• Issue 3,2009 Table of Contents
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    • >名家主持:风力发电机
    • 主持人语


      Abstract (60) HTML (0) PDF 0.00 Byte (0) Comment (0) Favorites


    • Development and research progress of wind power generators


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      Abstract:Wind power generator is one of the core components converting wind energy to electric energy. With the rapid developed technology of wind power generation including wind power generators since the end of 70's last century, various topologies of wind power generator and wind power systems are developed. The technologies and features of different kinds of wind power generators worldwide are firstly overviewed. Then their control features and drive train types and their strengths and weaknesses are analyzed and compared. Finally the latest development trend and research progress of wind power generator technologies are presented, hoping to offer reference for the research and development of wind power generation in China.

    • A novel modulation scheme for matrix converters of doubly-fed induction genrerators based on stator flux


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      Abstract:The dq model of matrix converter based on doubly-fed wind generator is established, and a fluxoriented modulation scheme of the matrix converter is proposed in this paper. By this strategy, the duty cycle Of every switch is easy to be calculated for clear physical means, and the input power factor is flexible. An important conclusion about the zero component transmission manners in Matrix converters is drawn. The active and reactive power can be controlled respectively and harmonic can be suppressed by this method. The modulation scheme is used in a four poles doubly fed wind generator. The validity of the flux-oriented modulation scheme is verified.

    • Design of large stator interior permanent magnet generator for wind energy


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      Abstract:This paper proposes the basic structure and work principle of the new stator interior permanent magnet (SIPM) generator. According to the present situation of the manufacture and application in wind power generation in China, the design of a 1.5 MW SIPM generator for wind energy is carried out. The main parameters and principle of design are proposed thereafter. A design example of direct-driven SIPM generator is given. The results of the design and analysis show the feasibility and correctness of the design scheme of large SIPM generator for wind energy.

    • Design of low-voltage cage induction generator driven directly by wind power


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      Abstract:For the using of Wind Power Generating System in wireless communication base-station, the special requires to wind power generators are analyzed in this paper; and the generator designing targets are given with examples analyzed. Based on the difference between the asynchronous machines two working models (eleetromotor and generator), a design method of the low-voltage cage induction generator driven directly by wind power is presented. And the method is verified by the computer-aided electromagnetic design software MathCAD.

    • Design and analysis of a PM generator for wind power with novel concentrated windings


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      Abstract:A permanent magnet brushless machine for wind power with novel concentrated windings is introduced in this paper. The special combination of stator slots/rotor poles is employed in the machine, resuiting in high power density and low cogging torque. The distinct topology and operation principle are analyzed by using a 3-phase 24/22-pole prototyped machine as an example. Based on finite element method, the design aspects of the prototyped generator are presented. Finally, the experimental results from the prototyped machine, including electro-magnetic-force (EMF), electromagnetic torque, output power and efficiency validate the design. It shows that the open-circuit EMF waveforms are inherently sinusoidal with concentrated windings and without skewing of stator slots or rotor poles, and hence it exhibits significantly higher torque density and efficiency. The results lay a new choice for small wind oower generation system.

    • >科学研究
    • Study on energy storage devices to defer distribution network capacity upgrade


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      Abstract:This paper discusses the possibility of energy storage devices as load balancing application, which is delaying utility investments in distribution network upgrades. The benefit of the distribution network capacity deferral value is quantified, and power and energy capacities for electricity energy storage systems are estimated. A practical system is utilized to evaluate the proposed methodology, and the siting of energy storage devices and its impact on the network loss are discussed. Finally, some important aspects of the application are analyzed. The main intention is to contribute to the development of methodologies that help understanding the role of energy storage in a distribution system.

    • Simulation and analysis for pitch control of doubly-fed induction wind turbine with PSCAD/EMTDC software


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      Abstract:This paper presents a simplified model of wind turbine variable pitch control. The pitch angle is adjusted by the feedback signals of generating speed and the output power of the wind turbine. And it can control generators speed constant and wind turbine output power steady. The variable pitch control is modeled using the simulation software PSCAD/EMTDC. The entire wind power system (including doubly-fed induction generators, converter and so on) is simulated. Results show that the variable pitch control strategy is feasible and correct.

    • Application of improved grey relational algorithm in faults diagnosis of power transformers


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      Abstract:Grey relational analysis (GRA) has applied in power transformer faults diagnose. Traditional Dissolved Gas Analysis (DGA) diagnostic model based on the GRA algorithm of single fault standard model vector has limited precision. An improved GRA algorithm is presented in this paper. The dispersion of DGA data is considered ; every kind of fault standard model vector is extended to six vectors ; the DGA data distribution range for every kind of fault is given; and the diagnose information is thus increased; the grey correlation degree of diagnostic model and all kinds of fault standard models are obtained to realize the fault diagnosis by using grey relational analysis theory. Example analysis results prove that the diagnostic accuracy of the presented algorithm is much higher than that of the others.

    • Simulation and analysis for substations lightning intruded wave protection


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      Abstract:针对一220 KV变电站的雷电侵入波保护进行仿真分析.考虑变电站雷击过电压最严重的一线一变的运行方式,对近区和远区雷击(即考虑到雷直击于变电站入口处及变电站进线段2 km处),母线加设避雷器和不加设避雷器进行比较分析.结果表明近区雷击产生较高的过电压,母线装设避雷器能有效抑制过电压,满足绝缘要求.

    • PSO-dynamic modification algorithm based static load models identification


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    • >科学研究
    • Inrush current restraint scheme of power transformer differential protection


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      Abstract:The inrush current generated in transformer is introduced, the used inrush current restraint schemes for transformer differential protection devices are analyzed, and the implemented schemes based on secondary-harmonics, waveforms symmetry, interruptive angles are compared in this paper. The reasons of transformer differential protection's malfunction and the problems of inrush current restraint methods are presented. They can provide theoretical support for protection operators to anlyse power system faults and check the orotections operation.

    • Impact and countermeasure of three-phase unbalanced operation for low voltage distribution systems


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      Abstract:Most of Chinese low-voltage distribution systems use three-phase four-wire Y/Yno(Y/Y) connection mode.The transformer unbalanced operation state is often caused by single-phase loads.The three-phase voltage imbalance and its impact to power quality are analyzed in this paper.Distribution transformer losses and line losses caused by the imbalance are investigated in detail.Some managing and technical countermeasures for the imbalance are also proposed.

    • Analysis of coupled eddy current-thermal field for heavy current bus bar


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      Abstract:A 3 D indirect coupled Finite Element Analysis (FEA) model of the coupled eddy current-thermal field is established for heavy current bus bar in switch cabinet. The eddy current field is calculated firstly, the distribution characters of magnetic flux density and joule heat is obtained. Then the thermal field distribution is calculated with the decentralized joule heat as heat sources. Experiments results verify that the FEA model is correct. The influence law of the operating current on thermal field is also studied. It will be a good reference for design switch cabinets with heavy current.

    • FEM based stress intensity factor analysis for rotor steel 30Cr1Mo1V


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      Abstract:Three-dimensional fracture parameters are calculated and analyzed using the degenerated singular element of 20-node solid186 by the ANSYS software in this paper. Results show that the displacement method and the J integral method are feasible to obtain stress intensity factor. 3 -D crack of a compact tension (CT) specimen with concrete size is also analyzed. The law for the stress intensity factor K1 variation at the crack tip of rotor steel 30Cr1Mo1V with the crack length and the load level changing is obtained. It provides a reasonable and effective method for studying on the crack propagation law.

    • Anion exchange resin pollution by tuebine oil and it''s recovery in condensate water treatment system


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      Abstract:The anion exchange resin in condensate polishing equipment is polluted by the turbine oil leaked into the condensate water treatment system. Experimental results for the pollution and its recovery are presented in this paper. The work exchange capacity variety of the polluted and recovered anion exchange resin is investigated at different temperature (20,30,40 ℃ ) and different oil concentration ( 30, 50,100,300,500,1 000,2 000,5 000 , 10 000 mg/L) respectively. The pollution and recovery degree is evaluated at different immersed time (6,12,24 h) and different solution pH value (7, 8, 9)respectively. The comparison tests for different recovery solution the anion exchange resin pollution will increase and the are also carried out. Experiment results show that recovery degree will decrease with the turbine oil concentration increasing, the immersed time extending and the solution pH value decreasing. The recovery solution with 10% NaCl+2% NaOH+3% Na3PO4+ 0.2% OP-10 has good regeneration efficiency.

    • >技术应用
    • Analysis and treatment for crack defects in bending waterwall tube of cold ash hopper


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      Abstract:The main reasons of generation units unplanned outage are the blasting accidents of four boiler tubes (including waterwall tube, economizer tube, superheater tube, reheater tube). The eliminations and preventions of boiler tube defects are very important work for power system security. This paper describes the discovering, detecting, analyzing and treating process for bending watel-wall tubes crack defects of cold ash hopper in the Kaifeng power plant 2×600 MW units. It provides reference experiences for boiler manufacturing, supervising and checking in thermal power plant eonstruction projects.

    • Analyse and treatment of oxidation air tubes blocking and breaking for wet FGD system


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      Abstract:The blocking and breaking of oxidation air tube is a common problem in the boiler wet FGD ( flue gas desulfurization) system of fossil-fired power plants. The FGD operation of a 300 MW fossil-fired power plant is analyzed in this paper. The oxidation air tube blocking and breaking result in decreasing of the CaSO3 oxidation efficiency and increasing the dissolving sulfite concentration in the slurry pool, enhancing the scaling on inner surface of the absorption tower, and reducing the CaCO3 utilization ratio, CaSO4 purity and FGD efficiency. The blocking and breaking reasons are analyzed and the resolving methods are also proposed. They will be a useful reference to improve economy and security of FGD.

    • Expert system application in wet limestone-gypsum flue gas desufurization


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      Abstract:Expert system is applied to the Wet Limestone-Gypsum Flue Gas Desulfurization (WFGD) of coal-fired power plant in the paper. And it consists of consulting subsystem and control subsystem. The consuhative help and faults diagnosis are implemented in the WFGD process, which are based on knowledge base and reasoning machine inference. Paraments monitoring and faults warning are also developed on the basis of desulfurization process simulation. The WFGD system is optimized with desulfurization optimization model. The improved expert system function, including management, permission and print, etc. are realized.

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