Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 5 Articles
This paper describes a new actively controlled multi-fan wind tunnel that generates\nnatural wind as a type of turbulence wind tunnel at a reduced cost.\nThe driving section of the wind tunnel has 100 PC cooling fans that are controlled\nby an original embedded system. The fluctuating velocity wind is successfully\ngenerated with a mean velocity of 7 m/s and two turbulent intensities\nof 2% and 3% based on Karmanâ??s power spectrum density function. The\ncase of 2% has the integral scales of 5 m, 10m and 20 m, and the case of 3%\nhas the integral scales of 3 m, 6 m and 15 m with a turbulence grid. In particular,\nthe wind with the turbulent intensity of 2% satisfies the Kolmogorovâ??s\n-5/3 multiplication rule of inertial subrange with the frequency range from\n0.01 Hz to 2.0 Hz. Consequently, the new wind tunnel can be used for studying\nengineering technology and research regarding conditions with natural\nwind....
In order to obtain the optimum power factor through maintaining the ratio of blade tip speed to wind speed, a new method for\ncontroller design of wind driven generator speed tracking is proposed basing on variable structure control theory. Integral variable\nof generator speed is introduced into the system equation. Switching surface of variable structure controller is founded with the error\nof generator speed. Adaptive estimation for wind disturbance and uncertain parameters of system dynamics model is adopted to\nderive control algorithm for rotation torque in the process of generator speed tracking. Simulation results show that speed tracking\nprecision of wind driven generator is improved by integral variable structure controller. The method proposed in this article is\neffective and feasible....
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Regarding PMSG-based wind turbine generation system, this paper proposes a supercapacitor energy storage unit (SCESU) which\nis connected in parallel with the DC-link of the back-to-back converter to enhance its high voltage ride through performance.The\nanalysis of the operation and control for the grid-side converter and SCESU are conducted. Based on real time digital simulators\n(RTDS), a model and a Hardware-in-the-Loop (HiL) platform of PMSG-based wind turbine with SCESU is developed, and the\nsimulation results show that the SCESU absorbs the imbalanced energy and the grid-side converter absorbs inductive reactive\npower during the period of voltage swell and verify the correctness and feasibility of the high voltage ride through control strategy....
Power curves are used to model power generation of wind turbines, which in turn is used\nfor wind energy assessment and forecasting total wind farm power output of operating wind farms.\nPower curves are based on ideal uniform inflow conditions, however, as wind turbines are installed in\nregions of heterogeneous and complex terrain, the effect of non-ideal operating conditions resulting\nin variability of the inflow must be considered. We propose an approach to include turbulence, yaw\nerror, air density, wind veer and shear in the prediction of turbine power by using high resolution\nwind measurements. In this study, two modified power curves using standard ten-minute wind\nspeed and high resolution one-second data along with a derived power surface were tested and\ncompared to the standard operating curve for a 2.5 MW horizontal axis wind turbine. Data from\nsupervisory control and data acquisition (SCADA) system along with wind speed measurements from\na nacelle-mounted sonic anemometer and wind speed measurements from a nearby meteorological\ntower are used in the models. The results show that all of the proposed models perform better than\nthe standard power curve while the power surface results in the most accurate power prediction....
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