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IEEE PES Transmission and Distribution Conference and Exposition

作者： Chang-you Yan Jian-fei Yang Liu Qi-Xun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing China

In this paper, a novel real time data compression and reconstruction method is proposed to process a large amount of steady state and transient data of power system. Based on the biorthogonality filters group with the linear wavelet (WT) of lifting scheme and Huffman coding approach, the new algorithm is studied and developed. The field data are used to test the method. The results prove that the method is valid with less data processing time and as high as about 9 times of compression ratio. This method is suitable for the real-time compression of mass data recorded continuously by dynamic monitoring devices of electric power system

关键词： Data compression Reconstruction algorithms Real time systems power system transients Steady-state Nonlinear filters Huffman coding Testing Data processing power system dynamics

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Novel method for disturbance identification in power systems

Novel method for disturbance identification in power systems

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IEEE General Meeting power& Energy Society

作者： T.S. Bi X.N. Song J.T. Wu Q.X. Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Sifang Protection and Control Company Limited Beijing China

With the development of power grid interconnection, it is necessary for operators to know about system dynamic status while disturbance occurs in power systems in order to take appropriate counter measures to ensure the power system security. The advent of wide area measurement system (WAMS) makes the monitoring of power system dynamic behavior become possible. Based on WAMS, a method for identifying different kinds of disturbance in power system is presented in this paper. Firstly, the features of disturbances (i.e. short circuit, load shedding and loss of generation) that frequently occur in power system are analyzed in detail. Then, based on the idea of pattern recognition, the suggested disturbance identification method is discussed. Finally, computer simulation results are carried out in North China power grid, which demonstrate the validity of theoretical analysis and the feasibility of the proposed disturbances identification method

关键词： power systems power system dynamics power system measurements power system security power system interconnection power grids Wide area measurements power system analysis computing power system simulation Integrated circuit interconnections

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A Practical Approach for Ride Through of Super Capacitor Energy Storage Based ASD system

A Practical Approach for Ride Through of Super Capacitor Ene...

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IEEE PES Transmission and Distribution Conference and Exposition

作者： Zhongdong Yin Minxiao Han Yunlong Du Zheran Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University China

A practical ride through scheme bases on super capacitor energy storage system for ASD (adjustable speed drive) equipment is presented in this paper. The topology of ASD discussed adopts AC-DC-AC structure and 12 pulses diode rectifier as input interface. Super capacitor (SC) module connects to inverter DC bus to support DC voltage while power quality problems such as voltage sag or short-term outage take place in power source. A SC energy storage system based 15 kVA ASD prototype was developed. Digital simulation and physical experiments were carried out to verify the correctness and validity of proposed ASD ride through topology and control strategies

关键词： Capacitors Energy storage Variable speed drives Topology Voltage fluctuations Diodes Rectifiers Inverters power quality Prototypes

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Perturbed trajectory prediction method based on wide area measurement systems

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Dianli Xitong Zidonghua/Automation of Electric power systems 2006年第23期30卷 27-32页

作者： Song, Fangfang Bi, Tianshu Yang, Qixun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Sifang Research Institute North China Electric Power University Beijing 102206 China

A novel method for perturbed trajectory prediction of post-fault rotor angle is presented in this paper, which is based on phasor measurement unit (PMU) measurements and trigonometric function curve fitting technique. A mathematical relationship of post-fault rotor angle and time is derived from a speed-governing system, which reveals that the perturbed trajectory of the post-fault rotor angle can be expressed by attenuation trigonometric functions. Using curve fitting technique and trigonometric function, a least square method to predict the perturbed trajectory is proposed. Numerical simulations are conducted in IEEE 9-bus system and the simplified north China grid to test the effectiveness of the proposed method. The proposed method can give more reasonable and more promising prediction results as compared with polynomial curve fitting technique.

关键词： Electric power systems

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power factor and power quality improvement in distribution networks via a novel dynamic reactive compensation equipment

Power factor and power quality improvement in distribution n...

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7th IET International Conference on Advances in power system control, Operation and Management, APSCOM 2006

作者： Ji, Hongquan Yang, Yihan Gu, Haibin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Changping District Beijing 102206 China School of Electrical Engineering North China Electric Power University Changping District Beijing 102206 China Power Design and Research Institute Baoding Power Supply Co. Hebei Province Baoding 071051 China

ISBN: (纸本)0863412467

In order to keep the power factor at a high level and maintain acceptable voltage quality in distribution systems, a novel dynamic reactive compensation equipment is proposed. This equipment, which consists of a special regulating autotransformer with a vacuum on-load tap-changer and an intelligent power factor controller (IPFC), adopts step-voltage- regulating control method. It bases on the principle of the capacitor bank's output is in direct ratio with the square of the voltage works on it. In the course of tap- changer switching, the capacitor bank is not cut-out from the power system all along, it is proved in theory that dangerous over-voltage and associated inrush current will not occur. Thus security of the operation on capacitor bank is improved greatly and its natural life will increase much too. Compared with any other dynamic reactive compensation this novel equipment is less expensive and would be more likely to be put to be practical use. In the end, experimental results are given to verify that the proposed equipment has good characteristic of dynamic reactive compensation.

关键词： power quality

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A simple method for measuring complex transfer impedance and admittance of shielded cable in substations

A simple method for measuring complex transfer impedance and...

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International Zurich Symposium on Electromagnetic Compatibility (EMC Zurich)

作者： Lei Qi Xiang Cui Xuesong Gu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control underMinistry of Education North China Electric Power University Baoding Hebei China

In substations, shielded cables are widely used to reduce transient electromagnetic interference to the relay and control equipments due to the switch operation. Both the transfer impedance and transfer admittance are quantities for expressing numerically the mechanism that allows the passage of electromagnetic energy across the cable shield. Theoretical models to compute both the quantities often rely on simplifying assumptions. This, together with the fact that the transfer impedance and admittance can vary considerably between cable samples of the same type, means that measurements become necessary. In this paper, based on the transmission line theory we present a simple method to measure the transfer impedance and admittance of shielded cable in magnitude as well as in phase over the frequency range (0.1 MHz-10 MHz) which covers the main interference frequencies in power system. To illustrate this method a coaxial cable with a braided shield has been measured and compared with the existing method. As an application, the proposed method is used to predict the induced voltage and current on the shielded cable due to the switch operation in substation

关键词： Admittance measurement Impedance measurement Cable shielding Substations Switches Electromagnetic measurements power cables Transmission line measurements Frequency power system transients

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Computation of power line tower lightning surge impedance using the electromagnetic field method

Computation of power line tower lightning surge impedance us...

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International Zurich Symposium on Electromagnetic Compatibility (EMC Zurich)

作者： Changzheng Gao Lin Li Bing Li Zhibin Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control underMinistry of Education North China Electric Power University Baoding Hebei China

The power line tower lightning surge impedance is computed using an electromagnetic field approach. After comparing the results computed by our method and those tested with both a vertical conductor and reduced scale 4-poles model of tower, the method we used is proved to be right and more practical as the soil and the grounding system of the tower can be considered in the method. Using this method, the lightning surge impedance of the full scale UHV tower with grounding system is analyzed and the results show that the lightning surge impedance of a tower on the perfect ground has a little difference with those of an actual tower considering both its grounding system and soil resistivity, and when the soil resistivity is changed, the surge impedance changes slightly. Furthermore, a circuit model of the tower is obtained by vector fitting method based on the results we computed. Using the circuit model, the lightning surge performance of a power transmission line can be analyzed more accurately by EMTP or other methods

关键词： Poles and towers Lightning Surges Impedance Electromagnetic fields power system modeling Soil Grounding Conductivity Circuits

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The short-term electric load forecasting grid model based on MDRBR algorithm

The short-term electric load forecasting grid model based on...

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IEEE General Meeting power& Energy Society

作者： Ran Li Jing Hua Li He Ming Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding Hebei China

In load forecasting of a bulk power system, the geographical scope of forecasting region is large, the main electrical load effecting factors in sub districts are different greatly. So it is very significance to establish different load forecasting model according to self-feature of each sub district of a large area, by which the forecasting load is closer to the fact load than establishing one model in whole to forecast electrical load. This paper presents a grid model in terms of geographical division for short-term load forecasting in a bulk power system. The subset model in each geographical grid, considering its own historical loads and meteorological conditions, is more effective and could lead to more accurate results. Therefore, every subnet model is established based on the mining default rules on rough sets (MDRBR) algorithm. First, the MDRBR algorithm is discussed, and the constructing process of the multi-layered rule-network of daily load forecasting is then analyzed in detail. Furthermore, the whole process of load forecasting based on the MDRBR algorithm is presented. Finally, an example using actual historical data shows that the grid forecasting model can yield high accurate results, reduce noises effectively, and is efficient in computation and rule searching

关键词： Load forecasting Load modeling Predictive models power system modeling Weather forecasting Meteorology Rough sets Algorithm design and analysis Noise reduction Grid computing

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Study on the control of DFIG and its responses to grid disturbances

Study on the control of DFIG and its responses to grid distu...

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IEEE General Meeting power& Energy Society

作者： Ming Yin Gengyin Li Ming Zhou Guoping Liu 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 Shijiazhuang Electricity Company Shijiazhuang Hebei China

The paper presents the dynamic model of doubly fed induction generator (DFIG) including the mechanical model, the generator model and the PWM voltage source converter model. The mechanical model uses two-mass model, and the generator model includes both the stator side and the rotor side dynamics. The PWM voltage source converter is modeled as an average model in which the action of power electronic switches is neglected. The paper features vector control of DFIG. On the rotor side converter, the control scheme enables the independent control of speed and reactive power from the stator. On the grid side converter, the control scheme is implemented to regulate the DC voltage and reactive power from the grid as well. In order to study the influence of the grid disturbances on the DFIG, grid voltage dip and quick frequency change are simulated with the engineering software, MATLAB/Simulink. Meanwhile, in the paper the pole-placement method and internal model control method are implemented for designing the PI controllers

关键词： Mathematical model Induction generators Pulse width modulation Pulse width modulation converters Voltage Stators Rotors Reactive power control Switching converters power electronics

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Dielectric barrier discharge in nitrogen and argon

Dielectric barrier discharge in nitrogen and argon

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IEEE International Conference on Plasma Science (ICOPS)

作者： Zhan Huamao Ding Lijian Li Chengrong Li Ming Beijing Key Laboratory of High Voltage & EMC Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China

Summary form only given. Dielectric barrier discharges in air are generally streamer-like discharges, however, a homogeneous discharge, called atmospheric pressure glow discharge, may be obtained in some noble gases such as helium and argon. Dielectric barrier discharges in nitrogen and argon are studied experimentally to determine mechanisms controlling the transition from glow to streamer discharge. The influences of the applied voltage, the gas gap distance, the gas pressure and other factors on the discharge are investigated. The characteristics of the dielectric barrier discharge in nitrogen and argon are analyzed and compared. The aim of the paper is to study the experimental conditions of obtaining an atmospheric pressure glow discharge in nitrogen and argon. The possibility of obtaining an atmospheric pressure glow discharge in air is examined by increasing the proportion of air in nitrogen gradually. The waveforms of the applied voltage and discharge current under different experimental conditions are reported, which is helpful to describe the characteristics of the discharge and judge whether the discharge is a glow discharge or not

关键词： Dielectrics Nitrogen Argon Glow discharges Laboratories Voltage Atmospheric waves Electromagnetic compatibility power system protection power system dynamics

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