检索结果-内蒙古大学图书馆

Classification and generalization of the load model based on model dynamic responses

Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2009年第2期24卷 132-138页

作者： Zheng, Xiaoyu Ma, Jin He, Renmu Tang, Yonghong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Sichuan Electric Power Research Institute Chengdu 610072 China

The time-variable characteristic of the load is a limiting factor in the using of the load model. Load classification is a good approach to solve this problem. A new load model classification and generalization method is proposed in this paper. First, load model responses are chosen as the characteristic vectors in the cluster analysis. Then, the multi-curve identification technique is applied in building the load models for each class. Finally, more robust and practical models are obtained after the combination of classes, which are also verified by their strong generalization capability and physical interpretation.

关键词： Cluster analysis

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A novel method to rapidly identify inrush current and internal fault current based on variation characteristic of fundamental current amplitude

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2009年第6期24卷 166-171页

作者： Ma, Jing Wang, Zengping Wu, Jie Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Zhejiang Electric Power Design Institute Hangzhou 310014 China

A new transformer protection principle based on two-instantaneous-value-product algorithm to extract the feature of fundamental current amplitude is put forward in this paper. First, the algorithm of two-instantaneous-value-product is developed, and variation trends of fundamental current amplitudes are analyzed in the case of inrush currents and internal fault currents. Whether the fundamental current amplitude reveals the descending feature or not can be used to distinguish the inrush current and the internal fault. The computational simplicity of the proposed scheme enables its implementation in real-time applications with low-cost microprocessors. dynamic testing results indicate that this method is able to clear internal fault even light fault less than a cycle and can not be affected by the current transformer saturation. Moreover, compared with the second harmonic restraint principle and the waveform comparison principle, the proposed algorithm has better performance.

关键词： Transformer protection

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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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power system real-time state estimation and prediction based on WAMS

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Dianli Xitong Zidonghua/Automation of Electric power systems 2009年第16期33卷 35-39+49页

作者： Li, Hong Li, Weiguo Bi, Tianshu Xiong, Haoqing Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Henan Electric Power Dispatching and Communication Center Zhengzhou 450052 China

A real-time state estimator based on WAMS is presented, in which the recursive extended least-squares algorithm is used to identify the state transition matrix, and the fading memory exponential weighted algorithm is employed to estimate the error covariance matrix of the linearized model. At the same time, the measurement weights are calculated on-line by the measurement standard deviations. When the filter is done by using observed data, the imprecise (or unknown) parameters and the noise covariance matrixes of the state estimation model are constantly identified and corrected on-line simultaneously, which makes the model follow the contingencies and the time-varying process adaptively. Therefore the estimated errors are reduced, and the filtering precision is high. Simulation results show that the proposed method has good performance under different scenarios such as normal operation, bad measurements, sudden load change/drastic generation variation and topology errors. This work is supported by Program for New Century Excellent Talents in University (No. NCET-05-0216). ©2009 State Grid Electric power Research Institute Press.

关键词： State estimation

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RETRACTED ARTICLE: Anti-islanding detection and protection for grid connected PV system using instantaneous power theory

RETRACTED ARTICLE: Anti-islanding detection and protection f...

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2009 International Conference on Industrial and Information systems, IIS 2009

作者： Wang, Fei Zhang, Chengcheng Mi, Zengqiang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China Foreign Language Teaching and Researching Department Hebei University Baoding 071000 Hebei Province China

ISBN: (纸本)9780769536187

Anti-islanding method with 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. © 2009 IEEE.

关键词： Electric power system control

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A novel algorithm of calculating the circulating current on the delta side of three phase wye-delta connected transformer

A novel algorithm of calculating the circulating current on ...

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IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Tao Zheng Qiang Liu Department of Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control China Electric Power University Beijing China

ISBN: (纸本)9781424452293

The circulating current on the delta side of wye-delta connected three-phase power transformer is hard to measure. The differential transformer protection has to adopt current phase compensation method to compensate the circulating current. However, the differential current hardly reflect the magnetic exciting current of transformer no matter what kind of current phase compensation methods used. It limits many algorithms of identifying inrush current, such as the promising one based on the equivalent instantaneous inductance. How to obtain the circulating currents in delta side has become a difficult problem in transformer protection. In this paper, based on the voltage equations of transformer, the calculation of the resistance and leakage inductance of winding is deduced. And then, a novel algorithm of calculating the circulating currents in delta side is proposed Simulation results of MATLAB verify the accuracy of this algorithm, which offers a new way to calculate the differential currents exactly.

关键词： power transformers Phase transformers Inductance Surge protection Equations Current measurement Asia power measurement Phase measurement MATLAB

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The finite elements analysis on magnetic field of controllable saturated reactor

The finite elements analysis on magnetic field of controllab...

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International Conference on power Electronics and Drive systems (PEDS)

作者： Wang Ziqiang Yin Zhongdong Yang Po Li Ke key Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control of Ministry of Education North China Electric Power University Beijing China Laboratory of Power System Protection and Dynamic Security Monitoring and Control of Ministry of Education North China Electric Power University Beijing China

In the power system, the controllable reactor can be used as reactive power compensation device to limit over-voltage operation, reduce no-load or light load loss and improve transmission capacity. It is with characters of simple structure, easy maintaining, low cost and high stability, etc. The magnetic field is closely related to the reactor performance. In this paper, aiming at a controllable saturated reactor prototype, using the finite elements method, the magnetic field is studied. Then, the precise 2-D prototype field-circuit coupling model is established based on the magnetic field analysis and the finite element analysis software - ANSYS. Using this model, the magnetic field and working currents concrete values under the condition that AC and DC excitations co-exist within the core are calculated. The analysis results indicate that finite element analysis theory can effectively analyze the magnetic field of the reactor.

关键词： Finite element methods Magnetic analysis Magnetic fields Inductors power system stability Software prototyping power system analysis computing Lighting control power system control Control systems

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A Novel MPPT Control Algorithm Based on Numerical Calculation for PV Generation systems

A Novel MPPT Control Algorithm Based on Numerical Calculatio...

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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： Jing Hu Jiancheng Zhang Hongbo Wu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control (North China Electric Power University) Baoding071003 China

In the future solar energy will be very important energy source. It is noticeable that the output characteristics of a PV array are influenced by the environment factors, and the conversion efficiency of PV arrays is very low. Therefore a Maximum power Point Tracking (MPPT) technique is needed to draw peak power from the solar array in order to maximize the produced energy. This paper introduces a novel MPPT control algorithm for photovoltaic (PV) power generation systems. The proposed algorithm based on numerical calculation is able to perform MPPT with only one step by quadratic interpolation. And a constant voltage tracking (CVT) startup is used in the MPPT method to enhance the accuracy and the speediness. The rationality and the feasibility of the algorithm developed in this paper are verified by building simulation model using MATLAB SIMULINK tool. The results indicate that the proposed approach can effectively improve the MPPT speed and accuracy simultaneously.

关键词： Control systems Solar power generation Photovoltaic systems Voltage power generation Solar energy Atmospheric modeling Mathematical model Costs Temperature

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Research on a Novel Series-Connected Voltage Fluctuation Generator

Research on a Novel Series-Connected Voltage Fluctuation Gen...

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International Conference on Energy and Environment Technology (ICEET)

作者： Renzhong Shan Zhongdong Yin Xiangning Xiao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control of Ministry of Education North China Electric Power University China

A novel voltage fluctuation and flicker generating main circuit topology is proposed in this paper, combined with passive and active to realize voltage fluctuation and flicker. The fundamental frequency power is supplied by system source and the other frequency fluctuation power is supplied by active components, so the capacitor of generator is easy to realize larger because of lower active loss. Full-bridge diode rectifier is adopted to maintain the stable DC-bus voltage, the later inverter is controlled by instantaneous value voltage and current double closed-loop to make sure good static and dynamic performance. The inverter output two frequency voltage waveforms, and added to fundamental frequency sinusoidal voltage waveform by transformer so that the typical sinusoidal modulation voltage fluctuation and flicker waveform is obtained. The simulation model is set up on the platform of Matlab/Simulink. Finally, the simulation and experimental results show that the proposed main circuit and control strategy is feasible and efficient.

关键词： Voltage fluctuations Frequency power supplies Inverters Circuit simulation Circuit topology Capacitors power generation Diodes Rectifiers

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Available Transfer Capability Evaluation Based on Sensitivity Analysis

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IFAC Proceedings Volumes 2009年第9期42卷 62-67页

作者： Yajing Gao Gengyin Li 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 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)

According to the definition of Available Transfer Capability by North America Electric Reliability Council (NERC), we know that ATC not only depends on the topology of power network but also on the parameters of components. So a series of adequacy indices are proposed to evaluate ATC. Through thorough analyses on these indices, the sensitivities of components parameters to these adequacy indices are deduced. The impact of components parameters’ small variations on ATC can be reflected by these sensitivities, the importance degree of each component can be embodied. Furthermore, by sensitivity analysis we can effectively identify ATC bottlenecks and get important guide information for operation and planning. The algorithm based on MATLAB 6.5 is developed. The correctness and effectiveness of the proposed sensitivity analysis method are verified using IEEE-RTS79 test system.

关键词： Available Transfer Capability adequacy indices sensitivity analysis

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