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Li H.,Central South University | Yang C.-H.,Central South University | Deng W.-L.,Xiangtan University | Ma X.-L.,Guangdong MingYang Wind Power Industry Group Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

When doubly-fed induction generator (DIFG) cuts in power grid, it will inevitably have an impact on the power grid. Excessive rush current will shorten the life of the motor, increase power grid voltage fluctuation, and may even cause the failure of the cutting-in grid. In this paper, the matrix converter is regarded as the AC-excitation systems and equalized as a virtual rectifier and virtual inverter. This control system regards the grid voltage and phase as given value, the stator voltage as a feedback value, and simplifies the solution of complex decoupling control. It will make DIFG stator voltage changes with grid voltage simultaneously by the control of voltage and phase of the virtual inverter. Thereby it reduces the impact current of the cutting-in grid. The experimental results show that the impact current of the cutting-in is little, and verify the feasibility of the control. © 2010 Chin.Soc.for Elec.Eng. Source

Chen C.,Xiangtan University | Chen C.,South China University of Technology | Xie Y.,South China University of Technology | Ma X.,Guangdong MingYang Wind Power Industry Group Co.
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2012

Aim to solve the poor dynamic performance and the low disturbance resistance of PI power decoupling controller for DFIG power generator system based on matrix converter, this paper propose a nonlinear control algorithm for the AC-excitation DFIG system. First, we establish the mathematical model of the DFIG, based on the model, use the inverse system theory and deduce the inverse model, add the inverse model in series to the front of the original system model, develop the whole system to a pseudo linear system. Consider the system performance influenced by the parameters of the linearized model, we use the predictive control to improve the robustness. The simulation results show that the control strategy has fast response and good dynamic performance. The off-grid and cut-grid experimental data validate that under sub-synchronous or super-synchronous state, the stator voltage and frequency can maintain stability and achieve variable speed constant frequency operation. Source

Song X.,Beihing University | Chen J.,Beihing University | Du G.,Beihing University | Cao R.,Guangdong MingYang Wind Power Industry Group Co.
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2014

With the aim of accurately taking into account viscous effects and profound influence of vortex sheet downstream on the aerodynamic performance of wind turbine blades, a model combing blade aerodynamic model based on the classic lifting-line theory with full free vortex wake model was presented, The numerical solution was insured to be fast and stable by parallel processing, fast multipole method (FMM) and predictor-corrector-relaxation scheme. The validity of present method were performed through comparisons with the National Renewable Energy Laboratory (NREL) experimental data and CFD results from the references, under axis flow and yaw condition, respectively. Source

Yan F.,Tianjin University | Yan F.,Guangdong MingYang Wind Power Industry Group Co. | Li Y.,Tianjin University | Luo Z.,Tianjin University | And 2 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2016

In this paper, the failure behavior of three-sheet 6061 aluminum alloy resistance spot is studied to evaluate the mechanical properties of the welded joint, the tensile-shear tests were performed in six different joint types. Mechanical performance of the joint was described in terms of peak load and energy absorption. The results showed that different joints exhibit different peak load and energy absorption. The rotation of nugget plays an important role in controlling the peak load and energy absorption during the tensile-shear test. Large rotation of nugget will lead to the low peak load and energy absorption. The maximum peak load and energy absorption is obtained when the sheet/sheet interface is subjected to pure shear. © 2016, Editorial Board of Transactions of the China Welding Institution, Magazine Agency Welding. All right reserved. Source

Ma L.,Beihang University | Chen J.,Beihang University | Du G.,Beihang University | Cao R.,Guangdong MingYang Wind Power Industry Group Co.
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2010

This influence of trailing edge's thickness on aerodynamic performance for large wind turbine airfoils was studied. The trailing edge's thickness of NREL wind turbine airfoils S814 and S827 with test data was numerically treated with XFOIL. The trailing edge's thickness changes between 0.5% and 5.0% relative to chord with constant maximum thickness, camber and chord. The results indicate that when trailing edge's thickness increases within certain range, lift coefficient and drag coefficient also increase, but lift-drag ratio increases and then decreases. Lift coefficient and lift-drag ratio of airfoils reach to the best conditions when trailing edge's thickness is around 1.5% relative to chord. The conclusion can be used to design the wind turbine blades. Source

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