检索结果-内蒙古大学图书馆

Cause analysis of turbine power disturbance inducing power system low frequency oscillation of resonance mechanism

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2007年第17期27卷 83-87页

作者： Xu, Yan-Hui He, Ren-Mu Han, Zhi-Yong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

Resonance mechanism is one of the theories that interpret power system low frequency oscillation. According to the resonance mechanism, power disturbance of prime mover can arouse power system forced low frequency oscillations. Therefore, the causes of turbine power disturbance were analyzed. The coupling model between thermodynamic system of plant and power system was set up by MATLAB. The possibility of combustion ratio of boiler and control valve of governing system disturbance inducing the variation of turbine power was researched in detail. The simulation results indicate that power system low frequency oscillations of resonance mechanism might be caused by the disturbance of control valve, when it's frequency is consistent with or close to power system natural oscillations frequency. Because of the biggish inertia of boiler, the disturbance of combustion ratio cannot invoke power system low frequency oscillation of resonance mechanism.

关键词： Electric power systems

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Flow transferring identification algorithm for multi-branches removal event with consideration of transient phenomena

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2007年第16期27卷 24-30页

作者： Xu, Hui-Ming Bi, Tian-Shu Huang, Shao-Feng Yang, Qi-Xun Key Lab. of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

Cascading trips caused by flow transferring are the crucial causation of a lot of well-known blackouts. It severely threatens the security and reliability of power systems. Flow transferring relativity factor (FTRF) is extended from single branch removal event to multi-branches removal event. According to refraction and reflection process of flow transferring, the calculation formula of FTRF for multi-branches chain removal event is deduced. Moreover, by using the relationship of node injection currents and branch currents, a method of post-fault branch current estimation and a flow transferring identification algorithm based on WAMS to distinguish flow transferring in transient period is presented. The simulation results of 10-generator 39-bus New England system show that the proposed estimation method and the identification algorithm work well.

关键词： Electric power systems

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Multi-swing stability assessment approach based on variation rate of transient energy for power systems

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2007年第16期27卷 13-18页

作者： Song, Fang-Fang Bi, Tian-Shu Yang, Qi-Xun Key Lab. of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

The lack of quantitative stability analysis software for power system is one of the main reasons for losing good chance to implement the emergency control and even finally resulting in the large outage. Recently, the rapidly developing wide area measurement system (WAMS) gives a new way for quick on-line quantitative transient stability assessment. Starting with the single machine energy function, the relationship between the variation rate of transient unbalance energy and multi-swing stability was analyzed in detail, and the corresponding characteristic of the variation rate of transient energy was proved. Then, a new multi-swing stability assessment criterion based on WAMS was proposed. Numerical simulations were conducted on 6-machine 22-bus system of China electric power research institute to demonstrate the effectiveness of this criterion.

关键词： Electric power systems

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HV power equipment running state detection based on image processing and recognition

HV power equipment running state detection based on image pr...

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2006 International Conference on power system Technology, powerCON2006

作者： Shutao, Zhao Baoshu, Li Xiaohui, Zhu North China Electric Power University Baoding 071003 China 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 North China Electric University

ISBN: (纸本)1424401119

Aimed at the necessary on the automatic detection level in unattended substation, a new method which monitoring and diagnosis the high-voltage (HV) power equipment running state based on image processing is put forward. Image processing techniques realize and strengthen the capability of the human vision. It is a non-contact measurement method, which can monitor the HV power equipment running state online. In recent years, it is widely applied in many fields and gets plentiful and substantial success. The HV power equipment running state detection process is introduced in this paper. After image preprocesses and feature extraction, the automatic target recognition algorithm based on the radial basis function neural network (RBFNN) is presented. © 2006 IEEE.

关键词： HVDC power transmission

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Three design schemes of compensation currents for D-STATCOM used for unbalanced load

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Dianli Xitong Zidonghua/Automation of Electric power systems 2007年第1期31卷 75-79页

作者： Zhu, Yongqiang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control School of Electric and Electronic Engineering North China Electric Power University Beijing 102206 China

Three design schemes of compensation currents for D-STATCOM in delta connection used for unbalanced load compensation are introduced. They are the schemes based on compensation principle of admittance, no zero sequence component design and an optional design method of maximum minimizing phase current. Comparisons are made considering technical indexes and engineering significance among the proposed three schemes. In serious unbalanced operating conditions, the obvious difference in amplitude among the compensation currents in three phases may lead to one or two phase overloading and the compensation capability is restricted. The optional design makes the compensation currents in three phases to be equal or close to each other as possible as it can, which is helpful to ensure the D-STATCOM having high-usage and desirable compensation effect. Similar performance can be obtained to some extent with the simpler scheme of no zero sequence component design.

关键词： Electric loads

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Study of image recognition used for unattended substation

Study of image recognition used for unattended substation

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2006 International Conference on power system Technology, powerCON2006

作者： Jun, Yang Xin, Ai Xiufang, Jia Yansong, Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Deshengmenwaizhuxinzhuang Beijing 102206 China Electric Power Company of Jinzhou Engineering Technology Department Liaohe Petroleum Exploration Bureau Linghai City Liaoning Province 121209 China

ISBN: (纸本)1424401119

It is a trend to construct unattended substation in power system *** paper systematically analyses the superiority and limitation of MATLAB and Visual C++ and illustrates how to compile m-files to cpp-files by MATLAB engines and integrate cpp-files code into existing C++ projects by Visual C++ to realize intelligent function on image recognition used for unattended substation. The intelligent function can effectively test illegal intrusion and fires through the detection and recognition of moving goals by three-image difference method and self-adapting threshold value segmentation algorithm and detect situations of disconnection link by use of image crop and image index processing and give warnings to alarm system. Because of lacking of brightness of image or nonlinear brightness and being influenced by kinds of noise,this paper determines to adopt contrast enhanced algorithm and high-frequency enhanced algorithm to repair grey-scale distribution and uses median filtering to remove noise of *** the end,this paper brings forward the expectation about the image recognition of the unattended substation. When non-uniform of image illumination distribution, grey-scale of background changes largely and image segmentation has not the fittest threshold, so the paper uses self-adapting threshold segmentation algorithm to gain the image segmentation. © 2006 IEEE.

关键词： Image recognition

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Simulation validation strategy based on wide area measurement

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Dianli Xitong Zidonghua/Automation of Electric power systems 2007年第18期31卷 11-15页

作者： Ma, Jin Sheng, Wenjin He, Renmu Yue, Chengyan Zhang, Jin Rhethanz, C. Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China ABB China Research Center Beijing 100016 China

Digital simulation is the guiding tool in power system operation and control. Thus, its veracity directly affects both the security and economical operation of a power system. Since the wide area measurement system (WAMS) can provide synchronous dynamic data independent of models and parameters, this paper presents a simulation validation strategy based on WAMS to decouple the system into small areas with fewer components at different voltage levels. Therefore, by taking the measured data of WAMS as dynamic equivalent signals in digital simulation, the simulation validation work can be carried out in a much specified area and the wrong component causing the error can be found. The realization method of the simulation validation strategy proposed is also presented via the PSS/E simulation tool. Detailed case studies show the effectiveness of the method.

关键词： Electric power systems

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Study on Transient Characteristics of Grid-connected Wind power Generators

Study on Transient Characteristics of Grid-connected Wind Po...

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2007 International power Engineering Conference (IPEC2007), vol.2

作者： Yan Zhang Li Lin Yihan Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China

With rapid development of wind power generation, it's necessary to study the dynamic characteristics of wind power generators when a fault occurs in the grid to assure the safe and stable operation of the wind farm. At present, the widely used wind power generators in the whole world are squirrel cage induction generator (SCIG) and doubly fed induction generator (DFIG). The models of SCIG wind power generation system and DFIG wind power generation system connected with the grid are built, and their transient operation characteristics are studied. A new control measure is put forward to improve the transient performance of the DFIG, which is proved effective through the simulation. Also the impact of the control measure on the SCIG running in parallel with the DFIG is also investigated.

关键词： Doubly fed induction generator Squirrel cage induction generator Transient operating characteristic Voltage control

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Load Modeling Considering Distributed Generation

Load Modeling Considering Distributed Generation

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power Tech Conference

作者： Wang Jili He Renmu Ma Jin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control of Ministry of Education North China Electric Power University Beijing China

Distributed generation is regarded as the developing direction of the power system in 21 century. Because distributed generation always connects with the distribution system, which has great influence on every aspects of power system. This paper studied the influence of distributed generation on load modeling. When the influence of distributed generation is not negligible, the composite induction motor load model can't effectively describe the actual load characteristic. This paper proposes a new load model-asynchronous generator +ZIP. The validity of the proposed load model is also testified via the comparison and contrast from a great deal of simulations. Then, composite induction-motor and asynchronous generator +ZIP load models were unified in one program.

关键词： Load modeling Distributed control power system modeling power system dynamics power system simulation Induction generators power systems Helium power system transients power system stability

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A new method for hybrid non-linear state estimation with PMU

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Dianli Xitong Zidonghua/Automation of Electric power systems 2007年第4期31卷 28-32页

作者： Qin, Xiaohui Bi, Tianshu Yang, Qixun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Sifang Research Institute North China Electric Power University Beijing 102206 China

A new method for hybrid non-linear state estimation with phasor measurement unit (PMU) is proposed, in which the direct voltage phasor measurement is transformed into indirect equivalent branch current measurement to conduct the hybrid iteration with SCADA measurement. The indirect measurement errors caused by constructing the equivalent current modification are also analyzed and calculated in detail. The accuracy of the hybrid estimation algorithm is analyzed qualitatively and calculated quantitatively. The theoretic analysis and simulation results demonstrate that the proposed method has higher estimation precision and better performance in convergence time and filtering effect.

关键词： State estimation

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