Analysis, Simulation, and Design of a 2kW Wind Turbine with Passive Pitch Control

　　Generally, wind turbines can be categorized into four types: the simplest one called no control, the one with local control containing electrical power control without functions of mechanical control, the one with passive control that has the power control and passive mechanical control, and the one with active control having the power control and active mechanical control. Most of the small wind turbines are designed with no control or local control due to cost effectiveness issues. Both of these two types, however, remain rooms for improvement in terms of performance. The purpose of the present study is to improve the performance of fixed-pitch TECO 2 kW wind turbine with additional passive pitch control mechanism along with parametric and sensitivity study. The cost of the proposed system can be reduced with standardization and mass production.
　　Software packages MATLAB/SimMechanics combining with FAST (Fatigue, Aerodynamics, Structures, and Turbulence), developed by NREL (National Renewable Energy Laboratory), are used for investigation in the present study. Based on the concept from the Spain made wind turbine, Windspot, that the over-speed control with passive pitch mechanism can be achieved by utilizing the centrifugal force, we propose and design a new passive control mechanism and investigate the feasibility of adding the mechanism onto the fixed-pitch TECO 2kW wind turbine. Under high wind conditions, the pitch control mechanism reduces the rotation speed of the wind turbine and limits the capture of wind energy for the purpose of adjusting output power, achieving higher utilization efficiency of wind power and providing protection for rotor blades.
　　Both the Windspot and the new-designed passive mechanism are modeled and parametrically studied. The optimal designs that give better performance are summarized and suggested as follows: (1) For the TECO 2kW wind turbine with Windspot passive control mechanism, the spring constant is 6200 N/m and weight stick length is 20 cm. (2) For the turbine with new design mechanism, the spring constant and stick length are 9000 N/m and 25 cm, respectively. It is shown that the cut-out wind speed can be extended with proper selection of the spring constant and stick length. As a results, the present study successfully demonstrate that the TECO 2 kW fixed-pitch wind turbine is improved by two types of passive pitch control mechanisms.