sensitivity method is applied to the parameter calibration work. Real applications via the proposed methods in the big NE power grid of China are studied, which fully show the efficiency of the proposed methods. © 2008 The Institution of Engineering and Technology.

关键词： Computer software

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PREDICTION ANALYSIS IN NONLINEAR systemS

PREDICTION ANALYSIS IN NONLINEAR SYSTEMS

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2008 International Conference on Machine Learning and Cybernetics(2008机器学习与控制论国际会议)

作者： YA-GANG ZHANG PO ZHANG ZENG-PING WANG Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry

The prediction analysis in nonlinear systems will be discussed carefully in this paper. We are mainly using CM (1,1) model to forecast data sequences, and the usual forecast precision is approximate to 90％. In this place we have found a generating rule that may realize chaotic synchronization at least in short and medium term, and we can analysis and forecast in this way. We hope to offer an effective prediction method to study certain properties of DNA base sequences, 20 amino acids symbolic sequences of protein structure, and the time series that can be symbolic in finance market et al.

关键词： Grey Prediction Chaotic Synchronization Symbolic dynamics Nonlinear system

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Application of Phase-shifting Reactor in Harmonic Suppression of the Independent power Supply system

Application of Phase-shifting Reactor in Harmonic Suppressio...

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11th International Conference on Electrical Machines and systems(第11届国际电机与系统会议)

作者： Lixia Zhou Qipeng Song Xiangning Xiao Zhongdong Yin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry

The electric propulsive shipping power grid is a typical independent power supply system, and the anti-jamming ability to non-linear load is quit weak because of the limitation of generation capacity. So the influence of the harmonics becomes more serious. Meanwhile, the variation range of the voltage and frequency is often large, which can cause the tuning point deviation of the passive filter easily. A novel method to suppress the harmonics of this kind grid by adopting the phase-shifting strategy is put forward in this paper. The phase current can be divided into two branches through phase-shifting windings, and specific phase-shifting angle can be achieved by choosing proper winding turns and connection way. The configuration of the phase-shifting windings is analyzed in detail and the optimal selection of the phase-shifting angle is also done. The accuracy and the effectiveness are verified by the EMTDC/PSCAD based simulation results.

关键词： Inductors Harmonics suppression power supplies power harmonic filters power grids Mesh generation power generation Voltage Frequency Tuning

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