检索结果-内蒙古大学图书馆

Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： B. X. Du Hongbo Li Yu Gao Li Wang Zhenxing Huo Key Laboratory of Power System Simulation and Control of Ministry of Education Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China Hebei Handan Power Supply Company Hebei China

In this paper, the deterioration investigation was carried on an ex-serviced 110 kV cross-linked polyethylene (XLPE) cable. XLPE sheets sliced from the cable insulation were taken as the test samples and the residual charge method was used as the diagnostic method. Two aluminum foils attached on the both sides of sample surface made the electrode constitution, between which the voltage was applied and the current was simultaneously measured. The residual charge was calculated to estimate the degree of the degradation. Additionally, Tan¿ test was carried out to assist the evaluation of cable degradation. Obtained results show that the degradation degree within the insulation varies with the changes of the position. The XLPE sheets near the outer semicon and the conductor aged more severely than that of the middle part. Meanwhile, the cable was anatomized and it was found that the water blocking layer had mildewed and the color of the outer part insulation turned into black.

关键词： Degradation Cable insulation Polyethylene Insulation testing Aluminum Electrodes Constitution Voltage Current measurement Conductors

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Power load modeling based on wide-area measurements and support vector machine

Power load modeling based on wide-area measurements and supp...

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2009 Asia-Pacific Power and Energy Engineering Conference, APPEEC 2009

作者： Wang, Zhenshu Li, Linchuan Niu, Li Key Laboratory of Power System Simulation and Control Ministry of Education Tianjin University Tianjin China School of Electrical Engineering Shandong University Jinan China State Nuclear Electric Power Design and Research Institute Beijing China

ISBN: (纸本)9781424424870

At present, the load modeling is still one of the difficult problems in power system. In this paper, a new method is presented which uses wide-area measurements and support vector machine (SVM) for load modeling. Based on wide-area measurements, this method does non-linear regression analysis on model with SVM. By using radial basis function (RBF), model structure is optimized, and Bayesian Framework is used for identifying parameters, then a kind of non-mechanical model is founded. This method can easily solve the problems in choosing structure and identifying parameters. The founded model has good generalization ability, flexible structure, and rapid calculation speed. In the end, this method has been programmed;the simulation verifies the validity of this model. © 2009 IEEE.

关键词： Support vector machines

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A Fuzzy Neural Network Based Fault Detection Scheme for Synchronous Generator with Internal Fault

A Fuzzy Neural Network Based Fault Detection Scheme for Sync...

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International Conference on Fuzzy systems and Knowledge Discovery (FSKD)

作者： Hongwei Fang Changliang Xia Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

A fuzzy neural network (FNN) based inter-turn short circuit fault detection scheme for generator is proposed. The second harmonic magnitude of field current and the negative sequence components of voltages and currents are used as inputs for the FNN fault detector. The negative sequence voltage and current are obtained from the phase voltages and currents using the symmetrical component analysis method. And the second harmonic magnitude of field current is achieved by the FFT technique. The FNN fault detector with Gauss membership functions is trained off-line using the training data which comes from the Multi-Loop simulation program. The proposed fault detection scheme can perform the inter-turn short circuit fault detection, the fault type classification, and the fault location identification. Experimental results corroborate the effectiveness of the proposed scheme, which is implemented on a TI's DSP.

关键词： Fuzzy neural networks Fault detection Synchronous generators Electrical fault detection Voltage Circuit faults Gaussian processes Training data Circuit simulation Fault location

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Modeling and analysis of PEMFC in distributed generation system

Modeling and analysis of PEMFC in distributed generation sys...

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International Conference on Sustainable Power Generation and Supply, SUPERGEN

作者： Bibin Huang Peng Li Dan Wang Fei Ding Chengshan Wang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

With the rising of distributed generation technology, fuel cell, as an important distributed generation source, has become increasingly attractive by virtue of their inherently clean, efficient and quiet service. The dynamic characteristics of distributed generation system lie largely on the property of DG sources in it. Firstly, the dynamic characteristics of the fuel cell in small, medium and large timescale are summarized in this paper. The impact of factors, such as temperature and pressure, are also discussed. Then, the paper describes the models of proton exchange membrane fuel cell (PEMFC) in small, medium and large timescale. Also an improved dynamic model of PEMFC in small timescale is proposed and validated by simulated results.

关键词： Distributed control Fuel cells Power system modeling Temperature Mathematical model Equivalent circuits Power system dynamics Delay Thermodynamics Voltage

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simulation of Three-Phase Four-Wire Shunt Active Power Filter

Simulation of Three-Phase Four-Wire Shunt Active Power Filte...

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IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC)

作者： Jidong Wang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

With the proliferation of nonlinear loads as power electronics equipment, the disadvantage of harmonic is more and more, which influence quality of power grid. Active power filter (APF) is a new harmonic restraint method comparing with passive filter, which is a power electronics device. This paper inspects harmonic current based on three-phase circuit instantaneous reactive power theory and simulates a three-phase four-wire shunt active power filter. The simulation results validate parameter is reasonable. The outcome indicates that active power filter can suppress harmonic and neutral wire current and balance three-phase current effectively.

关键词： Active filters Power harmonic filters Power system harmonics Reactive power Circuit simulation Power filters Power electronics Impedance Power system simulation Power grids

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Object-oriented analysis and design of transient stability simulation for distributed power generation system

Object-oriented analysis and design of transient stability s...

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International Conference on Sustainable Power Generation and Supply, SUPERGEN

作者： Dan Wang Ke Peng Yan Li Menghua Fan Chengshan Wang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

ISBN: (纸本)9781424449347

The designs of model abstraction and application abstraction of transient stability simulation for distributed power generation system are presented. The main classes are presented, which are called model classes, function classes and system integration classes. An AC/DC double layer bus-tree structure belongs to model classes for grouping elements of distributed generation system is presented, The DC bus tree structure includes subclasses of distributed sources and storages. The design scheme descries the double layer structure. In order to study the whole dynamic process of whole system, the digital simulation method capable of dealing with the stiff problem is integrated in function classes. With the efficiency and simpleness of calling mechanism for the functional functions of elements during computation, system integration classes are capable of considering the influence of typical microgrid operation modes which are grid-connected mode, island mode and grid-reconnected mode, etc, and capable of control the switchover from one mode to another mode.

关键词： Transient analysis Stability analysis Object oriented modeling Analytical models Distributed power generation Power system modeling Distributed control Tree data structures Digital simulation Grid computing

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A novel control algorithm for inverter-based distributed generation in unbalanced three-phase power systems

A novel control algorithm for inverter-based distributed gen...

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International Conference on Sustainable Power Generation and Supply, SUPERGEN

作者： Shengwei Li Yongli Li Jingliao Sun Qiang Jin Xuguang Li Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

ISBN: (纸本)9781424449347

In distribution power system, the unbalanced operating state, harmonics, negative sequence components, which are caused by the nonlinear or unbalanced loads, not only increase the power transmission losses, but also are harmful to the electric devices. In this situation, the Active Power Filter (APF) and the Static Var Generator (SVG) would be required. However as proved in this paper, the existing compensation methods are usually affected by the unbalanced and harmonic voltages. So a compensation algorithm based on the amended Park Transformation which is suitable for the unbalanced power systems is proposed. In addition, referring to the inverter-based distributed generation (IBDG) developed rapidly in recent years, the presented compensation algorithm is integrated with the active power control scheme to build a hybrid control algorithm used in IBDG existing distribution system. Based on the stated control algorithm, IBDG not only can supply the electric power, but also compensate for the reactive power, harmonics and negative sequence currents of the distribution power system. The feasibility and accuracy of the algorithm are verified by the DIgSILENT Powerfactory simulation.

关键词： control systems Distributed control Power system control Power systems Power system harmonics Power harmonic filters Hybrid power systems Active filters Power system simulation Power transmission

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Shaft crack analysis and diagnosis for the 600mw steam turbine generator

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key Engineering Materials 2009年 413-414卷 591-598页

作者： Dongxiang, Jiang Liangyou, Hong Qian, Huang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

Abstract: In order to find the cause of the shaft crack appeared in a 600MW steam turbine generator, several measurements are taken. The shaft assembly consists of three parts: shrink-fitted coupling, shaft and key which are used to transfer torque between coupling and shaft. First, the natural frequency of the shaft system is calculated. The result shows that the vibration signal contains the frequency nears the second natural frequency of the steam turbine shaft system. Second, stress field near the damaged coupling and shaft is analyzed using finite element method. The torque under different operation condition is calculated before stress analysis and applied to the shaft assembly, then. And, local stress concentrations position calculated is proved to be coincident with the place crack initiation. Finally, the cause of the fault is analyzed: at least three causes have found to be having something to do with the crack fault.

关键词： Finite element method

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Analysis of synchronous generator electro-magnetic torque and vibration with armature winding fault

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Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology 2009年第4期42卷 322-326页

作者： Fang, Hong-Wei Xia, Chang-Liang Li, Guo-Ping Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China Beijing Chatone Computer Room Equipment Company Beijing 100101 China

The air-gap magnetic field characteristic of the synchronous generator, caused by stator winding inter-turn short circuit fault, was analyzed in this paper with a consideration of the air-gap eccentricity. Then the characteristics of electro-magnetic torque and vibration of generator were obtained, especially the magnitudes and frequency variation of the instantaneous pulse torque. And the characteristic of the 17th and 19th order component of terminal current under this condition was also analyzed by the coupled field-circuit method. Lastly, in the dynamic simulation experiment, the vibration acceleration data in the vertical direction of a 7.5 kVA generator with stator winding inter-turn short circuit fault were acquired, and then these data were analyzed by discrete fast Fourier technique. The results show that the change of the double frequency vibration acceleration is bigger when stator winding inter-turn short circuit faults occur and the 17th and 19th order component of terminal current can be used to detect the dynamic eccentricity of machines with or without internal faults.

关键词： Stators

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Corrigendum to “Using fuzzy theory and information entropy for water quality assessment in three Gorges region, China” [Expert systems with Applications 37 (3) (2010) 2517–2521]

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Expert systems with Applications 2010年第6期37卷 4720-4720页

作者： Li Liu Jianzhong Zhou Xueli An Yongchuan Zhang Li Yang Dispatch & Communication Center Hunan Electric Power Company Hunan Province Changsha 410007 China College of Hydroelectric and Digitalization Engineering Huazhong University of Science and Technology Hubei Province 430074 Wuhan China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

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