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Research on the performance of wavelet packet transform based non-unit transient current protection

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2005年第SUPPL.期25卷 151-156页

作者： Wang, Zeng-Ping Liu, Hao-Fang Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Baoding 071003 China

The reflection and refraction of fault-generated wave on EHV lines were investigated and the equations of transient current detected by relay were deduced. Theoretical analysis shows that the protection based on the energy ratio of higher frequency components is more adaptive to various faults and can distinguish between the internal and external faults near the remote busbar more effectively. Such protection also has similar performance when used on EHV lines and series compensated EHV lines. The wavelet packet transform technique was employed to determine the energy ratio. Simulation results show that the proposed conclusions are correct.

关键词： Electric lines

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power system cascading outages assessment based on support vector machine

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2005年第SUPPL.期25卷 178-183页

作者： Deng, Hui-Qiong Ai, Xin Liu, Hao Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

A method of power system cascading outages assessment based on support vector machine (SVM) was provided in this paper. Taking full advantages of the ability of SVM to solve the problem with small sample, nonlinear and high dimension, this method constructs an assessment mode which uses resampling classification technique based on boosting method, pretreatment technique based on distance criterion and information fusion technique. This mode can help to improve the precision and stability of assessment, hence better generalization ability of assessment is guaranteed. At the end of this paper, an example is provided to demonstrate the validity of the proposed approach.

关键词： Electric power system protection

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Applied clusters and entropy in discreting attributes of load forecasting

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2005年第SUPPL.期25卷 65-70页

作者： Li, Jing-Hua Li, Ran Li, He-Ming Gu, Xue-Ping Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Baoding 071003 China

Attributes are require to be discrete when using data mining methods to establish forecasting model, for example, rough set, ANN and decision tree. But most discrete methods used before can't consider the relationship of conditional and decision attributes well, so the discrete results are not very satisfaction. This paper presents a new discrete method which combines clusters and entropy. First, cluster is adopted to get the waiting breakpoints. Then finally results are decided by their rate of entropy. According to clustering, the boundary value is greatly reduced. Meanwhile, through entropy which considers the condition attributes and decision attributes, attributes can be discreted more exactly. At last, the discrete results compared with the method based on the importance of breakpoints show that the proposed method assurance the quality of classing. The space of sample can be compressed effectively, which lightens the training load of model and the gotten rules are with good adaptability and useful value. The correctness and effectiveness are validated by the practical application and the accuracy of forecasting will be increased.

关键词： Electric load forecasting

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Data envelopment analysis based strategy of assessing schemes for power system black start

Data envelopment analysis based strategy of assessing scheme...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Yan, Liu Gu, Xueping Zhang, Dan IEEE 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 Dispatching Center of Yunnan Power Company Kunming 650011 China

ISBN: (纸本)0780391144

Restoration of a power system after a complete blackout is a very important issue to the safety of the power system. Reasonable black start schemes arc necessary to restore the power system as soon as possible. Based on data envelopment analysis, a new strategy for assessing black start schemes is proposed in this paper. Schemes' technical verification is taken into consideration in the process of the assessment Whether a scheme is effective is defined by employing its input and output indexes' values entirely. The application to a practical power system verifies that the method could provide dispatchers more comprehensive and objective decision references. © 2005 IEEE.

关键词： Standby power systems

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Load forecasting based on intelligence information processing

Load forecasting based on intelligence information processin...

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7th International power Engineering Conference, IPEC2005

作者： Zheng, Hua Xie, Li Zhang, Li-Zi Electricity Market Research Institute North China Electric Power University Beijing 102206 China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing 102206 China

ISBN: (纸本)9810544693

In electricity market, it is widely accepted that short-term load forecast is a key problem of market operation. In this paper, a novel model for load forecasting based on Intelligence Information Processing is presented. Here, we make full use of the excellent property reconstruction ability of independent component analysis, which is a new intelligence information processing technology for separating signals and making them independent mutually, and presents STLF model based independent property reconstruction. The load properties of different kinds are restructured to enhance its representation ability and simplifying STLF modeling by ANN. After neural network is trained by new properties with lower dimension, STLF model is built. Finally, the real load data of spot market in New England is applied to demonstrate the validity of the proposed approach.

关键词： Electric load forecasting

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Sensitivity analysis of parabolic lossy nonuniform transmission lines

Sensitivity analysis of parabolic lossy nonuniform transmiss...

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MAPE2005: IEEE 2005 International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications

作者： Liang, Gui-Shu Xu, Zhi-Hong Dong, Hua-Ying Ji, Changhu 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 Baoding Electrical Vocational and Technical College Baoding 071051 China

ISBN: (纸本)0780391284

The parabolic nonuniform line can be equivalent to the representation of a uniform line and a cascade connection of lumped element sections via Kuroda's Identities. Based on this equivalent circuit, a method in s-domain is present to obtain the sensitivity of output with respect to nonuniform line parameters, which calculates the sensitivities to uniform line and to lumped elements respectively. Final sensitivities in time domain are got by applying extended numerical inversion of Laplace transform(NILT). Examples and comparisons with sensitivity calculated by perturbation are presented. © 2005 IEEE.

关键词： Electric lines

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Sensitivity analysis of parabolic lossless nonuniform transmission lines based on port voltages and currents

Sensitivity analysis of parabolic lossless nonuniform transm...

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MAPE2005: IEEE 2005 International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications

作者： Liang, Gui-Shu Qi, Fang Dong, Hua-Ying Ji, Chang-Hu 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 Baoding Electrical Vocational and Technical College Baoding 071051 China

ISBN: (纸本)0780391284

This paper presents a new method of frequency-domain sensitivity analysis for parabolic lossless nonuniform transmission line. The frequency-domain sensitivity formulas are expressed by the line port voltages and currents. Therefore this method can avoid the possible numerical instability caused by negative capacitance in Kuroda's identity in [5]. Examples and comparisons with sensitivity determined by perturbation are presented. © 2005 IEEE.

关键词： Transmission line theory

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Electricity price forecasting based on GARCH model in deregulated market

Electricity price forecasting based on GARCH model in deregu...

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7th International power Engineering Conference, IPEC2005

ISBN: (纸本)9810544693

Since electricity market came into being, it has been generalized in many countries. In the research field of electricity market, electricity price has been one of the focused problems, which has great influence on the market. And then electricity price forecasting as a basic information tool to analyze the near future market, becomes more important than before. However, in such a competitive environment, the changes of electricity price are so volatile, even price spikes happened. So electricity price forecasting becomes more difficult. To solve above problem, we build a novel model to forecast electricity price based on GARCH (that is generalized autoregressive conditional heteroskedasticity), which fits for volatility modeling. First, electricity price is regarded as finance time series and analyze its volatility, which explains the presence of heteroskedasticity. Then price forecasting is proposed with GARCH model, which aims at modeling the dynamic character of price. Case studies testify the validity of the proposed model.

关键词： Electric rates

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Integrating radial basis function neural network with fuzzy control for load forecasting in power system

Integrating radial basis function neural network with fuzzy ...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Sheng, Siqing Wang, Cong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Provinece China School of Electrical Engineering North China Electrical Power University Baoding Hebei 071003 China

ISBN: (纸本)0780391144

Short-term load forecasting of power system is not only the basis of scheduling of generating sets, but also the basis of working out the transaction schedule in electricity market. This paper proposes a short-term load forecasting method based on combination of Radial Basis Function (RBF) neural network and fuzzy control, uses on-line self-modify factor fuzzy control to eliminate forecast error on the basis of RBF neural network forecasting. The practical examples show that the accuracy of short-term load forecasting and training speed can be improved and gains the very satisfactory results by the proposed method. © 2005 IEEE.

关键词： Electric load forecasting

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A new ultra high-speed protection scheme based on wavelet analysis

A new ultra high-speed protection scheme based on wavelet an...

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7th International power Engineering Conference, IPEC2005

作者： Yang, Ming-Yu Yao, Wan-Ye Wang, Zeng-Ping Zhang, Ju Jiao, Yan-Jun 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 Automation Department North China Electric Power University Baoding 071003 Hebei Province China

ISBN: (纸本)9810544693

A new ultra high-speed protection scheme is proposed in this paper. Using wavelet transform with multiresolution analysis, the current signals is decomposed into a series of detailed wavelet components. The spectral energies of the wavelet components are calculated and then employed to detect the faults. Characteristics of the proposed ultra high-speed protection algorithm are analyzed and results of simulation studies are given. The results show that the proposed algorithm is promising and easy to implement for computer relaying application.

关键词： Electric power system protection

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