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IEEE PES Asia-Pacific Power and Energy engineering Conference (APPEEC)

作者： Zhenshu Wang Linchuan Li Li Niu Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China School of Electrical Engineering Shandong University Jinan China State Nuclear Electric Power Design and Research Institute Beijing China

At present, the load modeling is still one of the difficult problems in power system. In this paper, a new method is presented which uses wide-area measurements and support vector machine (SVM) for load modeling. Based on wide-area measurements, this method does non-linear regression analysis on model with SVM. By using radial basis function (RBF), model structure is optimized, and Bayesian Framework is used for identifying parameters, then a kind of non-mechanical model is founded. This method can easily solve the problems in choosing structure and identifying parameters. The founded model has good generalization ability, flexible structure, and rapid calculation speed. In the end, this method has been programmed; the simulation verifies the validity of this model.

关键词： Load modeling Wide area measurements Support vector machines Power system modeling Power system dynamics Power system simulation control system synthesis Power system measurements Power system analysis computing Bayesian methods

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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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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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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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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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A kind of Low Leakage Inductance Planar Transformer

A kind of Low Leakage Inductance Planar Transformer

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第六届IEEE国际电力电子与运动控制会议 (2009 IEEE 6th International Power Electronics and Motion control Conference-ECCE Asia

作者： Li Hongzhu Yang Yugang Fred.C.Lee Wu Jiaju Liaoning Technical University/Institute of Electrical & Control Engineering Huludao125105China Virginia Polytechnic Institute and State University/Center for Power Electronics System BlacksburgV Nanchang Hangkong University/Nondestructive Test Key Laboratory of Ministry Education Nanchang33003

It's necessary to decrease the leakage inductance of transformer because it often produces a large voltage peak as device is turned off, meanwhile the large voltage peak is a source of EMI and produces a large voltage stress and affects the power supply's efficiency. This paper proposes a kind of low leakage inductance planar transformer with shunt magnetic circuit structure, the primary winding number of this structure can be decreased to 1 turn and the equivalent secondary winding can be decreased to less than 1 turn, therefore the leakage inductance can be decreased remarkably, and it can be used to various turns ratio of high frequency transformer expressly in the transformer of low voltage and large current power supply. This shunt magnetic structure is verified with Maxwell 3D.

关键词： Inductance Power transformer insulation Power supplies Magnetic circuits Electromagnetic interference Leg Stress Frequency Electronic equipment testing Transformer cores

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Variable structure controller based on extended state observer in gun turret system

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Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology 2009年第4期29卷 318-322页

作者： Chen, Jie Jin, Tian-Xu Bai, Yong-Qiang Department of Automatic Control School of Information and Science Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision of Ministry of Education Beijing Institute of Technology Beijing 100081 China

Considering the characteristics of the servo system, such as disturbance, nonlinearity and high inertia, variable structure controller (VSC) based on extended state observers (ESO) are designed for the aim of quick, stable and high-accuracy controlling processes. The disturbances and high-order factors are estimated and compensated using ESO. Dynamic compensation reduces the motion system to approximately a triple integrator which can be easily controlled using VSC. Because ESO provides a high-frequency path for the dynamic state not modelled, the chatter of VSC is reduced. Through tests in the gun turret system, it was shown that this controller is superior to the engineering PID and general VSC.

关键词： Variable structure control

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Validating measurement-based composite load model

Validating measurement-based composite load model

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8th International Conference on Advances in Power system control, Operation and Management (APSCOM 2009)

作者： Jin Ma Xiao-yu Zheng Yong-hong Tang Zhao-yang Dong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Sichuan Electric Power Research Institute Chengdu China Department of Electrical Engineering Hong Kong Polytechnic University Hong Kong China

Since the digital simulation is one of the basic tools in understanding the modern complex power systems, its veracity has direct effects on the decision making on the power system operation and control. However, the accuracy of the digital simulation is dependant heavily on the model validity. Among all the dynamic components of the power system, the load is one of the most difficult one to be modeled. The difficulty lies in the fact that the scenario when the load model is built is always different from the real situation raised by the faults. So the question naturally arises that whether the measurement-based load model could be applied in the digital simulation when analyzing different operation scenarios. And to what extent does the model keep valid? It is hard to answer these questions because the field data, which constitute the basis of the measurement-based load modeling, are limited. This paper reports our work on validating the load model via RTDS. By simulating various fault situations on a model of a real provincial power system in RTDS, we could get a great amount of data to build the model as well as research its validity. Two greatly concerned problems related to the measurement-based load model are addressed in this paper; one is the possibility of applying the load model for various fault scenarios and the other is the validity of the load model when the load composition changes. Suggestions for the measurement-based load modeling practice are also given from the model validation work.

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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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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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