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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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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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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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Research and development of an intelligent system dealing with alarm messages coming from regional power grid control centers

Research and development of an intelligent system dealing wi...

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International Conference on power system Technology (powerCON)

作者： Zhang, Xing Zhang, Haibo Key Laboratory of Power System Protection and Dynamic Security Monitoring North China Electric Power University Beijing China

ISBN: (纸本)9781424459407

In order to overcome the disadvantage that there are hardly any analysis functions on alarm messages in current EMS, an Intelligent Expert system which processes all alarm messages from the regional Grid Dispatching Center is designed and developed in this paper. When there is only one SCADA data source, the system receives and identifies real-time alarm messages from dispatching center, finds out and deletes the false alarm messages and then estimates the current state of power grid. If there is no fault but some abnormal warning information is generated by electrical equipments, the system analyses the abnormal warning information and suggests corresponding measures that dispatcher should take. If some fault has occurred, the system classifies the alarm messages and provides the necessary information for fault diagnosis after further processing. After the system is completed, it will improve the quality of surveillance and provide richer and more intelligent auxiliary decision support. ©2010 IEEE.

关键词： Expert systems

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The research on distributed dynamic power flow based on asynchronous iteration mode considering frequency change

The research on distributed dynamic power flow based on asyn...

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International Conference on power system Technology (powerCON)

作者： Xin, Baojiang Zhang, Haibo Key Laboratory of Power System Protection and Dynamic Security Monitoring North China Electric Power University Beijing China

ISBN: (纸本)9781424459407

In modern power system, power systems are being interconnected into a unified system. The structure of the power grid is more and more complex, and the relation between different regional power grids is more closed. In order to achieve a joint power grid scheduling, incident handling and fault simulation, objectively, the control centers are required to use distributed algorithm. But the distributed Energy Management system (EMS) and Dispatcher Training Simulator (DTS) used now are not mature and the frequency changes are not considered in the distributed algorithms. This makes impossible to obtain an accurate simulation of the actual power system operation status in the distributed EMS/DTS. Because the dynamic flow algorithm can reflect the actual system more exactly, a new method called distributed dynamic power flow based on asynchronous iteration mode considering frequency change is proposed in this paper. The whole idea of the algorithm is given. The generator unit in dynamic power flow, considering frequency changes, can be modeled in coordinate layer and used to calculate frequency changes and the power sent to the network. The network modeled in coordinate layer and subsystems, is used to calculate power flow and unbalance power of the interconnected system. By a dozen times iterative solution between generator unit and network unit, the unbalanced power are distributed in generator and load nodes finally. In this article, we take the IEEE 9 node system as an example to authenticate this method. The simulation results are the same as the real ones hence showing that the new algorithm is real and effective. ©2010 IEEE.

关键词： Energy management systems

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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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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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