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

作者： Li Bin Zhang Shuo P.A.Crossley Bo Zhiqian Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University of Technology Tianjin China AREVA T&D Automation슠and Information Systems Stafford UK

Automatic reclosure (AR) is extremely effective in improving the reliability, stability and security of the overall power system. However, the present autoreclosure operates blindly and practices employing a fixed time. In the case of permanent fault, a second shock to the system can cause irreparable damage to expensive equipments. According to characters of transient faults and permanent faults, this paper introduces the method of Bergeron line model into the field of single-phase adaptive reclosing (SPAR). Therefore, the paper proposes a novel scheme based on the calculation of Bergeron model to realize SPAR. Theoretical analysis and simulation prove that the proposed scheme of single-phase adaptive reclosing is valid with high sensitivity and reliability.

关键词： Circuit faults Transient analysis power system transients power transmission lines Adaptation model Fault currents Harmonic analysis

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Comprehensive method on evaluation of distribution network planning

Comprehensive method on evaluation of distribution network p...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies (DRPT)

作者： Jun Xiao Yanyan Cui Fengzhang Luo Mingzhi Liu Jianmin Wang Yinong Li Yubo Gao Saiyi Wang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China Tianjin Electric Power Corporation Tianjin China SMEPC Urban Power Supply Company Shanghai China Urban Power Supply Company SMEPC Shanghai 200122 China

Planning is vital for the development of power system; and the quality of planning has direct influence on security, reliability and economy of the power system in the future. Therefore, it is urgently needed to study quantitative evaluation method for distribution network planning. First, this paper proposes a practical comprehensive hierarchy and method on evaluation of distribution network planning. Second, the implementation steps for the evaluation of planning network are given, which include the determination of indices hierarchy and the evaluation of planning. In the end, this paper takes 10 kV network distribution planning of a district in China for example in order to illustrate the specific evaluation steps and methods based on the hierarchy, at the same time, the case shows that the evaluation method has strong feasibility and practicability. The planning evaluation hierarchy and method proposed in this paper can not only seize the key elements influencing the characteristics of network planning, but also describe the planning integrally and quantitatively, and possess significant engineering practicability.

关键词： power system planning power system reliability power system security Urban planning Meeting planning Laboratories power system simulation control system synthesis power system measurements control engineering education

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Simple method to determine power system delay margin

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Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第1期32卷 6-10页

作者： Dong, Cun Yu, Xiaodan Jia, Hongjie Jilin Electric Power Company Changchun 130021 China Key Laboratory of Power System Simulation and Control Tianjin University Tianjin 300072 China

Delay margin is defined as the maximum time delay that system can sustain without losing its small signal stability. An effective approach is given to calculate the system delay margin. It determines the system critical eigenvalue and the local delay margin by tracing eigenvalue locus of a complex matrix in a finite interval. The proposed method does not make any transformation to the original characteristic equation. It can be applied to the delay margin analysis in the complicated bulk power systems. SMIB system and WSCC 3-generator-9-bus system are employed to validate its effectiveness.

关键词： Electric power systems

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Protection scheme against chain over-load trip based on wide-area information

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Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第10期32卷 37-41页

作者： Wang, Yan Zhang, Yanxia Xu, Songxiao Key Laboratory of Power System Simulation and Control Tianjin University Tianjin 300072 China Baoding Electric Power Company Baoding 071000 China

Chain over-load trip is an early stage phenomenon of great blackouts. Anti-chain over-load trip scheme is an important measure to prevent large-scale blackouts. A principle of preventing chain over-load trip based on wide-area information is proposed. Taking important buses as units, the over-load current coefficient of each branch is calculated using relevant elements of the node impedance matrix in the normal operation conditions stored in the wide-area scheduling centre. The possibility of chain over-load trip cause'd by over-load branches is then estimated based on these coefficients, to help control centers take timely measures to prevent chain over-load trip and large-scale blackouts. simulation results on the IEEE-39 system indicate the feasibility of the method.

关键词： Electric power systems

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A novel approach to eliminate zero-sequence harmonics current

A novel approach to eliminate zero-sequence harmonics curren...

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IEEE Asia-Pacific Conference on Circuits and systems

作者： Qipeng Song Zhongdong Yin Chengxi Dai Changyin Zhang Weidong Shang Zhonghua Huang Key Laboratory of Power System Protection and Dynamic Monitoring and Control Ministry of Education University Beijing China Kaifeng Power Supply Corporation Kaifeng China Kaifeng Power Supply Corporation The state grid corporation of China Kaifeng

Zero-sequence harmonics caused by nonlinear loads usually result in high voltage distortion levels throughout the facility, neutral conductor overloading, motor heating, transformer heating, increased losses, and excessive harmonic injection onto the utility supply system. This paper presents a novel method to eliminate zero-sequence harmonics by using Zero-sequence Resister Block (ZRB) and Zig-Zag transformer. Zig-Zag transformer is a special connection of three-phase transformerpsilas windings. The ZRB is also a special connected transformer, whose three windings are wounded in the same core. The ZRB has zero reactance for positive and negative-sequence components but giving three times of self-reactance for zero-sequence reactance. In this paper, an analysis is carried out; simulations and laboratory tests are used to evaluate the performance of the Zig-Zag transformer and ZRB under various system conditions. The simulation and laboratory test results indicate that the combination of ZRB and Zig-Zag transformer as filter is a better and effective way to attenuate the neutral current, which also provides an innovational way to improve power quality.

关键词： power harmonic filters Heating Laboratories Harmonic distortion Conductors Transformer cores Performance analysis Analytical models system testing power quality

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Medium voltage distribution system reliability calculation with the consider of high voltage distribution system and substation

Medium voltage distribution system reliability calculation w...

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3rd International Conference on Electric Utility Deregulation and Restructuring and power Technologies (DRPT 2008), vol.1

作者： Chengshan Wang Yue Lv Jun Xiao Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

According to the operational features of distribution network, the paper presents a method to calculate the distribution system reliability that also considers multi-layers failure. Based on the regular reliability calculation, the results are promoted. Firstly, the distribution system is divided into different parts by different voltage level. Secondly, based on the characteristics of the distribution system, a comprehensive evaluation method, which combines the high and medium voltage distribution system and the substation's influence, is taken into account. Through integration of the boundary condition, using the series and parallel formula, the promoted results are calculated. An example demonstrates the effectiveness and the accuracy of the method. It is a method which can be utilized in the cases of general index, and also satisfies with the various needs of the reliability calculation.

关键词： Comprehensive Reliability Assessment Distribution system

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Hierarchical performance assessment method on the distribution network planning

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Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第15期32卷 36-40页

作者： Xiao, Jun Cui, Yanyan Wang, Jianmin Luo, Fengzhang Li, Yinong Wang, Saiyi Wang, Hong Key Laboratory of Power System Simulation and Control Tianjin University Tianjin 300072 China Shanghai Municipal Electric Power Corporation Shanghai 200080 China

Given the lack of a quantitative evaluation method, the paper presents a hierarchically structured method on the evaluation of distribution network planning according to the network characteristics. The evaluation method and implementation steps are proposed, including the performance indices and the planning evaluation. The current network and two planning alternatives of a district in Shanghai, China are evaluated using this method. The method includes a few new performance indices such as capabilities of against large area blackouts, matching degrees of high and medium voltage network power supply, margins of network expansion, etc, which reflect the adaptability and coordination of planning alternatives. The method can not only be used to compare a planned network against existing one, but also to evaluate various planning schemes. Case studies indicate that the method can take into account of the key elements quantitatively, and provide guidelines in the distribution network planning.

关键词： Zoning

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Prediction of Instability Separation Modes and Its Application in Practical Dynamic Security Region

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Transactions of Tianjin University 2007年第3期13卷 157-162页

作者：曾沅余贻鑫王红梅闵亮张沛 LEES T Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Electrical Power Research Institute

The transient critical boundary of dynamic security region (DSR) can be approximated by a few hyper planes correlated with instability separation modes. A method to fast predict instability separation modes is proposed for DSR calculation in power injection space. The method identifies coherent generation groups by the developed K-medoids algorithm, taking a similarity matrix derived from the reachability Grammian as the index. As an experimental result, reachability Grammian matrices under local injections are approximately invariant. It indicates that the generator coherency identifications are nearly consistent for different injections. Then instability separation modes can be predicted at the normal operating point, while average initial acceleration is considered as the measure of the critical generator group to amend the error. Moreover, based on these predicted instability separation modes, a critical point search strategy for DSR calculation is illustrated in the reduced injection space of the critical generators. The proposed method was evaluated using New England Test system, and the computation accuracy and speed in determining the practical DSR were improved.

关键词： instability separation mode dynamic security region K-medoids algorithm reachability Grammian

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Hierarchical yardstick competition approach to assessing operation performance of distribution utilities

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Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第4期32卷 20-24页

作者： Zhou, Ming Zhao, Wei Wang, Peng Li, Gengyin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China North China Bureau State Electricity Regulatory Commission Beijing 100070 China

Assessing distribution utilities' operation performance is an important precondition for effective supervision and competition promotion. A hierarchical yardstick competition approach to assessing the operation performance of distribution utilities is proposed. Firstly, a hierarchical analysis of indices reflecting the operation situation of distribution utilities is incorporated in the overall objective, the criteria layer and the index layer, by employing the analytic hierarchy process (AHP). Secondly, the judgment matrix and data envelopment analysis (DEA) are used to gain the weights and performance index of assessment criteria in the criteria layer and index layer, respectively. Finally, the overall relative performance index is derived by using the analytic hierarchy process. A numerical example is given to prove its feasibility and validity. This project is expected to provide scientific and practical reference to supervisors as well as managers of electric power companies for decision-making.

关键词： Analytic hierarchy process

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PSIM and SIMULINK Co-simulation for three-level adjustable speed drive systems

PSIM and SIMULINK Co-simulation for three-level adjustable s...

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IPEMC 2006: CES/IEEE 5th International power Electronics and Motion control Conference

作者： Yongchang, Zhang Zhengming, Zhao Baihua Liqiang, Yuan Haitao, Zhang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)1424404487

Applying co-simulation technology is a very important trend in power electronics simulation, which can make full use of the merits of different software to improve the efficiency of building up a system. In this paper, a simulation platform for three-level adjustable speed drive (ASD) based on co-simulation of PSIM and SIMULINK is presented, which includes the interface between PSIM and SIMULINK, main circuit in PSIM, space vector pulse width modulation (SVPWM), dead time and minimum pulse width, view of output voltage and its Fourier analysis in SIMULINK Based on this platform, the cause of large current when motor starts is studied. simulation and experimental results show that the minimum pulse width contributes a lot for the large starting current of the ASD. In conclusion, applying the simulation platform introduced in this paper, the dynamic behavior of the three-level ASD can be easily studied, which reduces the cost and improves efficiency at the same time compared to hardware investments, and may help to realize the optimal design of the ASD in practice. © 2006 IEEE.

关键词： Efficiency

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