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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： Jun Gu Tao Zheng Shaofeng Huang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control (North China E Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control (North China E

The mal-operation of transformer differential protection will occasionally take place after the removal of external fault due to current-transformer (CT) saturation. Study show that CT saturation can be divided into three kinds. Firstly, the influencing factors of CT saturation and effect of CT saturation to transformer differential protection are studied. Secondly, this paper analyzes the characteristic of the operating point when differential protection is mal-operated because of CT saturation. At last a method of different time delay in different areas is presented to prevent the differential protection from maloperation. Simulation results validate its feasibility and reliability. It is significant if the method is realized for transformer protection.

关键词： Circuit faults Fault currents Current transformers Surge protection power system protection power system transients Hysteresis Magnetization processes Magnetic flux Saturation magnetization

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Study on assessment method of load's disturbance property

Study on assessment method of load's disturbance property

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3rd International Conference on Deregulation and Restructuring and power Technologies, DRPT 2008

作者： Jia, Xiufang Bo, Zhang Fazhan, Liu Minghao, Sun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China Zhengzhou Power Supply Company Zhengzhou 450012 Henan Province China

ISBN: (纸本)9787900714138

Assessment of load's disturbing property needs to be studied for confirming power quality responsibility and making a power price by its quality. In this paper, load's disturbing property is assessed by means of the analytic hierarchy process (AHP) and the grey relational analysis (GRA). First, the weight of index such as power factor, current total harmonic distortion, unbalance factor and reactive power fluctuation, which can characterize load's property, is obtained by AHP method. In order to assess the degree of load disturbance, a standard load in power system is defined. Then, based on the GRA, can get relativity degree between each disturbing load and standard load. Relativity degree can describe the gap between each disturbing load and standard load. The degree that disturbing loads creates influence to the electrical network is known by means of relativity degree. Finally, Calculating examples are brought forth to validate feasibility of the method. © 2008 DRPT.

关键词： Analytic hierarchy process

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A new approach on implementing Hybrid dynamic simulation based on wide area measurements 16

A new approach on implementing Hybrid Dynamic simulation bas...

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16th power systems Computation Conference, PSCC 2008

作者： Han, Dong Ma, Jin Sheng, Wenjin He, Renmu Yue, Chengyan Zhang, Jin Germond, Alain Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing102206 China ABB Research Center Beijing China Ecole Polytechnique Federale de Laussane Switzerland

ISBN: (纸本)9780947649289

As the most important tool guiding the power system operation and control, digital simulation directly affects the secure and economic operation. Consequently, the dynamic simulation validation work has been highly focused recently. This paper proposes a new method to implement the Hybrid dynamic simulation. With this method, the data from Wide Area Measurements (WAMs) can be injected into the simulations, thus a big power grid is decoupled into several small systems. All data in these small systems are kept when the conventional digital simulation is carried out, while the boundaries of these small systems are replaced by the signals of WAMs. Then the space to search the erroneous component is limited to the decoupled system, which is much smaller with fewer components. Case studies show the efficiency of the proposed method in simulation validation work.

关键词： Geodesy

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Effect of uncertainty in load model on power system dynamic simulation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第19期28卷 69-74页

作者： Han, Dong Ma, Jin He, Ren-Mu Yue, Cheng-Yan Zhang, Jin Rehtanz, C. Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Limited CNCRC Beijing 100016 China

In order to solve the disadvantages of Mont-Carlo simulation method used in typical uncertainty analysis, this paper adopted a new method-probabilistic collocation method (PCM) to analyze quantitative uncertainties of dynamic load proportion in dynamic simulation and stability analysis. A case study-New England 10-machine 39-bus system, verified the practicability and validity of the proposed method for uncertainty analysis in dynamic simulation. The results showed that the uncertainties in load composition at buses which are close to the fault site and at the buses that have heavy loads, have strong effects on transient stability, while some load buses that have heavy loads, is little far from the fault site, still have stronger effects on transient stability. It is concluded that the proposed method could directly describe the desired output as a polynomial of parameters. Consequently, the probability distribution of the response could be acquired by probability density function of parameters and much fewer simulations.

关键词： dynamic loads

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United planning of urban distribution network substation based on differential variance bacterial colony chemotaxis algorithm

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第SUPPL.期28卷 58-64页

作者： Wang, Zhi-Qiang Liu, Wen-Xia Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Min. of Edu. North China Electric Power University Changping District Beijing 102206 China

An improved differential variance bacterial colony chemotaxis (DVBCC) algorithm was presented for the urban power network substation planning. Bacterial colony chemotaxis (BCC) algorithm improves the speed of convergence compared with bacterial chemotaxis (BC) algorithm through the introduction of perception in bacterial colony, and also increases the possibility of a local optimum. DVBCC adopts adaptive control perception scope according to colony' distribution condition, at the same time adds differential variance operator in order to increase the variety of bacterial colony and improves its robust and global optima searching capability. In this paper completed economy of substation optimization planning of 110 kV and 220 kV voltage grade in urban power network was taken as objective function, and factors of geographical effect was considered. The results indicated that DVBCC algorithm outperforms BCC and particle swarm optimization (PSO) algorithms in solving substation planning problem and the proposed model has good economy and practicability.

关键词： Biochemistry

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Transient Stability Analysis of Asynchronous Distribution Generation and its Impact on protection

Transient Stability Analysis of Asynchronous Distribution Ge...

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2008 IET 9th International Conference on Developments in power system protection (DPSP 2008)

作者： Tianshu Bi Hongwei Zhao Peng Dong Qixun Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring & Control (MOE) North China Electric Power University Beijing China

It is of great importance to study the dynamic behavior of distributed generation (DG), which might affect the fault level and protection system of distribution network greatly. In this paper, the transient stability of asynchronous type of DG is comprehensively analyzed. The critical shedding time and corresponding slip of DG are calculated. It is pointed out that the fault clearing time of existing relays cannot guarantee DG operates stable when a fault occurs in distribution network. The countermeasures to low down the possibility of instability of DG are suggested. Finally, case studies are carried out using PSCAD to demonstrate the viewpoint of this paper.

关键词： Torque Rotors Stability analysis Impedance Transient analysis Electromagnetics Resistance

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A fault classification method based on spectrum of fault component for EHV lines

A fault classification method based on spectrum of fault com...

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IEEE General Meeting power& Energy Society

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

This paper proposes a fault classification scheme for transmission lines based on spectrum of fault component. First it analyses the spectrum of fault component, then the characters of power frequency and nature frequencies in two data windows are used to identify fault type and fault phase respectively. The scheme performance was proven using ATP/EMTP simulations in a 500-kV power system considering different fault types and fault locations. The results show that the scheme works quickly and is not impacted by harmonics and the DC offset. It is also not sensitive to sampling rate and fault inception angle.

关键词： power transmission lines Circuit faults Frequency domain analysis Fault diagnosis Relays power systems Fault location

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Study of transient spectrum in transmission lines

Study of transient spectrum in transmission lines

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IEEE General Meeting power& Energy Society

When faults occur in transmission lines, the high frequency signals are caused by fault generated traveling waves and the spectrum is a series of harmonic in frequency domain. This paper utilizes lumped and distributed parameter models to express transmission lines respectively, analyzes the character of nature frequencies. Different influencing factors including different fault conditions, source impedance, bus capacitance, series compensated capacitance and shunt reactor are discussed in this paper. The results have been proven by ATP procedure in a typical 500- Kv power transmission line.

关键词： power transmission lines Capacitance Circuit faults Relays Copper Shunt (electrical) Inductors

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A security mechanism of Web Services-based communication for wind power plants

A security mechanism of Web Services-based communication for...

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IEEE General Meeting power& Energy Society

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

The IEC 61400-25 standard has defined mapping of power plant information model to Web services. How to ensure the security of Web services-based communication for wind power plants is a unsolved problem. WS-Security is a standard used to deal with the security requirement in application of Web services, while username/password and X.509 certificates are security tokens most commonly used in electric power utility. We propose a security mechanism that deal with the requirements of authentication, integrity, non-reputation, and confidentiality across the communication process based on WS-Security and the two security token. The security mechanism is implemented by extension of SOAP message, design of security agent, and the related security message processing algorithm. An instance is modeling based on IEC 61400-25 to demonstrate the security enhanced remote control of wind power plants. The result support the usefulness of the security mechanism for Web Services-based wind power plants communication.

关键词： Security Cryptography Wind power generation Web services Simple object access protocol Authentication IEC

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Approach on pricing electricity for large consumers based on hedonic price model

Approach on pricing electricity for large consumers based on...

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3rd International Conference on Deregulation and Restructuring and power Technologies, DRPT 2008

作者： Ming, Zhou Xiangxin, Li Gengyin, Li IEEE Department of Electrical Engineering NCEPU NCEPU Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education

ISBN: (纸本)9787900714138

With the start of trial operation of direct purchasing electricity for large consumers in China, the method on how to price electricity is of vital theoretical and practical significance. Hedonic electricity pricing method is proposed to calculate the implicit prices of different characteristics of electricity. Based on the proposed model, the prices of electricity production cost, power quality and reliability characteristics are obtained. Comparing with the two-part pricing method, the hedonic electricity price model uses multiple electricity characteristics to make the electricity purchase price, instead of using single electric energy. Numerical examples show that the proposed approach can make purchase price more reasonable and fair. © 2008 DRPT.

关键词： power markets

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