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Time series online prediction algorithm based on least squares support vector machine

Journal of Central South University of Technology 2007年第3期14卷 442-446页

作者：吴琼刘文颖杨以涵 Key Laboratory of Power System Protection and Dynamic Security Monitory and Control of Ministry of Education North China Electric Power University

Deficiencies of applying the traditional least squares support vector machine （LS-SVM） to time series online prediction were specified. According to the kernel function matrix＇s property and using the recursive calculation of block matrix, a new time series online prediction algorithm based on improved LS-SVM was proposed. The historical training results were fully utilized and the computing speed of LS-SVM was enhanced. Then, the improved algorithm was applied to timc series online prediction. Based on the operational data provided by the Northwest power Grid of China, the method was used in the transient stability prediction of electric power system. The results show that, compared with the calculation time of the traditional LS-SVM（75 1 600 ms）, that of the proposed method in different time windows is 40-60 ms, proposed method is above 0.8. So the improved method is online prediction. and the prediction accuracy（normalized root mean squared error） of the better than the traditional LS-SVM and more suitable for time series online prediction.

关键词： time series prediction machine learning support vector machine statistical learning theory

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Numerical prediction of EMI on the secondary DC cable in cable tunnel due to a direct lightning strike in substation

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IEEE TRANSACTIONS ON MAGNETICS 2006年第4期42卷 863-866页

作者： Lei, Q Xiang, C Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education School of Electrical Engineering North China Electric Power University Hebei 071003 China

Electromagnetic interference (EMI) on secondary de cable in cable tunnel due to a direct lightning strike in substation threatens the safe operation of electronic equipment and system connected to the cable. In order to reduce EMI, the cable shield is generally connected to the grounding grid at both ends. Ground potential difference between two grounding points of the cable shield can be high due to high impedance of the grounding grid at high frequencies. In this paper, we present a hybrid method to analyze this complex system. As a result, both the current flowing in the cable shield and the transverse voltage between the cable core and shield are calculated. Compared with the measured results, the proposed method is demonstrated to be correct and effective.

关键词： electromagnetic interference (EMI) grounding grid in substation lightning secondary cable

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Analysis of dynamic characteristics and control techniques applied to permanent-magnet direct drive generator based on double time coordinate

Analysis of dynamic characteristics and control techniques a...

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2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011

作者： Tang, Niang Hao, Jun-Wei Zhou, Shuang-Ya Xiao, Xiang-Ning Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Beijing 102206 China

ISBN: (纸本)9781612847221

The dynamic operating characteristics of direct drive permanent magnet synchronous generator (PMSG) were researched. A method of non-linear slope pre-charge for DC-bus voltage is proposed on purpose of protecting power electronic devices. By further analyzing, some problems of conventional control strategy for grid-connection are pointed out, and a novel analysis method named double-time coordinate system is proposed, based on which the corresponding control strategy is presented to suppress the gear twisting moment and reduce the impact of grid connected. Simulation and experimental results prove that the proposed theoretical analysis method and control strategy is effective under the platform PSCAD/EMTDC. © 2011 IEEE.

关键词： Permanent magnets

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Research on DC bias due to magnetic storm and DC transmission

Research on DC bias due to magnetic storm and DC transmissio...

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

作者： Shi, Weiping Liu, Lianguang Wang, Qian Liu, Zongqi Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing 102206

ISBN: (纸本)0780391144

This paper focuses on the research on the DC bias due to magnetic storm and HVDC. In the paper, we introduce the DC bias problem of Jiangsu Yang-Huai transmit electric system and Southern power Grids, discuss the harmful effect of the transformer DC bias and the significance of research, and analyze the compensation, weakening and elimination of transformer bias current. Finally, the problems that should be paid attention to and some corresponding suggestions are proposed. © 2005 IEEE.

关键词： HVDC power transmission

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Parallel operation of hybrid active power filter with passive power filter or capacitors

Parallel operation of hybrid active power filter with passiv...

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

作者： Xu, Yonghai Xiao, Xiangning Liu, Hao Wang, Hong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing China

ISBN: (纸本)0780391144

Harmonic pollution and reactive power compensation are the important power quality problems. This paper proposes a combined power filter system consisting of the parallel operation of a hybrid active power filter (HAPF) and the passive power filters or capacitors. The HAPF is formed by a single tuned LC filter per phase and a small-rated three-phase active filter, which are directly connected in series. The characteristics of the combined system and the harmonic current detection method using the combination of load current and the mains current are analyzed and simulated. The simulation results show that good filter performance can be obtained by the combined system. Experimental results from a 100kVA/380V hardware prototype parallel operation with capacitors are presented to conform the validity and effectiveness of the combined system. © 2005 IEEE.

关键词： Active filters

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Multiobjective optimization scheduling based on fuzzy genetic algorithm in cascaded hydroelectric stations

Multiobjective optimization scheduling based on fuzzy geneti...

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2005 IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Hu, Guoqiang He, Renmu Ma, Rui Wang, Peng Yang, Huachun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing China

ISBN: (纸本)0780391144

The multi-objective fuzzy optimal method based on the fuzzified optimal solutions of single objectives need not list all non-inferior solution sets, which can optimize directly objectives in value area of variables. This method can reflect the interrelation between individual objective optimal solutions and multi-objective optimal solution. On the basis of fundamental principle of multi-objective fuzzy optimization and genetic algorithm, combing with the concept of objective relative subject degree, this paper presents a multi-objective optimization approach for the hydroelectric power system with contradictory objectives. The proposal method considers the satisfied degree of various characters and contradictory objectives and seeks an appropriate optimized solution to make each objective optimal as possible considering each objective comprehensively. The simulation results of example show that the fuzzy genetic algorithm is an effective method for multi-objective optimization problem in the cascaded hydroelectric plants. © 2005 IEEE.

关键词： Hydroelectric power plants

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Research of analysis method of power system real-time digital simulation error

Research of analysis method of power system real-time digita...

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International Conference on Critical Infrastructure

作者： Wang, Xiangxu Guo, Chunlin Xiao, Xiangning Zhao, Chengyong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University China

ISBN: (纸本)9781424480814

Simulation accuracy has great effects on power system analysis and control. In this paper, in order to analyze the power system real-time digital simulation error, prony algorithm is used to extract the features of signal. Based on the analysis results of this algorithm, residual similar index was used to characterize the global error of simulation, and then frequency, damping and amplitude similar indexes were employed to represent features error of transient signals respectively. A calculation program for power system real-time digital simulation accuracy evaluation was employed to analyze the measured waveforms and results of fault simulations on RTDS. Simulation results have proved the validity of the proposed analysis method of power system real time digital simulation error. © 2010 IEEE.

关键词： Errors

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The study of complex torque coefficient approach's realization based on PSCAD/EMTDC

The study of complex torque coefficient approach's realizati...

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International Conference on Critical Infrastructure

作者： Wang, Jin Guo, Chunlin Xiao, Xiangning Zheng, Rui Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University China

ISBN: (纸本)9781424480814

The method, complex torque coefficient approach, which is used to analyze the sub synchronous oscillation (SSO) problems with the help of PSCAD/EMTDC are recommended. While how to achieve the complex torque coefficient approach by time-domain simulation method effectively has not been specified. With the simulation study of different systems like HVDC system, AC system with series compensation device, etc, amplitude, injection time and additivity of injected oscillating torques are discussed. A set of conclusion to the method is drawn for reference. © 2010 IEEE.

关键词： HVDC power transmission

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Synthetic quantitative assessment of power quality in competition market environment

Synthetic quantitative assessment of power quality in compet...

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

作者： Xu, Yonghai Chen, Lei Xiao, Xiangning Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry ot Education Beijing China

ISBN: (纸本)0780391144

A new method, which integrates the virtue of the probability and mathematical statistics with that of the fuzzy mathematics for power quality assessment, is proposed in this paper. The index showing an aspect of power quality is evaluated using probability and mathematical statistics respectively;the global unique index of these indexes can be obtained. The results obtained from each index unified are unified again using fuzzy synthetic appraisal in order to give an objective, overall and unique index of power quality. The special assessment method for voltage sag using the Average Sag Energy Index is also discussed. Finally, a transaction mode makes the maximum benefits for different unit commitment as objective function and takes the power quality into account is presented, and then power energy really becomes a commodity which would be evaluated a price according to power quality. © 2005 IEEE.

关键词： Electric power systems

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Sliding mode variable structure direct power control of permanent-magnet direct drive generator

Sliding mode variable structure direct power control of perm...

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2nd Annual Conference on Electrical and control Engineering, ICECE 2011

作者： Tang, Niang Xiao, Xiang-Ning Guo, Jing Zhou, Shuang-Ya Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing China

ISBN: (纸本)9781424481637

The pulse width modulation technique and dynamic operating mode characteristics of direct drive permanent magnet synchronous generator (PMSG) are researched firstly. A novel sliding mode variable structure directed power control algorithm applied to PMSG is proposed, and then design the controller using tip speed radio and flux-weakening control scheme. It can not only provide a constant switching frequency without involving any synchronous speed coordinate transformation and generator side phase information, but also can reduce the capacitance of generator-side converter. Simulation and experimental results show that the proposed theoretical analysis method and control strategy is effective under the platform PSCAD/EMTDC. © 2011 IEEE.

关键词： Permanent magnets

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