Showing papers on "Tip-speed ratio published in 1997"

On the Dynamic Behavior of a Wind Turbine-Generator System with a Darrieus-Savonius Hybrid Wind Turbine.

Abstract: In order to clarify the dynamic characteristics of a self-controlled Darrieus-Savonius hybrid wind turbine system, a system consisting of a hybrid wind turbine and an AC generator was tested under various wind conditions in the wind tunnel. We took up four types of wind blowing change for the test ; ramp, sinusoidal and square wind velocity changes and a similar wind velocity change to the field wind. A series of tests substantiated the effectiveness of our operating scheme wherein the tip speed ratio is maintained at a constant value. On the other hand, theoretical studies have been carried out on the characteristics of the system. A simulation model is presented in order to describe the system characteristics not only for the steady-state behavior but also for the dynamic behavior. In spite of its simplicity, the model can predict both characteristics of the system well. The appropriateness of the simulation model is confirmed by comparing with the experimental results. In addition, the field test data are discussed. As a result, it is confirmed that the system is operated and controlled satisfactorily in the field.

The design and testing of a wind turbine fo Malaysian wind condition

Abstract: This thesis describes a development of vertical axis wind turbine. A new vertical axis wind turbine of savonius type has been designed, constructed, and tested. This turbine has been designed and constructed to operate in low wind speed and it can capture wind at any direction or condition due to the shape and design of the rotor blade and the guide vanes. The wind turbine model has rotor radius of 300 mm and rotor height of 600 mm. After constructing the wind turbine for the experimental purpose, tests were carried out to measure and evaluate the performance of the rotor. During the testing, the parameters that were measured are wind speed, rotor speed, and rotor torque. Two experiments were conducted; the first experiment were carried out to measure the minimum starting wind speed of the rotor while the second experiment was carried out to evaluate the rotor performance based on its torque and power at different wind speed. For each experiment, the rotor parameters were measured when the rotor are constructed with and without the guide vanes. The experimental results were compared with both theoretical results of the model and with an ideal output of common savonius rotors. The experimental result shows that the turbine can operate at low wind speed (1m/s) at zero loads. At wind speed of 5.6 m/s ,the rotor were able to Produce maximum torque of 0.14 N.m, maximum Power of 1.6 Watt, and rotor speed of 100 RPM. Based on the rotor torque and power coefficients, the rotor is capable of producing higher torque than common savonius rotors but with lower tip speed ratio. The high torque of the rotor is because of the functionality of the guide vanes in minimizing the negative torque effects which is common problem for savonius rotors. However, the comparison between this rotor and other common savonius rotors might not be an accurate indication of the rotor capability because this model has six blades while common savonius rotors are of two or three blades.