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Zou J.-L.,Xian Jiaotong University | Ma X.-K.,Xian Jiaotong University | Yang Y.,Shanxi Electrical Power Corporation
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

Because of switching nonlinearity, the slow-scale bifurcation with the line period time-scale may occur in the power-factor-correction (PFC) Boost converter. Firstly, all factors that influence the slow-scale bifurcation were analyzed and the influencing results were also revealed. Secondly, the load current feedforward method was introduced to control the slow-scale bifurcation through keeping the PFC converter from saturating. Finally, the theoretical analysis and simulating results were verified by experiment. The research results are beneficial to understand the slow-scale bifurcation in PFC converters more clearly and is helpful to the design of PFC converters. © 2010 Chinese Society for Electrical Engineering. Source

Wang K.Y.,Xian Jiaotong University | Luo X.J.,Xian Jiaotong University | Wu L.,Shanxi Electrical Power Corporation | Liu X.C.,Xian Jiaotong University
Renewable Energy | Year: 2013

The increasing integration of wind power into the existing power system demands for effective strategies to deal with wind intermittency and uncertainty. Relying solely on thermal power to cover wind uncertainty will sacrifice the operating efficiency and economy of thermal generators. In view of this, the adjustable hydropower is preferred for complementing wind fluctuation and uncertainty and the coordinated dispatch problem of wind-hydro-thermal power is established. Based on a newly designed water supplementing wind strategy, the original complex problem is decomposed into wind-hydro subproblem and thermal subproblem. A novel stochastic constraint related to wind power uncertainty is proposed and handled according to stochastic programming theory. By introducing the concept of expected breed rate and elitist preservation strategy, the particle swarm optimization (PSO) algorithm is improved and combined with the exterior penalty function method for solving the complete optimization problem. Optimal generation scheduling schemes that can make full use of wind energy and ensure efficient and economic operating of thermal generators are obtained by the proposed approach. Meanwhile the coordinating operation of wind, hydro and thermal power under different water resources and wind penetrations respectively are revealed and discussed. •Wind-hydro-thermal coordination scheduling problem is established.•Water supplementing wind strategy is designed for handling wind uncertainty.•The PSO is improved based on expected breed rate and elitist preservation concepts.•The obtained generation scheduling can avoid efficiency losses of thermal units.•Water supplementing wind stratagy ensures full use of wind energy. © 2013 Elsevier Ltd. Source

Bian X.,Tsinghua University | Meng X.,Tsinghua University | Wang L.,Tsinghua University | MacAlpine J.M.K.,Tsinghua University | And 2 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2011

The variation of negative dc corona inception voltages with air pressure and humidity, using a point/plane electrode system, was studied using a perspex chamber in which the pressure and humidity could be varied. A method of calculation was developed to determine the corona inception voltages over a range of air pressures and humidities. The effective ionization coefficient was calculated as a linear interpolation of the effective ionization coefficients for dry air and water vapor. The validity of these calculations was confirmed by a series of experimental determinations of the corona inception voltages for the same range of pressures and humidities. A comparison of the negative and positive corona inception mechanisms was also made. Both the negative and positive corona inception voltages decreased with a decrease in the air pressure and an increase in the humidity. The greater values of the effective ionization intensity found in the critical zone for the negative corona accounted for their lower inception voltages. The mechanisms of the affect of the photo-absorption coefficient and Townsend's second coefficient on the negative and positive corona were also considered. © 2011 IEEE. Source

Shanxi Electric Power Research Institute and SHANXI Electrical POWER COMPANY | Date: 2011-08-29

Disclosed is a method for determining the spatial location of a conducting wire and an aerial earth wire of a power transmission line, so as to solve the problem that the method in the prior art is not applicable to determining the spatial location of the conducting wire and the aerial earth wire of the conventional power transmission line with respect to lightning shielding failures. In the present invention, according to the physical locations of the conducting wires and aerial earth wires, the power transmission line shielding efficiency is calculated based on that the corresponding lightning shielding failure trip rate is zero when the exposure arc is zero, thus providing designing and operating units with a reliable analytical method for preventing lightning shielding failures, and meanwhile working out the shielding efficiency of the conducting wire of each phase more accurately, so as to analyze the structural relations between the aerial earth wires and conducting wires to determine the lightning protection effect of the whole power transmission line. The present invention provides a supplementary analytical method of the shielding efficiency of the existing power transmission lines.

Shanxi Electric Power Research Institute and SHANXI Electrical POWER COMPANY | Date: 2011-08-29

An evaporative condenser radiating module for steam exhaust of a steam turbine comprises tube bundles and steam-water separating chambers. A steam-water separating chamber (

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