In order to study self-starting characteristics for H-type wind turbine, firstly, the effect of low Reynolds number and large separated flow on aerodynamic characteristics of airfoil were analyzed in detail, then two H-type wind turbines with different aerodynamic configurations were tested in a low speed wind tunnel for collecting the static torques at different phase angles and time-rotating speed curves in starting process. Based on theoretical analysis and experimental data, the cause of self-stating problem of H-type wind turbine has been revealed. The aerodynamic profile parameters of the wind turbine are closely related to the dependency of starting on initial phase position, and the minimum static torque determines whether the wind turbine has potential to start from rest. The time-rotating speed curves exhibit two different starting behaviour features, determined by the minimum dynamic torque in driving force conversion stage. Unless both the minimum static torque and minimum dynamic torque in driving force conversion stage are greater than the friction torque, the self-starting of the wind turbine cannot be realized. The typical self-starting behavior characteristics is that the time-rotating speed curve includes four different stages of initial linear acceleration, plateau, rapid acceleration and stable equilibrium with the final tip speed ratio more than 1.

In spite of the attractiveness of CFD methods and advanced measurement methods, there is still no full analysis of aerodynamic blade loads for vertical axis Darrieus-type wind turbines. Due to an inherently unsteady flow around the rotor blades, blade-wake-blade interaction and the occurrence of dynamic stall, the aerodynamics of this type of wind turbine is very complex. A two-bladed rotor have been investigated numerically for the tip speed ratio of 5. 0. This paper compares results for aerodynamic blade loads obtained applying such turbulence models as: the standard k-ε ; the RNG k-ε ; the Realizable k-ε and the SST k-ω . As a result, quantitative instantaneous blade forces as well as instantaneous wake profiles behind the rotor have been obtained. Aerodynamic wake behind the rotor is also visualized by using streak lines. All CFD results are compared with experimental data taken from literature. Good agreement between the numerical results and the experiment is shown for the aerodynamic blade loads as well as for aerodynamic wake behind the rotor.

Determining the flow structure in the flanged diffuser shrouding designed to be used for a wind turbine, plays a vital role in improving efficiency in small-scale wind turbine technology. In this study, the flow structure in the curved type flanged diffuser was investigated in terms of water flow velocity increase, by using particle image velocimetry (PIV) measurements. The dimensionless magnitude of the resultant velocity determined at downstream and up radial regions as well as at the flange downstream of the curved type wind turbine shroud, revealed that resultant velocity was increased by a factor of 1. 5. This increase of the wind velocity will result the wind energy interacting with the rotor blades to be enhanced by 3. 38 times more. By the designed shrouding component to be used in micro wind turbines, it is also aimed to start the power generations in these types at a lower value of cut-in wind speed value.

This paper analyzes the behavior of a Permanent Magnet Synchronous Generator (PMSG) wind turbine using the maximum power extraction (MPE) method in response to wind speed fluctuations. The behavior of the wind turbine in the frequency domain will be analyzed to have the wind turbine response in the frequency domain. By combining the wind speed frequency content and wind turbine frequency response, the frequency content of wind turbine output power fluctuation will be gained. A PMSG wind turbine system is simulated with real wind speed data in the PSIM software environment, and the results are compared with theoretical results for validation of the model.